DEVICE FOR PROVIDING MEDICAL CARE BASED ON A RECOGNIZED GASTRIC FUNCTION

Description

BACKGROUND

[0001] Many patients receive care in an intensive care unit or similar setting following surgery, injury, trauma, or acute medical illness. These and other patients may suffer from dysfunction or failure of one or more organ systems. Although some patients succumb from their illness and die, most eventually recover, albeit after application of intensive care techniques and prolonged hospitalization.

[0002] During application of intensive care techniques and / or hospitalization, decisions are made as to whether and when patients are ready for normalization (or accelerated normalization) of their care. Normalizing care can involve several types of clinical problems and intensive care techniques, some of which are discussed below. Document EP 1892010 A1 relates to a medical tube.I. Initiation of Enteral Feeding

[0003] Enteral feeding, i.e., instilling food into the stomach or intestines via a feeding tube or the mouth, is beneficial to some patients but deleterious to those patients whose gastrointestinal perfusion and function is suboptimal. Failures in enteral feeding can be classified as either "underfeeding" or "overfeeding". Underfeeding results when a critically ill patient is either not started on enteral feeds or else is administered suboptimal calories. Underfeeding can result in malnutrition and its associated complications (e.g., infections, low colloid oncotic pressure), resulting in prolongation of Intensive Care Unit (ICU) treatment and hospitalization. Overfeeding, in contrast, results when a patient is enterally fed but the patient's gastrointestinal tract (or overall circulatory system) is not yet sufficiently healthy to tolerate the increased stress of enteral feeding. Overfeeding can result in vomiting and aspiration of enteral feeds into the lungs, leading to aspiration pneumonitis / pneumonia. Overfeeding can also lead to ileus, fever, and abdominal tenderness, which can mimic other serious disorders, such as abdominal abscess / infection, and dead bowel syndrome.II. Weaning from Mechanical Ventilation

[0004] Mechanical ventilation is used to support adequate oxygenation and ventilation in patients with pulmonary dysfunction. Providing mechanical ventilation to a patient when it is not necessary can lead to recognized complications, such as muscle weakness and aspiration pneumonia, resulting in unnecessarily prolonged hospitalization. Discontinuing or weaning mechanical ventilation in a patient prematurely can lead to complications, such as pulmonary failure, intestinal dysfunction, cardiac arrhythmias, and a general setback in a patient's recovery.III. Weaning of Vasoactive Medications

[0005] Vasoactive agents, such as epinephrine, dobutamine, dopamine, norepinephrine, and milrinone, are commonly administered to critically ill patients in order to insure adequate perfusion of vital organs. Unnecessary administration of these agents can result in prolonged hospitalization and may cause complications, such as cardiac arthythmias. In contrast, insufficient administration of these agents can result in inadequate organ perfusion, resulting in organ dysfunction and death.SUMMARY

[0006] The invention is defined by the appended claims and relates to a device. Methods decribed herein are useful to understand the invention.

[0007] In the related art, it may be difficult to determine whether to initiate, terminate, or otherwise regulate intensive care techniques, including those discussed above, and exemplary embodiments generally relate to guiding medical care based on detected gastric function. For example, an amount, such as an effective dose, of a pharmacological challenge agent, such as a gastric acid stimulant or suppressant, is administered, and then a change, such as an acute change, in the gastric juice pH is measured. Medical care can then be guided based on the detected change in gastric juice pH. For example, patients demonstrating sufficient or significant change in gastric juice pH may have their medical care normalized in an accelerated fashion, while those not sufficiently responsive cannot and may even require more support.

[0008] Tests can be and have been performed showing advantages of guiding medical care based on detected gastric function. Results of such tests should, in many cases, be consistent or substantially consistent, with the following prophetic example.A. Related Art Procedure

[0009] An exemplary related art procedure and articulated result is provided below.

[0010] A 70 year old patient develops severe pneumonia requiring admission to an intensive care unit, intubation of the trachea, and mechanical ventilation. After three days of illness, enteral feeding is started. Two days later, enteral feeding is stopped as her abdomen has become swollen and tender, and there is a suspicion that she may have aspirated gastric contents. The following day (6 th< day of illness), her respiratory support has to be increased. On day nine of her illness, enteral feeding is restarted successfully.

[0011] By day fourteen, she is beginning to wean from the ventilator, but once again her abdomen becomes swollen and tender and so feeding is stopped. Weaning continues but is unsuccessful, and by day twenty-one she is back on full respiratory support and receiving total parenteral nutrition. On day twenty-five she develops bacteremia from an infection of her intravenous feeding line. The line is removed and broad spectrum antibiotics are started. By day thirty-two she is again fed enterally, and is slowly weaning from the ventilator. On day forty-five she is discharged from the ICU, having made a complete recovery.B. Basic Procedure Guiding Medical Care Based on Detected Gastric Function

[0012] An exemplary basic procedure for guiding medical care based on detected gastric function and its anticipated result is provided below.

[0013] The following prophetic test involves application of a gastric stimulation test on the same patient from section I(A) (Related Art Procedure). The 70 year old patient develops severe pneumonia requiring admission to an intensive care unit, intubation of the trachea, and mechanical ventilation. After three days of illness, it is decided that she would benefit from enteral nutrition. A commercially available probe, such as a VersaFlex pH sensor from Sierra Scientific Instruments, Los Angeles, CA, is inserted into the gastric lumen and connected to a pH recording device (e.g., Digitrapper from Sierra Scientific Instruments, Los Angeles, CA). The baseline gastric juice pH is 5.4 and shows no change 20 minutes after the administration of pentagastrin (6 micrograms / kg subcutaneously). Attempts at feeding or weaning from the ventilator are postponed.

[0014] One day later (day four) the baseline gastric juice pH is 6.2 and again shows no change 20 minutes after the administration of pentagastrin (6 micrograms / kg subcutaneously). Additional intravenous fluids and a low dose of intravenous Dobutamine are given in an attempt to improve splanchnic perfusion. One day later (day five) the baseline gastric juice pH is 5.9 and decreases to 1.8, 20 minutes after the administration of pentagastrin (6 micrograms / kg subcutaneously). Based on this positive challenge test, enteral feeding is initiated and is well tolerated by the patient. The patient gains strength and by day fourteen the dobutamine has been stopped and she is beginning to wean from the ventilator. On day seventeen she is weaned from the ventilator. On day eighteen (as opposed to day forty-five - see section I(A) above) she is discharged from the ICU, having made a complete recovery.II. Exemplary Embodiments

[0015] Various embodiments are directed to methods and apparatus (including processors, computer readable mediums, computer programs, etc.) for guiding medical care of a patient based on detected gastric function. Some of these embodiments are summarized below.A. Methods

[0016] One exemplary method of guiding medical care of a patient based on detected gastric function includes: measuring the patient's gastric juice H+ concentration to obtain a baseline gastric juice H+ concentration; determining a guidance H+ concentration differential indicative of relatively healthy gastric function; administering a gastric acid stimulant or suppressant; measuring the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice H+ concentration; calculating a measured H+ concentration differential between the baseline gastric juice H+ concentration and the stressed gastric juice H+ concentration; and performing one of the following based on a comparison between the guidance H+ concentration differential and the measured H+ concentration differential: 1) guiding medical care based on a relatively healthy gastric function if the measured H+ concentration differential is equal to or exceeds the guidance H+ concentration differential; and 2) guiding medical care based on a relatively unhealthy gastric function if the measured H+ concentration differential is less than the guidance H+ concentration differential.

[0017] In a second example, the method may further include: performing multiple measurements of the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain multiple stressed gastric juice H+ concentration values; calculating a rate of change of the gastric juice H+ concentration based on at least one of: differentials between the baseline gastric juice H+ concentration and the multiple stressed gastric juice H+ concentration values, and differentials between different stressed gastric juice H+ concentration values; and guiding medical care based on the calculated rate of change of the gastric juice H+ concentration.

[0018] In a example, the method may further include converting the baseline gastric juice H+ concentration and stressed gastric juice H+ concentration to baseline gastric juice pH and stressed gastric juice pH, respectively; wherein: the determining step includes determining a guidance pH differential indicative of relatively healthy gastric function based on the baseline gastric juice pH; the calculating step includes calculating a measured pH differential between the baseline gastric juice pH and the stressed gastric juice pH; and the performing step includes performing one of the following based on a comparison between the guidance pH differential and the measured pH differential: 1) guiding medical care based on a relatively healthy gastric function if the measured pH differential is equal to or exceeds the guidance pH differential; and 2) guiding medical care based on a relatively unhealthy gastric function if the measured pH differential is less than the guidance pH differential.

[0019] In the third example, the determining step may include determining the guidance pH differential indicative of relatively healthy gastric function to be relatively low if the baseline gastric juice pH is relatively low, and determining the guidance pH differential indicative of relatively healthy gastric function to be relatively high if the baseline gastric juice pH is relatively high.

[0020] The third example alternatively may further include: setting a minimum baseline gastric juice pH; comparing the measured baseline gastric juice pH to the minimum baseline gastric juice pH; administering a pharmacological agent to raise gastric juice pH if the measured baseline gastric juice pH is less than the minimum baseline gastric juice pH; and measuring the patient's gastric juice pH after the pharmacological agent administration to obtain a modified baseline gastric juice pH; wherein the calculating step includes calculating the measured pH differential between the modified baseline gastric juice pH and the stressed gastric juice pH.

[0021] In a fourth example, the guiding of medical care consistent with a relatively healthy gastric function includes providing instructions to perform at least one of: initiation, maintenance, or increase of enteral feeding; failing to initiate, reduction, or termination of mechanical ventilation; and failing to initiate, reduction, or termination of use of vasoactive agents; and the guiding of medical care consistent with a relatively unhealthy gastric function includes providing instructions to perform at least one of: failing to initiate, reduction, or termination of enteral feeding; initiation, maintenance, or increase of mechanical ventilation; and initiation, maintenance, or increase of use of vasoactive agents.

[0022] In the fourth example, the guiding of medical care consistent with a relatively healthy gastric function may include providing instructions to initiate enteral feeding. This method may further include measuring the patient's gastric juice H+ concentration after initiation of enteral feeding to obtain a post-feeding gastric juice H+ concentration, and guiding medical care based on the post-feeding gastric juice H+ concentration.

[0023] In a fifth example, the administering step includes administering approximately 6 micrograms / kg of pentagastrin subcutaneously.

[0024] In a sixth example, the method further includes determining a pharmacologically effective dosage of gastric acid stimulant; wherein the administering step includes administering the determined pharmacologically effective dosage of the stimulant that includes pentagastrin.

[0025] In the sixth example, the determining of the pharmacologically effective dosage of pentagastrin is based on patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, aspects of current personal medical condition, and genetics.

[0026] Alternatively, in the sixth example, the determining of the pharmacologically effective dosage of pentagastrin is based on patient weight in accordance with one of the following: a stepped methodology wherein 250 mcg is determined to be the pharmacologically effective dosage for patients weighing 40-70 kg, 500 mcg is determined to be the pharmacologically effective dosage for patients weighing 71-100 kg, and 750 mcg is determined to be the pharmacologically effective dosage for patients weighing more than 100 kg; and a linear methodology wherein the pharmacologically effective dosage of pentagastrin is based on 6mcg / kg, such that 300 mcg is determined to be the pharmacologically effective dosage for a patient weighing 50 kg, 450 mcg is determined to be the pharmacologically effective dosage for patients weighing 75 kg, and 600 mcg is determined to be the pharmacologically effective dosage for patients weighing 100 kg.

[0027] In a seventh example, the determining step includes determining the guidance H+ concentration differential to be approximately .01 millimole per liter.

[0028] In an eighth example, the determining step includes determining the guidance H+ concentration differential based on patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, aspects of current personal medical condition, and genetics.

[0029] In a ninth example, the method also includes measuring the patient's gastric contents volume prior to the administering of the gastric acid stimulant or suppressant; and wherein the determining step includes determining the guidance H+ concentration differential based on the measured gastric contents volume.

[0030] Alternatively, in the ninth example, the determining step includes: determining the guidance H+ concentration differential to be relatively lower if the gastric contents volume is relatively high, and determining the guidance H+ concentration differential to be relatively higher if the gastric contents volume is relatively low.

[0031] In a tenth example, the method further includes: performing multiple measurements of the patient's gastric juice H+ concentration after obtaining the stressed gastric juice H+ concentration; displaying the multiple H+ concentration measurements as a curve via a graph, with the x-axis representing the time that the H+ concentration measurements were taken and the y-axis representing H+ concentration values; calculating an area defined under the curve; and guiding medical care based on the calculated area.

[0032] In an eleventh example, the method further includes: performing multiple measurements of the patient's gastric juice H+ concentration after obtaining the stressed gastric juice H+ concentration; determining a rate of change of the multiple H+ concentration measurements via the derivative of at least one of the following functions: d(H(t)) / dt, where the function H(t) represents the measurement of H+ concentration in moles per liter (mol), and H(t), which represents the multiple measurements of H+ concentration in moles per liter (mol); and guiding medical care based on the determined rate of change, such that a relatively fast rate of change indicates a relatively healthy gastric function, and a relatively slow rate of change indicates a relatively unhealthy gastric function.

[0033] In a twelfth example, the guiding of medical care includes providing instructions to perform at least one of: determining patient disposition within a medical care facility; determining adequacy of resuscitation; detecting risk of developing stress ulcers; guiding usages of suppressants to reduce risk of at least one of stress ulcers and bleeding; determining risk of aspiration and guiding care to reduce the risk of aspiration; aiding detection of at least one of gut ischemia and abdominal compartment syndrome; and monitoring of gastric motility to reduce gastric residuals and risk of aspiration.B. Processors

[0034] One exemplary apparatus for guiding medical care of a patient based on detected gastric function is a processor that is used with at least one administering device that administers a gastric acid stimulant or suppressant, and at least one sensor that measures the patient's gastric juice H+ concentration prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice H+ concentration, and that measures the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice H+ concentration. The processor includes: a determination unit that determines a guidance H+ concentration differential indicative of relatively healthy gastric function; a calculation unit that calculates a measured H+ concentration differential between the baseline gastric juice H+ concentration and the stressed gastric juice H+ concentration; a comparison unit that compares the guidance H+ concentration differential to the measured H+ concentration differential; a primary instruction unit that provides instructions to guide medical care based on a relatively healthy gastric function if the measured H+ concentration differential is equal to or exceeds the guidance H+ concentration differential; and an alternative instruction unit that provides instructions to guide medical care based on a relatively unhealthy gastric function if the measured H+ concentration differential is less than the guidance H+ concentration differential.

[0035] In a second embodiment, the sensor performs multiple measurements of the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain multiple stressed gastric juice H+ concentration values; the calculation unit calculates a rate of change of the gastric juice H+ concentration based on at least one of: differentials between the baseline gastric juice H+ concentration and the multiple stressed gastric juice H+ concentration values, and differentials between the different stressed gastric juice H+ concentration values; and the primary instruction unit or the alternative instruction unit provides instructions to guide medical care based on the calculated rate of change of the gastric juice H+ concentration.

[0036] A third embodiment further includes a conversion unit that converts the baseline gastric juice H+ concentration and stressed gastric juice H+ concentration to baseline gastric juice pH and stressed gastric juice pH, respectively, wherein: the determination unit determines a guidance pH differential indicative of relatively healthy gastric function based on the baseline gastric juice pH; the calculation unit calculates a measured pH differential between the baseline gastric juice pH and the stressed gastric juice pH; and the primary instruction unit or the alternative instruction unit performs one of the following based on a comparison between the guidance pH differential and the measured pH differential: 1) guiding medical care based on a relatively healthy gastric function if the measured pH differential is equal to or exceeds the guidance pH differential; and 2) guiding medical care based on a relatively unhealthy gastric function if the measured pH differential is less than the guidance pH differential.

[0037] In an alternative of the third embodiment, the determination unit determines the guidance pH differential indicative of relatively healthy gastric function to be relatively low if the baseline gastric juice pH is relatively low, and determines the guidance pH differential indicative of relatively healthy gastric function to be relatively high if the baseline gastric juice pH is relatively high.

[0038] Another alternative of the third embodiment further includes a comparison unit that sets a minimum baseline gastric juice pH, and compares the measured baseline gastric juice pH to the minimum baseline gastric juice pH; wherein the administering device administers a pharmacological agent to raise gastric juice pH if the comparison unit determines that the measured baseline gastric juice pH is less than the minimum baseline gastric juice pH; the sensor measures the patient's gastric juice pH after the pharmacological agent administration to obtain a modified baseline gastric juice pH; and calculation unit calculates the measured pH differential between the modified baseline gastric juice pH and the stressed gastric juice pH.

[0039] In a fourth embodiment, the primary instruction unit provides instructions to perform at least one of: initiation, maintenance, or increase of enteral feeding; failing to initiate, reduction, or termination of mechanical ventilation; and failing to initiate, reduction, or termination of use of vasoactive agents; and the alternative instruction unit provides instructions to perform at least one of: failing to initiate, reduction, or termination of enteral feeding; initiation, maintenance, or increase of mechanical ventilation; and initiation, maintenance, or increase of use of vasoactive agents.

[0040] In an alternative of the fourth embodiment, the primary instruction unit provides instructions to initiate enteral feeding; the sensor measures the patient's gastric juice H+ concentration after initiation of enteral feeding to obtain a post-feeding gastric juice H+ concentration; and the primary instruction unit or the alternative instruction unit guides medical care based on the post-feeding gastric juice H+ concentration.

[0041] In a fifth embodiment, the administering device is configured to administer approximately 6 micrograms / kg of pentagastrin subcutaneously.

[0042] A sixth embodiment further includes a dosage determination unit that determines a pharmacologically effective dosage of gastric acid stimulant; wherein the administering device is configured to administer the determined pharmacologically effective dosage of the stimulant that includes pentagastrin.

[0043] In an alternative of the sixth embodiment, the dosage determination unit determines the pharmacologically effective dosage of pentagastrin based on patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, aspects of current personal medical condition, and genetics.

[0044] In another alternative of the sixth embodiment, the dosage determination unit determines the pharmacologically effective dosage of gastric acid stimulant or suppressant based on patient weight in accordance with one of the following: a stepped methodology wherein 250 mcg is determined to be the pharmacologically effective dosage for patients weighing 40-70 kg, 500 mcg is determined to be the pharmacologically effective dosage for patients weighing 71-100 kg, and 750 mcg is determined to be the pharmacologically effective dosage for patients weighing more than 100 kg; and a linear methodology wherein the pharmacologically effective dosage of pentagastrin is based on 6mcg / kg, such that 300 mcg is determined to be the pharmacologically effective dosage for a patient weighing 50 kg, 450 mcg is determined to be the pharmacologically effective dosage for patients weighing 75 kg, and 600 mcg is determined to be the pharmacologically effective dosage for patients weighing 100 kg.

[0045] In a seventh embodiment, the determination unit determines the guidance H+ concentration differential to be approximately .01 millimole per liter.

[0046] In an eighth embodiment, the determination unit determines the guidance H+ concentration differential based on patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, aspects of current personal medical condition, and genetics.

[0047] In a ninth embodiment, the processor is used with a volume measuring device for measuring the patient's gastric contents volume prior to the administering of the gastric acid stimulant or suppressant; and the determination unit determines the guidance H+ concentration differential based on the measured gastric contents volume.

[0048] In an alternative of the ninth embodiment, the determination unit: determines the guidance H+ concentration differential to be relatively lower if the gastric contents volume is relatively high, and determines the guidance H+ concentration differential to be relatively higher if the gastric contents volume is relatively low.

[0049] In a tenth embodiment, the sensor performs multiple measurements of the patient's gastric juice H+ concentration after obtaining the stressed gastric juice H+ concentration; the processor further comprises a display for displaying the multiple H+ concentration measurements as a curve via a graph, with the x-axis representing the time that the H+ concentration measurements were taken and the y-axis representing H+ concentration values; and an area calculation unit to calculate an area defined under the curve; and wherein the primary instruction unit or the alternative instruction unit guides medical care based on the calculated area.

[0050] In an eleventh embodiment, the sensor performs multiple measurements of the patient's gastric juice H+ concentration after obtaining the stressed gastric juice H+ concentration; the processor further comprises a rate determination unit for determining a rate of change of the multiple H+ concentration measurements via the derivative of at least one of the following functions: d(H(t)) / dt, where the function H(t) represents the measurement of H+ concentration in moles per liter (mol), and H(t), which represents the multiple measurements of H+ concentration in moles per liter (mol); and wherein the primary instruction unit or the alternative instruction unit guides medical care based on the determined rate of change, such that a relatively fast rate of change indicates a relatively healthy gastric function, and a relatively slow rate of change indicates a relatively unhealthy gastric function.

[0051] In a twelfth embodiment, the guiding of medical care includes providing instructions to perform at least one of: determining patient disposition within a medical care facility; determining adequacy of resuscitation; detecting risk of developing stress ulcers; guiding usages of suppressants to reduce risk of at least one of stress ulcers and bleeding; determining risk of aspiration and guiding care to reduce the risk of aspiration; aiding detection of at least one of gut ischemia and abdominal compartment syndrome; and monitoring of gastric motility to reduce gastric residuals and risk of aspiration.C. Apparatus

[0052] Some exemplary embodiments focus even more directly on parts of the apparatus, other than or in addition to a processor, for guiding medical care of a patient based on detected gastric function. At least one sensor is used to measure the patient's gastric juice H+ concentration to obtain a baseline gastric juice H+ concentration, and the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice H+ concentration. Exemplary embodiments are intended to cover any apparatus and / or method for performing these measurements, including but not limited to the ComforTec Z / pH probes and ZepHR pH recording device from Sandhill Scientific, Inc. and the VersaFlex pH sensor and Digitrapper pH recording device from Sierra Scientific Instruments. Similarly, exemplary embodiments are intended to cover any apparatus and / or method for administering the gastric acid stimulant or suppressant, including but not limited to a needle(s) with syringe(s), etc.

[0053] In addition, exemplary embodiments are intended to cover any apparatus for determining a guidance H+ concentration differential indicative of relatively healthy gastric function. In some exemplary embodiments, a processor is used to set the guidance H+ concentration differential based on one or more factors, including but not limited to patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, aspects of current personal medical condition, and genetics. In other embodiments, a processor or other device / method is used to set the guidance H+ concentration differential based on one or more factors, including but not limited to the measured baseline gastric juice H+ concentration or measured baseline gastric juice pH. In still other embodiments, a processor is not used, and instead the guidance H+ concentration differential is always set at a same value, such as approximately .01 millimole per liter.

[0054] Exemplary embodiments are also intended to cover any apparatus of calculating a measured H+ concentration differential between the baseline gastric juice H+ concentration and the stressed gastric juice H+ concentration; and any apparatus of performing one of the following based on a comparison between the guidance H+ concentration differential and the measured H+ concentration differential: 1) guiding medical care based on a relatively healthy gastric function if the measured H+ concentration differential is equal to or exceeds the guidance H+ concentration differential; and 2) guiding medical care based on a relatively unhealthy gastric function if the measured H+ concentration differential is less than the guidance H+ concentration differential.D. Computer Program / Non-Transitory Recording Medium

[0055] Still other exemplary embodiments focus on a computer program and / or non-transitory recording medium that stores a computer program for guiding medical care of a patient based on detected gastric function, and for use with an administering device that administers a gastric acid stimulant or suppressant, and at least one sensor that measures the patient's gastric juice H+ concentration prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice H+ concentration, and that measures the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice H+ concentration.

[0056] The program causes a computer to perform the following: determining a guidance H+ concentration differential indicative of relatively healthy gastric function; calculating a measured H+ concentration differential between the baseline gastric juice H+ concentration and the stressed gastric juice H+ concentration; comparing the guidance H+ concentration differential to the measured H+ concentration differential; providing instructions to guide medical care based on a relatively healthy gastric function if the measured H+ concentration differential is equal to or exceeds the guidance H+ concentration differential; and providing instructions to guide medical care based on a relatively unhealthy gastric function if the measured H+ concentration differential is less than the guidance H+ concentration differential.III. Other Exemplary Embodiments

[0057] Some other exemplary embodiments relate to: 1) specialized apparatus for enhancing this test, such as software and electronics facilitating and implementing this test, 2) specialized methods for enhancing results of this test, such as by using certain dosages of stimulant or supplement, or tailoring feeding based on specific changes in gastric juice pH, and 3) using the test results to enhance care, such as by guiding patients' dispositions within a hospital, monitoring adequacy or resuscitation, or detecting stress ulcers. However, this listing is merely provided for exemplary purposes to generally introduce the disclosed subject matter, and many exemplary embodiments are beyond the above categorizations. For example, some exemplary embodiments do not involve gastric juice pH, and instead focus on other methodologies, such as gastric volume. In fact, exemplary embodiments are intended to cover any method of assessing gastric function.

[0058] Throughout the present disclosure, various terms are used to describe and / or identify effects of pharmacological agents on the gastrointestinal system. Some of these terms are used consistently with common usage in the art, while others are used in a more generic fashion for convenience, breadth, accuracy, etc. For example, it is typical in the art to use the terms "robust," "moderate," and "modest" to reflect magnitudes, such as with regard to pH values, volumes, etc., and some of these terms are used herein consistent with this usage. Other terms, such as "acute," are sometimes used in the art merely to reflect rates of change or timing of change. However, the present disclosure deviates from this narrow usage and "acute" is used more broadly to also reflect magnitudes, such as with regard to pH values, volumes, etc.

[0059] The present disclosure also makes many references to effects on the gastrointestinal system by administrations of pharmacological agents, including but not limited to gastric acid stimulants and suppressants. It is common in the art to refer to administrations of gastric acid stimulants in terms of causing a challenge or stress to the gastrointestinal system, while administrations of gastric acid suppressants as blocking such reactions. However. the present disclosure describes such effects in a more generic fashion. For example, in the present disclosure, for reasons of convenience, breadth, accuracy, etc., all effects of gastric acid stimulants, suppressants, etc., are referred to in terms of "stress," such as "stress tests" involving the administrations of gastric acid stimulants, suppressants, etc. In other words, the present disclosure uses the term "stress" in a generic and broad fashion in many instances so as to be synonymous with challenge, reaction, effect, etc.

[0060] As a further example, many of the disclosed exemplary embodiments can be categorized in a completely different manner than discussed above. For example, many exemplary embodiments can be categorized as relating to: 1) enhancing the accuracy of pH differential based test results, 2) enhancing the efficiency of pH differential based tests, and 3) methodology bases other than pH differential based tests. Exemplary embodiments relating to these categories cover any applicable form and context, including but not limited to methods, apparatus, processors, computer readable mediums, software and computer programs, etc. A summary of certain embodiments is provided below in the context of the above categorizations for exemplary purposes only, and is not intended to constitute a complete listing or disclosure of inventive concepts captured by the present application.A. Enhancing Accuracy of pH Differential Based Test Results

[0061] As disclosed above, some exemplary embodiments can be categorized as, apparatus, processors, computer programs, etc., for enhancing the accuracy of pH differential based test results. The below listing of embodiments that enhance the test result accuracy is not intended as limiting, and instead is merely provided for exemplary purposes.

[0062] Enhancing test result accuracy can enable the state of health of the gastric system to be more precisely defined, such as by predicting the gastric system as being very healthy, healthy, moderately healthy, relatively unhealthy, unhealthy, very unhealthy, etc. This more precise definition of health can be beneficial in numerous respects, such as by enabling medical treatments to be more exactly tailored to a patient's actual condition, thereby improving the patient's response to medical treatment. More precisely estimating gastric system health can also enhance or improve diagnoses of various medical conditions, and in some cases may even enable the diagnoses of certain medical conditions that could not otherwise be diagnosed absent precise gastric system health data.

