Improved method for converting venous blood gas values ​​to arterial blood gas values

Abstract

A computer-implemented method, system, and decision support system configured to provide arterial-venous blood gas values without preparing arterial oxygenation saturation values or arterial blood gas values. The method includes providing arterial blood gas values from a subject by providing a mathematical model configured to output arterial blood gas values of the subject by converting these venous blood gas values with a predetermined default arterial oxygenation value provided for a subject for whom only venous blood gas values are provided. Thus, the present invention provides a method for providing arterial blood gas values from a particular subject without requiring the provision of an arterial blood sample from a painful arterial blood draw or the arterial oxygenation saturation value of the subject, thus reducing the pain to the patient and reducing the workload of the associated medical staff.

Description

Technical Field

[0001] The present invention relates to an improved method for converting venous blood gas values from a subject into arterial blood gas values of the subject, and a corresponding computer program product for performing this method on a computer system. Further, the present invention relates to a corresponding decision support system (DSS), preferably a portable data processing system, and a corresponding computer program product.

Background Art

[0002] The determination of the state of a patient with an acute disease is a complex process involving the evaluation of a number of physiological systems of the patient, such as, for example, the pulmonary system, the metabolic system, the renal system, and the circulatory system. Much of the information required for this evaluation is provided by the analysis of the patient's blood. Blood samples can be obtained from both arteries and veins. Arterial blood can be collected by placing an arterial catheter or cannula in the patient, or by performing an arterial puncture with a needle. Venous blood can be collected from a peripheral cannula or venipuncture (peripheral venous blood), from a catheter placed in a large vein or the right atrium (central venous blood), or from a pulmonary artery catheter placed in the pulmonary artery (mixed venous blood).

[0003] The placement of venous and arterial catheters is an invasive procedure and is generally limited to specialized / highly therapeutic departments. Further, arterial catheter insertion, cannula insertion, or puncture rather than venous increases the risk of complications such as bleeding, hemorrhage, thrombosis, embolism, nerve damage, or the formation of a pseudoaneurysm. The collection of arterial blood by arterial puncture is generally considered a more difficult procedure than the collection of venous blood by venipuncture. As a result, the routine collection of arterial blood is generally limited to specialized / highly therapeutic environments. For example, in other wards where patients are acutely omitted, such as in cardiology, abdominal surgery, thoracic surgery, and internal medicine, the routine collection of peripheral venous blood is most common.

[0004] Many of the measurements obtained from blood and used to assess a patient's condition are similar in venous and arterial blood samples. These include electrolytes and metabolites such as sodium (Na), potassium (K), and blood glucose. However, the acid-base state of arterial and venous blood is not the same regardless of the site of collection. Acid-base state generally refers to the following measurements in blood: pH, partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), bicarbonate concentration (HCO3), hemoglobin concentration (Hb) and concentration of abnormal forms of hemoglobin (e.g., carboxyhemoglobin (COHb), methylhemoglobin (MetHb)), oxygen saturation of hemoglobin (SO2), base concentration higher than baseline (base excess (BE)), and bicarbonate concentration at baseline pCO2 (standard bicarbonate SBC). The variation in acid-base state between arterial and venous blood is due to the removal of oxygen from the blood and the addition of carbon dioxide due to metabolism in tissues. Furthermore, in patients with circulatory or metabolic disorders, the production of strong acids in tissues due to anaerobic metabolism can also alter the acid-base balance.

[0005] The acid-base status of arterial blood is used to assess a patient's pulmonary and metabolic state. It has been argued that venous blood samples are unsuitable for assessing a patient's acid / base and respiratory status (Adrogue et al., 1989a, 1989b; Brandi et al., 1995; Radiometer 1997), and this is generally accepted in clinical practice. This is particularly true for peripheral venous samples, which "are not recommended for blood gas analysis because they provide little or no information about the patient's overall condition" (Radiometer 1997).

[0006] In the intensive care unit, the placement of arterial catheters is a routine procedure, and the acid-base status can be determined from arterial blood. Arterial blood gases are also measured in several other hospital departments, such as respiratory or renal. However, in other wards that accept patients with acute illnesses, such as cardiology, abdominal surgery, thoracic surgery, and internal medicine, arterial samples are not usually taken. Peripheral venous samples are typically taken and analyzed in the central laboratory. The samples are usually collected aerobically, meaning that no attempt is made to ensure that pO2 and pCO2 remain constant during sample handling. In these samples, only a small amount of information regarding the patient's acid-base status is measured, namely standard bicarbonate (SBCv) and hemoglobin (Hbv). Other acid-base parameters, namely pHv, carbon dioxide pressure (pCO2v), base excess (BEv), oxygen saturation (SO2v), and oxygen pressure (pO2v), are not measured, or if measured, are unlikely to reflect the true values ​​of venous blood at this sampling site, given the aerobic nature of the sample.

