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 / high-intensity treatment 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 / high-intensity treatment settings. 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 determine a patient's condition are the same in venous and arterial blood samples. These include electrolytes and metabolites such as sodium (Na), potassium (K), and blood glucose. However, the acid-base status of arterial and venous blood is not the same regardless of the site of collection. Acid-base status 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), methemoglobin (MetHb)), oxygen saturation of hemoglobin (SO2), concentration of base higher than reference conditions (base excess (BE)), and concentration of bicarbonate at reference pCO2 (standard bicarbonate SBC). The variation in acid-base status between arterial and venous blood is due to the removal of oxygen from and addition of carbon dioxide to the blood due to metabolism in tissues. Furthermore, in patients with circulatory or metabolic abnormalities, the production of strong acids in tissues due to anaerobic metabolism can also potentially change the acid-base status.

[0005] The acid-base status of arterial blood is used to determine the state of a patient's lungs and metabolism. It has been argued and is generally accepted in clinical practice that venous blood samples are not appropriate for determining a patient's acid / base and respiratory status (Adrogue et al., 1989a, 1989b; Brandi et al., 1995; Radiometer 1997). This is thought to particularly apply to peripheral venous samples, which "provide little or no information regarding the overall condition of the patient and are not recommended for blood gas analysis" (Radiometer 1997).

[0006] In an intensive care unit, arterial catheterization is a routine procedure, and the acid-base status can be determined from arterial blood. For example, arterial blood gases are also measured in some other hospital departments such as the respiratory or renal departments. However, in other wards that admit patients with acute diseases such as cardiology, abdominal surgery, thoracic surgery, and internal medicine, arterial samples are usually not taken. Usually, peripheral venous samples are taken and analyzed in a central laboratory. Samples are usually taken aerobically, i.e., no attempt is made to ensure that pO2 and pCO2 remain constant during sample handling. In this sample, only a small amount of information regarding the patient's acid-base status, i.e., standard bicarbonate SBCv and hemoglobin HBV, is measured. Other acid-base parameters, i.e., pHv, carbon dioxide pressure (pCO2v), base excess (BEv), oxygen saturation (SO2v), and oxygen pressure (pO2v), are not measured, and even if measured, in view of the aerobic nature of the sample, they probably do not reflect the true values of venous blood at this sample site.

[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 of 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 drawbacks compared to venous blood samples when collecting arterial blood samples. This method is essentially based on three steps, namely, a first step of measuring arterial oxygenation saturation, for example, by pulse oximetry, and a second step of measuring and estimating the values of the venous blood acid / base state and oxygenation state of a venous blood sample including peripheral venous blood (PVBG) or central venous blood (CVBG), preferably by anaerobic sampling, and a third step of applying a mathematical model for deriving the blood acid / base state and oxygenation state to convert the venous blood value to a desired estimated arterial blood value, i.e., one or more values of the acid-base state in arterial blood. The method generally 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, refer to the web page https: / / diagnostics.roche.com / global / en / products / instruments / v-tac-standalone-ins-6779.html.

[0008] As described above, current methods require the provision of a venous blood sample as well as an arterial oxygenation saturation value (SpO2) measured or estimated from the subject, such as by a pulse oximeter. The v-TAC algorithm then processes the venous blood gas value and the arterial oxygenation saturation value to provide an arterial blood gas value. In some cases, the arterial oxygenation value may not be present, may be subject to measurement error, or may be influenced by an incorrect reading from a healthcare provider who reads and enters the arterial oxygenation value from the pulse oximeter.

[0009] Accordingly, 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. SUMMARY OF THE INVENTION

[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 is to provide a method for providing arterial blood gas values by conversion from venous blood values, which does not require the preparation of an arterial oxygen saturation value (SpO2) by measurement or estimation, and is understood to provide a method for solving the above-mentioned problems of the prior art.

[0012] SUMMARY OF THE INVENTION Accordingly, the above object and several other objects are intended to be achieved by providing, in a first aspect of the present invention, a computer-implemented method for converting venous blood gas values to arterial blood gas values of a subject when an arterial oxygen saturation value (SpO2) obtained by measurement or estimation for the subject is not available, the method comprising: a. providing a predetermined default arterial oxygen saturation value as substitute value I; b. optionally adjusting substitute value I by input from a user; c. providing the venous blood gas values of a venous blood sample provided by the subject; d. applying a mathematical model to the venous blood gas values and substitute value I; e. providing an estimated arterial blood gas value based on the mathematical modeling applied to the values provided in step c and substitute value I. and including.

