System and method for determining oxygen consumption and carbon dioxide production and energy expenditure of a patient

Abstract

A system for determining a total energy expenditure of a patient (10) connected to an extracorporeal membrane oxygenation device (4) for oxygenation of blood of the patient and an mechanical ventilator (2), the system comprises one or more oxygen sensors configured to measure a first oxygen concentration within an inhalation and exhalation gas flow pathway (8) between the mechanical ventilator (2) and a lung(s) of the patient (10) and a second oxygen concentration within a membrane gas flow pathway (12) and / or at a membrane gas flow outlet of the oxygenation of the blood of the patient in the extracorporeal membrane oxygenation device, one or more carbon dioxide sensors configured to measure a first carbon dioxide concentration within the inhalation and exhalation gas flow pathway between the mechanical ventilator (2) and a lung(s) of the patient (10) and a second carbon dioxide concentration within the membrane gas flow pathway (12) of the oxygenation of the blood of the patient in the extracorporeal membrane oxygenation device, a first flow sensor configured to measure a first flow rate within the inhalation and exhalation gas flow pathway between the mechanical ventilator (2) and a lung(s) of a patient (10), and processing circuitry configured to determine based on the first oxygen concentration, the first carbon dioxide concentration, the first flow rate, the second oxygen concentration, the second carbon dioxide concentration, and a second flow rate through the membrane gas flow pathway received by the processing circuitry a first oxygen consumption and a first carbon dioxide production of the patient (10) through the mechanical ventilator (2), and a second oxygen consumption and a second carbon dioxide production of the patient through the extracorporeal membrane oxygenation device (4), wherein the system is further configured to determine a total energy expenditure based on the first oxygen consumption and the first carbon dioxide production and the second oxygen consumption and the second carbon dioxide production.

Description

[0001]P6990PC00 1 System and method for determining oxygen consumption and carbon dioxideproduction and energy expenditure of a patientThe present disclosure relates to a system for determining the oxygen consumption andthe carbon dioxide production and the energy expenditure of a patient connected to anextracorporeal membrane oxygenation device (ECMO) and a mechanical ventilator.Background Respiratory failure requiring pulmonary support influences in excess of 300,000 people in the United States per year. Approximately one-half of these patients suffer from acuterespiratory distress syndrome (ARDS). Acute respiratory distress syndrome is an acuteinflammatory lung disease with a mortality rate of 50%. This disease is characterized byincreased capillary permeability resulting from the development of interstitial oedema andalveolar flooding. For the vast majority of patients with ARDS, there is no specific treatment, or supportive therapy. Supportive therapy for ARDS focuses on mechanical ventilation (ventilatory support) by creating a positive pressure gradient, results in the inflation of the lungs. This is a reversal of the normal lung, which functions by utilizing negative pressures to ventilate the lung. Current ventilatory support may be damaging to the lung. Pulmonary "Volutrauma" resulting from high ventilator tidal volumes and airway pressures may cause a capillary leak syndrome pathologically indistinguishable from ARDS.Monitoring oxygen consumption and carbon dioxide production and indirect calorimetry(IC) of a patient with ARDS is an important but challenging task. Some ventilator systeminclude sensors for continuously measuring oxygen and carbon dioxide levels in the inspired or inhaled and expired gases to be able to monitor oxygen consumption and carbon dioxide production. IC is currently used to apply proper nutrition to critical ill patients. Improper patient nutrition has been associated with poor clinical outcome.Specifically, overfeeding can produce hyperglycaemia and fatty infiltration producing liverdysfunction as well as respiratory acidosis / hypercapnia which are associated with ventilator weaning difficulties. Underfeeding can depress the immune response and lead to loss of lean body mass. IC is currently considered the gold standard as a bedsidetechnique for measuring the Resting Energy Expenditure (REE) and is recommended by P6990PC00 2 important nutrition and intensive care societies, including the European Society for Clinical Nutrition and Metabolism (ESPEN). Oxygen consumption and carbon dioxide production and indirect calorimetry of a patient with ARDS may, however, be influenced by additional factors, which makes the use of the conventional ventilator systems for monitoring oxygenconsumption and carbon dioxide production and indirect calorimetry limited.Summary It is an object of the present disclosure to provide a system for improved monitoring ofoxygen consumption and carbon dioxide production and indirect calorimetry of a patientreceiving extracorporeal membrane oxygenation. In the present disclosure, the terms expired and expelled and exhaled may be usedinterchangeably. In the present