[0007] In recent years, methods for converting venous blood gas values ​​to arterial blood gas values ​​have been demonstrated. Over the years, several efforts have been made to reduce the need for arterial puncture, such as the method disclosed in International Patent Application Publication No. 2004 / 010861 (OBI Medical Aps, Denmark) for converting venous blood values ​​to arterial blood values. This has the advantage of not requiring the collection of an arterial blood sample and eliminates the disadvantages compared to collecting an arterial blood sample. This method is based on three steps in essence: a first step of measuring arterial oxygenation saturation by, for example, pulse oximetry; a second step of measuring and estimating the venous blood acid / base state and oxygenation state values ​​of a venous blood sample, including peripheral venous blood (PVBG) or central venous blood (CVBG), preferably by anaerobic sampling; and a third step of converting the venous blood values ​​to desired estimated arterial blood values, i.e., one or more values ​​of the acid / base state in arterial blood, by applying a mathematical model for deriving the blood acid / base state and oxygenation state. The method commonly described in International Publication No. 2004 / 010861 is now commercially available from OBI (A Roche company) under the trade name v-TAC (trademark). For further information, please refer to the webpage https: / / diagnostics.roche.com / global / en / products / instruments / v-tac-standalone-ins-6779.html.

[0008] As described above, current methods require the provision of venous blood samples and arterial oxygenation saturation values ​​(SpO2) measured or estimated from subjects using a pulse oximeter or similar device. The v-TAC algorithm then processes the venous blood gas values ​​and arterial oxygenation saturation values ​​to provide arterial blood gas values. In some cases, arterial oxygenation values ​​may not be available, may be affected by measurement errors, or may depend on erroneous readings by healthcare professionals who read and input the arterial oxygenation values ​​from the pulse oximeter.

[0009] Therefore, an improved method for converting venous blood values ​​to arterial blood values ​​is considered advantageous, and in particular, a more efficient and / or reliable method is considered advantageous. [Overview of the project]

[0010] Object of the invention A further object of the present invention is to provide an alternative to the prior art.

[0011] In particular, the object of the present invention may be understood to be a method for providing arterial blood gas values ​​by conversion from venous blood values, which does not require the preparation of measured or estimated arterial oxygenation saturation values ​​(SpO2), and which solves the aforementioned problems of the prior art.

[0012] Summary of the Invention Therefore, the above-mentioned objectives and several other objectives are intended to be achieved in a first embodiment of the present invention by providing a computer-implemented method for converting venous blood gas values ​​to arterial blood gas values ​​of a subject when measured or estimated arterial oxygenation saturation values ​​(SpO2) are unavailable for the subject, and this method is a. Provide a predetermined default arterial oxygenation saturation value as a substitute value I, b. The substituted value I may be adjusted at the user's discretion based on user input. c. To provide venous blood gas values ​​from venous blood samples provided by subjects, d. Applying mathematical models to venous blood gas values ​​and surrogate values ​​I, e. Based on the values ​​provided in step c and the mathematical modeling applied to substitute value I, estimate arterial blood gas values ​​are provided. Includes.

[0013] The present invention is particularly advantageous in providing a method for converting venous blood gas values ​​to arterial blood gas values ​​without providing measured or estimated arterial oxygenation saturation values ​​(SpO2). Thus, the present invention eliminates the need to provide estimated or measured arterial oxygenation saturation values ​​to perform the conversion, and therefore simplifies the work of converting venous blood gas values ​​to arterial blood gas values, and further ensures that if venous blood gas values ​​such as pH, pCO2, pO2, sO2, and Hb are available, at least arterial values ​​including pH, pCO2, BE, HCO3, tO2, and tCO2 can be estimated even if measured or estimated arterial oxygenation saturation values ​​cannot be provided.

[0014] Please understand that venous blood gas values ​​can be derived from peripheral venous blood samples.

[0015] Furthermore, it should be understood that the present invention can provide estimated arterial blood gas values ​​even if neither measured nor estimated arterial oxygenation values ​​are available.

[0016] Furthermore, it should be understood that the mathematical model may, at least in part, be a variant of the v-TAC algorithm as described in the cited prior art.

[0017] Another advantage of the present invention is that the possibility of measurement errors is reduced because the step of preparing arterial oxygenation saturation values ​​is eliminated from the method of converting arterial blood gas values ​​from venous blood gas values.

[0018] Another advantage of the present invention is that the step of preparing arterial oxygenation saturation values ​​is eliminated from the method of converting arterial blood gas values ​​from venous blood gas values, thus reducing the possibility of reading or input errors when a healthcare professional converts or transfers estimated or measured arterial oxygenation saturation values ​​to input into a suitable device or computer program product for converting venous blood gas values ​​and arterial oxygenation saturation values ​​from a pulse oximeter to arterial blood gas values.

[0019] Therefore, the present invention provides a computer implementation method for providing arterial blood gas values ​​from subjects such as patients to users such as physicians or other healthcare professionals without the need to prepare arterial oxygenation saturation values ​​and arterial blood samples or arterial blood gas values. By reducing the need for the aforementioned arterial oxygenation saturation values ​​and arterial blood samples, patient distress and pain, the complexity of patient care for the personnel involved, and the risk of errors are significantly reduced.

[0020] In the context of the present invention, the method is provided for specific subjects for whom arterial oxygenation saturation values ​​are not available.