[0063] Enhancing the test result accuracy can also enable the state of health of the gastric system to be more reliably defined, such as by more certainly predicting whether a patient's gastric system is healthy or unhealthy. This more reliable indication of gastric system health can be beneficial by helping to ensure both accuracy of diagnoses and that patients are subjected to appropriate medical treatments, i.e., that gastric systems are reliably deemed as sufficiently healthy or insufficiently healthy to receive certain medical treatments.1. Administer Stimulant if Baseline pH is High, or Suppressant if Baseline pH is Low

[0064] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments measure a patient's gastric juice pH to obtain a baseline gastric juice pH, and then challenge the gastric system by administering either a gastric acid stimulant or suppressant depending on the measured baseline gastric juice pH. This procedure provides enhanced results at least because a gastric acid stimulant based challenge is relatively more effective with a relatively high baseline gastric juice pH, while a gastric acid suppressant based challenge is relatively more effective with a relatively low baseline gastric juice pH.

[0065] The determination of whether to administer a gastric acid stimulant or suppressant depending on the measured baseline gastric juice pH can be performed in any applicable manner. For example, a certain baseline gastric juice pH can be selected to delineate administration of gastric acid stimulant versus suppressant, such that gastric acid stimulant is administered if the baseline gastric juice pH equals or exceeds the selected certain baseline gastric juice pH, while gastric acid suppressant is administered if the baseline gastric juice pH fails to equal or exceed the selected certain baseline gastric juice pH. In such exemplary embodiments, the certain baseline gastric juice pH can be selected based on any applicable criteria. In some exemplary embodiments, the certain baseline gastric juice pH is approximately at least 2.5 pH units, and in other exemplary embodiments, the certain baseline gastric juice pH is approximately at least 3.0 pH units. However, these values are only provided for exemplary purposes, and exemplary embodiments are intended to cover any selected baseline gastric juice pH applicable for such delineations.

[0066] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0067] An exemplary method includes measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, and administering a gastric acid stimulant or a gastric acid suppressant depending on the baseline gastric juice pH. The gastric acid stimulant is administered if the baseline gastric juice pH is equal to or exceeds a certain value, while the gastric acid suppressant is administered if the baseline gastric juice pH is less than the certain value. The patient's gastric juice pH is measured after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH. A pH differential, between the baseline gastric juice pH and the stressed gastric juice pH, is calculated to determine gastric function, and medical care is guided based on the determined gastric function.b. Apparatus

[0068] An exemplary apparatus includes a pH sensor for measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, a processor that determines whether the baseline pH equals or exceeds a certain value; and an administering device that administers a gastric acid stimulant if the baseline gastric juice pH is equal to or exceeds the certain value, or a gastric acid suppressant if the baseline gastric juice pH is less than the certain value. The sensor measures the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH. The processor calculates a pH differential between the baseline gastric juice pH and the stressed gastric juice pH to determine gastric function so that medical care can be guided based on the determined gastric function.c. Processor

[0069] An exemplary processor in accordance with this embodiment is used with an administering device that administers a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH.

[0070] The processor includes a determination unit that determines whether the baseline pH equals or exceeds a certain value, and an instruction unit that provides instructions for the administering device to administer a gastric acid stimulant if the baseline gastric juice pH is equal to or exceeds the certain value, or to administer a gastric acid suppressant if the baseline gastric juice pH is less than the certain value. The processor also includes a calculation unit that calculates a pH differential between the baseline gastric juice pH and the stressed gastric juice pH to determine gastric function so that medical care can be guided based on the determined gastric function.d. Computer Program

[0071] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH.

[0072] The computer program includes a determination program for determining whether the baseline pH equals or exceeds a certain value, and an instruction program for providing instructions for the administering device to administer a gastric acid stimulant if the baseline gastric juice pH is equal to or exceeds the certain value, or to administer a gastric acid suppressant if the baseline gastric juice pH is less than the certain value. A calculation program calculates a pH differential between the baseline gastric juice pH and the stressed gastric juice pH to determine gastric function so that medical care can be guided based on the determined gastric function.2. Perform Alternative Test with Other of Stimulant or Suppressant if pH Differential Fails to Demonstrate at Least an Acute Change in pH

[0073] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments calculate a pH differential between gastric juice pH prior to and after administration of a gastric system stress agent (such as gastric juice stimulant or suppressant, for example), and guide medical care consistent with a relatively healthy gastric function if the pH differential constitutes an acute change. An alternative gastric system stress test is conducted with a different gastric system stress agent if an acute change is not demonstrated. For example, the alternative test stresses the gastric system with a gastric juice suppressant if a stimulant was used in the originally challenge, or vice versa.

[0074] This procedure provides enhanced results at least because it enables identification of patients with a relatively healthy gastric function who, for whatever reason, fail to demonstrate an acute pH differential in the initial challenge. In other words, some patients may not demonstrate an acute pH differential after a challenge with one of stimulant or suppressant, even though their gastric system is relatively healthy. Conducting a challenge test with the other of stimulant or suppressant allows all or some of those patients to be identified and medical care to be guided accordingly.

[0075] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0076] An exemplary method in accordance with this embodiment includes measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, administering one of gastric acid stimulant and gastric acid suppressant, measuring the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH, and calculating a primary pH differential between the baseline gastric juice pH and the stressed gastric juice pH.

[0077] Medical care is guided consistent with a relatively healthy gastric function if the calculated primary pH differential demonstrates an acute change in pH. An alternative pH test is conducted if the calculated primary pH differential fails to demonstrate an acute change in pH. The alternative pH test includes: administering the other of gastric acid stimulant and gastric acid suppressant, measuring the patient's gastric juice pH after the administration of the other of gastric acid stimulant and gastric acid suppressant to obtain an alternative stressed gastric juice pH, calculating an alternative pH differential between the baseline gastric juice pH and the alternative stressed gastric juice pH, guiding medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and guiding medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH.b. Apparatus

[0078] An exemplary apparatus in accordance with this embodiment includes an administering device that administers one of gastric acid stimulant and gastric acid suppressant, a pH sensor that measures the patient's gastric juice pH prior to the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH, and a processor that calculates a primary pH differential between the baseline gastric juice pH and the stressed gastric juice pH.

[0079] The processor guides medical care consistent with a relatively healthy gastric function if the calculated primary pH differential demonstrates an acute change in pH. An alternative pH test is performed if the calculated primary pH differential fails to demonstrate an acute change in pH. In the alternative pH test: the administering device administers the other of gastric acid stimulant and gastric acid suppressant, the sensor measures the patient's gastric juice pH after the administration of the other of gastric acid stimulant and gastric acid suppressant to obtain an alternative stressed gastric juice pH, the processor calculates an alternative pH differential between the baseline gastric juice pH and the alternative stressed gastric juice pH, the processor guides medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and the processor guides medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH.c. Processor

[0080] An exemplary processor in accordance with this embodiment is used with an administering device that administers one of gastric acid stimulant and gastric acid suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH.

[0081] The processor includes a calculation unit that calculates a primary pH differential between the baseline gastric juice pH and the stressed gastric juice pH, and a primary guidance unit that provides advice for guiding medical care consistent with a relatively healthy gastric function if the calculated primary pH differential demonstrates an acute change in pH. The processor also includes an alternative guidance unit that provides instructions for conducting an alternative pH test if the calculated primary pH differential fails to demonstrate an acute change in pH. In the alternative pH test, the processor: a) instructs the pH sensor to measure the patient's gastric juice pH after the administration of the other of gastric acid stimulant and gastric acid suppressant to obtain an alternative stressed gastric juice pH, b) calculates an alternative pH differential between the baseline gastric juice pH and the alternative stressed gastric juice pH, c) provides advice for guiding medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and d) provides advice for guiding medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH.d. Computer Program

[0082] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers one of gastric acid stimulant and gastric acid suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH.

[0083] The computer program includes a calculation program for calculating a primary pH differential between the baseline gastric juice pH and the stressed gastric juice pH, a primary guidance program for providing advice for guiding medical care consistent with a relatively healthy gastric function if the calculated primary pH differential d emonstrates an acute change in pH, and an alternative guidance program for providing instructions for conducting an alternative pH test if the calculated primary pH differential fails to demonstrate an acute change in pH. The alternative pH test includes: instructing the administering device to administer the other of gastric acid stimulant and gastric acid suppressant, instructing the pH sensor to measure the patient's gastric juice pH after the administration of the other of gastric acid stimulant and gastric acid suppressant to obtain an alternative stressed gastric juice pH, calculating an alternative pH differential between the baseline gastric juice pH and the alternative stressed gastric juice pH, providing advice for guiding medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and providing advice for guiding medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH.3. If Baseline pH is Low, Use an Agent to Raise pH to Enable Use of Stimulant

[0084] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments measure a patient's gastric juice pH to determine a baseline gastric juice pH, and challenge the patient's gastric system with a stimulant if the determined baseline gastric juice pH is relatively high. A pharmacological agent, e.g., rapid acting acid suppressant and / or acid neutralizing buffer, is administered to raise the gastric juice pH if the determined baseline gastric juice pH is relatively low, and the patient's gastric system is challenged with stimulant after such rise in gastric juice pH.

[0085] It is often beneficial to conduct gastric system challenges with stimulant instead of suppressant, but gastric acid stimulant based challenges are often only effective with a relatively high baseline gastric juice pH. Thus, this procedure provides enhanced results at least because it enables stimulant based stress tests, even if the initially determined baseline gastric juice pH is too low. In other words, the benefits of a gastric acid stimulant based challenge are ensured by administering a pharmacological agent to raise the gastric juice pH to a sufficient pH level, if necessary.

[0086] The determination of whether the baseline gastric juice pH is sufficiently high to tolerate a stimulant based challenge can be performed in any applicable manner. For example, a certain baseline gastric juice pH can be selected to determine whether a pharmacological agent needs to be administered to raise the gastric juice pH before conducting the stimulant based challenge. For example, the stimulant based challenge can be conducted if the baseline gastric juice pH equals or exceeds the certain baseline gastric juice pH, while a pharmacological agent is administered to raise the gastric juice pH before conducting the stimulant based challenge if the baseline gastric juice pH fails to equal or exceed the certain baseline gastric juice pH. In such exemplary embodiments, the certain baseline gastric juice pH can be selected based on any applicable criteria. In some exemplary embodiments, the certain baseline gastric juice pH is approximately at least 2.5 pH units, and in other exemplary embodiments the certain baseline gastric juice pH is approximately at least 3.0 pH units. However, these values are only provided for exemplary purposes, and exemplary embodiments are intended to cover any selected baseline gastric juice pH applicable for such delineations.

[0087] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0088] An exemplary method includes measuring the patient's gastric juice pH to obtain a primary baseline gastric juice pH, and administering a gastric acid stimulant if the primary baseline gastric juice pH equals or exceeds the certain value. If the primary baseline gastric juice pH is less than the certain value, then a pharmacological agent is administered to raise gastric juice pH, the patient's gastric juice pH is measured after the pharmacological agent administration to obtain a secondary baseline gastric juice pH, and a gastric acid stimulant is administered after the gastric juice pH has been raised.

[0089] The method also includes measuring the patient's gastric juice pH after the gastric acid stimulant administration to obtain a stressed gastric juice pH, calculating a pH differential between: 1) one of the primary and the secondary baseline gastric juice pH, and 2) the stressed gastric juice pH, to determine gastric function, and guiding medical care based on the determined gastric function.b. Apparatus

[0090] An exemplary apparatus in accordance with this embodiment includes stimulant and pharmacological agent administering devices, a pH sensor that measures the patient's gastric juice pH to obtain a primary baseline gastric juice pH, and a processor that determines whether the primary baseline gastric juice pH equals or exceeds a certain value. The stimulant administering device administers a gastric acid stimulant if the primary baseline gastric juice pH is determined to equal or exceed the certain value.

[0091] An alternative operation is performed if the primary baseline gastric juice pH is determined to be less than the certain value. In the alternative operation, the pharmacological agent administers device administers a pharmacological agent to raise gastric juice pH, the pH sensor measures the patient's gastric juice pH after the pharmacological agent administration to obtain a secondary baseline gastric juice pH, and the stimulant administering device administers a gastric acid stimulant after the gastric juice pH has been raised. The pH sensor measures the patient's gastric juice pH after the gastric acid stimulant administration to obtain a stressed gastric juice pH. The processor calculates a pH differential between: 1) one of the primary and the secondary baseline gastric juice pH, and 2) the stressed gastric juice pH, to determine gastric function, so that medical care can be guided based on the determined gastric function.c. Processor

[0092] An exemplary processor in accordance with this embodiment is used with stimulant and pharmacological agent administering devices, and a pH sensor that measures the patient's gastric juice pH to obtain a primary baseline gastric juice pH. The processor includes a determination unit that determines whether the primary baseline gastric juice pH equals or exceeds a certain value, and a primary instruction unit that instructs the stimulant administering device to administer a gastric acid stimulant if the primary baseline gastric juice pH is determined to equal or exceed the certain value.

[0093] The processor also includes an alternative instruction unit that instructs that an alternative operation be performed if the primary baseline gastric juice pH is determined to be less than the certain value. In the alternative operation, the processor: a) instructs the pharmacological agent administering device to administer a pharmacological agent to raise gastric juice pH, b) instructs the pH sensor to measure the patient's gastric juice pH after the pharmacological agent administration to obtain a secondary baseline gastric juice pH, and c) instructs the stimulant administering device to administers a gastric acid stimulant after the gastric juice pH has been raised. The processor also includes a measurement instruction unit that instructs the pH sensor to measure the patient's gastric juice pH after the gastric acid stimulant administration to obtain a stressed gastric juice pH, and a calculation unit that calculates a pH differential between: a) one of the primary and the secondary baseline gastric juice pH, and b) the stressed gastric juice pH, to determine gastric function, so that medical care can be guided based on the determined gastric function.d. Computer Program

[0094] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with stimulant and pharmacological agent administering devices, and a pH sensor that measures the patient's gastric juice pH to obtain a primary baseline gastric juice pH. The computer program includes a determination program for determining whether the primary baseline gastric juice pH equals or exceeds a certain value, a primary instruction program for instructing the stimulant administering device to administer a gastric acid stimulant if the primary baseline gastric juice pH is determined to equal or exceed the certain value, and an alternative instruction program for instructing that an alternative operation be performed if the primary baseline gastric juice pH is determined to be less than the certain value.

[0095] The alternative operation includes: instructing the pharmacological agent administering device to administer a pharmacological agent to raise gastric juice pH, instructing the pH sensor to measure the patient's gastric juice pH after the pharmacological agent administration to obtain a secondary baseline gastric juice pH, and instructing the stimulant administering device to administers a gastric acid stimulant after the gastric juice pH has been raised. A measurement instruction program instructs the pH sensor to measure the patient's gastric juice pH after the gastric acid stimulant administration to obtain a stressed gastric juice pH. A calculation program calculates a pH differential between: 1) one of the primary and the secondary baseline gastric juice pH, and 2) the stressed gastric juice pH, to determine gastric function, so that medical care can be guided based on the determined gastric function.4. Setting pH Differential for Healthy Gastric Function Low if Baseline pH is Low, and Setting pH Differential for Healthy Gastric Function High if Baseline pH is High

[0096] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments determine gastric function based on a pH differential between gastric juice pH measured before and after administration of a gastric system stress agent, such as gastric acid stimulant or suppressant. The pH differential used to delineate healthy versus unhealthy gastric function can be determined based on the initially measured gastric juice pH prior to gastric system stress agent administration, i.e., baseline gastric juice pH. In other words, the pH differential values deemed sufficient to indicate healthy gastric function can vary depending on the baseline gastric juice pH.

[0097] Because pH differential values that indicate a healthy gastric function may vary depending on different patients or patient conditions, setting a static pH differential value to indicate healthy gastric function for all patients in all circumstances may result in less precise determinations of gastric function health. Thus, the above procedure provides enhanced results at least because tailoring pH differential values to indicate healthy gastric function enhances the accuracy of such determinations.

[0098] The varying of pH differential values that indicate a healthy gastric function can be performed in any applicable manner. For example, a guidance pH differential suitable to guide care can be determined based on the baseline gastric juice pH, and gastric function health can be determined by comparing the guidance pH differential to the actual gastric juice pH differential measured before and after administration of the gastric acid stimulant or suppressant. Medical care can be guided based on a relatively healthy gastric function if the actual gastric juice pH differential equals or exceeds the guidance pH differential, while medical care can be guided based on a relatively unhealthy gastric function if the actual gastric juice pH differential fails to equal or exceed the guidance pH differential.

[0099] In some exemplary embodiments, the guidance pH differential is set to be relatively low if the baseline gastric juice pH is relatively low, but set to be relatively high if the baseline gastric juice pH is relatively high. This setting of the guidance pH differential based on baseline gastric juice pH can be performed in any applicable manner. For example, some exemplary embodiments set the guidance pH based on baseline gastric juice pH using a logarithmic scale. More particularly, a logarithmic scale can be used that separates pH unit whole numbers by factors of ten, such that 7 pH units is separated from 6 pH units by a factor of 10, 6 pH units is separated from 5 pH units by a factor of 10, and 5 pH units is separated from 4 pH units by a factor of 10, etc. However, exemplary embodiments are intended to cover setting the guidance pH using procedures other than logarithms.

[0100] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0101] An exemplary method includes measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, determining a guidance pH differential suitable to guide care based on the baseline gastric juice pH, administering a gastric acid stimulant or suppressant, measuring the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH, and calculating a measured pH differential between the baseline gastric juice pH and the stressed gastric juice pH. Medical care is guided based on a relatively healthy gastric function if the measured pH differential is equal to or exceeds the guidance pH differential. Alternatively, medical care is guided based on a relatively unhealthy gastric function if the measured pH differential is less than the guidance pH differential.b. Apparatus

[0102] An exemplary apparatus in accordance with this embodiment includes an administering device that administers a gastric acid stimulant or suppressant, a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH, and a processor that determines a guidance pH differential suitable to guide care based on the baseline gastric juice pH, and that calculates a measured pH differential between the baseline gastric juice pH and the stressed gastric juice pH. The processor provides advice based on a comparison between the guidance pH differential and the measured pH differential.. For example, the processor guides medical care based on a relatively healthy gastric function if the measured pH differential is equal to or exceeds the guidance pH differential, or alternatively guides medical care based on a relatively unhealthy gastric function if the measured pH differential is less than the guidance pH differential.c. Processor

[0103] An exemplary processor in accordance with this embodiment is used with an administering device that administers a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH.

[0104] The processor includes a determination unit that determines a guidance pH differential suitable to guide care based on the baseline gastric juice pH, a calculation unit that calculates a measured pH differential between the baseline gastric juice pH and the stressed gastric juice pH, and a comparison unit that compares the guidance pH differential to the measured pH differential. The processor also includes a primary instruction unit that provides instructions to guide medical care based on a relatively healthy gastric function if the measured pH differential is equal to or exceeds the guidance pH differential, and an alternative instruction unit that provides instructions to guide medical care based on a relatively unhealthy gastric function if the measured pH differential is less than the guidance pH differential.d. Computer Program

[0105] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice pH.

[0106] The computer program includes a determination program for determining a guidance pH differential suitable to guide care based on the baseline gastric juice pH, a calculation program for calculating a measured pH differential between the baseline gastric juice pH and the stressed gastric juice pH, and a comparison program for comparing the guidance pH differential to the measured pH differential. A primary instruction program provides instructions to guide medical care based on a relatively healthy gastric function if the measured pH differential is equal to or exceeds the guidance pH differential. An alternative instruction unit provides instructions to guide medical care based on a relatively unhealthy gastric function if the measured pH differential is less than the guidance pH differential.5. Guiding Levels of Care Based on Whether the pH Differential Demonstrates: 1) Acute pH Change, 2) Moderate pH Change, or 3) Less Than a Moderate pH Change

[0107] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments determine gastric function based on a pH differential between gastric juice pH measured before and after administration of a gastric system stress agent, such as gastric acid stimulant or suppressant. The measured pH differential can be used to delineate various and multiple levels of gastric function health. For example, medical care is guided consistent with a very healthy gastric function if the calculated pH differential demonstrates an acute change in pH, while medical care can be guided consistent with a moderately healthy gastric function if the calculated pH differential only demonstrates a moderate change in pH. Further, medical care can guided consistent with an unhealthy gastric function if the calculated pH differential fails to demonstrate at least a moderate change in pH.

[0108] This procedure provides enhanced results by at least more particularly quantifying the health of the gastric system, so that medical care can be better tailored to actual gastric system health, thereby improving the patient's response to medical treatment. Also, as disclosed above, more precisely estimating gastric system health can be beneficial with regard to diagnoses of various medical conditions.

[0109] The pH differentials used to indicate acute and moderate pH changes can be determined in any applicable manner. In some exemplary embodiments, the pH changes deemed acute and moderate are pre-set. For example, in some of these exemplary embodiments, a change in pH that is greater than approximately 1 unit can be deemed acute, while a change in pH that is between approximately .5 unit and approximately 1 unit can be deemed moderate.

[0110] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0111] An exemplary method includes measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, administering one of gastric acid stimulant and gastric acid suppressant, measuring the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH, and calculating a pH differential between the baseline gastric juice pH and the stressed gastric juice pH. Medical care is guided consistent with a very healthy gastric function if the calculated pH differential demonstrates an acute change in pH. Medical care is guided consistent with a moderately healthy gastric function if the calculated pH differential demonstrates a moderate change in pH. Medical care is guided consistent with an unhealthy gastric function if the calculated pH differential fails to demonstrate at least a moderate change in pH.b. Apparatus

[0112] An exemplary apparatus in accordance with this embodiment includes an administering device that administers one of gastric acid stimulant and gastric acid suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH. A processor calculates a pH differential between the baseline gastric juice pH and the stressed gastric juice pH, and provides advice based on the calculated pH differential. For example, medical care is guided consistent with a very healthy gastric function if the calculated pH differential demonstrates an acute change in pH, medical care is guided consistent with a moderately healthy gastric function if the calculated pH differential demonstrates a moderate change in pH, and medical care is guided consistent with an unhealthy gastric function if the calculated pH differential fails to demonstrate at least a moderate change in pH.c. Processor

[0113] An exemplary processor in accordance with this embodiment is used an administering device that administers one of gastric acid stimulant and gastric acid suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH.

[0114] The processor includes a calculation unit that calculates a pH differential between the baseline gastric juice pH and the stressed gastric juice pH, and a primary instruction unit that provides advice to guide medical care consistent with a very healthy gastric function if the calculated pH differential demonstrates an acute change in pH. The processor also includes a secondary instruction unit that provides advice to guide medical care consistent with a moderately healthy gastric function if the calculated pH differential demonstrates a moderate change in pH, and a tertiary instruction unit that provides advice to guide medical care consistent with an unhealthy gastric function if the calculated pH differential fails to demonstrate at least a moderate change in pH.d. Computer Program

[0115] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers one of gastric acid stimulant and gastric acid suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the one of gastric acid stimulant and gastric acid suppressant to obtain a stressed gastric juice pH.

[0116] The computer program includes a calculation program for calculating a pH differential between the baseline gastric juice pH and the stressed gastric juice pH, a primary instruction program for providing advice to guide medical care consistent with a very healthy gastric function if the calculated pH differential demonstrates an acute change in pH, a secondary instruction program for providing advice to guide medical care consistent with a moderately healthy gastric function if the calculated pH differential demonstrates a moderate change in pH, and a tertiary instruction program for providing advice to guide medical care consistent with an unhealthy gastric function if the calculated pH differential fails to demonstrate at least a moderate change in pH.B. Enhancing Efficiency of pH Differential Based Tests

[0117] Other exemplary embodiments can be categorized as different methods, apparatus, processors, computer programs, etc., for enhancing the efficiency of pH differential based tests. The listing of embodiments that enhance the test efficiency is not intended as limiting, and instead is merely provided for exemplary purposes.

[0118] Enhancing the test efficiency can be beneficial in numerous respects. For example, enhancing efficiency can enable tests to be conducted at a lower cost, both in terms of labor and material, thereby helping to reduce otherwise rising medical costs while also enabling medical care providers to spend time saved on other activities. In addition, trauma caused to patients by undergoing the tests can be reduced, such as by reducing the patient's exposure to pharmacological agents (with regard to amount and / or concentration of the agents), and by reducing the amount of time that the patients undergo the tests. Increasing test efficiency can also facilitate early indication of gastric system health, which can be beneficial by expediting diagnoses of medical conditions and treatments, thereby improving the patient's medical condition.1. Administer Minimum Dosage of Stimulant or Suppressant, and if pH Differential is Low, Administer Standard Dose of Stimulant or Suppressant

[0119] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments conduct an initial gastric system stress test with a minimum dosage of gastric system stress agent, such as gastric acid stimulant or suppressant. A pH differential is calculated between gastric juice pH prior to and after administration of the minimum dosage, and medical care is guided consistent with a relatively healthy gastric function if the pH differential constitutes an acute change. An alternative gastric system stress test is conducted with a standard dosage of gastric system stress agent if an acute change is not demonstrated, and medical care is guided based on the results of the alternative test, i.e., medical care is guided consistent with a relatively healthy / unhealthy gastric function depending on whether the pH differential constitutes an acute change after administration of the standard dosage.

[0120] This procedure provides enhanced results at least by providing the opportunity of reducing the dosage of stress agent (pharmacological challenge agent) administered to the patient. This procedure may be beneficial by reducing, minimizing, or preventing any side-effects caused by the stress agent. Other, potentially secondary, benefits may also be achieved, such as reducing medical costs by virtue of the decreased stress agent dosage, etc.

[0121] In some exemplary embodiments, the gastric system stress agent is a gastric acid stimulant. In particular, some exemplary embodiments use pentagastrin as the gastric acid stimulant, wherein the minimum dosage of gastric acid stimulant is approximately 0.6 mcg / kg of pentagastrin, and the standard dosage of stimulant is approximately 6 mcg / kg of pentagastrin. Also, in some exemplary embodiments, a pH differential of approximately 1 pH unit is deemed sufficient to constitute an acute change to thereby indicate a relatively healthy gastric function. However, exemplary embodiments arc intended to cover any dosages and pH differentials that are applicable to determine gastric function so that medical care can be guided accordingly.

[0122] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0123] An exemplary method includes measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, administering a minimum dosage of a gastric acid stimulant or suppressant, measuring the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain a primary stressed gastric juice pH, and calculating a primary pH differential between the baseline gastric juice pH and the primary stressed gastric juice pH to determine gastric function. Medical care is guided consistent with a relatively healthy gastric function if the calculated primary pH differential demonstrates an acute change in pH.