[0013] The present invention is advantageously provided, inter alia, but not limited thereto, for a method for converting venous blood gas values to arterial blood gas values without the need to obtain arterial oxygen saturation values (SpO2) by measurement or estimation. Thus, the present invention eliminates the need to obtain arterial oxygen saturation values by estimation or measurement in order to perform the conversion, and thus simplifies the task of converting venous blood gas values to arterial blood gas values, and further ensures that at least arterial values including, but not limited to, pH, pCO2, pO2, sO2, and Hb, such as pH, pCO2, BE, HCO3, tO2, and tCO2, can be estimated even if arterial oxygen saturation values by measurement or estimation cannot be obtained.

[0014] It should be understood that venous blood gas values may be derived from a peripheral venous blood sample.

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

[0016] It should also be understood that the mathematical model may be, at least in part, 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 error is reduced because the step of obtaining arterial oxygen saturation values from the method of converting arterial blood gas values from venous blood gas values is eliminated.

[0018] Yet another advantage of the present invention is that the step of providing an arterial oxygen saturation value from a method of converting arterial blood gas values from venous blood gas values is eliminated, so that, for example, when a healthcare provider converts or transfers an estimated or measured arterial oxygen saturation value to the input of an apparatus or computer program product suitable for converting venous blood gas values and arterial oxygen saturation values to arterial blood gas values from a pulse oximeter, the possibility of a reading or input error is reduced.

[0019] Accordingly, the present invention provides a computer-implemented method for providing arterial blood gas values from a subject, such as a patient, to a user, such as a physician or other healthcare provider, without providing an arterial oxygen saturation value and without providing an arterial blood sample or arterial blood gas values. By reducing the need for the above-described arterial oxygen saturation value and arterial blood sample, the pain and discomfort of the patient, the complexity of patient care for the personnel involved, and the risk of error are significantly reduced.

[0020] In the context of the present invention, the method is provided for a particular subject for whom an arterial oxygen saturation value is not available.

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

[0022] In the context of the present invention, providing a blood value from a blood sample does not necessarily include a specific step of collecting or extracting a blood sample from a patient, and thus it should be understood that the measurement result may be obtained, transferred, or communicated from another entity or person, such as a nurse who has performed the measurement or extraction of the blood.

[0023] In one embodiment of the present invention, the estimated arterial blood gas value provided in step e excludes arterial pO2 because an arterial oxygen saturation value by measurement or estimation is not 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 surrogate value I in step a is based on clinical / medical guidelines such as World Health Organization guidelines, national 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 user's estimated body fat percentage.

[0028] In the context of the present invention, the relevant 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 neuromuscular or chest wall disorders, or patients with advanced heart failure.

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

[0030] In one embodiment of the present invention where 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 the present invention, long-term oxygen treatment should be understood as oxygen treatment for at least 12 hours per day for more than 30 days. It should be further understood that acute oxygen treatment may be an acute treatment of a patient associated with trauma or the onset of sudden pathology that requires emergency treatment. It should be noted that those skilled in the art are considered to be aware of the difference between acute oxygen treatment and long-term oxygen treatment.

[0032] In another advantageous embodiment of the present invention, step c further includes providing a hemoglobin value of a venous blood sample provided by the subject, and step d · Applying a mathematical model to the provided hemoglobin value further includes The estimated arterial blood gas values and blood gas values provided in step e are further based on the mathematical modeling of the hemoglobin value.

[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, is 0.7 in the aerobic metabolism of fat, and is 1.0 in the aerobic metabolism of carbohydrates.

[0034] In another preferred embodiment of the present invention, the mathematical model in step d · Adding O2, removing CO2 from venous blood, and in a ratio determined by a constant RQ set within a physiologically possible range of 0.7 to 1.0, such as a ratio of the respiratory quotient (RQ) set to 0.82, and · Performing a simulation until the estimated arterial blood gas value correlates with the provided venous blood gas value and the substitute value I in step a or step b is further mathematically applied.