[0021] Furthermore, in the context of the present invention, “predetermined default” should be understood as a value not based on information previously estimated, measured, or otherwise evaluated with respect to a particular subject.

[0022] In the context of the present invention, providing blood values ​​from a blood sample does not necessarily involve the specific step of collecting or extracting a blood sample from a patient, and therefore, it should be understood that the measurement results may be obtained, transferred, or communicated, for example, from another entity or person, such as a nurse, who performed the blood measurement or extraction.

[0023] In one embodiment of the present invention, the estimated arterial blood gas values ​​provided in step e exclude arterial pO2 because no measured or estimated arterial oxygenation saturation values ​​are provided.

[0024] In a preferred embodiment of the present invention, the venous blood gas value in step c is at least one of a venous acid / base parameter and a venous oxygenation parameter.

[0025] In another preferred embodiment, the estimated arterial blood gas value in step e is at least one of an arterial oxygenation parameter and an arterial acid-base status parameter.

[0026] In one embodiment of the present invention, the substitute value I in step a is based on clinical / medical guidelines such as World Health Organization guidelines, domestic health guidelines, regional guidelines, hospital guidelines, or physician guidelines.

[0027] In an advantageous embodiment of the present invention, the optional user input in step b is based on whether the subject is currently being treated with supplemental oxygen and / or one or more of the subject's body parameters. The body parameters may include one or more of age, lesion / disease, gender, weight, and the estimated body fat percentage of the user.

[0028] In the context of the present invention, the related lesion / disease may be one or more of, but not limited to, patients with chronic obstructive pulmonary disease (COPD), such as interstitial lung disease (ILD), such as cystic fibrosis (CF), such as pulmonary hypertension, such as patients with neuromuscular disorders or chest wall disorders, or patients with advanced heart failure.

[0029] Furthermore, in the context of the present invention, the estimated body fat percentage of the user should be understood as a visual assessment or other estimation made by a medical practitioner when providing the input according to the optional step b of the present invention.

[0030] In one embodiment of the present invention in which the subject receives supplemental oxygen treatment, the user input in step b may be based on whether the subject is receiving long-term oxygen treatment or acute oxygen treatment.

[0031] In the context of this invention, long-term oxygen therapy should be understood as oxygen therapy for at least 12 hours per day for more than 30 days. It should be further understood that acute oxygen therapy may be acute treatment for patients with trauma or sudden onset of pathology requiring emergency treatment. It should be noted that those skilled in the art are expected to be aware of the difference between acute and long-term oxygen therapy.

[0032] In another convenient embodiment of the present invention, step c further includes providing the hemoglobin value of a venous blood sample provided by a subject, and step d is • Applying a mathematical model to the provided hemoglobin values. It further includes, The estimated arterial acid-base status and blood gas values ​​provided in step e are further based on mathematical modeling of hemoglobin levels.

[0033] In a preferred embodiment of the present invention, the mathematical model in step d further applies that the true value of the respiratory quotient (RQ) can only vary between 0.7 and 1.0, being 0.7 for aerobic metabolism of fats and 1.0 for aerobic metabolism of carbohydrates.

[0034] In another preferred embodiment of the present invention, the mathematical model in step d is: • Adding O2 and removing CO2 from venous blood at a ratio determined by a certain RQ set within a physiologically possible range of 0.7 to 1.0, such as a percentage of the respiratory quotient (RQ) set to 0.82, and • Run the simulation until the estimated arterial blood gas values ​​correlate with the provided venous blood gas values ​​and the surrogate value I from step a or step b. This is then applied mathematically.

[0035] In a convenient embodiment of the present invention, the method further comprises providing a machine learning algorithm, and after step e, f: A step of providing arterial oxygenation values ​​measured by the subject, g: A step of comparing the surrogate value I from step a and / or step b with the measured arterial oxygenation value, h: A step in which the learning algorithm changes the subsequent surrogate value I after step a, based at least on the comparison performed in step g. It also includes.

[0036] This embodiment is particularly advantageous for continuously improving the method of converting venous blood gas values ​​to arterial blood gas values ​​based on empirical data.

[0037] In one embodiment of the present invention, the surrogate value I in step a is an arterial oxygen saturation percentage between 0.85 and 1.00.

[0038] In the context of this invention, the percentages should be understood as decimals where 1.00 represents 100% arterial oxygen saturation and 0.85 represents 85% arterial oxygen saturation of the subject. It should be noted that those skilled in the art will be aware of how these values ​​are converted.

[0039] In a second embodiment, the present invention relates to a system configured to convert venous blood gas values ​​to arterial blood gas values ​​of a subject when measured or estimated arterial oxygenation saturation values ​​are unavailable for the subject, wherein the system • A user interface such as a touchscreen configured to provide information to the user and receive input from the user, • An input / output device configured to receive data from peripheral devices such as a blood gas analysis system or apparatus, A processor configured to process data and utilize algorithms, mathematical blood gas models, or simulations, preferably configured to utilize the mathematical model described in claim 1. It is equipped with, The system is configured to provide the user with estimated arterial blood gas values, and the system includes: • Venous blood gas values ​​from venous blood samples from subjects, and • A surrogate value I which is a predetermined default oxygenation saturation value, or • User-inputted substitute value I for representing oxygenation saturation It will be provided.