disclosure, the terms expiration and exhalation may beused interchangeably. In the present disclosure, the terms inspired and inhaled may be used interchangeably. In the present disclosure, the terms inspiration and inhalation may be used interchangeably. In the present disclosure, one breathing comprises one exhalation and one inhalation.The present disclosure relates to a system for determining a total energy expenditure of apatient connected to an extracorporeal membrane oxygenation device for oxygenation ofblood of the patient and a mechanical ventilator, the system comprises^ one or more oxygen sensors configured to measure a first oxygenconcentration within an inhalation and exhalation gas flow pathway betweenthe mechanical ventilator and a lung(s) of the patient and a second oxygenconcentration within a membrane gas flow pathway and / or at a membrane gasflow outlet of the oxygenation of the blood of the patient in the extracorporealmembrane oxygenation device, ^one or more carbon dioxide sensors configured to measure a first carbondioxide concentration within the inhalation and exhalation gas flow pathway between the mechanical ventilator and a lung(s) of the patient and a second carbon dioxide concentration within the membrane gas flow pathway of theoxygenation of the blood of the patient in the extracorporeal membrane oxygenation device, P6990PC00 3 ^a first flow sensor configured to measure a first flow rate within the inhalationand exhalation gas flow pathway between the mechanical ventilator and alung(s) of a patient, and ^processing circuitry configured to determine based on the first oxygenconcentration, the first carbon dioxide concentration, the first flow rate, the second oxygen concentration, the second carbon dioxide concentration, and a second flow rate through the membrane gas flow pathway received by the processing circuitry ^a first oxygen consumption and a first carbon dioxide production of thepatient through the mechanical ventilator, and^ a second oxygen consumption and a second carbon dioxide productionof the patient through the extracorporeal membrane oxygenation device,wherein the system is further configured to determine a total energy expenditure based onthe first oxygen consumption and the first carbon dioxide production and the second oxygen consumption and the second carbon dioxide production. The presently disclosed system takes into account the fact that ventilatory support forcritically ill patients may be supplemented with an extracorporeal membrane oxygenationdevice in order to protect the lungs from damages and / or provide sufficient oxygenation ofthe blood until the lungs have recovered sufficient oxygenation capability.In ECMO, blood is pumped outside of a body of the patient to a heart-lung machine thatremoves carbon dioxide and sends oxygen-filled blood back to tissues in the body. Bloodflows from one side of the heart of the patient, preferably the right side of the heart, to theextracorporeal membrane oxygenation device in the heart-lung machine. The oxygenatedblood may preferably be warmed up before the blood is sent back to the body. Thismethod allows the blood to "bypass" the heart and lungs, allowing these organs to rest and heal, and to protect the lungs from ventilatory support damages.The ECMO device may be connected to the patient as either a venous-venous-arterial(VVA) ECMO with double venous cannulation (combination of venous access is variable) for drainage and femoral artery cannulation for perfusion, or venous-arterial-venous (VAV) ECMO with single venous drainage and right femoral artery and right internal jugular vein for perfusion or venous-venous-venous-arterial (VVVA) with double-lumen cannula acting only as venous drainage and right femoral artery as perfusion or venous-venous-arterial- P6990PC00 4 venous (VVAV) ECMO with double venous cannulation and right femoral artery and vein as perfusion or VVVA with triple venous drainage and femoral artery as perfusion or similar. The presently disclosed system assesses the total oxygen consumption and carbondioxide production (gas exchange) for patients receiving both ventilatory and ECMOsupport. This is useful since gas exchange takes place both across the lungs and theextracorporeal membrane oxygenation device. The ventilatory gas exchange of patientsreceiving ventilatory support and an ECMO gas exchange of the ECMO support can be used to calculate the correct total resting energy expenditure (REE), using the IndirectCalorimetry (IC) method. The system and method can calculate total oxygen consumption(VO2), total carbon dioxide production (VCO2), Resting Energy Expenditure (REE) andRespiratory Quotient (RQ) by continuously measuring the airway flow, oxygen concentration and carbon dioxide concentration of the inspiration and expiration of thepatient as well as the oxygen concentration and the carbon dioxide concentration of theECMO gas flow after passing the ECMO device. The oxygen concentration and the carbon dioxide concentration of the ECMO gas flow before passing the ECMO device may be known, e.g. if air is used or if the content and concentration of the gas is known. The oxygen concentration and the carbon dioxide concentration of the ECMO gas flow before passing the ECMO device may be received by or known to the processing circuitry, sothat the processing circuitry