[0035] In an advantageous embodiment of the present invention, the method further includes providing a machine learning algorithm, and after step e, f: a step of providing a measured arterial oxygenation value of the subject, g: Comparing the surrogate value I of step a and / or step b with the measured arterial oxygenation value; h: Changing the subsequent surrogate value I of step a based at least on the comparison performed in step g by a learning algorithm; and further comprising.

[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 of step a is an arterial oxygen saturation percentage between 0.85 and 1.00.

[0038] In the context of the present invention, the percentage should be understood as a decimal 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 are considered to know how these values are converted.

[0039] In a second aspect, 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 oxygen saturation values of the subject are not available. The system comprises: · A user interface such as a touch screen configured to provide information to the user and receive input from the user; · An input / output device configured to receive data from a peripheral device such as a blood gas analysis system or device; · A processor configured to process data and utilize an algorithm, a mathematical blood gas model, or a simulation, preferably configured to utilize the mathematical model according to claim 1; and comprising; The system is configured to provide the user with an estimated arterial blood gas value. The system has: · Venous blood gas values from a venous blood sample from a subject, and · Substitute value I, which is a predetermined default oxygen saturation value, or · Substitute value I input by the user representing the oxygen saturation value is provided.

[0040] In the context of the present invention, the user interface is understood to be any device configured to display the user interface and receive input from a user 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 a memory configured to store data and / or one or more computer program products.

[0041] In the context of the present invention, the processor is understood to be any suitable type of logic circuit configured to process basic instructions and data provided to this processor in response to these, such as a CPU in a computer configured to execute a computer program product, such as a computer-implemented method according to the first aspect of the present invention.

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

[0043] In a preferred embodiment of the present invention, the system is a decision support system, and the system is configured to provide the user with decision support regarding a subject, such as decision support regarding the flow rate of oxygen from an oxygen supplementation device to a patient. This embodiment is particularly advantageous for obtaining decision support when adjusting the flow rate of oxygen from the oxygen supplementation device to the patient. The decision support can help a healthcare worker, such as a nurse or a doctor, reach the desired oxygen level of the patient with less adjustment than the normal adjustment of the oxygen flow rate. The adjustment less than the normal adjustment saves the time of the healthcare worker and also shortens the time the patient feels discomfort.

[0044] In a third aspect, 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 program including instructions for causing the computer to execute the computer-implemented method of the first aspect of the present invention when the program is executed by the computer.

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

[0046] In a fourth aspect, the present invention relates to the use of the system according to the second aspect of the present invention, such as a user adjusting the flow rate of supplemental oxygen to a patient based on the 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 adjusting the flow rate of supplemental oxygen to a patient based on decision support provided by the system based on the user's 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 with reference to the embodiments described.

[0049] Next, a computer-implemented 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 implementing the present invention and should not be construed as limiting other possible embodiments that fall within the technical scope of the appended claims.

Brief Description of the Drawings

[0050]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

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

[0052] An anaerobic blood sample is obtained from a specific subject for which an arterial oxygenation saturation value is not available. The blood sample is analyzed using an associated blood gas analyzer (not shown). The blood gas analyzer provides anaerobic blood gas values that are provided to a mathematical model. The mathematical model transforms the anaerobic blood gas values and provides a predetermined default oxygenation saturation value as Substitute Value I, and based on the anaerobic blood gas values and Substitute Value I, provides a user, such as a physician or other healthcare provider, 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 value may be an arterial blood gas value.

[0053] Figure 2 shows another schematic view of a method according to an embodiment of the present invention. A peripheral venous blood sample is provided from a specific subject for which an arterial oxygenation saturation value is not available. 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 transforms the venous blood gas values and a predetermined default arterial oxygenation saturation value, i.e., Substitute Value I, into an output 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 the vein, and the a and c of the output represent, respectively, that they are arterial and that they are calculated values.