[0040] In the context of the present invention, a user interface should be understood as any device configured to display a user interface and to receive user input to be received on a digital device such as a computer having a screen, keyboard, and mouse, or a smartphone, tablet, or other suitable device. In a preferred embodiment, the digital device or system further comprises memory configured to store data and / or one or more computer program products.

[0041] In the context of the present invention, the processor should be understood as any suitable type of logic circuit that processes basic instructions and data provided to the processor in response to them, such as a CPU in a computer configured to execute a computer program product, particularly as a computer implementation method according to the first aspect of the present invention.

[0042] In the context of the present invention, an input / output device should be understood as any suitable device configured to receive / transmit input data, output data, or other processed data between a system and a peripheral device such as a blood gas analyzer. It may be further configured to acquire the respective media data as input to be sent to a computer, or to transmit the computer data to a storage medium as storage output. The input / output device may be wired or wireless, for example, by receiving / transmitting data via a wired connection such as a data cable, or by receiving / transmitting data wirelessly, for example by a wireless signal.

[0043] In a preferred embodiment of the present invention, the system is a decision support system, configured to provide the user with decision support regarding a subject, such as decision support regarding the flow rate of oxygen from an oxygen supplement to the patient. This embodiment is particularly advantageous for obtaining decision support when adjusting the flow rate of oxygen from an oxygen supplement to the patient. Decision support can help healthcare professionals, such as nurses or doctors, reach the patient's desired oxygen level with fewer adjustments than usual. Fewer adjustments than usual save time for healthcare professionals and also reduce the time the patient experiences discomfort.

[0044] In a third embodiment, the present invention relates to a computer program product configured to enable a computer system, preferably a portable computer system, comprising at least one computer to which data storage means are connected, the computer program product includes instructions causing the computer to execute a computer implementation method of the first embodiment of the present invention when the program is executed by the computer.

[0045] This aspect of the present invention is particularly advantageous in that it can be achieved by a computer program product that enables a computer system to perform the operation of the computer implementation method of the first aspect of the present invention when downloaded or uploaded to a computer system. Such a computer program product may be provided on any type of computer-readable medium or via a network.

[0046] In a fourth embodiment, the present invention relates to the use of the system according to a second embodiment of the present invention, such as a user adjusting the flow rate of supplemental oxygen to a patient based on estimated blood gas values ​​provided by the system.

[0047] In another embodiment of the present invention, the use of the system relates to the use of a decision support system according to a second aspect of the present invention, such as a user adjusting the flow rate of supplemental oxygen to a patient based on decision support provided by the system based on estimated arterial blood gas values ​​of the patient.

[0048] Each of the individual aspects of the present invention may be combined with any other aspect. These and other aspects of the present invention will become apparent from the following description and with reference to the embodiments described.

[0049] Next, the computer implementation method, system, and computer program product according to the present invention will be described in more detail with reference to the accompanying drawings. The drawings illustrate one way of carrying out the present invention and should not be construed as limiting other possible embodiments that fall within the technical scope of the accompanying claims. [Brief explanation of the drawing]

[0050] [Figure 1] Figure 1 is a schematic diagram of a method according to one embodiment of the present invention. [Figure 2] Figure 2 is another schematic diagram of the method according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic flowchart illustrating the operation of a computer program product according to one embodiment of the present invention. [Modes for carrying out the invention]

[0051] Figure 1 shows a schematic diagram of a method according to one embodiment of the present invention.

[0052] An anaerobic blood sample is obtained from a specific subject, and arterial oxygenation saturation values ​​are unavailable for this subject. The blood sample is analyzed using an associated blood gas analyzer (not shown). The blood gas analyzer provides anaerobic blood gas values, which are then converted into a mathematical model. The mathematical model converts the anaerobic blood gas values ​​and provides a predetermined default oxygenation saturation value as a surrogate value I, and based on the anaerobic blood gas values ​​and surrogate value I, provides the user, such as a physician or other healthcare professional, with an estimated / calculated aerobic blood gas value. It should be understood that the anaerobic blood sample may be a venous blood sample, and the aerobic blood gas values ​​may be arterial blood gas values.

[0053] Figure 2 shows another schematic diagram of a method according to one embodiment of the present invention. A peripheral venous blood sample is obtained from a specific subject, for which arterial oxygenation saturation values ​​are unavailable. The peripheral venous blood sample is analyzed using a blood gas analyzer BGA, and venous blood gas values ​​from the blood gas analyzer BGA, such as pH, pCO2, pO2, sO2, Hb, fMETHb, and fCOHbv, are input into a mathematical model, preferably the VTAC algorithm. The mathematical model then converts the venous blood gas values ​​and a predetermined default arterial oxygenation saturation value, i.e., surrogate value I, into outputs representing calculated arterial blood gas values ​​such as pH, PCO2, BE, HCO3, tO2, and tCO2. It should be understood that, with respect to the input, v represents venous blood, and a and c in the output represent arterial blood and calculated values, respectively.