[0124] An alternative test is conducted if the calculated primary pH differential fails to demonstrate an acute change in pH. The alternative test includes: a) administering a standard dosage of gastric acid stimulant or suppressant that exceeds the minimum dosage, b) measuring the patient's gastric juice pH after the administration of the standard dosage of the gastric acid stimulant or suppressant to obtain an alternative stressed gastric juice pH, c) calculating an alternative pH differential between: i) one of the baseline gastric juice pH and the primary stressed gastric juice pH, and ii) the alternative stressed gastric juice pH, d) guiding medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and e) guiding medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH. In some exemplary embodiments, the alternative pH differential is calculated between the baseline gastric juice pH and the alternative stressed gastric juice pH, while in other exemplary embodiments, the alternative pH differential is calculated between the primary stressed gastric juice pH and the alternative stressed gastric juice pH.b. Apparatus

[0125] An exemplary apparatus in accordance with this embodiment includes an administering device that administers a minimum dosage of a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the minimum dosage of gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the minimum dosage of gastric acid stimulant or suppressant to obtain a primary stressed gastric juice pH. A processor calculates a primary pH differential between the baseline gastric juice pH and the primary stressed gastric juice pH to determine gastric function. The processor guides medical care consistent with a relatively healthy gastric function if the calculated primary pH differential demonstrates an acute change in pH.

[0126] An alternative test is conducted if the calculated primary pH differential fails to demonstrate an acute change in pH. In the alternative test, a) the administering device administers a standard dosage of gastric acid stimulant or suppressant that exceeds the minimum dosage, b) the pH sensor measures the patient's gastric juice pH after the administration of the standard dosage of the gastric acid stimulant or suppressant to obtain an alternative stressed gastric juice pH, and c) the processor calculates an alternative pH differential between: i) one of the baseline gastric juice pH and the primary stressed gastric juice pH, and ii) the alternative stressed gastric juice pH, such that the processor guides medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and guides medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH. In some exemplary embodiments, the alternative pH differential is calculated between the baseline gastric juice pH and the alternative stressed gastric juice pH, while in other exemplary embodiments, the alternative pH differential is calculated between the primary stressed gastric juice pH and the alternative stressed gastric juice pH.c. Processor

[0127] An exemplary processor in accordance with this embodiment is used with an administering device that administers a minimum dosage of a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the minimum dosage of gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the minimum dosage of gastric acid stimulant or suppressant to obtain a primary stressed gastric juice pH.

[0128] The processor includes a calculation unit that calculates a primary pH differential between the baseline gastric juice pH and the primary stressed gastric juice pH to determine gastric function, and a primary instruction unit that instructs medical care to be guided consistent with a relatively healthy gastric function if the calculated primary pH differential demonstrates an acute change in pH. The processor also includes an alternative instruction unit that instructs that an alternative test be conducted if the calculated primary pH differential fails to demonstrate an acute change in pH. In the alternative operation, the processor: a) instructs the administering device to administer a standard dosage of gastric acid stimulant or suppressant that exceeds the minimum dosage, b) instructs the pH sensor to measure the patient's gastric juice pH after the administration of the standard dosage of the gastric acid stimulant or suppressant to obtain an alternative stressed gastric juice pH, and c) calculates an alternative pH differential between: i) one of the baseline gastric juice pH and the primary stressed gastric juice pH, and ii) the alternative stressed gastric juice pH, such that instructions are provided to guide medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and instructions are provided to guide medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH. In some exemplary embodiments, the alternative pH differential is calculated between the baseline gastric juice pH and the alternative stressed gastric juice pH, while in other exemplary embodiments, the alternative pH differential is calculated between the primary stressed gastric juice pH and the alternative stressed gastric juice pH.d. Computer Program

[0129] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers a minimum dosage of a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the minimum dosage of gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that measures the patient's gastric juice pH after the administration of the minimum dosage of gastric acid stimulant or suppressant to obtain a primary stressed gastric juice pH.

[0130] The computer program includes a calculation program for calculating a primary pH differential between the baseline gastric juice pH and the primary stressed gastric juice pH to determine gastric function, and a primary instruction program for instructing medical care to be guided consistent with a relatively healthy gastric function if the calculated primary pH differential demonstrates an acute change in pH. An alternative instruction program instructs that an alternative test be conducted if the calculated primary pH differential fails to demonstrate an acute change in pH. The alternative test includes: a) instructing the administering device to administer a standard dosage of gastric acid stimulant or suppressant that exceeds the minimum dosage, b) instructing the pH sensor to measure the patient's gastric juice pH after the administration of the standard dosage of the gastric acid stimulant or suppressant to obtain an alternative stressed gastric juice pH, and c) calculating an alternative pH differential between: i) one of the baseline gastric juice pH and the primary stressed gastric juice pH, and ii) the alternative stressed gastric juice pH, such that instructions are provided to guide medical care consistent with a relatively healthy gastric function if the calculated alternative pH differential demonstrates an acute change in pH, and instructions are provided to guide medical care consistent with a relatively unhealthy gastric function if the calculated alternative pH differential fails to demonstrate an acute change in pH. In some exemplary embodiments, the alternative pH differential is calculated between the baseline gastric juice pH and the alternative stressed gastric juice pH, while in other exemplary embodiments, the alternative pH differential is calculated between the primary stressed gastric juice pH and the alternative stressed gastric juice pH.2. Take Initial Stressed pH Measurement Early (Such as at Earliest Significant Gastric Response of Most People to Stimulant or Suppressant), and Take a Subsequent Stressed pH Measurement if a Negative Response is Determined

[0131] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments conduct an initial gastric system stress test, such as by calculating a pH differential between a baseline pH and a stressed pH that is taken early, and in some cases, at or soon after a minimum period defined by the earliest significant gastric response of many patients to a stress agent (including gastric acid stimulant or suppressant). Medical care can be guided consistent with a relatively healthy gastric function if the pH differential constitutes an acute change. An alternative gastric system stress test is conducted after a subsequent period if an acute change is not demonstrated, and medical care is guided based on the results of the alternative test, i.e., medical care is guided consistent with a relatively healthy / unhealthy gastric function depending on whether the pH differential constitutes an acute change after administration of the standard dosage. The subsequent period exceeds the minimum period, but is no greater than a duration of a healthy or relatively healthy volunteer's gastric response to the stress agent, i.e., the known or estimated duration of action of the stress or challenge agent. For example, the subsequent period may not exceed an estimated duration of gastric response to the stress agent.

[0132] This procedure provides enhanced results at least by providing the opportunity of expediting the test results. Patients demonstrating an acute change in gastric juice pH in the initial gastric system stress test can have medical care guided early, i.e., after the minimum period defined by the earliest significant gastric response of many patients to a stress agent, instead of having to wait until after a longer standard period. Even patients failing to demonstrate an acute change in gastric juice pH in the initial gastric system stress test may benefit by the closer monitoring of pH changes in the subsequent test, which provides additional information regarding gastric system health.

[0133] Exemplary embodiments are intended to cover taking stressed pH measurements after any and all applicable minimum and standard periods. For example, in some exemplary embodiments, the minimum period is approximately 15 minutes, such that the patient's gastric juice pH is measured at approximately 15 minutes after administration of the gastric system stress agent to obtain the initial stressed gastric juice pH. Also in some of these embodiments, the subsequent period is approximately 45 minutes, such that the patient's gastric juice pH is measured at approximately 45 minutes after the pentagastrin administration to obtain the subsequent stressed gastric juice pH.

[0134] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0135] An exemplary method includes measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, administering one of gastric acid stimulant and gastric acid suppressant, and estimating a minimum period for a gastric response to administration of the stimulant or suppressant. The patient's gastric juice pH is measured approximately at the minimum period to obtain an initial stressed gastric juice pH, and an initial pH differential, between the baseline gastric juice pH and the initial stressed gastric juice pH, is calculated to determine gastric function. Medical care is guided consistent with a relatively healthy gastric function if the calculated initial pH differential demonstrates an acute change in pH.

[0136] A subsequent test is conducted if the calculated initial pH differential fails to demonstrate an acute change in pH. The subsequent test includes: estimating a subsequent period for gastric response to administration of the stimulant or suppressant, the subsequent period exceeding the minimum period and being no greater than an estimated duration of gastric response to the stimulant or suppressant, measuring the patient's gastric juice pH approximately at the subsequent period to obtain a subsequent stressed gastric juice pH, calculating a subsequent pH differential between the baseline gastric juice pH and the subsequent stressed gastric juice pH to determine gastric function, guiding medical care consistent with a relatively healthy gastric function if the calculated subsequent pH differential demonstrates an acute change in pH, and guiding medical care consistent with a relatively unhealthy gastric function if the calculated subsequent pH differential fails to demonstrate an acute change in pH.b. Apparatus

[0137] An exemplary apparatus in accordance with this embodiment includes a pH sensor that measures the patient's gastric juice pH to obtain a baseline gastric juice pH, an administering device that administers one of gastric acid stimulant and gastric acid suppressant, and a processor that estimates a minimum period for a gastric response to the administration of the stimulant or suppressant. The pH sensor measures the patient's gastric juice pH approximately at the minimum period to obtain an initial stressed gastric juice pH. The processor calculates an initial pH differential between the baseline gastric juice pH and the initial stressed gastric juice pH to determine gastric function. The processor guides medical care consistent with a relatively healthy gastric function if the calculated initial pH differential demonstrates an acute change in pH.

[0138] A subsequent test is conducted if the calculated initial pH differential fails to demonstrate an acute change in pH. In the subsequent test, the processor estimates a subsequent period for gastric response to administration of the stimulant or suppressant, the subsequent period exceeding the minimum period and being no greater than an estimated duration of gastric response to the stimulant or suppressant, the pH sensor measures the patient's gastric juice pH approximately at the subsequent period to obtain a subsequent stressed gastric juice pH, and the processor calculates a subsequent pH differential between the baseline gastric juice pH and the subsequent stressed gastric juice pH to determine gastric function, such that the processor guides medical care consistent with a relatively healthy gastric function if the calculated subsequent pH differential demonstrates an acute change in pH, and the processor guides medical care consistent with a relatively unhealthy gastric function if the calculated subsequent pH differential fails to demonstrate an acute change in pH.c. Processor

[0139] An exemplary processor in accordance with this embodiment is used with a pH sensor that measures the patient's gastric juice pH to obtain a baseline gastric juice pH, and an administering device that administers one of gastric acid stimulant and gastric acid suppressant. The processor includes an estimating unit that estimates a minimum period for a gastric response to the administration of the stimulant or suppressant, a pH measurement instruction unit that instructs the pH sensor to measure the patient's gastric juice pH approximately at the minimum period to obtain an initial stressed gastric juice pH, and a calculation unit that calculates an initial pH differential between the baseline gastric juice pH and the initial stressed gastric juice pH to determine gastric function.

[0140] The processor also includes a primary instruction unit that instructs that medical care be guided consistent with a relatively healthy gastric function if the calculated initial pH differential demonstrates an acute change in pH, and an alternative instruction unit that instructs that a subsequent test be conducted if the calculated initial pH differential fails to demonstrate an acute change in pH. In the subsequent test, the processor: a) estimates a subsequent period for gastric response to administration of the stimulant or suppressant, the subsequent period exceeding the minimum period and being no greater than an estimated duration of gastric response to the stimulant or suppressant, b) instructs the pH sensor to measure the patient's gastric juice pH approximately at the subsequent period to obtain a subsequent stressed gastric juice pH, and c) calculates a subsequent pH differential between the baseline gastric juice pH and the subsequent stressed gastric juice pH to determine gastric function, such that instructions are provided to guide medical care consistent with a relatively healthy gastric function if the calculated subsequent pH differential demonstrates an acute change in pH, and instructions are provided to guide medical care consistent with a relatively unhealthy gastric function if the calculated subsequent pH differential fails to demonstrate an acute change in pH.d. Computer Program

[0141] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with a pH sensor that measures the patient's gastric juice pH to obtain a baseline gastric juice pH, and an administering device that administers one of gastric acid stimulant and gastric acid suppressant. The computer program includes an estimating program for estimating a minimum period for a gastric response to the administration of the stimulant or suppressant, a pH measurement instruction program for instructing the pH sensor to measure the patient's gastric juice pH approximately at the minimum period to obtain an initial stressed gastric juice pH, and a calculation program for calculating an initial pH differential between the baseline gastric juice pH and the initial stressed gastric juice pH to determine gastric function.

[0142] A primary instruction program instructs that medical care be guided consistent with a relatively healthy gastric function if the calculated initial pH differential demonstrates an acute change in pH, and an alternative instruction program for instructing that a subsequent test be conducted if the calculated initial pH differential fails to demonstrate an acute change in pH. The subsequent test includes: estimating a subsequent period for gastric response to administration of the stimulant or suppressant, the subsequent period exceeding the minimum period and being no greater than an estimated duration of gastric response to the stimulant or suppressant, instructing the pH sensor to measure the patient's gastric juice pH approximately at the subsequent period to obtain a subsequent stressed gastric juice pH, and calculating a subsequent pH differential between the baseline gastric juice pH and the subsequent stressed gastric juice pH to determine gastric function, such that instructions are provided to guide medical care consistent with a relatively healthy gastric function if the calculated subsequent pH differential demonstrates an acute change in pH, and instructions are provided to guide medical care consistent with a relatively unhealthy gastric function if the calculated subsequent pH differential fails to demonstrate an acute change in pH.C. Methodology Bases Other than pH Differential Based Tests

[0143] Still other exemplary embodiments can be categorized as different methods, apparatus, processors, computer programs, etc., for determining or helping to determine gastric system health using methodologies different or even unrelated to the measurements of pH differentials. The below listing of embodiments that use other methodologies to determine gastric system health is not intended as limiting, and instead is merely provided for exemplary purposes.

[0144] The use of methodologies that do not purely rely on pH differentials to determine gastric system health can be beneficial in numerous respects. For example, certain methodologies may provide advantages over relying on pH differentials (under all or only certain circumstances) in various respects, such as in terms of costs, reliability, accuracy, speed, efficiency, etc. In some cases, these other methodologies can be used with and / or in addition to pH differential measurements to enhance accuracy, reliability and / or efficiency of gastric system health determinations. Use of the other methodologies can thereby help to provide at least all of the benefits discussed above with regard to enhancing test accuracy and efficiency.1. Obtaining Multiple Stressed Gastric Juice Measurements, and Calculating a Rate of Change of pH Based on the Multiple Measurements

[0145] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments measure a patient's baseline gastric juice pH, administer a gastric system stress agent (such as gastric acid stimulant or suppressant, for example), and then obtain multiple stressed gastric juice pH values. A rate of change of gastric juice pH is calculated based on the baseline pH and the multiple stressed pH values, and gastric function is determined based on the calculated rate of change.

[0146] This procedure provides enhanced results at least because it can provide more data, and thus a deeper understanding of gastric function, than tests that rely purely on pH differential between baseline pH and a single stressed pH. This procedure may, in some cases, also enable gastric system health to be determined on an expedited basis. For example, in some cases, gastric system health can be determined early based on an initial high rate of pH change calculated from stressed pH values measured shortly after stress agent administration (and well prior to measurement of the stressed pH measurement forming the basis of tests that rely purely on pH differential).

[0147] Exemplary embodiments are intended cover any applicable manner of determining rate of change of gastric juice pH. For example, the patient's gastric juice pH can be measured on at least one of a continuous basis, substantially continuous bases, semi-continuous basis, and periodic basis. In some exemplary embodiments, the patient's gastric juice pH is measured on a continuous basis via streaming data.

[0148] Exemplary embodiments are also intended to cover any applicable use derived from the determined rate of change of gastric juice pH. In some exemplary embodiments, medical care is guided consistent with a relatively healthy gastric function if the calculated rate of change of gastric juice pH demonstrates an acute rate of change, while medical care is guided consistent with a relatively unhealthy gastric function if the calculated rate of change of gastric juice pH fails to demonstrate an acute rate of change.

[0149] Exemplary embodiments are further intended to cover integrations of other types of data, different from rate of change of gastric juice pH, in order to determine gastric system health. For example, the volume of the patient's gastric juice secreted after the stimulant or suppressant administration can be measured, and a guidance rate of change of gastric juice pH sufficient to indicate healthy gastric function can be set based on the measured gastric volume. In some of these exemplary embodiments, the guidance rate of change of gastric juice pH sufficient to indicate healthy gastric function can be set to be relatively lower if the measured gastric volume is relatively high, while the guidance rate of change of gastric juice pH sufficient to indicate healthy gastric function can be set to be relatively higher if the measured gastric volume is relatively low. A relatively healthy gastric function can be determined if the calculated rate of change of gastric juice pH equals or exceeds the guidance rate of change of gastric juice pH, while a relatively unhealthy gastric function can be determined if the calculated rate of change of gastric juice pH is less than the guidance rate of change of gastric juice pH.

[0150] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0151] An exemplary method includes measuring the patient's gastric juice pH to obtain a baseline gastric juice pH, administering a gastric acid stimulant or suppressant, and performing multiple measurements of the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain multiple stressed gastric juice pH values. A rate of change of gastric juice pH is calculated based on the baseline gastric juice pH and the stressed gastric juice pH values to determine gastric function, and medical care is guided based on the determined gastric function.b. Apparatus

[0152] An exemplary apparatus in accordance with this embodiment includes an administering device that administers a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that performs multiple measurements of the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain multiple stressed gastric juice pH values. A processor calculates a rate of change of gastric juice pH based on the baseline gastric juice pH and the stressed gastric juice pH values to determine gastric function, such that medical care can be guided based on the determined gastric function.c. Processor

[0153] An exemplary processor in accordance with this embodiment is used with an administering device that administers a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that performs multiple measurements of the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain multiple stressed gastric juice pH values.

[0154] The processor includes a calculation unit that calculates a rate of change of gastric juice pH based on the baseline gastric juice pH and the stressed gastric juice pH values, and a primary instruction unit that provides instructions to guide medical care consistent with a relatively healthy gastric function if the calculated rate of change of gastric juice pH demonstrates an acute rate of change. The processor also includes a secondary instruction unit that provides instructions to guide medical care consistent with a relatively unhealthy gastric function if the calculated rate of change of gastric juice pH fails to demonstrate an acute rate of change.d. Computer Program

[0155] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers a gastric acid stimulant or suppressant, and a pH sensor that measures the patient's gastric juice pH prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice pH, and that performs multiple measurements of the patient's gastric juice pH after the administration of the gastric acid stimulant or suppressant to obtain multiple stressed gastric juice pH values.

[0156] The computer program includes a calculation program for calculating a rate of change of gastric juice pH based on the baseline gastric juice pH and the stressed gastric juice pH values, and a primary instruction program for providing instructions to guide medical care consistent with a relatively healthy gastric function if the calculated rate of change of gastric juice pH demonstrates an acute rate of change. A secondary instruction program provides instructions to guide medical care consistent with a relatively unhealthy gastric function if the calculated rate of change of gastric juice pH fails to demonstrate an acute rate of change.2. Determining Gastric Function Based on Gastric Juice Volume Secreted after Administration of a Pharmacological Challenge Agent

[0157] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments determine gastric juice volume secreted after administration of a pharmacological challenge agent (such as a gastric system stress agent, including but not limited to gastric acid stimulants and suppressants), and guide medical care based on the measured gastric juice volume secreted. This procedure is inherently beneficial by providing an alternative to gastric system stress tests based solely on pH differential(s), and in some cases may provide specific benefits over such tests at least in terms of cost, reliability, accuracy, speed, efficiency, etc. In some cases, the gastric volume measurements can be used with and / or in addition to pH differential measurements to enhance accuracy, reliability and / or efficiency of gastric system health determinations, thereby providing benefits discussed above with regard to enhancing test accuracy and efficiency.

[0158] Exemplary embodiments are intended to cover any and all applicable implementations of the above volume based stress test. In some exemplary embodiments, the patient's gastric juice volume is measured prior to and after administration of the pharmacological challenge agent to obtain a baseline gastric juice volume and a stressed gastric juice volume. A volume differential, between the baseline and stressed gastric juice volumes, is calculated to determine the gastric juice volume secreted after the pharmacological challenge agent administration. In other exemplary embodiments, the patient's gastric juice contents are aspirated prior to the pharmacological challenge agent administration, and the gastric juice volume is measured after the administration of the pharmacological challenge agent to determine the gastric juice volume secreted.

[0159] Exemplary embodiments are also intended to cover any and all applicable usages and applications of the above volume based stress test. For example, in some exemplary embodiments, medical care is guided consistent with a relatively healthy gastric function if the measured gastric juice volume secreted demonstrates an acute change in volume, while medical care is guided consistent with a relatively unhealthy gastric function if the measured gastric juice volume secreted fails to demonstrate an acute change in volume.

[0160] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0161] An exemplary method includes administering a pharmacological challenge agent, determining gastric juice volume secreted a period after administration of the pharmacological challenge agent, and guiding medical care based on the measured gastric juice volume secreted.b. Apparatus

[0162] An exemplary apparatus in accordance with this embodiment includes an administering device that administers a pharmacological challenge agent, a volume sensor that measures gastric juice volume, and a processor that determines gastric juice volume secreted a period after the administration of the pharmacological challenge agent, and provides advice for guiding medical care based on the determined gastric juice volume secreted.c. Processor

[0163] An exemplary processor in accordance with this embodiment is used with an administering device that administers a pharmacological challenge agent, and a volume sensor that measures gastric juice volume. The processor includes a determination unit that communicates with the volume sensor to determine gastric juice volume secreted a period after the administration of the pharmacological challenge agent, and a primary instruction unit that provides instructions to guide medical care consistent with a relatively healthy gastric function if the determined gastric juice volume secreted demonstrates an acute change in volume. The processor also includes a secondary instruction unit that provides advice to guide medical care consistent with a relatively unhealthy gastric function if the determined gastric juice volume secreted fails to demonstrate an acute change in volume.d. Computer Program

[0164] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers a pharmacological challenge agent, and a volume sensor that measures gastric juice volume. The computer program includes a determination program for communicating with the volume sensor to determine gastric juice volume secreted a period after the administration of the pharmacological challenge agent, and a primary instruction program for providing instructions to guide medical care consistent with a relatively healthy gastric function if the determined gastric juice volume secreted demonstrates an acute change in volume. A secondary instruction program provides advice to guide medical care consistent with a relatively unhealthy gastric function if the determined gastric juice volume secreted fails to demonstrate an acute change in volume.3. Determining Gastric Function Based on Gastrointestinal Motility Change after Pharmacological Challenge Agent Administration

[0165] Exemplary embodiments, which are intended to cover all applicable mediums of expression including but not limited to methods, apparatus, processors, computer programs, etc., enhance the guiding of care based on gastric function that is detected / determined by challenging the gastric system. Some exemplary embodiments measure a patient's gastrointestinal motility prior to and after administration of a pharmacological challenge agent (such as a gastric system stress agent, including but not limited to gastric acid stimulants and suppressants) to determine baseline and stressed motilities, and calculate a motility differential between the baseline and stressed motilities.

[0166] This procedure is inherently beneficial by providing an alternative to gastric system stress tests based solely on pH differential(s) and / or volume differential(s), and in some cases may provide specific benefits over such tests at least in terms of cost, reliability, accuracy, speed, efficiency, etc. In some cases, the gastrointestinal motility measurements can be used with and / or in addition to pH and / or volume differential measurements to enhance accuracy, reliability and / or efficiency of gastric system health determinations, thereby providing benefits discussed above with regard to enhancing test accuracy and efficiency.

[0167] Exemplary embodiments are also intended to cover any and all applicable usages and applications of the above motility based stress test. For example, in some exemplary embodiments, medical care is guided consistent with a relatively healthy gastric function if the motility differential demonstrates an acute change in gastrointestinal motility, while medical care is guided consistent with a relatively unhealthy gastric function if the motility differential fails to demonstrate an acute change in gastrointestinal motility.

[0168] Examples of such exemplary embodiments are provided below in the contexts of methods, apparatus, processors, and computer programs. However, these contexts are merely provided for exemplary purposes, and exemplary embodiments are intended to cover all possible mediums.a. Method

[0169] An exemplary method includes measuring the patient's gastrointestinal motility to determine a baseline motility, administering a pharmacological challenge agent, and measuring the patient's gastrointestinal motility after the pharmacological challenge agent administration to determine a stressed motility. A motility differential, between the baseline motility and stressed motility, is calculated to determine gastric function, and medical care is guided based on the determined gastric function.b. Apparatus

[0170] An exemplary apparatus in accordance with this embodiment includes an administering device that administers a pharmacological challenge agent, and a motility sensor that measures the patient's gastrointestinal motility prior to the administration of the pharmacological challenge agent to determine a baseline motility, and that measures the patient's gastrointestinal motility after the pharmacological challenge agent administration to determine a stressed motility. A processor calculates a motility differential between the baseline motility and stressed motility to determine gastric function so that medical care can be guided based on the determined gastric function.c. Processor

[0171] An exemplary processor in accordance with this embodiment is used with an administering device that administers a pharmacological challenge agent, and a motility sensor that measures the patient's gastrointestinal motility prior to the administration of the pharmacological challenge agent to determine a baseline motility, and that measures the patient's gastrointestinal motility after the pharmacological challenge agent administration to determine a stressed motility. The processor includes a calculation unit that communicates with the motility sensor to calculate a motility differential between the baseline motility and stressed motility, and a primary instruction unit that guides medical care consistent with a relatively healthy gastric function if the motility differential demonstrates an acute change in gastrointestinal motility. The processor also includes a secondary instruction unit that guides medical care consistent with a relatively unhealthy gastric function if the motility differential fails to demonstrate an acute change in gastrointestinal motility.d. Computer Program

[0172] An exemplary computer program in accordance with this embodiment is used with a processor for guiding medical care of a patient based on detected gastric function, the processor being used with an administering device that administers a pharmacological challenge agent, and a motility sensor that measures the patient's gastrointestinal motility prior to the administration of the pharmacological challenge agent to determine a baseline motility, and that measures the patient's gastrointestinal motility after the pharmacological challenge agent administration to determine a stressed motility. The computer program includes a calculation program for communicating with the motility sensor to calculate a motility differential between the baseline motility and stressed motility, and a primary instruction program for guiding medical care consistent with a relatively healthy gastric function if the motility differential demonstrates an acute change in gastrointestinal motility. A secondary instruction program guides medical care consistent with a relatively unhealthy gastric function if the motility differential fails to demonstrate an acute change in gastrointestinal motility.D. Other Inventive Features

[0173] Exemplary embodiments include a myriad of other inventive features, some of which are combinable with any and all of the above exemplary embodiments, while others can be practiced in a separate and distinct manner from the above embodiments. As with the exemplary embodiments disclosed above, these other inventive features can be provided in any relevant form, i.e., methods, apparatus, processors, computer programs, etc.

[0174] A summary of features included in other exemplary embodiments is provided below. Each of the below features can either be practiced with and included in each of the above exemplary embodiments, or alternatively practiced separately from these embodiments. The below listing is merely provided for exemplary purposes and is not intended as a complete disclosure of inventive features.1. Guiding of Medical Care

[0175] Exemplary embodiments are intended to cover any applicable use or application of the pH differential based stress tests. In some exemplary embodiments, medical care is guided consistent with a relatively healthy gastric function if the calculated pH differential demonstrates an acute change in pH, such as at least one pH unit, while medical care is guided consistent with a relatively unhealthy gastric function if the calculated pH differential fails to demonstrate such an acute change. However, the change of one pH unit is merely provided for exemplary purposes, and exemplary embodiments are intended to cover any applicable parameters defining an acute change in pH.

[0176] In some exemplary embodiments, the guiding of medical care consistent with a relatively healthy gastric function includes providing medical advice relating to the performance of at least one of: initiation, maintenance, or increase of enteral feeding; failing to initiate, reduction, or termination of mechanical ventilation; and failing to initiate, reduction, or termination of use of vasoactive agents. In these and other exemplary embodiments, the guiding of medical care consistent with a relatively unhealthy gastric function includes providing medical advice relating to performance of at least one of: failing to initiate, reduction, or termination of enteral feeding; initiation, maintenance, or increase of mechanical ventilation; and initiation, maintenance, or increase of use of vasoactive agents.