[0054] Figure 3 is a schematic flowchart representing the operation of a computer program product according to an embodiment of the present invention. The flowchart shows a computer-implemented method for converting venous blood gas values into arterial blood gas values of a subject when a measured or estimated arterial oxygenation saturation value (SpO2) for the subject is not available, and the steps of this method are a. providing a predetermined default arterial oxygenation saturation value as Substitute Value I; b. Optionally, adjust the surrogate value I by input from the user, and c. Provide the venous blood gas values of the venous blood sample provided by the subject, and d. Apply a mathematical model to the venous blood gas values and the surrogate value I, and e. Provide an estimated arterial blood gas value based on the mathematical modeling applied to the values provided in step c and the surrogate value I including.

[0055] The present invention can be implemented by hardware, software, firmware, or any combination thereof. Some of the present invention or its features can also be implemented as software executed on one or more data processors and / or digital signal processors.

[0056] Arterial blood gas is estimated as given in the following four steps as an example for a particular subject.

[0057] Step 1: Collect an anaerobic venous blood sample from the subject and analyze it using standard blood gas analysis techniques to provide the acid / base and / or blood gas values (pH, pCO2, pO2, sO2, HBV, METHb, COHb) of the venous blood.

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

[0059] Step 3: For a blood sample passing through the tissue from artery to vein, the ratio of the amount of CO 2 (i.e., CO 2 production rate (VCO 2 )) and the removed O 2 (i.e., O 2 utilization rate (VO 2 )) is the respiratory quotient (RQ = VCO 2 / VO 2) is defined as follows. RQ is often approximated using the following equation through measurements of inspired and expired air taken in the oral cavity, i.e., the inspired oxygen concentration (FiO 2 ) and the inspired carbon dioxide concentration (FiCO 2 ), as well as the end-tidal oxygen concentration (Fe’O 2 ) and the end-tidal carbon dioxide concentration (Fe’CO 2 ), or the mixed expired oxygen concentration (FeO 2 ) and the mixed expired carbon dioxide concentration (FeCO 2 ). RQ = Fe’CO 2 -FiCO 2 or RQ = FeCO 2 -FiCO 2 FiO 2 - Fe’O 2 FiO 2 - FeO 2

[0060] The approximation of RQ by this method often gives values that can vary significantly. However, the true value of RQ in tissues can only vary between 0.7 and 1.0, being 0.7 in the aerobic metabolism of fat and 1.0 in the aerobic metabolism of carbohydrates. In this step, a mathematical model of the acid / base and oxygenation state of the blood (e.g., Rees et al, 1996, 1997, etc.) is used to add O 2 in a ratio determined by a constant respiratory quotient set within the physiologically possible range of 0.7 to 1.0, and a simulation is performed to remove CO 2 from the venous blood. This simulation is run until the simulated oxygen saturation equals the surrogate value I in step 2.

[0061] Step 4: Next, using the blood acid / base and surrogate value I models, calculate an estimated value of the arterial blood acid / base status. This is possible because simulation of the removal of CO2 and O2 from venous blood at a constant RQ ensures that when the simulated arterial oxygenation matches surrogate value I, the values of the other simulated arterial acid-base variables should also match the provided venous values.

[0062] The basic assumption underlying this method is that venous-arterial conversion can be performed using a constant value of RQ. This requires that anaerobic metabolism occurs little or not at all in the tissue from which the venous blood sample is taken. If anaerobic metabolism is present, the strong acid (H + ) generated by this process is thought to combine with bicarbonate (HCO3 - ) in the blood to form CO 2 in the following reversible reaction H + + HCO 3 - ⇔ CO 2 + H 2 O

[0063] The increased production of CO 2 by this reaction increases the apparent VCO 2 without an accompanying increase in VO 2 , thus meaning that the RQ increases. The degree of anaerobic metabolism depends on the patient's circulatory and metabolic status. In normal, well-perfused peripheral limbs, the likelihood of anaerobic metabolism occurring is low. The quality of limb perfusion can be clinically judged by the presence of a clearly palpable arterial pulse, normal capillary reaction, and normal color and temperature of the limb. Central venous blood or mixed venous blood is a mixture of blood from several sites and can therefore contain blood from areas of the body with anaerobic metabolism. Therefore, the choice of sample site is important.

[0064] Step 5: Output of arterial values such as pH, pCO2, BE, HCO3, tO2, and tCO2. Since the arterial oxygenation saturation value by measurement or estimation is not provided, it should be noted that this method cannot provide arterial pO2 like the cited prior art at present, but can provide the above-mentioned arterial values that may be beneficial to physicians or other medical personnel.