[0054] Figure 3 is a schematic flowchart illustrating the operation of a computer program product according to one embodiment of the present invention. The flowchart shows a computer implementation method that provides a method for converting venous blood gas values ​​to arterial blood gas values ​​for a subject when measured or estimated arterial oxygenation saturation values ​​(SpO2) are unavailable for the subject, and the steps of this method are: a. Provide a predetermined default arterial oxygenation saturation value as a substitute value I, b. The substituted value I may be adjusted at the user's discretion based on user input. c. To provide venous blood gas values ​​from venous blood samples provided by subjects, d. Applying mathematical models to venous blood gas values ​​and surrogate values ​​I, e. Based on the values ​​provided in step c and the mathematical modeling applied to substitute value I, estimate arterial blood gas values ​​are provided. Includes.

[0055] The present invention can be implemented in hardware, software, firmware, or any combination thereof. It is also possible to implement the present invention or some of its features as software running on one or more data processors and / or digital signal processors.

[0056] Arterial blood gas analysis is estimated to be given in the following four steps, as an example for a specific subject.

[0057] Step 1: Anaerobic venous blood samples are collected from the subject and analyzed using standard blood gas analysis techniques to provide venous blood acid / base and / or blood gas values ​​(pH, pCO2, pO2, sO2, Hbv, METHb, COHb).

[0058] Step 2: Since the arterial oxygenation saturation value is not available for this particular subject, a predetermined default arterial oxygenation saturation value is prepared as surrogate value I.

[0059] Step 3: For a blood sample passing through tissue from artery to vein, the ratio of the amount of CO2 added (i.e., CO2 production rate (VCO2)) and O2 removed (i.e., O2 utilization rate (VO2)) due to aerobic metabolism is defined as the respiratory quotient (RQ = VCO2 / VO2). RQ is often approximated using the following formula through measurements of inspired oxygen concentration (FiO2) and inspired carbon dioxide concentration (FiCO2), as well as end-tidal oxygen concentration (Fe'O2) and end-tidal carbon dioxide concentration (Fe'CO2) or mixed exhaled oxygen concentration (FeO2) and mixed exhaled carbon dioxide concentration (FeCO2), obtained by measuring inspiratory and exhaled breath taken orally. RQ= Fe'CO 2 -FiCO 2 or RQ= FeCO 2 -FiCO 2 FiO2-Fe'O2FiO2-FeO2

[0060] Approximating RQ using this method often yields values ​​that can vary considerably. However, the true value of RQ in tissues can only vary between 0.7 and 1.0, being 0.7 for aerobic fat metabolism and 1.0 for aerobic carbohydrate metabolism. In this step, a simulation is performed in which O2 is added and CO2 is removed from venous blood using a mathematical model of the acid / base and oxygenation state of the blood (e.g., Rees et al, 1996, 1997) at a ratio determined by a constant respiratory quotient set to the physiologically possible range of 0.7 to 1.0. This simulation is run until the simulated oxygen saturation equals the surrogate value I from step 2.

[0061] Step 4: Next, estimates of the arterial acid / base state of arterial blood are calculated using models of blood acid / base and surrogate value I. This is possible because, when the removal of CO2 and O2 from venous blood by simulation at a constant RQ matches the surrogate value I for arterial oxygenation by simulation, the simulated values ​​of other arterial acid / base variables should also match the provided venous values.

[0062] A fundamental assumption in this method is that venous-arterial conversion can be performed using a constant RQ value. This requires that little to no anaerobic metabolism occurs in the tissue from which the venous blood sample is taken. If anaerobic metabolism is present, the strong acid (H) produced by this process will be... + ) is bicarbonate (HCO3) in the blood. - It is thought that it combines with ) and forms CO2 through the following reversible reaction. H + +HCO3 - ⇔ CO2 + H2O

[0063] The increase in CO2 production due to this reaction increases apparent VCO2 without an increase in VO2, and therefore RQ increases. The degree of anaerobic metabolism depends on the patient's circulatory and metabolic state. In normal, well-perfused peripheral limbs, anaerobic metabolism is unlikely to occur. The quality of limb perfusion can be clinically determined by the presence of clearly recognizable arterial pulsations determined by palpation, normal capillary response, and normal color and temperature of the limbs. Central venous blood or mixed venous blood is a mixture of blood from several sites and therefore may contain blood from areas of the body with anaerobic metabolism. Therefore, the selection of the sample site is important.

[0064] Step 5: Output of arterial values ​​such as pH, pCO2, BE, HCO3, tO2, and tCO2. It should be noted that, because measured or estimated arterial oxygenation saturation values ​​are not provided, this method cannot currently provide arterial pO2 like the cited prior art, but it can provide the aforementioned arterial values ​​which may be useful to physicians or other healthcare professionals.

[0065] Simulations using the present invention were performed on data from the following three clinical studies.