[0177] However, the above disclosures are not intended to constitute a complete list of types of medical care that can be guided based on results of the disclosed stress test. For example, in other exemplary embodiments, the type of medical care to be guided includes at least one of: 1) applicability of enteral feeding, ventilation, or use of vasoactive agents; 2) patient disposition within a medical care facility; 3) detection of risk of stress ulcers; and 4) adequacy of resuscitation. In still other exemplary embodiments, the guiding of medical care includes providing medical advice relating to at least one of: determining patient disposition within a medical care facility; determining adequacy of resuscitation; detecting risk of developing stress ulcers; guiding usages of suppressants to reduce risk of stress ulcers and / or bleeding; determining risk of aspiration and guiding care to reduce such risk; aiding detection of intra-abdominal hypertension and / or abdominal compartment syndrome; and monitoring of gastric motility to reduce gastric residuals and risk of aspiration. Some of these embodiments include other applicable tests and measurements to enhance the guidance of care. One such embodiment continuously measures the patient's esophageal pH to determine reflux events and risk of aspiration, and then provides advice relating to at least one of patient positioning, acid suppressant medication, and enteral feeding route, based on the determined likelihood of aspiration.2. Pharmacological Challenge Agents

[0178] Exemplary embodiments are intended to cover administration of any applicable pharmaceutical challenge agent, such as any gastric system stress agent, including but not limited to gastric acid stimulants and suppressants. Some exemplary embodiments administer pentagastrin as a stimulant, and / or omeprazole as a suppressant.a. Determining Type of Pharmacological Challenge Agent

[0179] Exemplary embodiments are intended to cover any applicable method of determining the type of gastric acid stimulant or suppressant to be administered. Some exemplary embodiments determine the type of gastric acid stimulant or suppressant based on baseline gastric juice pH. Other exemplary embodiments determine the type of gastric acid stimulant or suppressant to be administered based on patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, and genetics.b. Determining Dosage

[0180] Exemplary embodiments are intended to cover any applicable method of determining dosage, such as a pharmaceutically effective dosage, of the pharmaceutical challenge agent, such as gastric juice stimulant or suppressant. For example, some exemplary embodiments determine the pharmacologically effective dosage of gastric acid stimulant or suppressant based on the type of medical care to be guided. Other exemplary embodiments administer a set dosage of stimulant or suppressant. In one such embodiment, 6 mcg / kg of pentagastrin is administered.

[0181] In other exemplary embodiments, the determination of the pharmacologically effective dosage of gastric acid stimulant or suppressant is based on patient characteristics, including at least one of age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, and genetics. In some of these embodiments, the pharmacologically effective dosage of gastric acid stimulant (such as pentagastrin) or suppressant (such as omeprazole) is determined based on patient weight. As an example of this weight based dosing, one embodiment determines dosages such that: 250 mcg is determined to be the pharmacologically effective dosage for patients weighing 40-70 kg, 500 mcg is determined to be the pharmacologically effective dosage for patients weighing 71-100 kg, and 750 mcg is determined to be the pharmacologically effective dosage for patients weighing more than 100 kg. In another embodiment, the pharmacologically effective dosage of pentagastrin is based on 6 mcg / kg, such that 300 mcg is determined to be the pharmacologically effective dosage for a patient weighing 50 kg, 450 mcg is determined to be the pharmacologically effective dosage for patients weighing 75 kg, and 600 mcg is determined to be the pharmacologically effective dosage for patients weighing 100 kg.

[0182] Exemplary embodiments are also intended to cover issues involving dosing other than determining a pharmaceutically effective dose. For example, some exemplary embodiments determine a maximum dosage of gastric acid stimulant or suppressant, such that a dosage of gastric acid stimulant or suppressant is administered that does not exceed the maximum dosage. Exemplary embodiments are intended to cover any manner of determining the maximum dosage. In some embodiments, the maximum dosage is determined based on potentially disadvantageous side effect reduction.

[0183] Exemplary embodiments are intended to cover any applicable manner of introduction of the pharmacological challenge agent, such as gastric acid stimulant or suppressant. Exemplary embodiments also cover tailoring the manner of administration of the gastric acid stimulant or suppressant. In one embodiment, the manner of introduction of gastric acid stimulant or suppressant is determined based on whether a gastric acid stimulant or a gastric acid suppressant is administered. In other words, the fact that a stimulant or suppressant is used determines the manner of administration. In one such embodiment, gastric acid stimulants are administered subcutaneously, while gastric acid suppressants are administered intravenously.c. Manner of Administration

[0184] In other exemplary embodiments, the manner of introduction of gastric acid stimulant or suppressant is determined based on patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, and genetics. In one such embodiment, the manner of introduction is tailored such that gastric acid stimulant is administered intravenously for patients with relatively poor peripheral circulation.3. Period Separating Agent Administration and Stress Measurement

[0185] Exemplary embodiments are intended to cover any applicable period separating pharmacological challenge agent (such as gastric acid stimulant or suppressant) administration and the measuring of the patient's gastric juice pH, gastric juice volume, gastrointestinal motility, etc., to determine stressed pH, volume, motility, etc. Some exemplary embodiments set a standard period between the administering of the gastric acid stimulant or suppressant and the measuring of the patient's gastric juice pH, volume, motility, etc., to obtain the stressed gastric juice pH, volume, motility, etc. In one such embodiment, the standard period is approximately 45 minutes, such that approximately 45 minutes always separates the gastric acid stimulant or suppressant administration and the measuring of gastric juice pH, volume, motility, etc. to obtain the stressed gastric juice pH, volume, motility, etc.4. Aspiration

[0186] Exemplary embodiments are intended to cover any applicable manner of facilitating and / or enhancing accuracy of gastric juice pH measurements. For example, some exemplary embodiments aspirate gastric contents prior to the measuring of the patient's gastric juice pH to obtain a stressed gastric juice pH to provide enhanced results, such as to enhance freshness of gastric juice for measurement. In other words, some exemplary embodiments aspirate the gastric contents in an effort to remove gastric contents secreted prior to gastric response to the pharmacological challenge agent so that the gastric contents measured reflect those contents secreted as a result of the challenge agent. In one such embodiment, the aspiration of the gastric contents is performed after the administration of the gastric acid stimulant or suppressant, but of course prior to the measuring of the stressed gastric juice pH. In this exemplary embodiment, the aspiration can be performed approximately 15 minutes prior to the measuring of the stressed gastric juice pH.5. pH Differential

[0187] Exemplary embodiments are intended to cover any beneficial usage of pH differentials to indicate gastric system health. Some exemplary embodiments set a standard pH differential as indicating a healthy gastric system for all patients, while other embodiments use various criteria to vary the pH differential sufficient to indicate healthy gastric function. One such embodiment measures the volume of the patient's gastric juice secreted after the stimulant or suppressant administration, and sets a guidance pH differential sufficient to indicate healthy gastric function based on the measured gastric volume. In other words, the guidance pH differential sufficient to indicate healthy gastric function varies depending on the volume of the patient's gastric juice secreted after the stimulant or suppressant administration. The guidance pH differential sufficient to indicate healthy gastric function can be set to be relatively lower if the measured gastric volume is relatively high, or set to be relatively higher if the measured gastric volume is relatively low. A relatively healthy gastric function can be determined if the calculated pH differential equals or exceeds the guidance pH differential, or a relatively unhealthy gastric function can be determined if the calculated pH differential is less than the guidance pH differential.6. Additional Tests and Measurements

[0188] Exemplary embodiments are intended to cover additional tests conducted subsequent to any and all of the disclosed tests based on pH differential, gastric juice volume, gastrointestinal motility, etc., that enhance the guidance of medical care. In some embodiments that guide care to include enteral feeding, the patient's gastric juice pH is measured after initiation of enteral feeding to obtain a post-feeding gastric juice pH, and medical care is guided based on the post-feeding gastric juice pH. In one such embodiment, care is guided to include providing advice to maintain or increase the rate of nutrition if the post-feeding gastric juice pH is less than or equal to the stressed gastric juice pH, or providing advice to decrease the rate of nutrition if the post-feeding gastric juice pH is greater than the stressed gastric juice pH.

[0189] Other exemplary embodiments that involve tests conducted subsequent to the disclosed tests based on pH differential, gastric juice volume, gastrointestinal motility, etc., performing multiple measurements of the patient's gastric juice pH after obtaining the stressed gastric juice pH, and displaying the multiple measurements. The multiple pH measurements can be displayed as a curve via a graph, with the x-axis representing the time that the pH measurements were taken and the y-axis representing pH values.

[0190] Exemplary embodiments are intended to cover any applicable and beneficial usages and applications of the displayed pH measurements disclosed above. For example, some exemplary embodiments calculate the area defined under the curve, and provide medical advice based on the calculated area. One such embodiment determines the rate of change of the multiple pH measurements via the derivative of the curve, and provides medical advice based on the determined rate of change, such that a relatively fast rate of change indicates a relatively healthy gastric function, while a relatively slow rate of change indicates a relatively unhealthy gastric function. Another embodiment determines the period for reaching the pH low point via the second derivative of the curve, and provides medical advice based on the determined period, such that a relatively short period indicates a relatively healthy gastric function, while a relatively long period indicates a relatively unhealthy gastric function.

[0191] Yet another embodiment stores the curve data representing the multiple pH measurements as a function of time and patient profile data including at least one of age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, and genetics, compares the stored curve to curves of multiple patients with similar profiles, and provides medical advice based on the comparison. The comparing can include calculating differences between data points and the curve using the total non-linear least squares data modeling technique. Medical advice can be provided based on responses to medical care of patients with similar profiles and / or gastric contents volume measurements. Alternatively, medical advice can be provided based on algorithms that receive data relating to at least one of pH measurements, gastric contents volume measurements, and patient profile, and recommend certain medical treatments based on the data. The algorithms can be based on non-linear regression analysis, can have artificial intelligence capabilities, or can take any other applicable or beneficial form.

[0192] Other exemplary embodiments involve tests conducted prior to, during, or subsequent to, the disclosed tests based on pH differential, gastric juice volume, gastrointestinal motility, etc. One such embodiment determines an angle of incline of the patient laying on a bed or table, the angle being defined by a line, extending from the patient's sternal notch to umbilicus, and a surface on which the bed or table rests. Medical care can then be guided based on the determined angle of incline.

[0193] These and other features and advantages are described in, and will be apparent from, the following detailed description of various exemplary embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0194] Various examples and embodiments are described in detail with reference to the following figures, wherein: Fig. 1 is a schematic of an apparatus; Fig. 2 is a schematic of an indicator / controller in accordance with an exemplary embodiment; Fig. 3 is a schematic of an indicator / controller in accordance with another exemplary embodiment; Fig. 4 is a schematic of a pop-up screen of the exemplary indicator / controller of Fig. 3; Fig. 5 is a schematic of another pop-up screen of the exemplary indicator / controller of Fig. 3; Fig. 6 is a schematic of an apparatus in accordance with another exemplary embodiment, and particularly shows an aspirator that aspirates gastric contents; Fig. 7 is a schematic of an apparatus in accordance with another exemplary embodiment, and particularly shows a volume sensor that measures gastric volume; Fig. 8 is a schematic of an apparatus in accordance with another exemplary embodiment, and particularly shows an incline sensor that determines an angle of incline of a patient; Fig. 9 is a schematic of an apparatus in accordance with another exemplary embodiment, and particularly shows an esophageal sensor to monitor a patient's esophageal pH; Fig. 10 is a schematic of an apparatus in accordance with another exemplary embodiment, and particularly shows a sensor that measures baseline pH and a separate sensor that measures stressed pH; Fig. 11 is a schematic of an apparatus in accordance with another exemplary embodiment, and particularly shows a pH sensor that performs multiple measurements of gastric juice pH to obtain multiple baseline and / or stressed gastric juice pH values; Fig. 12 is a schematic of an apparatus in accordance with another exemplary embodiment, and particularly shows a motility sensor that measures gastrointestinal motility; and Fig. 13 is a flowchart of an exemplary method and apparatus for guiding care based on H+ concentration differential(s). DETAILED DESCRIPTION

[0195] For convenience of explanation, exemplary embodiments are described below with reference to the figures in the context of guiding medical care of human patients based on detected gastric function. However, the specifically disclosed embodiments are not intended to be limiting and are merely provided for exemplary purposes. For example, all embodiments are intended to be used in any applicable field of endeavor, such as care of non-human patients including but not limited to animals, less complex organisms, chemical or pharmaceutical production, etc.

[0196] A table of contents of exemplary embodiments specifically disclosed in the Detailed Description is provided below. I. Overview A. General Procedure B. Exemplary Uses of the Procedure C. Exemplary Recipients of the Procedure II. Types of Pharmaceutical Challenge Agents (Stimulants / Suppressants) A. Use of Stimulant Versus Suppressant 1. Automatic Use of Stimulant or Suppressant 2. Based on Baseline Gastric Juice pH 3. Ambiguous Results B. Stimulant Administration in Patients with Relatively Low Gastric Juice pH 1. Sodium Citrate 2. Sodium Bicarbonate 3. Gastric Acid Suppressant 4. Administrating Neutralizing Agent Prior to Measuring Baseline Gastric Juice pH C. Exemplary Stimulants 1. Pentagastrin 2. Stimulant Selection Methodologies 3. Other Exemplary Stimulants D. Exemplary Suppressants 1. Omeprazole and Ranitidine 2. Suppressant Selection Methodologies III. Dosages and Administrations of Pharmacological Challenge Agents (Stimulants / Suppressants / Acid Neutralizers) A. Dosages B. Administrations C. Vial Size IV. Gastric Juice H+ / pH Measurement, Determining GI Tract's Response to Challenge, and Guiding Care Based on Measured H+ / pH A. Timing of Gastric Juice H+ / pH Measurement B. Exemplary Methods and Apparatus for Determining Gastric Juice H+ / pH 1. Gastric Juice Obtaining / Sampling Device 2. H+ / pH Measuring Device 3. Enhanced pH Measurements 4. Calibration 5. Other Exemplary Embodiments C. Methods and Apparatus for Determining GI Tract's Response to Challenge and Guiding Care Based on Determined H+ / pH 1. Gastric Juice H+ / pH Data Interpretation a. Gastric Juice pH Differential b. Gastric Juice H+ Concentration Differential c. Gastric Juice pH, H+ Concentration, and Volume d. Gastric Juice pH, H+ Concentration, and Volume Trending e. Gastric Juice pH, H+ Concentration, and Volume Algorithms 2. Spectrum of Intensities of Care 3. Gastric Juice pH Indicator / Controller a. Dedicated Inputs / Outputs b. Touchscreen Display c. Incline Controller d. Other Exemplary Structures and Operations D. Exemplary Packaging of Equipment 1. Kit 2. Processor 3. Computer Program V. Other Exemplary Types of Enhanced Care A. Disposition of Patients Within a Hospital B. Adequacy of Resuscitation C. Detection of Risk for Stress Ulcers D. Detection of Effect of Acid Suppressant Medication E. Detection of Risk of Aspiration of Gastric Contents F. Gastric Residual Volume Monitoring G. Detection of Gut Ischemia in Intra-abdominal Hypertension H. Drug Absorption I. Enteral Tolerance J. Combination of Methodologies in Guiding Care K. Exemplary Processes and Devices in Guiding Care VI. Other Diagnostic Methodologies A. Gastric Perfusion 1. Pulse Oximetry 2. Near Infrared Spectroscopy B. Gastric Volume C. Motility D. Combination of Methodologies VII. Other Therapeutic Exemplary Embodiments A. Feeding Intolerance 1. OverviewA. General Procedure

[0197] Exemplary embodiments generally relate to guiding medical care based on detected gastric function. For example, an amount, such as an effective dose, of a pharmacological challenge agent, such a gastric acid stimulant or suppressant, is administered, and then a change, such as an acute change, in the gastric juice pH is measured.

[0198] In some exemplary embodiments, patients demonstrating significant or sufficient change in gastric juice pH may have their medical care normalized in an accelerated fashion, while those not responsive may not, and may even require more support. However, in some situations, such as with patients failing to demonstrate an acute change in gastric juice pH over a prolonged period, other exemplary embodiments include cautiously initiating enteral feeding. For example, in these exemplary embodiments, enteral feeding is initiated at a slow rate and closely monitored to quickly recognize any negative side effects that would warrant cessation of the enteral feeding. However, the above disclosure is merely provided for exemplary purposes, and other embodiments may be significantly different. For example, some exemplary embodiments do not even monitor gastric juice pH, and instead employ other methodologies, such as monitoring gastric volume. In fact, exemplary embodiments are intended to cover any method of assessing gastric function.B. Exemplary Uses of the Procedure

[0199] The ability of the gastric cells to respond to a pharmacological challenge, such as the one disclosed above, is a good indicator of the perfusion and function of the gastrointestinal tract. In contrast to related art pharmacological tests for use in the diagnoses of specific chronic illnesses and rare endocrine disorders, the exemplary embodiments relate to the use of this challenge test to guide the care of patients suffering from a wide variety of illnesses. These illnesses include, and are not limited to, acute critical illnesses, and also include illnesses related to or unrelated to the gastrointestinal tract. Exemplary embodiments can also be used for patients who are subjected to a wide variety of treatments, including those directly related to the gastrointestinal tract as well as those unrelated to the gastrointestinal tract. For example, exemplary embodiments can allow for the monitoring of organs unrelated to gastric acid secretion or suppression per se.

[0200] Thus, exemplary uses of this test may include assessing gastrointestinal perfusion and / or gastric function in order to (among other things): 1.) guide the decision to extubate and / or wean a patient from mechanical ventilation (i.e. decrease ventilating support), or to increase ventilating support; 2.) guide the decision to initiate, increase, terminate, or wean enteral feeding; 3.) guide the decision to initiate, increase, terminate, or wean vasoactive agents; 4.) guide decisions relating to care (including critical care) options based on the adequacy of resuscitation; 5.) guide usages of acid suppressants to more effectively manage the risk of stress ulcers and / or bleeding; 6) determining risk of aspiration and guiding care to reduce such risk; 7.) aiding detection of intra-abdominal hypertension and / or abdominal compartment syndrome; and / or 8.) monitoring of gastric motility to reduce gastric residuals and risk of aspiration. However, as disclosed above, exemplary embodiments are not limited to these uses and can cover other uses not specifically described herein, such as those directly related to gastric function as well as those not directly related to or even completely unrelated to the gastric function.C. Exemplary Recipients of the Procedure

[0201] Any patient with an acute or other illness may be subjected to and / or benefit from the above exemplary procedure. As an example, patients receiving care in an ICU or similar setting following surgery, injury, trauma, or acute medical illness, are likely candidates. In particular, patients with acute organ failure are at risk for inadequate gastrointestinal perfusion and dysfunction and are candidates for use of this method. Patients for whom decisions need to be made regarding either initiating, terminating, weaning, or otherwise modifying enteral feeding, vasoactive agents, mechanical ventilation, acid suppressants, and / or motility agents, may benefit from the use of the disclosed method. These patients face acute medical situations, in which their condition may be changing and appropriate changes in medical treatment may be required.

[0202] However, exemplary embodiments are not limited to the above exemplary patients. For example, exemplary embodiments may be applicable to people who are not subjected to critical care. Exemplary embodiments may be applicable to non-ICU patients at a hospital, patients at a nursing home (such as at an assisted living facility, for example). However, the disclosed procedures can also be used for patients who are not even hospitalized. Exemplary embodiments are intended to cover apparatus and methods performed outside of a professional care facility, and may even be performed by the patient himself / herself. In fact, exemplary embodiments are not even limited to human patients and can be performed on animals, such as pets, zoo animals, etc., or even less complex organisms.II. Types of Pharmacological Challenge Agents (Stimulants / Suppressants)

[0203] Exemplary embodiments are intended to cover and include any currently known or later developed methods, apparatus, compositions, etc., that challenge a patient's gastrointestinal (GI) tract or otherwise enable assessment of gastric function. For example, exemplary embodiments can include, but are not limited to, pharmacological challenge agents, such as any one or more currently known or later developed gastric acid stimulants or suppressants. Any one of multiple conditions of the patient, such as gastric juice pH, gastric volume, etc., can be monitored before and after administration of the pharmacological challenge agent (such as gastric acid stimulant or suppressant) to assess gastric function. Patient care, such as initiating, terminating, or otherwise modifying ventilation, enteral feeding, use of vasoactive agents, use of acid suppressants, and / or use of motility agents, for example, can then be performed based on this gastric function assessment.

[0204] Exemplary uses of gastric acid stimulants and suppressants are discussed below for exemplary purposes only. As discussed above, other exemplary embodiments are intended to cover any method of assessing gastric function and can include methods that do not include use of gastric acid stimulants and suppressants.A. Use of Stimulant Versus Suppressant

[0205] Exemplary embodiments that assess gastric function by using gastric acid stimulants and / or suppressants are intended to cover and include use of either gastric acid stimulants or suppressants, as well as use of both stimulants and suppressants. In other words, some embodiments include use of only stimulants, while others include use of only suppressants, and still others include use of both stimulants and suppressants.1. Automatic Use of Stimulant or Suppressant

[0206] The use of a stimulant versus a suppressant can be automatically determined, such as via automatic protocols. For example, a stimulant may always be used in some exemplary embodiments, while other exemplary embodiments may always use a suppressant. Exemplary embodiments that always use a stimulant or always use a suppressant can be beneficial because of simplicity. In other words, methods in accordance with these exemplary embodiments are easy to perform because there is no analysis as to whether a stimulant or suppressant is to be used, which may be beneficial by reducing performance errors, increasing speed of performance, etc.

[0207] As one exemplary alternative to always using a stimulant or always using a suppressant, the use of a stimulant or suppressant can be dictated based on one or more patient characteristics. These patient characteristics can include one or a combination of factors, including but not limited to: age, gender, fitness, weight, body composition such as percentage of body fat, ethnicity, family history, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable.2. Based on Baseline Gastric Juice pH

[0208] However, still other exemplary embodiments can include an analysis as to whether a benefit may be achieved via use of a stimulant verses a suppressant (or acid neutralizer), and vice versa, to ultimately assess gastric function. Exemplary embodiments are intended to cover and include any methods and apparatus for making this determination. For example, this determination can be made based on the detected baseline gastric juice pH. It may be beneficial to use a gastric acid stimulant if the baseline gastric juice pH is greater than a certain amount, such as 2.5 pH units or in some cases 3 pH units. Alternatively, it may be beneficial to use a gastric acid suppressant if the baseline gastric juice pH is less than a certain amount, such as 2.5 pH units and in some cases 3 pH units. In other words, a relatively high baseline gastric juice pH may, under certain circumstances, make it beneficial to use a gastric acid stimulant, while a relatively low baseline gastric juice pH may warrant a gastric acid suppressant or use of an acid neutralizer before the stimulant is used.

[0209] If the baseline gastric juice pH is very low, e.g., 1 or 2 pH units, then even in the presence of good gastric function, it will be difficult (or unlikely) to detect a significant decrease in pH in response to the stimulant. This difficulty relates to the fact that pH is a LOG function, and thus the amount of acid needed for the pH to decrease from 2 to 1 is much greater than the amount of acid needed for the pH to decrease from 6 to 5. In cases with very low baseline gastric juice pH, it may be desirable to use a gastric acid suppressant in the test and assess for an increase in gastric juice pH. Alternatively, and as discussed in more detail below in section II(B), the baseline gastric juice pH can be increased by administering an acid suppressant (e.g., H2 blocker) or acid neutralizer (e.g., sodium citrate), and then administering an acid stimulant for the test using the new (and higher) baseline gastric juice pH, e.g., pH of 2.5, 3, 4 pH units, or higher.

[0210] The above embodiment is only provided as one example and is not intended to be limiting. For example, other factors can be used to dictate usage of a gastric acid stimulant versus a suppressant, including but not limited to patient characteristics, such as one or any combination of factors, including but not limited to: age, gender, fitness, weight, body composition such as percentage of body fat, ethnicity, family history, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable.3. Ambiguous Results

[0211] A positive signal indicating a healthy gastric function may be manifested by a change in several pH units from the baseline value, although a change of 1.0 pH unit in response to the challenge agent is usually indicative of a positive signal. A change of 1 pH unit typically unambiguously indicates a relatively healthy gastric function because, as discussed above, gastric acid production measured in pH units is a LOG function. Therefore, a decrease in "only" 1 pH unit corresponds to a 10 fold change, e.g., 1000 percent increase, in the hydrogen ion concentration.

[0212] However, failure to demonstrate a change of 1 pH unit or more does not necessarily indicate an unhealthy gastric function for use to guide medical care as disclosed above. Thus, exemplary embodiments are directed to situations in which the differential between the baseline and stressed pH tests is less than one.

[0213] In accordance with one such exemplary embodiment, after an ambiguous test (resulting in a pH differential of less than 1 pH unit), the test is repeated with the opposite pharmacological agent. For example, if stimulant (such as pentagastrin) is initially used and yields a negative response (failing to demonstrate an acute change in gastric juice pH, such as a change of 1 pH unit), a challenge test is subsequently conducted with a suppressant (such as with omeprazole). In this case, it may be beneficial to allow for at least 1-3 hours in between tests. This exemplary embodiment may be particularly applicable in situations where the baseline pH itself is moderately low, such as 2.0 - 3.0 pH units.

[0214] For patients continuing to fail to demonstrate an acute change in gastric juice pH for an extended period, it may be beneficial to conduct a pharmacological challenge once every 1-3 days, although more frequent measurements can be made if deemed useful. If the patient is receiving enteral nutrition, it may be preferable to discontinue feeding for several hours (e.g., 2 hrs.) prior to a pharmacological challenge. Alternatively, one can discontinue feeding immediately prior to the test but begin the test by first removing / aspirating all of the gastric contents (including enteral feeds) through the indwelling tube (e.g. nasogastric Salem Sump tube). At this point after a brief period of equilibration (e.g., 15 minutes), the baseline gastric pH can be determined and the pharmacological challenge initiated. This reduces, minimizes or prevents any confounding effect from the presence of significant quantities of residual enteral feeds or other gastric contents, e.g. gastric secretions.B. Stimulant Administration In Patients with Relatively Low Gastric Juice pH

[0215] As indicated above in section II(A)(2) (Use of Stimulant Versus Suppressant / Based on Baseline Gastric Juice pH), it may be beneficial to use a gastric acid stimulant if the baseline gastric juice pH is greater than a certain amount, such as 2.5 or 3 pH units. Most critically ill patients typically have a gastric juice pH sufficiently high enough to allow for a reduction following administration of the gastric acid stimulant, e.g., pentagastrin. Thus, a gastric acid stimulant can typically be used as the pharmacological challenge agent.

[0216] However, some patients have a relatively low baseline gastric juice pH, such as less than 2.5 pH units. The exemplary embodiments discussed in section II(A)(2) above administer a gastric acid suppressant to perform the pharmacological challenge under these circumstances. However, alternatively, a pharmacological agent could be administered to raise the gastric juice pH to a sufficiently high level to enable measurement of gastric function challenge with a gastric acid stimulant.

[0217] Thus, exemplary embodiments are intended to cover additional steps to enable usage of stimulants for patients evidencing a lower baseline gastric juice pH. For example, for patients evidencing a relatively low baseline pH, such as less than 2.5 pH units, an additional step of neutralizing the pH in the stomach can be performed by administering a small dose / volume of concentrated buffer / base into the stomach, such as through an indwelling tube with access to the stomach, e.g., commonly a nasogastric or orogastric tube.