[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 data sets were used for the simulation.

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

[0071] Simulations were performed to convert VBG to arterial values using the following: SpO2 measured for each dataset. As surrogate value I, a constant of 90% for all datasets. As surrogate value I, a constant of 94% for all datasets.

[0072] Using statistical methods, the VBG and three conversion results were compared to the ABG reference, and the following were calculated: Mean bias (mean difference). 95% limits of agreement calculated as 1.96*SD.

[0073] The results for each of pH and pCO2 are listed in the table shown below.

Table 1

[0074]

Table 2

[0075] The simulations show that the present invention can perform the conversion of venous pH and pCO2 (not pO2) values to arterial values close to the case where measured SpO2 for each dataset is used with predetermined patient-independent constants, and with significantly better accuracy and precision than when only VBG values are used without the conversion according to the present invention.

[0076] Briefly, the present invention relates to a computer-implemented method, system, and decision support system configured to provide arterial-venous blood gas values without the need to prepare arterial oxygenation saturation values or arterial blood gas values. The method includes providing a mathematical model configured to output arterial blood gas values for a subject by converting these venous blood gas values with a predetermined default arterial oxygenation value for a subject for whom only venous blood gas values are provided. Accordingly, the present invention provides a method for providing arterial blood gas values from a particular subject without the need to provide an arterial blood sample from an arterial blood draw with pain or without the need for an arterial oxygenation saturation value of the subject, thus reducing pain to the patient and reducing the work of associated medical personnel.

[0077] The following presents preferred embodiments and aspects of the present invention as a list of items.

[0078] Item 1 . A computer-implemented method for converting venous blood gas values to arterial blood gas values for a subject when a measured or estimated arterial oxygenation saturation value for the subject is not available, comprising: a. providing a predetermined default arterial oxygenation saturation value as substitute value I; b. optionally, adjusting substitute value I by input from a user; c. providing venous blood gas values of a venous blood sample provided by the subject; d. applying a mathematical model to the venous blood gas values and substitute value I; e. providing an estimated arterial blood gas value based on the mathematical modeling applied to the values provided in step c and substitute value I. A computer-implemented method comprising:

[0079] The computer-implemented method according to item 1, wherein the venous blood gas value in step c is at least one of a venous acid / base parameter and a venous oxygenation parameter.

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

[0081] Item 4. The surrogate value I in step a is a computer-implemented method according to any of the preceding items, based on clinical / medical guidelines such as World Health Guidelines, national health guidelines, regional guidelines, hospital guidelines, or physician guidelines.

[0082] Item 5. The user input in step b, optionally, is · Whether the subject is currently being treated with supplemental oxygen, and / or · The physical parameters of the subject Based on one or more of The physical parameters are · Age, · Lesions / diseases such as COPD, · Gender, · Weight, and · The estimated body fat percentage of the user Including one or more of, a computer-implemented method according to any of the preceding items.

[0083] Item 6. Step c further includes · Providing the hemoglobin value of the venous blood sample provided by the subject And Step d further includes · Applying a mathematical model to the provided hemoglobin value And The estimated arterial acid-base status value and arterial blood gas value provided in step e are based on a computer-implemented method according to any of the preceding items, further based on the mathematical modeling of the hemoglobin value.

[0084] Item 7. A computer-implemented method according to any of the preceding items, further applying that in the mathematical model in step d, the true value of the respiratory quotient (RQ) can only vary between 0.7 and 1.0, being 0.7 in the aerobic metabolism of fat and 1.0 in the aerobic metabolism of carbohydrates.

[0085] Item 8. The mathematical model in step d · adding O2 and removing CO2 from venous blood in a ratio determined by a constant RQ set within the physiologically possible range of 0.7 to 1.0, such as the ratio set for the respiratory quotient (RQ) of 0.82, and · performing a simulation until the estimated arterial blood gas values correlate with the provided venous blood gas values and the substitute value I in step a or step b A computer-implemented method according to any of the preceding items, further mathematically applying.