[0066] Ekstrom M et al. (2019).Calculated arterial blood gas values ​​from a venous sample and pulse oximetry:Clinical validation.PLoS ONE 14(4):e0215413. doi:10.1371 / journal.pone.0215413

[0067] Rees SE et al. (2012).Calculating acid-base and oxygenation status during COPD exacerbation using mathematically arterialised venous blood.Clin Chem Lab Med 50(12):2149-2154.doi:10.1515 / cclm-2012-0233

[0068] Tygesen G et al. (2012).Mathematical arterialization of venous blood in emergency medicine patients.Eur J Emerg Med 19:363-372. doi:10.1097 / MEJ.0b013e32834de4c6

[0069] A total of n=472 datasets were used in the simulation.

[0070] Each dataset consists of arterial blood gas measurements (ABG) used as a reference, and venous blood gas measurements (VBG) accompanied by associated SpO2 measurements from a pulse oximeter.

[0071] We performed a simulation to convert VBG to arterial values ​​using the following: SpO2 measured for each dataset. As a surrogate value I, we use a 90% constant for all datasets. As a surrogate value I, we use a 94% constant for all datasets.

[0072] Using statistical methods, we compared VBG and the three transformed results with ABG references and calculated the following: Mean bias (mean difference). The 95% agreement limit is calculated as 1.96*SD.

[0073] The results for pH and pCO2 are listed in the table below. [Table 1]

[0074] [Table 2]

[0075] The simulations demonstrate that the present invention can convert venous pH and pCO2 (not pO2) values ​​to arterial values ​​using a predetermined patient-independent constant, with accuracy and precision close to that obtained by using SpO2 measured for each individual dataset, and significantly better than using only VBG values ​​without the conversion according to the present invention.

[0076] In summary, the present invention relates to a computer implementation method, system, and decision support system configured to provide arterial and venous blood gas values ​​without providing arterial oxygenation saturation values ​​or arterial blood gas values. The method includes providing arterial blood gas values ​​from a subject by providing a mathematical model configured to output the subject's arterial blood gas values ​​by converting these venous blood gas values ​​with a predetermined default arterial oxygenation value provided for the subject. Thus, the present invention provides a method for providing arterial blood gas values ​​from a specific subject without requiring the provision of arterial blood samples from painful arterial blood collection or the subject's arterial oxygenation saturation values, thereby reducing discomfort to the patient and alleviating the workload of the relevant healthcare professionals.

[0077] The following lists preferred embodiments and aspects of the present invention.

[0078] Item 1 A computer implementation method for converting venous blood gas values ​​to arterial blood gas values ​​for a subject when measured or estimated arterial oxygenation saturation values ​​are unavailable for that subject, a. Provide a predetermined default arterial oxygenation saturation value as a substitute value I, b. The substituted value I may be adjusted at the user's discretion based on user input. c. To provide venous blood gas values ​​from venous blood samples provided by subjects, d. Applying mathematical models to venous blood gas values ​​and surrogate values ​​I, e. A step to provide estimated arterial blood gas values ​​based on the values ​​provided in step c and the mathematical modeling applied to substitute value I. Computer implementation methods, including those mentioned above.

[0079] Item 2. The venous blood gas value in step c is at least one of the venous acid / base parameter and the venous oxygenation parameter, according to the computer implementation method of Item 1.

[0080] Item 3. The arterial blood gas value in step e is at least one of the arterial oxygenation parameter and the arterial acid-base status parameter, according to the computer implementation method of Item 1 or 2.

[0081] Item 4. The surrogate value I for step a is a computer implementation method based on any of the preceding items, which is based on clinical / medical guidelines such as World Health Guidelines, National Health Guidelines, Regional Guidelines, Hospital Guidelines, or Physician Guidelines.

[0082] Item 5. Voluntary user input in step b is: • Whether the subject is currently being treated with supplemental oxygen, and / or • Subject's physical parameters Based on one or more of the following, Body parameters are, ·age, • Diseases / lesions such as COPD, ·sex, • Weight, and • User's estimated body fat percentage A computer implementation method using any of the preceding items, including one or more of the following.

[0083] Item 6. Step c is, • To provide the hemoglobin value of the venous blood sample provided by the subject. It further includes, Step d, • Applying a mathematical model to the provided hemoglobin values. It further includes, The estimated arterial acid-base status values ​​and arterial blood gas values ​​provided in step e are computer implementations of any of the preceding items, further based on mathematical modeling of hemoglobin values.

[0084] Item 7. A computer implementation method according to any of the preceding items, further applying that the mathematical model in step d can only vary between 0.7 and 1.0, which is 0.7 for aerobic metabolism of fats and 1.0 for aerobic metabolism of carbohydrates.

[0085] Item 8. The mathematical model in step d is: • Adding O2 and removing CO2 from venous blood at a ratio determined by a certain RQ set within a physiologically possible range of 0.7 to 1.0, such as a percentage of the respiratory quotient (RQ) set to 0.82, and • Run the simulation until the estimated arterial blood gas values ​​correlate with the provided venous blood gas values ​​and the surrogate value I from step a or step b. A computer implementation method based on one of the preceding items, which further applies mathematically to the above.