[0218] Fig. 1 shows an exemplary administering device 102 that administers to a patient the pharmacological agent to raise the gastric juice pH to a sufficiently high level to enable measurement of gastric function challenge with the gastric acid stimulant. However, the administering device 102 shown in Fig. 1 is not intended as limiting, and as discussed above, exemplary embodiments are intended to cover any currently known and later developed methods and apparatus for introducing the pharmacological agent. For example, the exemplary administering device 102 shown in Fig. 1 is not intended as limiting with regard to structure of the device, manner of administration, location on the patient of administration, etc.1. Sodium Citrate

[0219] For example, if the baseline gastric juice pH is low (e.g., less than or equal to 2.5 pH units), 5-30 ml (1 / 2 to 1 ounce) of a 0.3 mole / L commercially available non-particulate antacid (e.g., sodium citrate) can be administered via the NGT or OGT, and the gastric juice pH can be measured at a later time, such as in 5 minutes. This administration should increase the gastric juice pH in most patients and may allow for a more reliable determination of pentagastrin (or other stimulant) induced gastric acid stimulation. If the above antacid administration is not sufficient, then an additional dose of this antacid can be administered to attain a higher gastric juice pH, such as pH of at least 4 pH units prior to challenging the patient with gastric acid stimulant.

[0220] Many over-the-counter antacids are particulate. The administration of a particulate antacid is not as desirable since if it gets into the lungs, e.g., after aspiration of gastric contents, it can cause toxicity. For this reason, in situations of low baseline gastric pH it is preferable to raise the pH with a non-particulate antacid such as sodium citrate or sodium bicarbonate (describe above) since this will minimize the risk of aspiration in hospitalized patients who are already at increased risk of aspiration of gastric contents.

[0221] Table 2 (below), as disclosed in Gibbs, Charles P., Lynn Spohr, and Donald Schmidt. The Effectiveness of Sodium Citrate as an Antacid. Rep. no. 57:44-46, 1982. Ed. Ronald D. Miller. American Society of Ancsthesiologists. Print., hereafter "Gibbs," shows that 30 ml of 0.3 M sodium citrate can neutralize up to 255 ml of acid (pH 1.0). This disclosure is particularly relevant to the above analysis because gastric volume of a patient is typically less than 200 ml in the fasted state. Table 2. Volume (ml) of HCI ( pH 0.8, 1 and 1.5) Neutralized by 30 ml 0.3 M Sodiu Citrate, Kolantyl Gel ®< , and Mylanta ®< pHHydrochloric Acid0.811.5Sodium Citrate (8.5)140255750Kolantyl Gel ®< (8.1)100160360Mylanta ®< (8.0)75100300

[0222] In another example, Atanassoff, Peter G., Roman Rohling, Eli Alon, and Sorin J. Brull. "Effects of Single-dose Oral Ranitidine and Sodium Citrate on Gastric PH during and after General Anesthesia."Canadian Journal of Anesthesia 42.5 (1995): 382-86. Print., hereafter "Atanassoff (1995)," studied the effects of sodium citrate on gastric juice pH. The gastric juice pH in elective surgical patients was (mean ± SEM) 1.2±0.1, at baseline prior to the administration of sodium citrate. Sodium citrate (50 ml of 0.3 M) administered into the stomach via a nasogastric tube significantly increased the gastric juice pH to a mean of 4.8 (range 6.7-7.0) within two minutes of administration. Figure 3 of this publication demonstrates that gastric juice pH was well maintained above 6 for at least 2 hours after administration.

[0223] In another example, Dewan, David M. "Sodium Citrate Pretreatment in Elective Cesarean Section Patients." ANESTH ANALG 64.34 (1985): 382-86. Print., hereafter "Dewan," reported that administration of 30 ml of 0.3 M sodium citrate resulted in a significant increase in gastric juice pH when used as pretreatment in elective cesarean section patients. These and other publications report effectiveness of sodium citrate to increase gastric juice pH, and in particular prior to surgery requiring general anesthesia. For this reason, sodium citrate is administered to many patients prior to general anesthesia to reduce the risk of possible aspiration with acidic gastric contents.2. Sodium Bicarbonate

[0224] As an alternative to sodium citrate, sodium bicarbonate, which is an FDA approved and commercially available drug typically available in ICUs, can be used to raise the gastric juice pH to a sufficiently high level to enable measurement of gastric function with a gastric acid stimulant. For example, 8.4% sodium bicarbonate (50 ml vial) (such as is disclosed in "Hospira Sodium Bicarbonate Injection 8.4% 50 Ml Vials - Mountainside Medical Equipment." Medical Supplies / Medical Equipment / Hospital Medical Supplies / Hospital Equipment. Web. 02 June 2011. <http: / / www.mountainside-medical.com / products / Sodium-Bicarbonate.html>., hereafter "Hospira," ), can be used. In particular, 5 mls of this 8.4% solution can be administered into a patient's stomach at least 15 minutes prior to baseline measurement of gastric juice pH and administration of stimulant, such as pentagastrin. Approximately 5 ml of this drug is adequate to neutralize 50 ml of gastric juice that has a pH of 1.0 unit.

[0225] As an alternative to this procedure, 1 ml of this sodium bicarbonate buffer solution can be administered every 10 minutes, checking the pH after each administration and continuing until the pH rises to at least 3 units. As a further alternative, 15 ml of a 0.3 ml of a 0.3 M solution of sodium citrate can be administered every 10 minutes, checking the pH after each administration and continuing until the pH rises to at least 3 units. These exemplary embodiments involve simple titration of acid with a base, such as known base, such as is disclosed in "Neutralization (chemistry)." Wikipedia, the Free Encyclopedia. Wikimedia Foundation, Inc., 13 Apr. 2011. Web. 13 Apr. 2011. <http: / / cn.wikipedia.org / wiki / Neutralization (chemistry)>., hereafter "Neutralization (chemistry),". This disclosure explains that, in chemistry, neutralization is a chemical reaction whereby an acid and a base react to form a salt, and discloses an application in which excess gastric acid in the stomach (acid indigestion) is typically neutralized by the ingestion of sodium bicarbonate (NaHCO3) or another neutralizing agent, such as an antacid.3. Gastric Acid Suppressant

[0226] As an alternative to using the above compositions that neutralize the gastric juice pH in the stomach in situations involving low baseline gastric juice pH, such as a pH of less than 2.5 or 3.0 units, a gastric acid suppressant (e.g., ranitidine 50 mg IV) can be administered. Based on the pharmacokinetics and pharmacodynamics effects of ranitidine, this administration should increase the gastric pH over the next several hours after administration. For example, at four hours after administration of IV ranitidine, the gastric juice pH should be sufficiently high (e.g., at least 2.5, 3.0, or 4.0 pH units) to enable measurement of gastric function challenge with a gastric acid stimulant, such as pentagastrin.

[0227] For example, Atanassoff, Peter G., Eli Alon, and Thomas Pasch. "Effects of Single-Dose Intravenous Omeprazole and Ranitidine on Gastric PH During General Anesthesia." ANESTH ANALG 75.95 (1992): 95-98. Print., hereafter "Atanassoff (1992)," discloses effects of ranitidine or omeprazole on gastric juice pH in patients. As shown in Atannasof's Figure 2, intravenous administration of ranitidine (50 or 100 mg) increased the gastric juice pH from approximately 1.5 to at least 3.5 after a median of 43 and 48 min, respectively. Similar results were observed after intravenous administration of omeprazole in this study (such as Figure 1).

[0228] In another example, Baak, L. C., J. B. Jansen, and C. B. Lamers. "Repeated Intravenous Bolus Injections of Omeprazole: Effects on 24-Hour Intragastric PH, Serum Gastrin, and Serum Pepsinogen A and C." Scand J Gastroenterol 26 (1991): 737-46. Print., hereafter "Baak," discloses that the baseline median gastric juice pH in study subjects was 1.4 (range, 1.0-1.7). After administration of intravenous omeprazole, gastric juice pH increased from less than 2 at Baseline to greater than 5 within 1.5 hours. These data indicate that omeprazole could be administered to patients with low baseline gastric juice pH in order to temporarily increase gastric juice pH to a more optimal level for testing with pentagastrin or another potent gastric acid stimulant. These data also indicate that the acid inhibitory effect of the omeprazole wanes over time, thereby allowing testing with a potent acid stimulant (e.g., pentagastrin 6 mcg / kg) with a low likelihood of a false negative result.

[0229] The above exemplary embodiment thereby uses a gastric acid suppressant to raise gastric juice pH to a level sufficiently high to enable challenge with a gastric acid stimulant, such as pentagastrin. This exemplary procedure is thereby different from the procedure in section II(A) (Use of Stimulant versus Suppressant), wherein gastric function is determined based on sufficiency of response to administration of a gastric acid suppressant.4. Administering Neutralizing agent Prior to Measuring Baseline Gastric Juice pH

[0230] Another exemplary embodiment takes more of an active or preventative approach to the issue of stimulant administration in patents with a relatively low gastric juice pH. For example, a pharmacological agent, such as any of the agents disclosed above, can be initially administered prior to measuring the patient's gastric juice pH. This alternative exemplary embodiment may be advantageous by ensuring, or at least increasing the likelihood, that the patient's baseline gastric juice pH will be sufficiently high to enable use of gastric acid stimulant (such as pentagastrin) to assess gastric function.C. Exemplary Stimulants1. Pentagastrin

[0231] Any currently known or later developed gastric acid stimulant can be used in accordance with the disclosed exemplary embodiments. It may be beneficial in certain exemplary embodiments to use pentagastrin under certain circumstances. Pentagastrin is a synthetic pentapeptide that contains the carboxyl terminal tetrapeptide responsible for the actions of natural gastrins, and its most prominent action is in the stimulation of gastric acid secretion. In many patients, pentagastrin stimulates gastric acid secretion approximately 10 minutes after subcutaneous, intramuscular, or intravenous injection, with peak response occurring in most cases 20-30 minutes after administration. The duration of activity of pentagastrin in most patients is usually between 60-80 minutes. In addition, pentagastrin has a short half-life of approximately 10 minutes.

[0232] A potentially beneficial route of administration of gastric acid stimulant, such as pentagastrin, is subcutaneous, although any alternative route, e.g., intravenous, intramuscular, oral, etc., may be acceptable. It may be beneficial to use any dosage of gastric acid stimulant that has minor, relatively minor, or no significant side effects, and that is effective at stimulating gastric acid secretion. However, it is possible to use a dosage and route of administration of the gastric acid stimulant causing significant side effects, depending on circumstances.

[0233] A typically beneficial dose of pentagastrin in most patients is equal to or approximately 6 micrograms / kg for subcutaneous administration. For example, Isenberg, Jon I., Morton I. Grossman, Vernon Maxwell, and John H. Walsh. "Increased Sensitivity to Stimulation of Acid Secretion by Pentagastrin in Duodenal Ulcer." Journal of Clinical Investigation 55 (1975): 330-37. Print, hereafter "Isenberg," discloses that gastric acid output (mEq / 30 minutes), in response to different doses of pentagastrin, plateaus in the 2 to 6 mcg / kg range. Isenberg's disclosed relationship between pentagastrin dosage and acid production in 30 minutes is provided below. Pentagastrin DosageAcid Production in 30 Minutes0 meg / kgmean 1.9 mEq0.2 meg / kgmean 7.8 mEq2 meg / kgmean 13.6 mEq6 meg / kgmean 14.2 mEq

[0234] However, as disclosed above, any stimulant that is beneficial can be used. In fact, even nutrition can be used in place of stimulant. For example, a patient may have a gastric juice pH of 4.0 with no, or a small amount of, nutrition. Nutrition can then be administered, such as 50 ml of liquid food that is typically used for enteral nutrition, e.g., osmolite 1 cal. This nutrition can be administered into the stomach via the mouth or a tube (such as a plastic tube and / or standard nasogastric tube). A transient increase in gastric juice pH may occur. However, a decrease in gastric juice pH (such as an acute decrease, e.g., 2.5 pH units) at a later time (such as approximately 45 minutes later) may indicate a positive response indicative of gastric perfusion sufficient for administration of enteral nutrition. This exemplary embodiment is particularly effective to determine gastric function because the administration of food, and in particular protein, into the stomach stimulates gastric acid secretion in a relatively healthy gut.2. Stimulant Selection Methodologies

[0235] The use of a certain type of stimulant can be automatically determined, such as via automatic protocols. For example, a certain stimulant (such as pentagastrin) may always be used in some exemplary embodiments, while other exemplary embodiments may always use another specific stimulant. Pentagastrin is especially beneficial since its effects on gastric acid production have been well characterized, and it has a very good safety profile. In addition, its short half-life and duration of effect (less than 90 minutes) are desirable because of its speedy effect in the stimulation test, but then its short half-life enables its effects to quickly wear off without (or with minimal or minor) residual effects.

[0236] However, still other exemplary embodiments can include an analysis as to whether a benefit may be achieved via use of a certain type of stimulant. Exemplary embodiments are intended to cover and include any methods and apparatus for making this determination. For example, this determination can be made based on detected baseline gastric juice pH. It may be beneficial to use a certain stimulant after detection of a relatively high baseline gastric juice pH, while it may be beneficial to use a completely different stimulant after detection of a relatively low baseline gastric juice pH. However, other factors can be used to dictate usage of a specific stimulant, including but not limited to patient characteristics, such as one or any combination of factors, including but not limited to: age, gender, fitness, weight, body composition such as percentage of body fat, ethnicity, family history, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable.3. Other Exemplary Stimulants

[0237] As discussed above, the various methods and apparatus of the disclosed exemplary embodiments are intended to include any useful or beneficial type of stimulant. For example, some exemplary embodiments use pure gastrin, while other embodiments use the four-peptide version of gastrin, i.e., tetragastrin, and still other embodiments use histamine or betazole hydrocholoride.

[0238] In situations where acid secretory responses to the above stimulants are not significantly different, it may be beneficial to choose the appropriate stimulant to test gastric function based on safety, possibility of side-effects, availability, and / or cost. For example, large doses of histamine have been reported to produce severe hypotension, while orally administered betazole hydrocholoride has been reported to have few side effects.D. Exemplary Suppressants1. Omeprazole and Ranitidine

[0239] Any currently known or later developed acute acting gastric acid suppressant can be used. Exemplary gastric acid suppressants include proton pump inhibitors (e.g., omeprazole) and histamine H2 receptor antagonists (e.g., ranitidine). Proton pump inhibitors may be beneficial to determine gastric function given their direct mechanism of action.

[0240] As discussed above regarding stimulants, beneficial dosages and routes of administration for the gastric acid suppressant are relatively free of side effects and result in a significant pharmacological effect within several hours (such as less than 2 or 3 hours) of administration. Exemplary doses that are typically free or relatively free from potentially negative side effects include omeprazole (80 mg intravenous) or ranitidine (50 mg intravenous). However, it is possible to use a dosage and route causing significant side effects depending on circumstances2. Suppressant Selection Methodologies

[0241] The use of a certain type of suppressant can be automatically determined, such as via automatic protocols. For example, a certain suppressant (such as omeprazole) may always be used in some exemplary embodiments, while other exemplary embodiments may always use another specific suppressant.

[0242] However, still other exemplary embodiments can include an analysis as to whether a benefit may be achieved via use of a certain type of suppressant. Exemplary embodiments are intended to cover and include any methods and apparatus for making this determination. For example, this determination can be made based on detected baseline gastric juice pH. It may be beneficial to use a certain suppressant after detection of a relatively high baseline gastric juice pH, while it may be beneficial to use a completely different suppressant after detection of a relatively low baseline gastric juice pH. However, other factors can be used to dictate usage of a specific suppressant, including but not limited to patient characteristics, such as one or any combination of factors, including but not limited to: age, gender, fitness, weight, body composition such as percentage of body fat, ethnicity, family history, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable.III. Dosages and Administrations of Pharmacological Challenge Agents (Stimulants / Suppressants / Acid Neutralizers)A. Dosages

[0243] It may be advantageous to tailor the amount and / or concentration (dosage) of pharmacological challenge agent, such as a gastric acid stimulant or suppressant, administered to patients. For example, benefits may be achieved by limiting administration to only a dosage of stimulant or suppressant that is necessary to sufficiently challenge a patient's GI tract. Limiting the amount of administered stimulant or suppressant to only that amount needed to sufficiently challenge the GI tract may be beneficial by reducing, minimizing or preventing any potentially disadvantageous side effects of the stimulant or suppressant.

[0244] In one exemplary embodiment, a dose of 1 mcg / kg of pentagastrin is administered, either subcutaneously or intramuscularly, which is typically large enough to stimulate gastric acid secretion in a healthy adult. A dose of 1 meg / kg is also sufficiently small to reduce or minimize the likelihood of potential adverse effects because adverse effects are typically dose related, with larger doses being more likely to cause adverse effects or poorer tolerability.

[0245] However, the amount of GI tract challenge deemed sufficient can vary based on a number of factors, such as the reason for the test, i.e., whether the test is being used to determine: 1) applicability of enteral feeding, ventilation and / or use of vasoactive agents, 2) guiding the disposition of a patient within a hospital, such as whether the patient should remain in an intensive care unit (ICU), emergency room, etc., 3) detection of risk for stress ulcers, and / or 4) adequacy of other treatment or resuscitation. In other words, the maximum dosage of stimulant or suppressant can vary based on the reason for conducting the test. For example, a relatively large dosage of stimulant or suppressant may be necessary to determine whether to initiate enteral feeding, while a lower amount may be sufficient to monitor adequacy of resuscitation, and an even lower dosage of stimulant or suppressant can be sufficient to determine whether a patient should remain in an ICU.

[0246] Other factors can be used to determine dosage of stimulant or suppressant as an alternative to the above analysis, or as part of the above analyses relating to dosage determination. For example, dosage of stimulant or suppressant can be determined based on patient characteristics, such as one or more combination of factors, including but not limited to: age, gender, fitness, weight, body composition such as percentage of body fat, ethnicity, family history, personal medical history, genetics, and / or other factors currently known or later determined to be relevant or applicable.

[0247] For example, if body weight is used to affect or dictate the dosage, some exemplary embodiments administer a relatively higher dosage to relatively heavy patients, and contrarily a relatively lower dosage to relatively lighter patients. A chart is provided below showing exemplary dosages for various weights. Patient Weight40-70 kg71-100 kg101 kg or morePentagastrin Dosage250 mcg500 mcg750 mcg

[0248] The above chart shows dosages based on stepped changes in weight, i.e., 40-70 kg, 71-100 kg, 101 kg or more. This stepped weight dosing is justified with the flat dose response curve for pentagastrin at 2 to 6 meg / kg observed in many studies, e.g., Isenberg et al (1975) described above. However, the above stepped weight changes may not be the most accurate way to determine dosages, especially if weight is the sole factor in determining dosage. For example, in this scheme, a 70 kg patient receives a much lower dosage of stimulant or suppressant than a 71 kg patient, even though only 1 kg separates the two patients.

[0249] Thus, other schemes may be more accurate. For example, dosages can be determined more linearly based on a patient's weight, such as by other weight based dosing techniques. For example, a certain dosage of stimulant or suppressant (such as 6 mcg) can be used based on any weight increment (such as 1 kg increments). A chart is provided below in accordance with one example of this scheme, i.e., 6 mcg / kilogram. Patient Weight50 kg75 kg100 kg125 kgPentagastrin Dosage300 mcg450 mcg600 mcg750 mcg

[0250] Weight based dosing may be effective and / or beneficial in many medical applications. For example, drugs can be administered, especially drugs for injection (i.e., liquid state), using weight based dosing. This is in contrast to pills (or capsules, tablets, etc.) that are only available to medical care providers in a limited number of dosage amounts. However, liquids for injection can be administered in many different amounts (volumes), thereby allowing for many different dosage amounts, if required, based on different body weights.

[0251] For example, Raschke, Robert A., Brendan M. Reilly, James R. Guidry, Joseph R. Fontana, and Sandhya Srinivas. "The Weight-based Heparin Dosing Nomogram Compared with a "Standard Care" Nomogram." Annals of Internal Medicine 119.9 (1993): 874-81. Print., hereafter "Raschke," discloses employing weight based dosing for the administration of heparin, which is an injectable drug commonly administered to hospitalized patients. Pentagastrin can similarly be administered using weight based dosing because it is generally available in an injectable form, i.e., as a liquid. As disclosed above, a dose of 6 meg / kg can elicit a robust gastric acid secretory response and is thus a beneficial method of dosing.

[0252] It may also be advantageous to set a maximum dosage (amount and / or concentration) of pharmacological challenge agent, such as stimulant or suppressant, regardless of other factors, such as patient's weight. Setting a maximum dosage may be beneficial for a variety of reasons, such as would be the case if a certain dosage causes certain potentially disadvantageous side effects in a threshold number or percentage of patients. For example, a certain relatively high dosage of stimulant or suppressant should not be used if it causes a certain potentially disadvantageous side effect in a relatively high number or percentage of patients, and even for patients weighing over 101 kg. A chart is provided below illustrating an example of this analysis for patients weighing more than 101 kg. Percentage of Patients Demonstrating a certainDosagesPotentially Disadvantageous Side Effect250 mcg.001%500 mcg.01%600 mcg.02%750 mcg10%

[0253] In the above example, the percentage of occurrence of the side effect is nominal for 250 mcg - 600 mcg, but becomes much more significant (10%) at 750 meg. Thus, in this case, it may be beneficial (in some or all cases) to avoid administration of a 750 mcg dosage, and thus a maximum dosage may be set at 600 meg. For example, a 150 kg patient would still receive a maximum dosage of 600 mcg.

[0254] This approach to dosing medications can be effective and / or beneficial in many aspects of clinical practice. For example, administration of acetaminophen (Tylenol) can be weight based (10-15 mg / kg) in small individuals, e.g., in children. However, in the related art, the maximum dose typically administered is 1000 mg every 6 hours, even in patients with significant obesity. For example, a 120 kg individual may receive this maximum dose of 1000 mg, but should not be dosed with 1200-1800 mg (corresponding with 10-15 mg / kg),

[0255] Other exemplary embodiments address reducing, minimizing, or preventing side effects of the pharmacological agent in other ways. For example, some exemplary embodiments initiate administration of the pharmacological challenge agent at a low or very low dosage regardless of patient weight. In one exemplary embodiment, a low dosage of 0.6 meg / kg of pharmacological agent, such as gastric acid stimulant (for example, pentagastrin), is initially administered. A sufficient change in gastric juice pH, such as a drop of at least 1 pH unit, may indicate a healthy or reasonably healthy GI tract response. However, if there is no change in gastric juice pH, or an insufficient change in pH, then the pharmacological challenge agent can be re-administered after a sufficient period, such as at least one hour, at a higher dosage, such as 6 mcg / kg. A sufficient change in gastric juice pH may then indicate a somewhat healthy GI tract and care can be provided accordingly.

[0256] In some exemplary embodiments, the low dosage can be referred to as a minimum dosage, and the higher dosage can be referred to as a standard dosage. In the above exemplary embodiment, the minimum dosage (e.g., 0.6 mcg / kg) would be 10% of the standard dosage (e.g., 6 mcg / kg). However, exemplary embodiments are not limited to these dosages, and are instead intended to cover any dosage relationship that may be beneficial. For example, the minimum dosage can be any amount less than the standard dosage.

[0257] In fact, the minimum and standard dosages can be determined based on the same or similar methodology as discussed above with regard to maximum dosages. Thus, in some exemplary embodiments, the minimum dosage can be set to an amount that is very low and thus very unlikely to cause potentially disadvantageous side effects, while sufficiently high to cause an acute change in gastric juice pH in patients with a healthy gastric function.B. Administrations

[0258] Exemplary embodiments are intended to cover and include any known or later developed methods and apparatus for challenging a patient's GI tract. These methods and apparatus include any known or later developed pharmacological agent, including but not limited to the gastric acid stimulants and suppressants discussed in Section II (Types of Pharmacological Challenge Agents).

[0259] Exemplary embodiments can also include any currently known and later developed methods and apparatus for introducing a pharmacological agent, such as a gastric acid stimulant or suppressant, to a patient. For example, the pharmacological challenge agent can be introduced subcutaneously, intramuscularly, intravenously, orally, in gaseous form, etc. In fact, some embodiments administer the pharmacological challenge agent, such as pentagastrin, as snuff and inhaling. This embodiment would thereby also include use of the pharmacological challenge agent as a suspended liquid.

[0260] As one example, Fig. 1 shows an exemplary administering device 100 that administers to a patient a pharmacological challenge agent, such as a gastric acid stimulant or suppressant. However, the administering device 100 shown in Fig. 1 is not intended as limiting, and as discussed above, exemplary embodiments are intended to cover any currently known and later developed methods and apparatus for introducing the pharmacological challenge agent. For example, the exemplary administering device 100 shown in Fig. 1 is not intended as limiting with regard to structure of the device, manner of administration, location on the patient of administration, etc.

[0261] In fact, the manner of introduction of the pharmacological challenge agent can be tailored to achieve some benefit. It may be beneficial to tailor the manner of introduction based on whether a stimulant is used versus a suppressant. For example, it may be beneficial to administer a stimulant (such as pentagastrin) subcutaneously because it has a very rapid onset. Administration of pentagastrin subcutaneously has been shown to elicit a robust acid secretory response in less than 1 hour. In contrast, onset of action can be longer with gastric acid suppressants, such as famotidine or omeprazole, and it is therefore desirable to administer these suppressants intravenously to speed up the pharmacological response. The manner of introduction can also, or alternatively, be determined based on the specific type of stimulant or suppressant.

[0262] Alternatively, or in addition to the above analysis, the manner of introduction can be determined based on patient characteristics, such as one of any combination of factors, including but not limited to: age, gender, fitness, weight, body composition such as percentage of body fat, ethnicity, family history, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable.

[0263] As one example, patients with poor peripheral circulation (perfusion), such as can occur with severe diabetes or severe peripheral vascular disease, for example, may respond better to an intravenous dose of stimulant. This beneficial response may be due to the fact that poor peripheral perfusion may impair absorption and transport of stimulant from the subcutaneous space to the central circulation and target site (parietal cells of the stomach).

[0264] However, the above disclosure is only provided as one example of tailoring introduction of the pharmacological challenge agent to achieve a benefit. Exemplary embodiments are intended to cover any beneficial tailoring of the administration of the pharmacological challenge agent consistent with the disclosed guiding of medical care based on detected gastric function.

[0265] In fact, as yet another example, the manner of introduction can be determined based on speed of the GI tract's response. In other words, a certain manner of introduction, such as subcutaneous or intravenous administration, may cause a faster GI tract response, which may be beneficial under certain circumstances. For example, in many circumstances, the onset of a decrease in gastric juice pH is likely to be faster following intravenous rather than subcutaneous administration.

[0266] In general, tailoring administration of the pharmacological challenge agent to achieve a faster GI tract response can be beneficial because it can speed up gastric function detection. Determining that gastric function is sufficient to tolerate nutrition would allow ramping up to goal calories more quickly. As disclosed above, health benefits are achieved by providing patients with nutrition as soon as the nutrition can be tolerated. Other benefits could also be achieved by achieving a faster GI tract response.