[0086] Item 9. Further comprising providing a machine learning algorithm and, after step e, f: providing the arterial oxygenation value by measurement of the subject; g: comparing the substitute value I in step a and / or step b with the measured arterial oxygenation value; h: changing the subsequent substitute value I in step a based at least on the comparison performed in step g by the learning algorithm A computer-implemented method according to any of the preceding items, further comprising.

[0087] Item 10. The computer-implemented method according to item 1, wherein the substitute value I in step a is an arterial oxygen saturation ratio between 0.85 and 1.00.

[0088] Item 11. A system configured to convert venous blood gas values to arterial blood gas values of a subject when arterial oxygenation saturation values by measurement or estimation for the subject are not available, · A user interface such as a touch screen configured to provide information to a user and receive input from the user, and · An input / output device configured to receive data from a peripheral device such as a blood gas analysis system or apparatus, and · A processor configured to process data and utilize an algorithm, a mathematical blood gas model, or a simulation, and preferably configured to utilize the mathematical model according to item 1 Comprising The system is configured to provide the user with estimated arterial blood gas values. The system includes · Venous blood gas values from a venous blood sample from a subject, and · A substitute value I that is a predetermined default oxygen saturation value, or · A substitute value I input by the user representing the oxygen saturation value Is provided, the system

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

[0090] Item 13. The decision support system is further configured to adjust the flow rate of assisted oxygen to the subject based on one or more user inputs, and the user has received decision support regarding the flow rate of assisted oxygen from the decision support system, according to item 12

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

[0092] Item 15. Use of the system according to item 11, wherein The user adjusts the flow rate of assisted oxygen to the patient based on the estimated blood gas values provided by the system

[0093] Item 16. A method for treating oxygen deficiency in a subject receiving supplemental oxygen, comprising: · Performing the step according to Item 1; · Determining whether the estimated arterial blood gas value is within a threshold range and whether the estimated arterial blood gas value is outside the threshold range; · Treating the subject based on the estimated arterial blood gas value, such as by adjusting the flow rate of supplemental oxygen per minute. A method comprising the above.

[0094] Item 17. A lung ventilation device configured to supply oxygen to a subject, comprising: - A ventilator; - A processor configured to execute a mathematical model that enables conversion of venous blood gas values and SpO2 values into estimated ABG values; - An input interface data-connected to the processor and configured to receive at least the measured venous blood gas value and SpO2 value from the subject; - A user interface; - A controller data-connected to the processor and the ventilator and configured to control and adjust the ventilator based on the estimated arterial blood gas value from the processor. The lung ventilation device is provided with the above components. A lung ventilation device that executes the computer-implemented method according to Item 1 when the SpO2 value cannot be received from the subject.

[0095] Item 18. The device according to Item 17, wherein the device is unable to receive an SpO2 value, a substitute value I is implemented, and the numerical value of I is further reported to the user and optionally, approval from the user regarding the numerical value of I is requested, in order to provide the estimated ABG value necessary for the device to supply oxygen to the subject.

[0096] Item 19. A computer-implemented method according to Item 1, wherein the estimated arterial blood gas value provided in step e consists of pH, pCO2, BE, HCO3, tO2, and tCO2.

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

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

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

[0100] Although the present invention has been described in connection with specific embodiments, it should in no way be construed as being limited to the examples presented. The scope of the present invention should be construed in light of the appended claims. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, references such as "a" or "an" should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements shown in the drawings should also not be construed as limiting the scope of the present invention. Furthermore, the individual features described in different claims may perhaps be combined advantageously, and even if these features are recited in different claims, it is not excluded that the combination of features is impossible and disadvantageous.

Claims

1. A computer-implemented method for converting venous blood gas values into arterial blood gas values of a subject when measured or estimated arterial oxygen saturation values for the subject are not available, comprising: a. providing a predetermined default arterial oxygen saturation value as a substitute value I; b. optionally adjusting the substitute value I by input from a user; c. providing venous blood gas values of a venous blood sample provided by the subject; d. applying a mathematical model to the venous blood gas values and the substitute value I; e. providing an estimated arterial blood gas value based on the values provided in step c and the mathematical modeling applied to the substitute value I A computer-implemented method.