[0086] Item 9. Provide machine learning algorithms. It further includes, After step e, f: A step of providing arterial oxygenation values ​​measured by the subject, g: A step of comparing the surrogate value I from step a and / or step b with the measured arterial oxygenation value, h: A step in which the learning algorithm changes the subsequent surrogate value I after step a, based at least on the comparison performed in step g. A computer implementation method according to any of the preceding items, further including the above.

[0087] Item 10. The surrogate value I in step a is an arterial oxygen saturation percentage between 0.85 and 1.00, according to the computer implementation method of Item 1.

[0088] Item 11. A system configured to convert venous blood gas values ​​to arterial blood gas values ​​for a subject when measured or estimated arterial oxygenation saturation values ​​are unavailable for that subject, • A user interface such as a touchscreen configured to provide information to the user and receive input from the user, • An input / output device configured to receive data from peripheral devices such as a blood gas analysis system or apparatus, A processor configured to process data and utilize algorithms, mathematical blood gas models, or simulations, preferably configured to utilize mathematical models according to item 1. It is equipped with, The system is configured to provide the user with estimated arterial blood gas values, and the system includes: • Venous blood gas values ​​from venous blood samples from subjects, and • A surrogate value I which is a predetermined default oxygenation saturation value, or • User-inputted substitute value I for representing oxygenation saturation A system that provides this.

[0089] Item 12. The system is a decision support system, configured to provide the user with decision support regarding a subject, such as decision support regarding the flow rate of oxygen from an oxygen supplement to the patient, according to Item 11.

[0090] Item 13. The decision support system is further configured to adjust the flow rate of supplemental oxygen to a subject based on one or more user inputs, and the user receives decision support regarding the flow rate of supplemental oxygen from the decision support system, as per item 12.

[0091] Item 14. A computer program product that enables a computer system, preferably a portable computer system, to perform the method according to Item 1 when downloaded or uploaded.

[0092] Item 15. Use of the system in accordance with Item 11, The user adjusts the flow rate of supplemental oxygen to the patient based on estimated blood gas values ​​provided by the system.

[0093] Item 16. A method for treating oxygen deficiency in a subject receiving supplemental oxygen, • Perform the steps according to item 1, • To determine whether the estimated arterial blood gas values ​​are within the threshold range, and whether the estimated arterial blood gas values ​​are outside the threshold range. • Treating subjects based on estimated arterial blood gas values, such as by adjusting the flow rate of supplemental oxygen per minute. A method that includes this.

[0094] Item 17. A lung ventilation device configured to supply oxygen to a subject, - A ventilator, - A processor configured to run a mathematical model that enables the conversion of venous blood gas values ​​and SpO2 values ​​into estimated ABG values, - An input interface that is data-connected to a processor and configured to receive at least venous blood gas values ​​and SpO2 values ​​measured from a subject, - User interface and, - A controller that is data-connected to the processor and ventilator, and configured to control and adjust the ventilator based on arterial blood gas values ​​estimated from the processor. It is equipped with, A lung ventilation device that performs the computer implementation method according to item 1 when SpO2 values ​​cannot be obtained from the subject.

[0095] Item 18. The device, in accordance with Item 17, is unable to receive an SpO2 value in order to provide the device with an estimated ABG value necessary for supplying oxygen to the subject, a surrogate value I is performed, and the device further informs the user of the value of I and optionally seeks the user's approval regarding the value of I.

[0096] Item 19. A computer implementation method according to Item 1, wherein the estimated arterial blood gas values ​​provided in step e consist of pH, pCO2, BE, HCO3, tO2, and tCO2.

[0097] Item 20. A computer implementation method according to Item 1, wherein the estimated arterial blood gas values ​​provided in step e consist of one or more of pH, pCO2, BE, HCO3, tO2, and tCO2.

[0098] In the context of this invention, the following definitions and abbreviations may be used. [Table 3]

[0099] Individual elements of one embodiment of the present invention may be implemented in any suitable manner with respect to material, function, and logic, such as being implemented in a single unit, in multiple units, or as part of separate functional units. The present invention may be implemented in a single unit or distributed among different units and processors with respect to material and function.

[0100] While the present invention has been described in relation to specific embodiments, it should not be construed as being limited to the examples presented. The scope of the invention should be interpreted in light of the appended claims. In the context of the claims, the terms “comprising” or “comprises” do not preclude other possible elements or steps. Nor should references such as “a” or “an” be construed as precluding plural. The use of reference numerals in the claims relating to elements shown in the drawings should also not be construed as limiting the scope of the invention. Furthermore, individual features described in different claims may be combined, perhaps conveniently, and the fact that these features are mentioned in different claims does not preclude the possibility that such combinations are impossible or inconvenient.

Claims

1. A computer implementation method for converting venous blood gas values ​​to arterial blood gas values ​​for a subject when measured arterial oxygenation saturation values ​​are not provided for the subject, a. A step of providing a predetermined default arterial oxygenation saturation value as a surrogate value I based on clinical / medical guidelines, b. A step of adjusting the substitute value I based on input from the user, c. Providing venous blood gas values ​​for venous blood samples provided by the subject, d. The step of applying a mathematical model to the venous blood gas values ​​and the surrogate value I, e. A step of providing estimated arterial blood gas values ​​based on the mathematical model applied in step d, Includes, A computer implementation method wherein the estimated arterial blood gas value provided is selected from one or more of pH, pCO2, BE, HCO3, tO2, and tCO2.