[0267] Further, in some exemplary embodiments, the manner of introduction is based on reducing, minimizing or preventing potentially negative side effects caused by the pharmacological challenge agents. In other words, a certain manner of introduction may reduce, minimize or prevent such potentially negative side effects. For example, intravenous administration of pentagastrin can cause transient mild side effects, e.g., anxiety, palpitations, etc. However, subcutaneous administration may reduce, minimize, or even prevent these effects, such as by enabling a more gradual increase in serum concentration. However, as previously disclosed, the above exemplary embodiments are not intended to be limiting, and other exemplary embodiments can cover other tailorings of pharmacological challenge agent administrations to provide the above or other benefits.C. Vial Size

[0268] Exemplary embodiments are intended to cover any useful or beneficial method and / or apparatus for facilitating storage, delivery and / or administration of the pharmacological challenge agent to patients. In many embodiments, the pharmacological challenge agent is stored in a vial and administered to the patient from the vial using known, related art, and / or later developed techniques. A few embodiments that include different vial sizes, dosages, and types of administration are disclosed below in the context of the pharmacological challenge agent being pentagastrin, however, as disclosed above, embodiments are not limited to pentagastrin and instead are intended to cover any useful or beneficial pharmacological challenge agent.

[0269] One exemplary embodiment includes a vial size appropriate for a pentagastrin dose of 1 meg / kg. In some of these embodiments, it may be beneficial to provide this dose at a concentration of 250 mcg / ml in a vial containing a volume of 0.5 to 1.0 ml (125 to 250 mcg of drug). This concentration may enable a relatively small volume of the pentagastrin to be administered, which may be beneficial in certain situations, e.g., subcutaneous or intramuscular dosing, where it may be generally preferable to inject a small volume so as to reduce, minimize or prevent potential patient discomfort associated with the injection.

[0270] In another exemplary embodiment of pentagastrin dosing of 1 mcg / kg, a vial is used that contains a less concentrated formulation (e.g., 100 mcg / ml), which may be beneficial or otherwise desirable, such as for use with a vial containing 2 ml (200 mcg in 2 ml). For example, a patient weighing 80 kg may receive a dose of 80 mcg (0.8 ml volume).

[0271] This lower concentration (100 mcg / ml) may reduce, minimize or prevent any stinging, pain, or other adverse effects associated with subcutaneous or intramuscular administration. This lower concentration may also be beneficial or otherwise desirable if the drug is administered intravenously, because this concentration may reduce, minimize or prevent possible irritation of the vein that could cause pain and / or phlebitis. Another potential benefit to a less concentrated formulation is potentially greater or enhanced ease in measuring the correct dose and / or greater or enhanced accuracy of the dose. For example, with a higher concentration (250 mcg / ml), a 1 meg / kg dose in a 50 kg patient would be one-fifth of 1 ml (equal to 0.2 ml), which can be challenging to obtain accurately. Contrarily, the lower concentration (e.g., 100 mcg / ml) would require a volume of 0.5 ml in this same patient, which may be easier to accurately draw-up in the syringe. The above dosages, volumes, etc., are merely provided for exemplary purposes, and are not intended as limiting or an exhaustive list of possible dosages, volumes, etc.

[0272] Another exemplary embodiment uses a higher dose of pentagastrin, such as 6 mcg / kg, and the vial contains 3 ml of pentagastrin (250 mcg / ml equal to 750 mcg in 3 ml). This vial size may be beneficial by enabling dosing of even large patients, e.g., 100 kg patient, who would require 600 mcg that may be contained in this 750 mcg vial.

[0273] Yet another exemplary embodiment enables incrementally higher dosing based on a patient's initial response to the pharmacological challenge agent. This incrementally higher dosing can be performed with a vial containing 3 ml of pentagastrin (250 mcg / ml or 750 mcg in 30 ml). For example, in order to reduce or minimize potential side effects, a lower but generally effective dose of pentagastrin is initially administered (e.g., 1 mcg / kg subcutaneously). A sufficiently positive gastric secretory response obviates additional doses of pentagastrin from this vial. However, an inadequate or equivocal response to the lower dose (1 mcg / kg) indicates that the patient can be challenged with a higher dose (e.g., 6 meg / kg). The exemplary vial size enables dosing of even large patients, e.g., 100 kg patient who would require a low dose of 100 mcg followed, in some cases, by a higher dose of 600 mcg, totaling 700 mcg that may be contained in the 750 mcg vial.

[0274] As indicated above, in all of the above exemplary embodiments, the dosages, volumes, etc., are merely provided for exemplary purposes, and are not intended as limiting or an exhaustive list of possible dosages, volumes, etc.IV. Gastric Juice H+ / pH Measurement, Determining GI Tract's Response to Challenge, and Guiding Care Based on Measured H+ / pH

[0275] Exemplary embodiments are intended to cover any and all currently known and later developed apparatus that measure gastric function and enable medical care to be guided based on the detected gastric function, in accordance with the above disclosures. More specifically, exemplary embodiments can include apparatus that enable a patient's GI tract to be challenged, such as by use of one or any number of pharmacological challenge agents, to then measure the GI tract's reaction to the challenge, and to then guide care based on the GI tract's measured reaction.

[0276] Components of the exemplary apparatus can include one or any combination of: 1) apparatus for administering a pharmacological agent (discussed in section III(B) above), 2) apparatus for obtaining and / or measuring gastric juice H+ concentration or pH (such as for performing the baseline H+ concentration or pH test and / or stressed H+ concentration or pH test(s)), 3) apparatus for determining the GI tract's response to the pharmacological challenge, such as by determining any differential between the baseline and stressed H+ concentration or pH tests, and 4) apparatus for guiding care based on the GI tract's response. Each of these components is discussed below.A. Timing of Gastric Juice H+ / pH Measurement

[0277] In general, exemplary embodiments relate to guiding medical care based on detected gastric function. The gastric function can be detected by initially measuring gastric juice H+ concentration or pH prior to administration of the pharmacological challenge agent. This initial measurement can be termed a baseline H+ concentration or pH test. A pharmacological challenge agent, such as a gastric acid stimulant or suppressant, is administered to a patient. After a period, the patient's gastric juice H+ concentration or pH is again measured, which can be termed a stressed H+ concentration or pH test. Any H+ concentration or pH differential between the baseline and stressed H+ concentration or pH tests is then determined. The following examples are provided in terms of pH, but are also applicable in terms of H+ concentrations.

[0278] Exemplary embodiments are intended to cover any period, i.e., time between baseline pH test and / or pharmacological challenge agent administration and stressed pH test. In many exemplary embodiments, the period is measured between administration of pharmacological challenge agent and stressed pH test. It is advantageous for the period to be the time that it takes for the patient's GI tract to react to the pharmacological challenge agent to provide information sufficient to guide the patient's care. An exemplary reaction could be a pH change of 1 unit to indicate that the patient's GI tract is sufficiently healthy to initiate enteral feeding.

[0279] This period can be set to a certain standard time for all patients under all circumstances, such as, for example, 45 minutes. In other words, in this example, a 45 minute gap would always separate the pharmacological challenge agent administration and stressed pH test. Exemplary embodiments using the standard time are particularly applicable if the GI tracts of a large number (such as a substantial majority) of different types of patients react to the pharmacological challenge agents at a uniform or fairly uniform rate. A standard time is particularly beneficial because of simplicity, ease of administration, error avoidance, etc. For example, one exemplary, typical reported duration of action of pentagastrin is 60 to 90 minutes. Therefore, 45 minutes falls into a time period where sufficient time has elapsed since administration to ensure that the drug has arrived at the target cell (i.e., parietal cells), thereby enabling the patient's gastric system to react, and yet is within the known duration of action of this drug such that effects of the pharmacological challenge agent have not deteriorated or worn off.

[0280] However, some exemplary embodiments do not necessarily use a standard time for all patients and / or under all circumstances. For example, certain circumstances could warrant using different periods. In an exemplary embodiment, a relatively shorter period could be used in urgent situations, such as situations where it would be beneficial to urgently apply a certain treatment that is dictated by the test results. For example, it may be very beneficial to expedite initiation of enteral feeding or other treatment in certain critically ill patients. Alternatively, determining whether a certain patient should remain in an ICU may not be so urgent and thus a relatively larger period could be used.

[0281] Alternatively, or in addition to this analysis, various patient characteristics can be used to determine the period, such as one or any combination of aspects including but not limited to: age, gender, fitness, weight, body composition such as percentage of body fat, ethnicity, family history, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable.

[0282] In accordance with some exemplary embodiments as discussed above, gastric acid stimulant or suppressant, such as pentagastrin, is administered, and then gastric juice pH is measured 45 minutes later (which approximates time of peak acid production). However, peak acid production can occur earlier or perhaps later, and even as late as 75 minutes after pentagastrin administration. Therefore, another exemplary embodiment measures the gastric juice pH earlier than the exemplary embodiments discussed above, such as at 15 minutes post pentagastrin administration. If a positive response (such as at least 1 unit decrease) is detected, then no further measurements need to be taken and care can be provided assuming a healthy gastric response. This procedure provides the benefit of expediting the guiding of care based on a healthy gastric function.

[0283] However, if the response is negative at 15 minutes, then the gastric juice pH can be measured at a later time, i.e., such as at 30 minutes post pentagastrin administration. If a positive response is detected, then further measurements do not need to be taken and care can be provided based on a fairly healthy gastric response. If a negative response is detected, then the gastric juice pH can be measured at a still later time, i.e., gastric juice pH can be measured such as at 45 minutes or even 75 minutes from pentagastrin administration.

[0284] The initial and subsequent stressed pH measurements can be performed at any times post stimulant or suppressant administration that may be beneficial. For example, the initial stressed pH measurement can be set to the earliest significant gastric response of most patients to the stimulant or suppressant, which may be approximately 15 minutes post pentagastrin administration, for example. The last subsequent stressed pH measurement can be set to the end of duration of gastric response of most patients to the stimulant or suppressant, which may be approximately 90 minutes post pentagastrin administration. Also, exemplary embodiments are intended to cover any number of subsequent stressed pH measurements that may be beneficial.

[0285] In addition or as an alternative to the above analysis, other exemplary embodiments can take into account the peak gastric response of most patients to the gastric acid stimulant or suppressant. For example, the peak acid production response for most patients to pentagastrin is approximately 45 minutes after administration, and the latest peak acid production for many patients to pentagastrin is approximately 75 minutes after administration. Thus, in some exemplary embodiments, the initial stressed pH measurement is performed at approximately 45 minutes after pentagastrin administration. If a negative response is detected, then a subsequent stressed pH measurement is taken in approximately another 30 minutes, i.e., approximately 75 minutes after the pentagastrin administration. As with other exemplary embodiments, another negative response results in care being guided based on a relatively unhealthy gastric function, while a positive response results in care being guided based on a relatively healthy gastric function.

[0286] The above exemplary embodiments, which include initial and subsequent stressed pH measurements (after an initial negative response), are beneficial because they ensure that gastric function is more accurately tested. The fact that earlier measurements of pH (e.g., at 15 minutes post pentagastrin administration) are negative is generally not useful if a positive response is eventually noted within the expected duration of action of the drug, e.g., 90 minutes from pentagastrin administration. In other words, if two measurements of gastric pH are performed 15 and 45 minutes after pentagastrin administration, and one pH measurement (at 15 minutes) is negative (less than 1 unit pH change) and one pH measurement (at 45 minutes) is positive (greater than 1 unit pH change), the negative pH value in this context has only a limited or even no diagnostic value.

[0287] The above exemplary embodiments aspirate gastric juice at the time of pH measurement. In other words, the stimulant or suppressant is administered, and after a suitable period has expired, the gastric juice is aspirated and the pH measured. However, it is possible that gastric secretion of mucous and other non-acid containing secretions may remain and increase in volume in the stomach, such that aspirated and collected gastric juice (at the time of pH measurement) includes freshly secreted acid diluted with other gastric secretions. Therefore, it may be beneficial at a certain time before pH measurement to aspirate all of the gastric contents, wait a period, and then aspirate the gastric contents for pH measurement. This results in measurement of a smaller and fresher aliquot of gastric juice, enhancing reliability of the measurement.

[0288] Fig. 6 is a schematic of an apparatus in accordance with an exemplary embodiment that includes an aspirator 104 that aspirates gastric contents. The aspirator 104 provides a suction or other force so that gastric contents are sucked or otherwise moved from the stomach of the patient 2, through orogastric or nasogastric tube 106, and into a collector 108 or other structure.

[0289] In accordance with an exemplary embodiment discussed above, the patient's gastric juice pH is measured approximately 45 minutes after pentagastrin administration. This exemplary embodiment (as well as other embodiments) can be modified to include the above additional procedure by aspirating all of the gastric contents at some period before pH measurement, such as at approximately 30 minutes after pentagastrin administration. The gastric juice for pH measurement would then be generated between approximately 30 to approximately 45 minutes after pentagastrin administration to reduce, minimize, eliminate, or prevent dilution of freshly secreted acid with other gastric secretions. This procedure enables detection of small quantities of acid secretion, which still reflect a well perfused gut.

[0290] The above example of aspirating all of the gastric contents approximately 30 minutes after pentagastrin administration is only provided as an example. This aspiration can be provided at any time that is beneficial, and can occur prior to stimulant or suppressant administration or even prior to measurement of baseline pH.

[0291] The above procedure can be combined with use of a pH probe / sensor, in which aspiration of gastric contents can be performed with a NGT or OGT, while pH measurements may be performed with an indwelling pH probe / sensor (e.g., VersaFlex pH sensor from Sierra Scientific Instruments, Los Angeles, CA). In yet other alternative embodiments, the above measurements of pH, such as at 15, 30, 45, 60 minutes, etc., can each be performed after aspirating gastric contents so as to reduce, minimize or avoid measurement of freshly secreted gastric juice that has been diluted with other gastric secretions. In other words, in exemplary embodiments including multiple pH measurements, all or some of these measurements can be performed after aspiration of gastric contents.B. Exemplary Methods and Apparatus for Determining Gastric Juice H+ / pH

[0292] Exemplary embodiments are intended to cover any and all currently known and later developed methods and apparatus for determining gastric juice H+ concentration or pH. The following examples are provided in terms of pH, but are also applicable in terms of H+ concentrations.

[0293] Fig. 1 is a schematic of an apparatus in accordance with an exemplary embodiment, including an apparatus 1 for measuring gastric juice pH in a patient 2. Exemplary embodiments of the measuring apparatus 1 are intended to cover and include any method and device 3 for obtaining and / or sampling the patient's gastric juice so that the gastric juice pH can be measured, and any method and device 7, 8 to measure the gastric juice pH. Fig. 1 also shows an exemplary orogastric or nasogastric tube 4, exemplary syringe 5 for aspiration, and exemplary connector 6 that connects to the pH measuring device 7, 8. Fig. 1 further shows an administering device 100 that administers a pharmacological challenge agent, and an administering device 102 that administers a pharmacological agent to raise gastric pH so that the stress test can be conducted with a gastric acid stimulant. Exemplary methods and apparatus are discussed below.1. Gastric Juice Obtaining / Sampling Device

[0294] Exemplary embodiments include any currently known or later developed method and device 3 for obtaining / sampling gastric juice so that the gastric juice pH can be measured. Specific methods and apparatus can be selected based on a variety of factors, including but not limited to one or a combination of any of: ease of use; cost, such as cost of the device, cost of servicing the device, etc.; invasiveness / noninvasiveness of the device; reducing, minimizing or preventing side effects; etc., for example.

[0295] Some exemplary embodiments are discussed below wherein the obtaining / sampling device 3 includes at least one of a catheter, a probe and a sensor. However, the below disclosures of these devices are only provided for exemplary purposes and not intended as limiting. Each of these exemplary devices is discussed below.

[0296] Some exemplary embodiments are intended to include any currently known or later developed catheter capable of performing the above operation. For example, a related art catheter is a plastic (usually disposable) device that is inserted into the patient's body and has at least one lumen useful for aspirating things from the body, e.g., aspiration of gastric juice from the stomach, or aspiration of residual enteral feeds from the stomach. This same lumen (or a separate lumen) can, when not being used for aspirating, be used to administer drugs or enteral feed into the patient. A currently known or later developed Salem Sump tube (often 16F or 18F in size) can be inserted through the nose (nasogastgric) or mouth (orogastric) into the stomach. This catheter / tube can be used to aspirate gastric contents, and when not being used to aspirate can be used to administer drugs or enteral feed into the stomach.

[0297] Some exemplary embodiments include a probe. Any currently known or later developed probe can be used that is applicable. One related art probe is a generally plastic (usually disposable) device that is inserted into the patient's body, and in some exemplary embodiments includes at least one sensor, e.g., pH sensor, or manometry sensor, associated with it.

[0298] The terms catheter, tube, and probe are often used interchangeably in the art because there can be considerable overlap in their structures and functions. For example, a catheter with a lumen is often understood to have one or more sensors (e.g., pH sensor) associated with it. This structure allows the user to monitor pH, also aspirate fluid, e.g., gastric juice, and insert drugs or enteral feed. However, regardless of the common usage in the art regarding this terminology, exemplary embodiments are intended to cover any apparatus or method for obtaining / sampling gastric juice.

[0299] It is often beneficial that the devices used for hospitalized patients, e.g., ICU, patients, have properties / structures allowing them to be inserted into a patient with depressed mental status or who may be sedated and / or unconscious for other reasons, e.g., recent stroke or head injury. Therefore, it may be beneficial for the catheter, tube, or probe to be sufficiently smooth and stiff to allow for easy or relatively easy insertion into the esophagus, stomach, or small bowel. Increased stiffness may also be beneficial because these patients often cannot assist with insertion, e.g., by attempting to swallow the tube, which is helpful during insertion of more flimsy tubes. Therefore, sufficient stiffness allows an operator, such as a medical care provider, to push the tube forward into the patient without the tube kinking or bending backward or coiling. Exemplary embodiments are intended to cover any structure or method of achieving the desired stiffness, including but not limited to usage of: 1) a stiffer plastic, 2) a large diameter tube, e.g., a standard 16F or 18F Salem Sump tube generally has sufficient stiffness to be used in hospitalized patients, and / or 3) a guide wire to allow for transient increased stiffness during insertion, after which the guide wire can be removed.

[0300] In some exemplary embodiments, the obtaining / sampling device 3 is used in conjunction with a separate apparatus to measure pH of the gastric juice and another separate apparatus to indicate the measured pH. In other exemplary embodiments, the obtaining / sampling device 3 includes the apparatus to measure the gastric juice pH. For example, the obtaining / sampling device 3 can be a plastic tube (NG or OG Salem Sump tube, or tube for post-pyloric feeding) that has a pH sensor / probe built into it. In still other exemplary embodiments, the obtaining / sampling device alternatively or additionally includes the apparatus to indicate the measured pH. In fact, in one such exemplary embodiment, the apparatus to measure the gastric juice pH is integral and / or unitary with the apparatus to indicate the measured pH. For example, the obtaining / sampling device 3 can be a plastic tube (NG or OG) that has both a pH probe and pH indicator built into it. The above embodiments can be used with any currently known, related art or later developed technologies for measuring pH, including pH sensors that require bed-side calibration as well as those not requiring such bed-side calibration, e.g.., pre-calibrated sensors or sensors manufactured to sufficiently high specifications so as to obviate bed-side or further calibration.

[0301] In one exemplary embodiment, the obtaining / sampling device 3 can include a special orogastric or nasogastric tube 4 that can be inserted into a patient's stomach. This tube 4 can enable stomach contents to be suctioned and thus sampled, which is consistent with current intensive care. Alternatively, this tube 4 can additionally be used to facilitate or enable feeding. Providing the additional feeding function can be advantageous for a variety of reasons, such as enabling feeding to occur on an expedited basis should feeding be warranted, reduced invasiveness, etc.

[0302] This tube 4 can include or be used with a syringe 5 for aspiration of gastric juice from a patient's stomach. In other words, the syringe 5 can create suction within the tube 4 to obtain a sample of gastric juice. The syringe 5 can include a connector 6, such as at a tip end, that connects to a pH measuring device 7 that measures pH of the gastric juice sample. The connector 6 can include any structure to accomplish the above operation, such as a luer connector, for example. The pH measuring device 7 can also include any currently known or later developed apparatus for measuring pH. A pH measuring device can be selected based on one or a combination of any number of factors, including but not limited to accuracy, reliability, cost, ease of use and operation, ability to provide relatively fast measurement results, etc. Also, as disclosed above, the pH measuring device 7 can include the apparatus to indicate the measured pH, or alternatively send a signal to that apparatus for separate indication.

[0303] Another exemplary embodiment includes a pH measuring sensor / device that is encapsulated into the distal end of a standard 18 French tube that is inserted into the gastric lumen either through the mouth or nose. This tube would allow for the drainage of stomach contents, if necessary for other medical reasons, and administration of enteral feeds into the stomach, if feeding is deemed warranted. Alternative manufacturers of pH containing probes and pH monitors can be used. For example, a pH probe (such as a currently available Versa Flex Disposable pH Catheter manufactured by Sierra Scientific Instruments, Los Angeles, CA) can be connected with another commercially available pH recorder / monitor, e.g., Digitrapper (Sierra Scientific Instruments, Los Angeles, CA), which allows continuous or semi-continuous measurement of pH to at least 0.1 pH unit accuracy. Potential advantages provided by continuous, substantially continuous, or semi-continuous measurement of pH are disclosed below with regard to two separate exemplary embodiments.

[0304] In another exemplary embodiment, the gastric juice obtaining / sampling device and pH measuring device include a disposable pH probe that can either have no lumen, be a single lumen, or alternatively have two or more lumens. The multi-lumen probe may be advantageous by allowing for simultaneous aspiration of gastric juice with measurement of the pH of the gastric juice using pH strips or a pH monitor. This structure may also be advantageous by enabling an infusion of food into the stomach via the pH probe's lumen.

[0305] Exemplary embodiments are intended to cover a probe of any size that can perform the above operation adequately. For example, the probe can be relatively small (e.g., 4F), somewhat larger (e.g., 6F), or even as large as a typical nasogastric tube (e.g., 16F or 18F). The larger tube size may be beneficial in exemplary embodiments using a multilumen probe through which one can feed the patient or administer medications.

[0306] The pH probe may have a pH sensor, such as on its tip. However, commercially available pH probes can also be used that include multiple sensors to allow for measurement of pH at 2 or even 3 separate locations. For example, the pH sensors can be spaced 20 cm apart. This structure may provide more accurate measurements and reduce, minimize or avoid errors. For example, detecting a pH of 2.0 units from the distal (tip) sensor and a pH of 7.0 units from the more proximal sensor helps to confirm that the probe is in the correct position, where the tip is in the stomach and the proximal sensor is in the esophagus, therefore resulting in less acidic gastric juice pH there. In contrast, pH measurements of 7.0 units at both sensors suggests that the probe is not in the stomach and that the pH of 7.0 units does not represent gastric juice pH. In another example, a pH of 7 units in the distal sensor and pH of 2 units in the proximal sensor would indicate that the distal tip has migrated into the duodenum.

[0307] Another exemplary embodiment includes an NG tube with a structure similar to that disclosed above, and in particular with one distal sensor and one proximal sensor. This structure may be beneficial by only requiring intubation of one tube for both feeding and sensing, saving time and resources while enhancing patient comfort. Also, providing an NG tube with sensors may obviate an x-ray to ensure the NG tube is in the correct location . In this example, detecting a pH of 2.0 units from the distal (tip) sensor and a pH of 7.0 units from the more proximal sensor helps to confirm that the NG tube is in the correct position, where the tip is in the stomach and the proximal sensor is in the esophagus, therefore resulting in less acidic gastric juice pH at that location. Providing an NG tube with a sensor also makes it easier to determine whether a prescribed PPI or H2 Blocker has sufficiently increased the pH of the stomach, and to monitor dosages and pH over time to reduce the incidence of stress ulcer prophylaxis.

[0308] In another exemplary embodiment, the NG tube may include only one sensor. This structure may still provide many of the same or similar benefits as with the NG tube having two sensors. For example, x-rays to confirm NG tube placement may still be obviated by slowly inserting the tube and observing when the pH drops suddenly, indicating that the sensor has entered the acidic environment of the stomach and thus is in the correct position.

[0309] Another exemplary embodiment includes two sensors fitted onto a small bowel feeding tube. Measuring pH at both sensors confirms that the small bowel tube has been inserted correctly. For example, a pH of 7 units in the distal sensor and a pH of 2 units in the proximal sensor indicates that the distal tip has migrated into the duodenum and thus is in the correct position. In this exemplary embodiment, it may still be advantageous to perform a pharmacological stimulation test to determine whether the gastrointestinal tract is sufficiently perfused, even though feeding will take place in the small bowel. In this example, a lower pH measurement from the proximal sensor may measure the gastric response from the pharmacological challenge, and its measured pH unit drop help indicate the level of perfusion.

[0310] Some exemplary embodiments add various features and / or operations to the catheters, tubes and / or probes disclosed above. For example, sensors can be attached to Percutaneous Endoscopic Gastrostomy (PEG) tubes often used for long term patient feeding. In one exemplary embodiment, a pH sensor is attached to a PEG tube to provide continuous, semi-continuous or intermittent pH measurements. The pH measurements provided by this pH sensor can provide data indicating the gastric system's response to the feed, whether the feed is being processed properly, necessity of further feeding or different types of feeding, etc.

[0311] In another embodiment, one or multiple pH and / or impedance sensors are attached at various locations of a jejunal feeding tube. It may be particularly advantageous to provide pH sensors at different locations within the gastrointestinal tract along the jejunal tube. For example, in the case of a nasojejunal tube separate pH sensors can be located in the stomach, upper small bowel, and lower small bowel. Measurements from these sensors can be used to provide various benefits, such as to ensure proper tube placement, to indicate motility or other aspects of food processing, etc. As an alternative, or in addition to the above pH sensors, impedance sensors can be placed along the jejunal tube, such as at the same or similar locations as those disclosed above, to provide various benefits, such as to indicate motility, etc. Exemplary embodiments are also intended to cover adding the same or other sensors and sensor configurations to other types of tubes, such as nasogastric tubes.

[0312] In other alternative embodiments, probes can be used that provide continuous or substantially continuous pH measurement. Using a continuous, substantially continuous, or semi-continuous method of pH measurement may be beneficial by providing additional useful information, such as the time taken for a pH decrease to occur. For example, if pH starts to drop (e.g., 1 unit) at 10 minutes after pentagastrin administration, then this likely represents a very robust splanchnic perfusion (circulation) and one can start enteral feeding very aggressively, e.g., 25% of goal with increase of 25% every 4 hours. On the other hand, if pH decreases by at least 1 unit but does not cross the 1 unit threshold for 45 minutes, this might indicate a less robust perfusion (circulation) necessitating a slower increase in enteral feeding infusion rates.

[0313] Exemplary embodiments cover still other types of apparatus that measure gastric juice pH. One such exemplary embodiment does not include a tube for obtaining the gastric juice, and instead uses a capsule that can be inserted into the patient. Once positioned, the capsule can transmit information regarding gastric juice pH to an indicator outside of the patient. One such currently commercially available catheter-free capsule is marketed as the Bravo ™< pH monitoring system by Given Imaging, Ltd.

[0314] The capsule may be especially beneficial by providing data indicating gastric juice pH over short periodic increments or even continuously providing streaming data. More closely monitoring the gastric juice pH (and thus gastric function) in this way enables exemplary embodiments to further enhance care, such as is disclosed above with regard to using a continuous, semi-continuous, substantially continuous, periodic, or other method of pH measurement.