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

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

4. The computer-implemented method according to any one of claims 1 to 3, wherein the substitute value I in step a is based on clinical / medical guidelines such as World Health Organization guidelines, national health guidelines, regional guidelines, hospital guidelines, or physician guidelines.

5. User input in optional step b is applied, The user input 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 physical parameters are · age, · lesions / diseases such as COPD, · gender, · weight, and · estimated body fat percentage of the user The computer-implemented method according to claim 1, comprising one or more of.

6. Step c further comprises · providing the hemoglobin value of the venous blood sample provided by the subject Including, Step d further comprises · applying the mathematical model to the provided hemoglobin value Including, The estimated arterial acid-base status value and arterial blood gas value provided in step e are further based on the mathematical modeling of the hemoglobin value. The computer-implemented method according to any one of claims 1 to 5.

7. The computer-implemented method according to any one of claims 1 to 6, wherein 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, is 0.7 in the aerobic metabolism of fat, and is 1.0 in the aerobic metabolism of carbohydrates.

8. The mathematical model in step d is - adding O2 and removing CO2 from venous blood in a ratio determined by a constant RQ set within the physiologically possible range of 0.7 to 1.0, such as a ratio set for the respiratory quotient (RQ) of 0.82, and - performing a simulation until the estimated arterial blood gas value correlates with the provided venous blood gas value and the surrogate value I in step a or step b. The computer-implemented method according to any one of claims 1 to 7, further mathematically applying the above.

9. Further including providing a machine learning algorithm and, after step e, f: providing the arterial oxygenation value measured for the subject; g: comparing the surrogate value I in step a and / or step b with the measured arterial oxygenation value; h: changing the subsequent surrogate value I in step a based at least on the comparison performed in step g by the learning algorithm. The computer-implemented method according to any one of claims 1 to 8, further including the above.

10. The surrogate value I in step a is an arterial oxygen saturation ratio between 0.85 and 1.00, according to the computer-implemented method of claim 1.

11. A system configured to convert a venous blood gas value into an arterial blood gas value for a subject by measurement or estimation, - a user interface such as a touch screen configured to provide information to the user and receive input from the user, - an input / output device configured to receive data from a peripheral device such as a blood gas analysis system or device, - a processor configured to process data and utilize an algorithm, a mathematical blood gas model, or a simulation, preferably configured to utilize the mathematical model according to claim 1. The system includes The system - the venous blood gas value from a venous blood sample from the subject, and - A substitute value I which is a predetermined default oxygen saturation value, or - The substitute value I input by the user representing the oxygen saturation value A system configured to provide the user with estimated arterial blood gas values when provided to the system.

12. The system is a decision support system, and the system is configured to provide the user with decision support regarding the subject, such as decision support regarding the flow rate of oxygen from the assisted oxygen device to the patient. The system according to claim 11.

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

14. A computer program product that enables a computer system, preferably a portable computer system, to execute the method according to claim 1 when downloaded or uploaded to the computer system.

15. Use of the system according to claim 11, wherein the user adjusts the flow rate of assisted oxygen to the patient based on the estimated blood gas values provided by the system.

16. A method for treating oxygen deficiency in a subject receiving assisted oxygen, - performing the steps according to claim 1, - determining whether the estimated arterial blood gas value is within a threshold range and whether the estimated arterial blood gas value is outside the threshold range, - treating the subject based on the estimated arterial blood gas value, such as by adjusting the flow rate of assisted oxygen per minute A method comprising.

17. A pulmonary ventilation device configured to supply oxygen to a subject, - A ventilator, - A processor configured to execute a mathematical model that enables conversion of venous blood gas values and SpO2 values into estimated ABG values, - An input interface configured to be data-connected to the processor and receive at least the venous blood gas value and SpO2 value measured from the subject, - A user interface - A controller that is data-connected to the processor and the ventilator and is configured to control and adjust the ventilator based on the estimated arterial blood gas values from the processor and comprising A lung ventilation device that executes the computer-implemented method according to claim 1 when the SpO2 value cannot be received from the subject **Claim 18** The device is unable to receive an SpO2 value, the surrogate value I is implemented, and the numerical value of I is further reported to the user and optionally approval from the user regarding the numerical value of I is requested, in order to provide the estimated ABG value necessary for the device to supply oxygen to the subject. The device according to claim 17

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