2. The computer implementation method according to claim 1, wherein the venous blood gas value in step c is at least one of the venous acid / base parameter and the venous oxygenation parameter.

3. The computer implementation method according to claim 1 or 2, wherein the arterial blood gas value in step e is at least one of the arterial oxygenation parameter and the arterial acid-base status parameter.

4. The user input in step b above is - Whether the subject is currently being treated with supplemental oxygen, and / or - Physical parameters of the subject Based on one or more of the following, The aforementioned physical parameters are ·age, • Diseases / pathologies such as COPD, ·sex, • Weight, and - Estimated body fat percentage of the user The computer implementation method according to claim 1, comprising one or more of the following.

5. The aforementioned step c is, - To provide the hemoglobin value of the venous blood sample provided by the subject. It further includes, The aforementioned step d is, - Applying the mathematical model to the provided hemoglobin value. It further includes, The computer implementation method according to claim 1 or 2, wherein the estimated arterial acid-base status value and arterial blood gas value provided in step e are further based on the mathematical model of the hemoglobin value.

6. The computer implementation method according to claim 1 or 2, further applying that the mathematical model in step d has a true respiratory quotient (RQ) that can only vary between 0.7 and 1.0, being 0.7 for aerobic metabolism of fats and 1.0 for aerobic metabolism of carbohydrates.

7. The mathematical model in step d is, - Adding O2 and removing CO2 from venous blood at a ratio determined by a constant RQ set within a physiologically possible range of 0.7 to 1.0, and - Perform the simulation until the estimated arterial blood gas values ​​correlate with the provided venous blood gas values ​​and the surrogate value I in step a or step b. A computer implementation method according to claim 1 or 2, further applying the mathematical principle.

8. The computer implementation method further includes the step of providing a machine learning algorithm, and after step e, f: A step of providing arterial oxygenation values ​​measured by the subject, g: A step of comparing the surrogate value I from step a and / or step b with the arterial oxygenation value obtained by the measurement, h: A step of fitting a subsequent surrogate value I following step a based at least on the comparison performed in step g by the learning algorithm, A computer implementation method according to claim 1 or 2, including the method described in claim 1 or 2.

9. The computer implementation method according to claim 1, wherein the substitute value I in step a is an arterial oxygen saturation percentage between 0.85 and 1.

00.

10. A system configured to convert venous blood gas values ​​to arterial blood gas values ​​for a subject when measured arterial oxygenation saturation values ​​are not provided for the subject, A user interface configured to provide information to a user and receive input from the user, - An input / output device configured to receive data from peripheral devices, A processor configured to process data and utilize the mathematical model described in claim 1, The system is equipped with, - Venous blood gas values ​​from venous blood samples from the subject, and - The surrogate value I, which is a predetermined default oxygenation saturation value based on clinical / medical guidelines, or - User-inputted surname value I, representing the oxygenation saturation value. When supplied to the system, it is configured to provide the user with estimated arterial blood gas values. A system in which the estimated arterial blood gas values ​​provided are selected from one or more of pH, pCO2, BE, HCO3, tO2, and tCO2.

11. The system according to claim 10, wherein the system is a decision support system, and the system is configured to provide the user with decision support regarding the flow rate of oxygen from an auxiliary oxygen device to a patient.

12. The decision support system according to claim 11, wherein the decision support system is further configured to adjust the flow rate of supplemental oxygen to a subject based on one or more user inputs, and the user receives decision support regarding the flow rate of supplemental oxygen from the decision support system.

13. A computer program that, when downloaded or uploaded to a computer system, enables the computer system to perform the method according to claim 1.

14. The system according to claim 10, A system that allows the user to adjust the flow rate of supplemental oxygen to a patient based on the estimated arterial blood gas values ​​provided by the system.

15. A lung ventilation device configured to supply oxygen to a subject, - A ventilator, - A processor configured to run a mathematical model that enables the conversion of venous blood gas values ​​and SpO2 values ​​into estimated ABG values, - An input interface that is data-connected to the processor and configured to receive measured at least the venous blood gas values ​​and SpO2 values ​​from the subject, - User interface, - A controller that is data-connected to the processor and the ventilator and configured to control and adjust the ventilator based on the estimated arterial blood gas values ​​from the processor, Equipped with, A lung ventilation device that performs the computer implementation method described in claim 1 when SpO2 values ​​are not received from the subject.

16. The lung ventilation device according to claim 15, wherein the lung ventilation device is unable to receive an SpO2 value in order to obtain the estimated ABG value necessary for the lung ventilation device to supply oxygen to the subject, the substitute value I is implemented, and the user is further informed of the value of I and the user's approval regarding the value of I.

17. The computer implementation method according to claim 1, wherein the estimated arterial blood gas value provided in step e does not include an estimated arterial pO2 value.

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