[0315] Taking multiple pH measurements enables the rate of pH change after administration of the pharmacological challenge agent to be used to better determine gastric function so that care can be provided accordingly. For example, a rapid rate of gastric juice pH change can evidence a very healthy gastric function, warranting immediate indication of a high rate of nutrition increase. Gastric juice pH changes after feeding may even indicate a fairly healthy gastric function, evidencing acceptability of increasing the amount or rate of increase of nutrition. A slow rate of gastric juice pH change may evidence a rather less healthy gastric function, warranting no increase, or a slow rate of increase, of nutrition. As discussed with other exemplary embodiments, no gastric juice pH change evidences a rather unhealthy gastric function.

[0316] In other words, in the previously disclosed exemplary embodiments, a change in pH after administration of a gastric acid stimulant or suppressant is used to determine gastric function. However, more closely monitoring gastric juice pH, such as by taking multiple pH measurements over time, enables rate of pH change to be determined. Once determined, this rate of pH change can be used as an indicator of gastric function similarly to the simple pH change of the previously disclosed embodiments. However, use of the rate of pH change may be especially beneficial for various reasons. For example, the rate of pH change may speed up the determination of gastric function

[0317] In other words, in some of the previously disclosed embodiments relying on pH change, the stressed pH test(s) are not conducted until certain periods have elapsed, such at 15 minutes, 30 minutes, 45 minutes, etc., after administration of stimulant or suppressant. However, using rate of pH change, such as by taking multiple measurements over time, enables an earlier monitoring of gastric reaction. For example, a high rate of pH change may be detected well prior to the initial stressed pH measurement of the previously disclosed embodiments, such as at 5 minutes post stimulant or suppressant administration. As previously disclosed, speeding-up the determination of gastric function is beneficial by enabling care to be guided on an expedited basis.

[0318] Exemplary embodiments are not limited to the methods disclosed above. The above exemplary embodiments cover determining the rate of pH change by monitoring gastric juice pH via streaming data or otherwise monitoring pH on a continuous, semi-continuous, substantially continuous periodic, or other basis. However, exemplary embodiments are intended to cover any method or apparatus that directly, indirectly, or otherwise enables assessment, estimation or determination of rate of pH change.2. H+ / pH Measuring Device

[0319] As shown in Fig. 1, in some of the above exemplary embodiments, the measuring apparatus 1 includes discrete components, i.e., the obtaining / sampling device 3 (tube 4, syringe 5, connector 6, etc.) and pH measuring device 7. However, exemplary embodiments are not limited to this structure. For example, exemplary embodiments can include one or more integral or unitary devices that combine all or some of the above components.

[0320] In an exemplary embodiment, an indicator 8 is functionally and / or structurally connected to the pH measuring device 7 to indicate the pH of the gastric juice sample to a user. In other words, the pH measuring device 7 measures the pH of gastric contents provided by the obtaining / sampling device 3, and provides or otherwise transmits the measured pH to the indicator 8 that indicates to an operator the measured and received pH. This functional and / or structural connection can be in any currently known or later developed form, such as wiring, wireless transmission equipment, etc.

[0321] Exemplary embodiments include other structures. For example, Fig. 10 is a schematic of an apparatus in accordance with an exemplary embodiment, wherein one sensor measures baseline pH and a separate sensor measures stressed pH. Specifically, one syringe / aspirator 5, connector 6, and pH measuring device 7 is used to measure gastric contents pH to obtain a baseline pH for indication by the indicator 8. Any or all of these devices, i.e., the syringe / aspirator 5, connector 6, and pH measuring device 7, are then discarded and / or replaced with another syringe / aspirator 122, connector 124, and / or pH measuring device 126 used to measure gastric contents pH to obtain a stressed pH. The pH measuring device 126 can be connected (structurally and / or functionally) to the indicator 8 for indication of the stressed pH. In another exemplary embodiment, the pH sensor could be an in-dwelling type sensor that has been calibrated before insertion in the stomach. This in-dwelling pH sensor would measure both the baseline pH and the stressed pH, then communicate the measurements back to a common pH recorder.

[0322] Exemplary embodiments are intended to cover and include any indicator 8 that provides any sort of indication of the measured pH or of the hydrogen ion concentration, which is the basis of reflection of pH measurements. The indicator 8 can provide local indication, such as on the indicator itself, and / or provide indication remote from the indicator 8. For example, the indicator can provide the indication in a part of an ICU remote from the patient, at a separate section of a hospital, or in a facility remote from a hospital, for example. In an exemplary embodiment, the measured pH is transmitted to a database accessible to a patient's medical care provider, such as the patient's doctor.

[0323] Exemplary embodiments are intended to cover and include an indicator 8 that provides any sort of pH indication. For example, the indication can be provided through sound, such as the indicator 8 generating and outputting an artificial voice signal so that the operator can hear the measured pH. Alternatively, or in addition to the above, the indicator 8 can provide visual indication of the measured pH, such as on the indicator 8 itself and / or remotely from the indicator 8. The visual indication can be provided via any currently known or later developed display, such as liquid crystal display (LCD), organic light emitting diode (OLED), etc.

[0324] As indicated above with regard to the measuring apparatus 1 components, the indicator 8 can be a separate device or be provided as integral or unitary with any or all of the measuring apparatus 1 components. In one exemplary embodiment, the indicator 8 is unitary with the pH measuring device 7. This exemplary embodiment may be advantageous by providing a simple structure that is user friendly, compact, etc.

[0325] In some exemplary embodiments, the indicator 8 indicates results of the baseline pH test and the stressed pH test. In other exemplary embodiments, the indicator additionally indicates any differential between the baseline and stressed pH tests. In still other exemplary embodiments, the indicator 8 indicates the differential and does not indicate the baseline pH and / or stressed pH.

[0326] In some exemplary embodiments, the indicator 8 also includes a controller capable of performing various operations. These operations can relate to anything relevant to the procedure, such as facilitating detection of gastric function, facilitating the guiding of care, etc.

[0327] For example, the controller can help to implement the timing of gastric juice pH measurement, as discussed above in Section IV(A) (Timing of Gastric Juice pH Measurement). As discussed in Section IV(A), a period or gap in time separates the baseline pH test / pharmacological challenge agent administration and the stressed pH test. Some exemplary embodiments use a fixed period while others use different periods based on various data. However, regardless of whether the period is fixed or changeable, the controller can help implement the period, i.e., ensure that the appropriate time elapses between the baseline pH test / pharmacological challenge agent administration and the stressed pH test.

[0328] For example, the controller may prevent the stressed pH test from occurring until after the proper period has elapsed. In addition, or as an alternative, the controller may generate and send a signal to the indicator 7 or some other apparatus to provide some indication, such as via an alarm, that a stressed pH test has been attempted prior to the proper period elapsing. In addition, or as a further alternative, the controller can generate and send a signal to the indicator 7 or some other apparatus to provide some sort of indication that the period has elapsed and the stressed pH test should be performed. This indication can help prevent the stressed pH test from being taken too late.3. Enhanced H+ / pH Measurements

[0329] Exemplary embodiments are intended to cover any and all currently known and later developed methods and apparatus for enhancing, improving and / or optimizing pH measurements, including but not limited to gastric pH and esophageal pH. For example, related art apparatus used for pH sensing over an extended period are subject to at least two types of challenges or limitations. These challenges or limitations of related art pH sensing technology are evident with antimony sensors used for ambulatory pH monitoring studies that have a duration of approximately 18 - 24 hours, and can be more pronounced when used for monitoring ICU patients for even longer periods, such as 48 - 72 hours.

[0330] The first type of challenge or limitation is caused by structural aspects of the related art sensors, and in particular the related art sensors not having a structure: 1) amenable to being deposited in the correct or desired location of the patient's body; 2) that reduces, minimizes, or avoids patient discomfort upon being deposited and remaining in the patient's body; and / or 3) that remains functional and accurate over an extended period, i.e., a long useful measurement life. The third type of challenge or limitation can be caused, at least in part, by coating of the related art pH sensors over an extended period with fluids and / or particles, including but not limited to gastric juice secretions, tube feeds, administered medications (e.g., Carafate), etc., which reduces sensor functionality and / or accuracy over time.

[0331] Exemplary embodiments provide enhanced pH sensing apparatus and methods that address the first and second challenges or limitations of the related art sensors discussed above, by providing a sensor having a structure: 1) amenable to being deposited and remaining in the correct or desired location of the patient's body over the extended period; and / or 2) that reduces, minimizes, or avoids patient discomfort upon being deposited and remaining in the patient's body over the extended period. For example, exemplary embodiments include an 1 8F Salem Sump type tube modified to include at least one pH sensor, 18F Salem Sump type tube modified to include 2 pH sensors (one gastric and one esophageal) and impedance sensors in the esophageal location, and a 12 F fine bore feeding tube with a removable stylet / guide wire modified to include pH and / or impedance sensors. The 18F tube is of sufficient rigidity that it can be inserted into the stomach through the nose or mouth in a patient who is not sufficiently conscious or cooperative to aid in this insertion, e.g. aided in conscious or cooperative patients by swallowing the typically thin and flimsy tube (e.g. 6 F). The 12 F fine bore tube has sufficient rigidity when the removable guide wire is inserted to facilitate insertion in an unconscious or uncooperative patient, however, after insertion the guide wire can be removed, resulting in a less rigid and more comfortable tube.

[0332] Exemplary embodiments also provide enhanced pH sensing apparatus and methods that address the third challenges or limitations of the related art sensors discussed above. For example, some exemplary embodiments can reduce, minimize, remove or otherwise prevent coating, debris or other build-up on or around the pH sensor to enhance its useful measurement life and precision over time. In one such embodiment, a fluid, such as a liquid or even gas, is used to remove or clean debris or other deposits (e.g., protein buildup) from the pH sensor.

[0333] This operation can be implemented using any currently known or later developed technology. For example, the sensor can be attached to a catheter having a lumen (i.e., a hollow tube), which is either housed within, or is external to, a larger catheter body. It may be beneficial to provide the lumen within the catheter body for various reasons, such as to make the apparatus more compact, to obviate structures on the catheter body exterior that may potentially contact or catch-on the patient, etc. However, some exemplary embodiments provide the lumen at or on the catheter body exterior. In some exemplary embodiments, the catheter body and lumen are unitary, i.e., formed from a single structure, while the catheter body and lumen of other embodiments are integral or otherwise formed of two separate structures that are connected together. The catheter body and lumen can be formed of any material, such as synthetic resin, that enables the above functionality.

[0334] The lumen can extend from a proximal end (external to the patient) to or adjacent to the gastric pH sensor at a distal end. The proximal end of the lumen can include any structure that enables introduction of a fluid, such as a liquid or gas, into the interior of the lumen. In some embodiments, a syringe is used to introduce the fluid into lumen. In these embodiments, the proximal end of the lumen includes a Leur-lock or similar adapter that allows an operator to connect the syringe, such as a standard medical grade syringe (e.g., B-D 3, 5, 10, or 20 ml). In one exemplary embodiment, the syringe is a 20 ml syringe, such as the syringe disclosed in http: / / catalog.bd.com / bdCat / viewProduct.doCustomer?productNumber=301031,

[0335] After being introduced at the proximal end, the fluid travels distally within the lumen and is ejected from the lumen at the distal end. The fluid contacts the sensor after being ejected so as to reduce or otherwise remove debris on or at the sensor. Exemplary embodiments are intended to include any structure at the lumen distal end enabling or facilitating this ejection. In some embodiments, the lumen distal end defines a small hole, slit, or other suitable aperture disposed so as to direct the fluid to or at the sensor. In one such embodiment, the hole, slit, or other suitable aperture is disposed adjacent to, and points toward, the pH sensor. The hole, slit, or other suitable aperture can also be structured to increase the ejected fluid velocity to enhance the debris removal, such as by using a nozzle or nozzle-like effect.

[0336] In some of the embodiments discussed above, the fluid is a liquid (e.g., water, saline and / or 0.9% NaCl), that is introduced and travels through the lumen, and is ultimately squirted or otherwise ejected from the lumen in a sufficient volume, such as approximately 3 to 20 ml, in order to reduce or otherwise remove a coating, debris or other build-up on or around the pH sensor. This procedure can be performed once or several times as desired to accomplish or ensure certain results. This operation can be performed after detection of actual or suspected degradation of sensor functionality or accuracy, or alternatively can be performed prophylactically, e.g., every 12 hours (for several days), to reduce, minimize, or prevent any coating, debris or other build-up from developing on or around the sensor.

[0337] As disclosed above, some of the embodiments use water, saline and / or 0.9% NaCl as the fluid. However, embodiments are intended to cover any applicable fluid, such as a specialized liquid cleaning formula. In fact, such a formula can be advantageous if it is: 1) not toxic to patients; and 2) more likely to reduce, remove, break-down or otherwise prevent deposits (e.g., protein) on or around pH sensors. Exemplary liquid cleaning fluids include: 1) non-toxic proteolytic enzymes, such as pancreatic enzyme (which is disclosed in Dandeles, Lauren M., Amy E. Lodolce. "Efficacy of Agents to Prevent and Treat Enteral Feeding Tube Clogs." The Annals of Pharmacotherapy 45 (2011): 676-680. Print. hereafter "Dandeles et al 2011," ), and / or 2) papain (which is disclosed in "Proteolytic Enzymes for Ear, Nose, & Throat Problems." Dr. Grossan's Ear, Nose and Throat Consultant Pages. 12 June 2012. Web. <http: / / www.ent-consult.com / enzymes.html>, ). The fluids used in other exemplary embodiments include a mixture of different liquid cleaning formulas and / or other fluids (such as water, saline and / or 0.9% NaCl).

[0338] Some of the embodiments disclosed above are directed solely to reducing, removing or otherwise preventing the coating, debris and / or other build-up on or around pH sensors used to measure gastric pH, i.e., gastric juice disposed in a patient's stomach. These embodiments may be particularly beneficial because of the increased likelihood of coating, debris, and / or other build-up on or around a gastric pH sensor (as opposed to other sensors, such as esophageal sensors) due to the fact that the gastric secretions and possibly external tube feeds are in this location and thus more likely to adversely affect the sensor's function.

[0339] However, some of the above exemplary embodiments are directed solely to reducing, removing or otherwise preventing the coating, debris or other build-up on or around pH sensors used to measure esophageal pH, i.e., fluid disposed in and / or around a patient's esophagus. Still other exemplary embodiments are directed to reducing, removing or otherwise preventing the coating, debris or other build-up on or around multiple pH sensors, such as sensors used to measure gastric pH, i.e., gastric juice disposed in a patient's stomach, and esophageal pH, i.e., fluid disposed in and / or around a patient's esophagus.

[0340] Exemplary embodiments are intended to cover any currently known or later developed apparatus and methods to perform this operation involving multiple pH sensors. One such embodiment includes the structure disclosed above for reducing or removing coating, debris or other build-up on or around the pH sensors used to measure gastric pH, i.e., gastric juice disposed in a patient's stomach, and in addition includes a separate lumen having a structure enabling fluid to exit at or otherwise proximate the esophageal pH sensor. Another embodiment includes a single lumen with separate fluid exit structures, such as small holes, slits, or other suitable apertures, disposed so as to separately direct the fluid to or at the gastric sensor and the esophageal sensor. In these embodiments, fluid is introduced at the single lumen proximal end, and travels distally to a location at or adjacent to the esophageal sensor. Some of the fluid is ejected at the esophageal sensor, while the remaining fluid travels distally past the esophageal sensor to be ejected at or adjacent to the gastric sensor.

[0341] In some embodiments, the fluid exit structures at the esophageal sensor and the gastric sensor are the same. However, other embodiments use different fluid exit structures to provide a variety of benefits. For example, it may be beneficial for the fluid exit structure adjacent the esophageal sensor to be structured to prevent or otherwise avoid an excessive amount of fluid from exiting to ensure that a sufficient volume of fluid is available for the gastric sensor, especially because coating, debris or other build-up is more likely to occur, or be heavier, at the gastric sensor. As an example, a small slit may be used as the fluid exit structure at the esophageal sensor, while a larger aperture may be more appropriate at the gastric sensor.

[0342] Exemplary embodiments are intended to cover any currently known or later developed methods and apparatus for reducing, removing or otherwise preventing coating, debris and / or other build-up on or around pH sensors, and are not limited to the exemplary embodiments disclosed above that utilize fluids. In fact, other embodiments instead involve mechanical cleaning of such sensors, which can be accomplished using any currently known or later developed technology. One such embodiment uses a lumen that extends from the proximal end of the catheter to adjacent or otherwise proximal the pH sensor. A wire or other suitable structure can be introduced along the lumen to actuate a flap back and forth over the sensor to reduce or remove the coating, debris and / or other build-up. The embodiments that utilize mechanical cleaning techniques can be applied to any of the sensors disclosed above, including gastric sensors and / or esophageal sensors.

[0343] Embodiments disclosed above involve reducing, removing or otherwise preventing coating, debris or other build-up on or around pH sensors while the sensors remain in the patient's body, thereby obviating removal of the catheters, sensors, etc., from the patients. This operation can be beneficial for a variety of reasons, such as by reducing patient trauma, discomfort, etc., reducing effort required by hospital staff, reducing or preventing interruption of pH measurements, etc.

[0344] However, other embodiments involve reducing, removing or preventing coating, debris or other build-up after removal of pH sensors from patients. In accordance with these embodiments, the catheter, sensor, etc., is removed from the patient and cleaned outside of the patient. Embodiments are intended to cover any currently known or later developed methods and apparatus for such cleaning, such as reducing, removing or preventing any coating, debris or other build-up using water, saline and / or a non-toxic abrasive method, e.g., rubbing the sensor or other related structure with any applicable material, such as clean medical grade gauze. The sensor and related structure can then be reinserted into the patient after such cleaning. The embodiments that reduce or remove the coating, debris or other build-up after removal of pH sensors from patients may be beneficial by ensuring that the sensors are sufficiently clean.

[0345] Exemplary embodiments are intended to cover still other techniques of reducing, removing or otherwise preventing coating, debris or other build-up on or around pH sensors. For example, the sensors or other adjacent structures may be formed of a material, or coated with a material, that makes it more difficult for, reduces, or prevents debris or other unwanted materials from adhering to the sensors or other adjacent structures.4. Calibration

[0346] Exemplary embodiments include any type of currently known, related art, or later developed pH measuring device usable with any of the disclosed methods and apparatus, including pH measuring devices that require calibration. Some embodiments include pH sensors that require calibration immediately prior to use, such as 2 or 3 point calibration with USP buffers of 4.0 and 7.0 pH units. This type of calibration can be referred to as "on-site" calibration, or "bed-side" calibration.

[0347] However, it may be beneficial to use pH sensing apparatus that do not require this calibration at the bedside for various reasons, such as to reduce or minimize interruptions in patient care including direct care. A few embodiments for providing pH sensors that do not require "on-site" calibration are provided below for exemplary purposes, and are not intended as an exhaustive list of pH sensors usable with the disclosed methods and apparatus.

[0348] Some embodiments avoid "on-site" calibration by adopting certain manufacturing tolerances, such as strict manufacturing tolerances. In other words, pH sensing catheters can be manufactured with sufficient accuracy and precision that no "on-site" calibration is required. In one such example, accuracy is ±0.2 pH units and precision is ±0.1 pH units, which is sufficiently accurate and precise for many medical contexts. One such applicable medical context includes differentiation between gastric or esophageal pH of 2.0 vs. 5.0, which does not require a high degree of accuracy or precision because the differences in pH being measured are fairly large.

[0349] In addition, the pH sensor manufacturer can randomly or systematically sample manufactured sensors and test them with USP buffer solutions of known pH. This process can be performed in any sequence or any frequency, such as intermittently, in order to verify that the desired accuracy and precision is being obtained, or at least to increase the chances of obtaining the desired accuracy and precision.

[0350] In accordance with some other embodiments that avoid "on-site" calibration by performing factory testing, the pH sensor tests all manufactured sensors with USP buffer solutions of known pH in order to verify that they have the desired accuracy and precision, e.g., accuracy of 0.2 pH units and precision of ±0.1 pH units. In these embodiments, only sensors passing this testing i.e., meeting the sensor specifications, are released for commercial use. Sensors not meeting the specifications can be recycled, re-tooled, or discarded.

[0351] Still other embodiments avoid "on-site" calibration by performing factory "pre-calibration." In accordance with one such embodiment, the manufacturer calibrates all manufactured sensors in the factory with USP buffer solutions of known pH. The calibration factor for each sensor is obtained, and recorded or "burned" into an electronic memory device or other electronic recording medium. The calibration factor recorded on the recording medium can be communicated to a pH recorder or other device to receive the pH data. However, other embodiments communicate the calibration factor differently to the pH recorder or other device. In one such embodiment, the calibration factor is printed on the pH sensor packaging and can then be entered manually into the pH recorder or scanned (e.g., bar code) into the pH recorder.5. Other Exemplary Embodiments

[0352] Exemplary embodiments are intended to include still other methods and apparatus for determining gastric juice pH. For example, in one exemplary embodiment, a feeding tube apparatus designed for safer and / or quicker insertion includes pH sensor(s) and / or impedance sensor(s), enabling pH and / or impendence monitoring for patients intubated with such an apparatus.

[0353] In one such embodiment, the pH and / or impedance sensors are integrated into a tube that contains a magnet in its tip. An external magnet is used to facilitate, enhance or optimize placement of the tip of the tube, often post-pyloric for a naso duodenal or naso jejunal tube.

[0354] In another exemplary embodiment, a feeding tube and electromagnetic insertion guidance system includes pH and / or impedance sensors. This tube can either be a nasogastric tube or a longer tube designed for post pyloric insertion. Benefits of using this modified feeding tube include ease of insertion with the capability for pH and / or impedance monitoring, e.g., in the stomach and / or esophagus. In one embodiment, pH and / or impedance sensors are integrated in a nasogastric feeding tube incorporating a mechanism for enhanced guidance and positioning (e.g., an clectromagnetic device).

[0355] In other embodiments, a sensor (e.g., pH sensor) is located in the tip of a naso jejunal tube, enabling continuous, semi-continuous or intermittent pH measurements in the small bowel. Small bowel pH measurements can be useful or beneficial in several ways. For example, these pH measurements may assist with confirmation of tube placement. In this case, as the distal tip of the tube leaves the stomach (low pH) and enters the small bowel, the pH rises, thereby providing confirmation of placement. Secretion of bicarbonate into the small bowel typically results in a much less acidic environment there (e.g., pH 7) compared with the stomach (e.g., pH 2-5).

[0356] Related art systems for introducing feeding tubes may allow for relatively easy insertion of the tube, but do not provide monitoring of correct placement of the tube. This deficiency may be significant or otherwise important because it is common for feeding and other such tubes to migrate (i.e., move) within the patient due to several potential factors, such as traction / pulling of the tube by the patient. Therefore, another embodiment includes continuous or semi-continuous measurement of small bowel pH to enable the clinician to verify that the tip of the feeding tube continues to be in the correct location (small bowel) and has not migrated (i.e., moved) into the stomach. This unintended migration or otherwise improper tube placement may be particularly dangerous for a patient where it is imperative that feeds are administered only into the small bowel, and not into the stomach. One such example includes certain critically ill patients with no effective lower esophageal sphincter, which is the part of the body, which normally minimizes the retrograde movement of gastric contents into the esophagus.C. Methods and Apparatus For Determining GI Tract's Response to Challenge and Guiding Care Based on Determined H+ / pH1. Gastric Juice H+ / pH Data Interpretation

[0357] Exemplary embodiments guide medical care based on detected gastric function. Some exemplary embodiments detect gastric function by determining a change in H+ concentration or pH caused by administration of a pharmacological challenge agent, such as gastric acid stimulant or suppressant. The change in gastric juice H+ concentration or pH (gastric juice H+ concentration or pH differential) can be determined by calculating the difference in gastric juice H+ concentration or pH immediately before administration of the stimulant or suppressant and the gastric juice H+ concentration or pH after a sufficient period has elapsed subsequent to administration. The following examples are provided in terms of pH, but are also applicable in terms of H+ concentrations.

[0358] In general, a relatively large change in gastric juice pH indicates a relatively healthy GI tract with robust splanchnic perfusion and care can be provided accordingly, such as by initiating enteral feeding, for example. Alternatively, no change in gastric juice pH, or a relatively small change, indicates a relatively unhealthy GI tract response and care can be provided accordingly, such as by not introducing enteral feeding, for example.a. Gastric Juice pH Differential

[0359] Exemplary embodiments are directed to many inventive aspects further specifying and / or providing additional benefits beyond the above indications of relatively healthy / unhealthy gastric function based on relatively large / small changes in gastric juice pH. For example, certain pH differentials may be deemed sufficient in some contexts, while other entirely or slightly different pH differentials may be deemed sufficient in other contexts. Examples of some of these inventive aspects are provided below for exemplary purposes only, and are not intended to form a complete listing.

[0360] For example, the pH differential deemed sufficient may depend on the type of care at issue, i.e., enteral feeding, ventilation, vasoactive agents, patient disposition within the hospital, etc. In other words, in some exemplary embodiments, the pH differential used to indicate sufficient gastric function for a certain type of care, such as enteral feeding, may be fixed, such as at 1 pH unit. In other words, a pH differential of 1 pH unit may be deemed sufficient to initiate enteral feeding. Contrarily, in other exemplary embodiments, the pH differential deemed sufficient to determine patient disposition within the hospital, such as determining whether a patient remains in an ICU, may be different. In other words, a lower pH differential (than would be required to start enteral feeding), such as 0.5 pH units, may be sufficient to move a patient out of an ICU (assuming other data warrants such a move). In still other exemplary embodiments, the pH differential deemed sufficient to guide care may depend on patient characteristics, such as one or any combination of factors, including but not limited to: age, gender, fitness, weight, body composition, such as percentage of body fat, ethnicity, family history, current medical condition, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable. In other words, as an example, the pH differential deemed sufficient to guide care of a young patient may be higher than that required for an older patient.

[0361] The pH differential deemed sufficient to guide care can also be affected by other factors, such as instrument accuracies. For example, some exemplary embodiments can take into account accuracy of pH monitors. A pH monitor that is accurate to 0.001 pH units easily enables detection of a difference between 1.0 pH unit and 0.8 pH unit, and thus exemplary embodiments incorporating such a monitor can make determinations as to the sufficiency of detected pH differential accordingly.

[0362] The pH differential deemed sufficient for certain types of care can be based on still other factors, such as the baseline gastric juice pH. In other words, a certain pH differential may be sufficient to guide care after detection of a relatively low baseline gastric juice pH, while a different pH differential may be sufficient to guide the same type of care after a relatively high baseline gastric juice pH. One exemplary basis for this distinction is that pH values follow a logarithmic scale in relation to hydrogen ion concentration, as indicated in the table below. pHMolarity (moles / L)70.000000160.00000150.0000140.000130.00120.0110.1

[0363] As indicated above, a pH of 7 has a hydrogen ion concentration of 0.0000001 moles per liter of the gastric contents. Each unit drop in pH therefore requires 10 times the concentration of hydrogen ions. For example, a pH drop from 7 to 6 requires 10 times the hydrogen ions to be present in the sample, while a pH drop of 6 to 5 requires a further 10 times the hydrogen ions. A pH drop from 7 to 5 would therefore require 100 times the hydrogen ions, and 7 to 4, 1000 times the hydrogen ions. This increase in hydrogen ions may appear large, but these measurements are relative to a typical gastric acid response and the pH of the initial sample. For example, studies have shown that the parietal cells in the stomach produce gastric acid at a hydrogen ion concentration of 0.160 moles per liter, such as: 1) Feldman, Mark. "Gastric Bicarbonate Secretion in Humans: Effect of Pentagastrin, Bethanechol, and 11,16,16-Trimethyl Prostaglandin E2." Journal of Clinical Investigation 72 (1983): 295-303. Print., hereafter "Feldman," , 2) Hollander, Franklin. "Variations in the Chlorine Content of Gastric Juice and Their Significance."Studies in Gastric Secretion 4 (1932): 585-604. Print., hereafter "Hollander,", 3) Makhlouf, G. M., J. P. McManus, and W. I. Card. "Gastroenterology." Official Publication of the American Gastroenterological Association 51.4 (1966): 455-65. Print., hereafter "Makhlouf,", and 4) Hirst, B. H., L. A. Labib, J. D. Reed, and J. G. Stephen. "Relationship Between Hydrogen Ion Concentration and Flow of Gastric Juice During Inhibition of Gastric Secretion in the Cat." J. Physiol. 306 (1980): 51-63. Print., hereafter "Hirst,". The Feldman et al (1983) study showed the typical basal, or non-stimulated, gastric acid production in healthy adults was 31 ml / h, while pentagastrin stimulated gastric acid production over 120 ml / h.

[0364] Given such a high production of gastric acid at a high hydrogen ion concentration, it is therefore easier for gastric juice pH to decrease by at least one unit when starting at a higher pH because the inherent hydrogen ion concentration is so low at these higher pH levels. In contrast, when the initial pH is low, e.g. 2.0, it is more difficult to drop even one pH unit. Therefore, the same volume of stimulated gastric acid production can result in different units of pH drop depending on the initial pH.

[0365] The following exemplary table demonstrates the relationship of how the same volume of stimulated gastric acid production can result in different units of pH drop depending on the initial pH. The exemplary table is generated using an exemplary method of calculating the resulting pH (which is merely provided for exemplary purposes and not intended as limiting) uses the following formula: pH = − log H + GJ 1 * V GJ 1 + H + GJ 2 * V GJ 2 / V GJ 1 + V GJ 2

[0366] Wherein: H +< GJ1 = Hydrogen ion concentration of the initial gastric volume in moles per liter, V GJ1 = Volume of the initial gastric contents, H +< GJ2 = Hydrogen ion concentration of the stimulated gastric juice in moles per liter, and V GJ2 = Volume of the stimulated gastric juice.

[0367] In this exemplary calculation, the volume of the initial gastric contents, V GJ1 = 0.200 liters, the hydrogen ion concentration of the stimulated gastric juice, H +< GJ2 = 0.147 moles / liter, and the volume of the stimulated gastric juice, V GJ2 = 0.008 liters. The exemplary table thus shows that for the same volume of stimulated gastric juice, the resulting pH measurements, pH2, vary depending on the initial pH measurement, pH1. This exemplary table and calculation show that higher initial pH measurements result in a higher pH differential compared to lower initial pH measurements which result in a lower pH differential. pH1 H+ GJ1 (M / L) H+ GJ2 (M / L) pH2 70.00000010.0056622.2470660.00000100.0056632.2469950.00001000.0056712.2463340.00010000.0057582.2397530.00100000.0066232.1789420.01000000.0152771.8159610.10000000.1018150.99219

[0368] An exemplary embodiment therefore uses a non-linear scale, such that a relatively large change or decrease in pH (such as a change or drop of one or more units) is considered a sufficient pH differential if the initial pH is high, but a relatively small change or decrease in pH (such as a change or drop of less than one unit) is considered a sufficient pH differential if the initial pH is low. Another exemplary embodiment can therefore use a non-linear scale that also follows a logarithmic function, where the level of gastric acid concentration in the stimulation response is in proportion to the pH unit drop of a valid test result (sufficient pH differential). In other words, a much larger pH differential deemed sufficient to indicate healthy gastric function would be required for a high baseline pH as compared to a low baseline pH, and that this difference can be represented in magnitudes of ten. An exemplary embodiment can also display the non-linear scale of valid test results (i.e., pH differentials deemed sufficient) in a table format that can be viewed, such as by medical staff. Another exemplary embodiment may use this non-linear scale programmed as software into a pH meter, or other testing device that may calculate and then communicate the determination as to whether a valid test result is achieved.b. Hydrogen Ion (H+) Concentration Differential

[0369] Exemplary embodiments for further specifying and / or providing indications of relatively healthy / unhealthy gastric function can be based directly on the hydrogen ion (hereafter H+) concentration of the gastric contents, as specified in moles per liter (mol) or millimoles per liter (mmol). For example, measurements can be taken of gastric juice molarity before the gastric stimulation test, documenting in moles per liter, and then measurements can be taken again after the gastric stimulation test. The differential of the two measures of H+ concentration in moles per liter can then be used to assess the relative health of the gastric function and to help guide care. Certain H+ concentration differentials may be deemed sufficient in some contexts, while other entirely or slightly different H+ concentration differentials may be deemed sufficient in other contexts. Examples of some of these inventive aspects are provided below for exemplary purposes only, and are not intended to form a complete listing.

[0370] Fig. 13 is a flowchart of an exemplary method and apparatus for guiding care based on H+ concentration differential(s). In one embodiment covered by the flowchart of Fig. 13, a processor is used to guide medical care of a patient based on detected gastric function. The processor is used with at least one administering device that administers a gastric acid stimulant or suppressant, and at least one sensor that measures the patient's gastric juice H+ concentration prior to the administration of the gastric acid stimulant or suppressant to obtain a baseline gastric juice H+ concentration, and that measures the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain a stressed gastric juice H+ concentration.

[0371] As shown in Fig. 13, the processor includes a determination unit that determines a guidance H+ concentration differential indicative of relatively healthy gastric function. This determination can be performed in a variety of ways. For example, the guidance H+ concentration differential can be preset prior to initiation of the procedure, such as even before the patient is examined. In one such embodiment, as disclosed below, a certain guidance H+ concentration differential can be used for all patients, such as 0.01 mmol. Alternatively, the guidance H+ concentration differential can be determined and calculated based on data, such as patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, aspects of current personal medical condition, and genetics. Depending on the patient characteristics on which the guidance H+ concentration differential is based, the determination may be performed prior to or after certain steps of the procedure are performed, such as after measurement of the baseline H+ concentration. According to these embodiments, any currently known or later developed algorithm, program, etc. can be used to make the appropriate determination of guidance H+ concentration differential, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0372] The processor also includes a calculation unit that calculates a measured H+ concentration differential between the baseline gastric juice H+ concentration and the stressed gastric juice H+ concentration. Any currently known or later developed algorithm, program, etc. can be used to make the appropriate calculation of the measured H+ concentration differential, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0373] The processor also includes a comparison unit that compares the guidance H+ concentration differential to the measured H+ concentration differential to determine their relative values. Any currently known or later developed algorithm, program, etc. can be used to make the appropriate calculation of the measured H+ concentration differential, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0374] The processor also includes a primary instruction unit that provides instructions to guide medical care based on a relatively healthy gastric function if the measured H+ concentration differential is equal to or exceeds the guidance H+ concentration differential. In other words, if the comparison unit determines that the measured H+ concentration differential is equal to or exceeds the guidance H+ concentration differential, i.e., "Yes," then the primary instruction unit provides instructions to guide medical care based on a relatively healthy gastric function. Any currently known or later developed algorithm, program, etc. can be used to provide the appropriate instructions regarding guidance of care that correspond to the comparison between measured H+ concentration differential and guidance H+ concentration differential, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0375] Similarly, the processor includes an alternative instruction unit that provides instructions to guide medical care based on a relatively unhealthy gastric function if the measured H+ concentration differential is less than the guidance H+ concentration differential. In other words, if the comparison unit determines that the measured H+ concentration differential is less than the guidance H+ concentration differential, i.e., "No," then the alternative instruction unit provides instructions to guide medical care based on a relatively unhealthy gastric function. Any currently known or later developed algorithm, program, etc. can be used to provide the appropriate instructions regarding guidance of care that correspond to the comparison between measured H+ concentration differential and guidance H+ concentration differential, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0376] In some embodiments, the sensor performs multiple measurements of the patient's gastric juice H+ concentration after the administration of the gastric acid stimulant or suppressant to obtain multiple stressed gastric juice H+ concentration values; the calculation unit calculates a rate of change of the gastric juice H+ concentration based on at least one of: differentials between the baseline gastric juice H+ concentration and the multiple stressed gastric juice H+ concentration values, and differentials between the different stressed gastric juice H+ concentration values; and the primary instruction unit or the alternative instruction unit provides instructions to guide medical care based on the calculated rate of change of the gastric juice H+ concentration. Any currently known or later developed algorithm, program, etc. can be used to provide these operations, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0377] In some embodiments, the processor further includes a conversion unit that converts the baseline gastric juice H+ concentration and stressed gastric juice H+ concentration to baseline gastric juice pH and stressed gastric juice pH, respectively, wherein: the determination unit determines a guidance pH differential indicative of relatively healthy gastric function based on the baseline gastric juice pH; the calculation unit calculates a measured pH differential between the baseline gastric juice pH and the stressed gastric juice pH; and the primary instruction unit or the alternative instruction unit performs one of the following based on a comparison between the guidance pH differential and the measured pH differential: 1) guiding medical care based on a relatively healthy gastric function if the measured pH differential is equal to or exceeds the guidance pH differential; and 2) guiding medical care based on a relatively unhealthy gastric function if the measured pH differential is less than the guidance pH differential. Any currently known or later developed algorithm, program, etc. can be used to provide these operations, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0378] In some of these embodiments, the determination unit determines the guidance pH differential indicative of relatively healthy gastric function to be relatively low if the baseline gastric juice pH is relatively low, and determines the guidance pH differential indicative of relatively healthy gastric function to be relatively high if the baseline gastric juice pH is relatively high. Any currently known or later developed algorithm, program, etc. can be used to provide these operations, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0379] In some of these embodiments, the processor further includes a comparison unit that sets a minimum baseline gastric juice pH, and compares the measured baseline gastric juice pH to the minimum baseline gastric juice pH; wherein the administering device administers a pharmacological agent to raise gastric juice pH if the comparison unit determines that the measured baseline gastric juice pH is less than the minimum baseline gastric juice pH; the sensor measures the patient's gastric juice pH after the pharmacological agent administration to obtain a modified baseline gastric juice pH; and calculation unit calculates the measured pH differential between the modified baseline gastric juice pH and the stressed gastric juice pH. Any currently known or later developed algorithm, program, etc. can be used to provide these operations, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0380] In some embodiments, the processor further includes a dosage determination unit that determines a pharmacologically effective dosage of gastric acid stimulant; wherein the administering device is configured to administer the determined pharmacologically effective dosage of the stimulant that includes pentagastrin. The dosage determination unit can determine the pharmacologically effective dosage of pentagastrin based on patient characteristics, including at least one of: age, gender, fitness, weight, body composition, percentage of body fat, ethnicity, family history, personal medical history, aspects of current personal medical condition, and genetics. As one example, the dosage determination unit determines the pharmacologically effective dosage of gastric acid stimulant or suppressant based on patient weight in accordance with one of the following: a stepped methodology wherein 250 mcg is determined to be the pharmacologically effective dosage for patients weighing 40-70 kg, 500 mcg is determined to be the pharmacologically effective dosage for patients weighing 71-100 kg, and 750 mcg is determined to be the pharmacologically effective dosage for patients weighing more than 100 kg; and a linear methodology wherein the pharmacologically effective dosage of pentagastrin is based on 6mcg / kg, such that 300 mcg is determined to be the pharmacologically effective dosage for a patient weighing 50 kg, 450 mcg is determined to be the pharmacologically effective dosage for patients weighing 75 kg, and 600 mcg is determined to be the pharmacologically effective dosage for patients weighing 100 kg. Any currently known or later developed algorithm, program, etc. can be used to provide these operations, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0381] In some embodiments, the processor is used with a volume measuring device for measuring the patient's gastric contents volume prior to the administering of the gastric acid stimulant or suppressant; and the determination unit determines the guidance H+ concentration differential based on the measured gastric contents volume. The determination unit can determine the guidance H+ concentration differential to be relatively lower if the gastric contents volume is relatively high, and determine the guidance H+ concentration differential to be relatively higher if the gastric contents volume is relatively low. Any currently known or later developed algorithm, program, etc. can be used to provide these operations, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0382] In some embodiments, the sensor performs multiple measurements of the patient's gastric juice H+ concentration after obtaining the stressed gastric juice H+ concentration; the processor further comprises a display for displaying the multiple H+ concentration measurements as a curve via a graph, with the x-axis representing the time that the H+ concentration measurements were taken and the y-axis representing H+ concentration values; and an area calculation unit to calculate an area defined under the curve; and wherein the primary instruction unit or the alternative instruction unit guides medical care based on the calculated area. In other embodiments, the sensor performs multiple measurements of the patient's gastric juice H+ concentration after obtaining the stressed gastric juice H+ concentration; the processor further comprises a rate determination unit for determining a rate of change of the multiple H+ concentration measurements via the derivative of at least one of the following functions: d(H(t)) / dt, where the function H(t) represents the measurement of H+ concentration in moles per liter (mol), and H(t), which represents the multiple measurements of H+ concentration in moles per liter (mol); and wherein the primary instruction unit or the alternative instruction unit guides medical care based on the determined rate of change, such that a relatively fast rate of change indicates a relatively healthy gastric function, and a relatively slow rate of change indicates a relatively unhealthy gastric function. Any currently known or later developed algorithm, program, etc. can be used to provide these operations, including but not limited to mathematical formulae, computational procedures, software programming, application specific integrated circuits, and any other means deemed beneficial.

[0383] Various currently known or later developed algorithm(s), program(s), etc. are disclosed above as being usable to provide the above operations. However, it is understood and intended that the same, similar or other algorithm(s), program(s), etc. are usable to perform other and / or similar operations provided in other portions of the present disclosure and with regard to other contexts / embodiments.

[0384] In another exemplary embodiment, an absolute value of H+ concentration differential may be deemed sufficient to indicate a threshold where the gastric function of the patient is deemed sufficiently healthy to enable specific types of care. For example, in an exemplary embodiment an H+ concentration differential of 0.01 mmol may be sufficient to determine the patient is competent to receive enteral nutrition. This threshold of 0.01 mmol may be sufficient since it equates to a comparable drop on the pH scale to a little over pH 4 when the initial measurement is in the neutral pH range, e.g. 7. A target H+ concentration differential may be advantageous compared to pH measurement since it is an absolute measure on a linear scale and therefore is less subjective to interpretation compared to the logarithmic scale of the pH measurement. An exemplary H+ concentration differential may vary depending on the assessment being sought. For example, exemplary embodiments for H+ concentration differential may be different when assessing overall gastric perfusion, risk of stress ulcers, risk of non-occlusive bowel necrosis, etc.

[0385] Exemplary embodiments for H+ concentration differential may also vary based on other factors, such as the patient's condition and current care being received. For example, in an exemplary embodiment a patient already being enterally fed and showing signs of intolerance to enteral nutrition, e.g. vomiting, may require a higher H+ concentration differential to indicate if the patient should be fed at the same of higher level. In another example, a patient receiving acid suppressant therapy may require a higher H+ concentration differential to account for the effect of the acid suppressant medication. In exemplary embodiments, the acid suppressant dosing could be done after the gastric stimulation test to minimize any potential effect on the gastric stimulation test. In still other exemplary embodiments, the H+ concentration differential deemed sufficient to guide care may depend on patient characteristics, such as one or any combination of factors, including but not limited to: age, gender, fitness, weight, body composition, such as percentage of body fat, ethnicity, family history, current medical condition, personal medical history, genetics, or any other factor currently known or later determined to be relevant or applicable. In other words, as an example, the H+ concentration differential deemed sufficient to guide care of a young patient may be higher than that required for an older patient.

[0386] It is important to note that H+ concentration measurements and the subsequent H+ concentration differential measure are affected by many factors. For example, the volume of gastric contents will affect the H+ concentration measurement since the concentration is based on volume. In exemplary embodiments it may be advantageous to suction out the gastric contents before conducting the gastric stimulation test and H+ concentration measurements. In another example, the output of non-acidic gastric secretions via non-parietal cells will affect the H+ concentration measurement since these secretions may neutralize the gastric acid and thus lower the H+ concentration. Similarly, acid suppressant therapy may neutralize gastric acid or inhibit the production of gastric acid by the parietal cells depending on the therapy being received. In exemplary embodiments, algorithms built into software could capture and process many of these variables to help provide information to the clinician and help guide care.c. Gastric Juice pH, H+ Concentration, and Volume

[0387] In accordance with the above exemplary embodiments, the pH formulas discussed above translate directly as the log of the molarity of the gastric contents, where molarity is defined as moles of hydrogen ion (H+) per liter. The following formula for pH is used to generate the above pH / molarity table: pH = − log molarity

[0388] The above, exemplary embodiments are intended to cover methodologies that base sufficiency of gastric function on a fixed gastric acid output (regardless of baseline gastric juice pH), substantially fixed gastric acid output, and non-fixed gastric acid output. However, since molarity is dependent on volume, the pH and H+ concentration measurements will vary depending on the volume of the gastric contents. For example, if there is a large volume of gastric contents before the gastric acid stimulation, the resultant gastric acid produced will be diluted by the existing gastric contents, reducing the resulting pH drop and H+ concentration differential. Conversely, if there is a small volume of gastric contents before the gastric acid stimulation, the resultant gastric acid produced will be less diluted by the existing gastric contents, increasing the resulting pH drop and H+ concentration differential. Therefore, the same volume of stimulated gastric acid production could result in different units of pH drop and H+ concentration differential depending on the initial volume of the gastric contents. One exemplary method of calculating the resulting pH (which is merely provided for exemplary purposes and not intended as limiting) uses the following formula: pH = − log H + GJ 1 * V GJ 1 + H + GJ 2 * V GJ 2 / V GJ 1 + V GJ 2

[0389] Wherein: H +< GJ1 = Hydrogen ion concentration of the initial gastric volume in moles per liter, V GJ1 = Volume of the initial gastric contents, H GJ2 = Hydrogen ion concentration of the stimulated gastric juice in moles per liter, and V GJ2 = Volume of the stimulated gastric juice.

[0390] Utilizing the above exemplary method of calculating pH one can generate the following table that shows how the post stimulation pH measurement may vary depending on the initial gastric volume. In this exemplary table, the initial pH measurement is noted in furthermost left column. In this exemplary calculation, the patient is assumed to produce 20ml of gastric acid in response to the stimulation. The exemplary calculation thus shows a general trend where the post-stimulation pH measurement is lower when there is less volume, such as with an initial gastric juice volume of 5ml versus compared to when there is more volume, such as an initial gastric juice volume of 500ml. This calculation is exemplary, as there are other factors in the gastric environment that may affect the post-stimulation pH measurements, such as the stimulation of basal secretions that will have the effect of neutralizing a portion of the acid secretions. pH1pH2 Based on Different Levels of Vgj 10.005 0.010 0.025 0.050 0.100 0.200 0.300 0.400 0.500 70.89510.95021.08281.24081.44751.69241.84811.96242.052860.89510.95021.08281.24081.44751.69241.84811.96242.052850.89510.95021.08281.24071.44741.69221.84781.96212.052440.89510.95011.08261.24031.44661.69061.84531.95882.048330.89470.94931.08051.23621.43841.67441.82131.92702.009020.89060.94111.06041.19691.36391.53871.63411.69541.738710.85130.85130.86660.89790.92660.95290.97260.98070.9851

[0391] Thus, some exemplary embodiments measure, and take into account, gastric contents volume in analyzing pH and / or H+ concentration to determine whether the pH and / or H+ concentration differential is sufficient to indicate healthy gastric function. In other words, a relatively small pH and / or H+ concentration differential would be sufficient to indicate healthy gastric function if the gastric contents volume was relatively high while a relatively high pH and / or H+ concentration differential would be sufficient to indicate healthy gastric function if the gastric contents volume was relatively low. The gastric contents volume may be obtained by aspirating all of the gastric contents (including enteral feeds) through an indwelling tube (e.g., nasogastric Salem Sump tube).

[0392] Fig. 7 is a schematic of an apparatus in accordance with an exemplary embodiment that includes a volume sensor 110 that measures gastric volume. As shown in Fig. 7, an aspirator 104 aspirates gastric contents by providing a suction or other force so that gastric contents are sucked or otherwise moved from the stomach of the patient 2, through the orogastric or nasogastric tube 106, and into the collector 108 or other structure. The volume sensor 110 measures the volume of gastric contents collected in the collector 108.

[0393] The above structures are merely provided for exemplary purposes, and not intended to be limiting. In fact, exemplary embodiments are intended to cover any currently known or later developed apparatus or method for achieving the above operation. For example, another exemplary embodiment for obtaining gastric contents volume uses impedance sensors (e.g., VersaFlex Disposable pH + impedance Catheter, size 6 F, from Sierra Scientific Instruments, Los Angeles, CA). While these sensors can be used to measure the passage of bolus through the esophagus, one exemplary embodiment modifies related art impedance sensors to effectively measure the passage of gastric contents from the stomach into the small bowel. In an exemplary embodiment, a series of impedance sensors would be positioned along the catheter and measure the presence and passage of bolus as it transits the length of stomach and into the small bowel. This approach is beneficial at least by obviating aspiration of gastric contents to determine gastric volume, enabling determination of gastric volume more quickly and easily. This approach may also be used to provide gastric volume measurements on a continuous basis, enabling new algorithms to assess patient condition and assist in the guidance of care.

[0394] In another exemplary embodiment a new type of sensor and algorithms can correlate the electrical properties of gastric contents to determine the volume of gastric contents. In other words, the electrical properties change as gastric contents are processed and volume is reduced. This approach may be advantageous in that it could be more accurate in measuring the volume of the gastric contents. This approach is beneficial at least by obviating aspiration of gastric contents to determine gastric volume, enabling determination of gastric volume more quickly and easily. This approach may also be used to provide gastric volume measurements on a continuous basis, enabling new algorithms to assess patient condition and assist in the guidance of care.

[0395] An exemplary embodiment may also display the pH, H+ concentration and gastric volume measurements and the corresponding indication of valid test results (i.e., pH and / or H+ concentration differential sufficient to indicate healthy gastric function) in a viewable table format such as by medical staff.

[0396] In another exemplary embodiment, this gastric volume, H+ concentration information, and pH information is programmed as software into a pH meter, or other testing device, that calculates and then indicates whether a valid test result is achieved (indicate whether the pH and / or H+ concentration differential is sufficient to show healthy gastric function). In this exemplary embodiment, medical staff may enter the initial pH, H+ concentration, and gastric volume measurements into the device interface, and then post stimulation enter a second pH, H+ concentration, and gastric volume measurement into the device interface. Programming via an application resident within the device, or via a remote application, may then receive the measurements, calculate a test result using algorithms, and then indicate on the interface of the device if a valid or invalid test result has occurred. In another exemplary embodiment, the device may use additional algorithms to receive the pH, H+ concentration, and volume measurements, and suggest guidance of care in areas such as level of nutrition, use of pharmacological agents, and other care decisions that can be indicated by knowing the current health and responsiveness of the gastrointestinal tract.

[0397] The above exemplary embodiments assume that the gastric contents (or a portion thereof) are returned to the patient. However, another exemplary embodiment aspirates the gastric contents and does not replace the aspirated contents prior to administering the gastric acid stimulant or suppressant. The resulting gastric contents generated after the stimulant or suppressant administration would thus mainly be secreted by virtue of the stimulant or suppressant. With less dilution from previous gastric contents, the measured pH and / or H+ concentration could be interpreted differently, with a more significant drop in pH and larger H+ concentration differential the likely overall effect.

[0398] An exemplary embodiment displays the pH, H+ concentration, and gastric volume measurements, and the corresponding indication of valid test results (pH and / or H+ concentration differential sufficient to indicate healthy gastric function) in a viewable table format such as by medical staff. Another exemplary embodiment programs this gastric volume, H+ concentration and pH information as software into a pH meter, or other testing device, that calculates and then communicates whether a valid test result (pH differential sufficient to indicate healthy gastric function) is achieved. In this exemplary embodiment, the medical staff may enter the initial pH, H+ concentration, and gastric volume measurements into the device interface, indicate the gastric contents were permanently aspirated, and then post stimulation enter a second pH and gastric volume measurement into the device interface. Programming via an application resident within the device, or via a remote application, may then receive the measurements, calculate a test result using algorithms, and then present on the interface of the device whether a valid or invalid test result has occurred. In another exemplary embodiment, the device uses additional algorithms to receive the pH, H+ concentration, and volume measurements and suggest guidance of care in areas such as level of nutrition, use of pharmacological agents, and other care decisions that can be guided by determining the current health and responsiveness of the gastrointestinal tract.

[0399] The above exemplary embodiments (including both embodiments where the gastric contents are returned to the patient and alternatively where they are retained) can be modified or expanded to include other analyses that may be beneficial. For example, the measured gastric volume, in addition to the pH and / or H+ concentration differential, can be used as a factor to help determine gastric function. In other words, the gastric contents can be aspirated and not returned prior to stimulant or suppressant administration. The gastric contents can then be measured after stimulant or suppressant administration to determine any volume differential, i.e., to determine the volume of gastric juice secreted after stimulant or suppressant administration.

[0400] The secretion of a relatively large volume of gastric juice generally indicates a relatively healthy gastric function, while the secretion of a relatively low volume generally indicates a relatively unhealthy gastric function. Thus, the gastric juice volume, measured after stimulant or suppressant administration, can be compared to volume(s) anticipated for a relatively healthy patient. This comparison can be used to provide data (in addition to the pH and H+ concentration differentials discussed above) to determine gastric function. For example, the gastric volume can be used to set the pH and / or H+ concentration differential deemed sufficient to indicate healthy gastric function.

[0401] In other words, a relatively large volume of secreted gastric juice (indicating healthy gastric function) can be used to reduce the pH and H+ concentration differential deemed sufficient to indicate healthy gastric function. Contrarily, a relatively low volume of sec...

Claims

1. A device for insertion into a stomach of a patient for use with enteral feeding, comprising: an indwelling tube (4, 106) for enteral feeding into the stomach, the tube (4, 106) having a length; one or more impedance sensors attached along the length of the indwelling tube (4, 106), wherein the one or more impedance sensors are configured to detect a presence or passage of a bolus transitioning through the stomach; a controller (8), characterized in that the device is configured to determine measurements of a volume of gastric contents by correlating the presence or passage of the bolus transitioning through the stomach to the volume of gastric contents such that the measurements of the volume of gastric contents provide guidance via the controller for patient care, wherein the guidance for patient care comprises instructions provided via the controller (8) to perform at least one of: initiation, maintenance, increase, reduction, or termination of enteral feeding, a determination of initiating, terminating, or weaning enteral feeding, a determination of modifying vasoactive agents, mechanical ventilation, acid suppressants, or motility agents.

2. The device of claim 1 wherein the one or more impedance sensors are attached along the length at a position such that the one or more sensors are placed within the stomach when the indwelling tube (4, 106) is inserted into the patient.

3. The device of any of claims 1 or 2 wherein the controller (8) comprises a processor configured to provide the instructions.

4. The device of any of claims 1 to 3 wherein an intensity of treatment of the patient care is determined as a function of the measurements.

5. The device of any of claims 1 to 4 wherein the guidance for patient care comprises a nutritional readiness score being a single numerical value and determined from the measurements of the gastric volume.

6. The device of any of claims 1 to 5 wherein the device is configured to provide the measurements on a continuous basis.