can determine the second oxygen consumption and thesecond carbon dioxide production of the patient through the extracorporeal membraneoxygenation device based also on the oxygen concentration and the carbon dioxideconcentration of the ECMO gas flow before passing the ECMO device.The system of the present disclosure may use IC in critically ill patients, whosimultaneously undergo ventilatory support and ECMO support, based on the principle that there are two sides of gas exchange, the natural lung and the extracorporealmembrane oxygenation device of the ECMO-circuit.More precisely, the system may be configured to determine the IC in critically ill patientssimultaneously undergoing ventilatory support and ECMO support, and where ICdetermination at the natural lung may be performed as in any other patient on ventilatorysupport, and the IC determination may be performed in a membrane lung of the ECMOdevice, where the second oxygen concentration and the second carbon dioxide P6990PC00 5concentration are measured after the oxygenation in the ECMO device and / or before theoxygenation in the ECMO device.The present disclosure further relates to a system for determining the oxygenconsumption and carbon dioxide production of a patient connected to an extracorporealmembrane oxygenation device and a mechanical ventilator, wherein the system comprises a first oxygen sensor configured to measure a first oxygen concentration within an inhalation and exhalation gas flow pathway between the mechanical ventilator and a lung(s) of a patient, a first carbon dioxide sensor configured to measure a first carbon dioxide concentration within the inhalation and exhalation gas flow pathway between the mechanical ventilator and a lung(s) of a patient, a first flow sensor configured to measure a first flow rate within the inhalation and exhalation gas flow pathway between the mechanical ventilator and a lung(s) of a patient, and a second oxygen sensor configuredto measure a second oxygen concentration within a membrane gas flow pathway and / orat the membrane gas flow outlet of the oxygenation of the blood of the patient in theextracorporeal membrane oxygenation device, a second carbon dioxide sensor configured to measure a second carbon dioxide concentration within the membrane gas flow pathwayand / or at the membrane gas flow outlet of the extracorporeal membrane oxygenationdevice, processing circuitry configured to determine based on the first oxygenconcentration, the first carbon dioxide concentration, the first flow rate, the second oxygen concentration, the second carbon dioxide concentration, and a second flow rate throughthe membrane gas flow pathway received by the processing circuitry a first oxygenconsumption and a first carbon dioxide production of the patient through the mechanical ventilator, and a second oxygen consumption and a second carbon dioxide production of the patient through the extracorporeal membrane oxygenation. The system may beconfigured to determine a total energy expenditure based on the first oxygen consumptionand the first carbon dioxide production and the second oxygen consumption and the second carbon dioxide production. The measurement of the second oxygen concentration and second carbon dioxide concentration in the extracorporeal membrane oxygenation device may be at a gas outlet and possibly also at a gas inlet of the extracorporeal membrane oxygenation device. Further sensors or sets of sensors may be used for this. P6990PC00 6 Brief description of drawings Various embodiments are described hereinafter with reference to the drawings. The drawings are examples of embodiments and are intended to illustrate some of the features of the presently disclosed system and method for determining a total energy expenditure.Fig. 1 shows an example of schematic view of the presently disclosed system fordetermining a total energy expenditure.Fig. 2 shows an example of a detailed schematic view of the presently disclosed systemfor determining a total energy expenditure.Fig. 3 shows an example of a flowchart of the presently disclosed method for determininga total energy expenditure. Detailed description The present disclosure concerns a system and a method for determining a total energyexpenditure of a patient.Gas, such as air, oxygen, oxygenated air, or a mixture of oxygen and nitrogen, at the secondflow rate can be provided to the extracorporeal membrane oxygenation device by a gassource, wherein the gas source can e.g. be ^a pressure vessel comprising the pressurized gas, wherein the pressure vessel maycomprise a pressure regulator for providing a constant pressure and / or flow independent on the pressure in the pressure vessel, ^a cryogenic storage dewar comprising the liquified gas, wherein the cryogenicstorage dewar may comprise a pressure regulator for providing a constant pressureand / or flow independent on the pressure in the pressure vessel, ^a pump for pumping gas like e.g. air through the extracorporeal membraneoxygenation device, or ^a fan for blowing gas like e.g. air through the extracorporeal membrane oxygenationdevice.The second flow rate may be known to the processing circuitry, e.g. by being providedmanually by a user. The user may know the second flow rate based on a setting of thepressure regulator, a pump speed of the pump, or a fan speed of the fan. P6990PC00 7Alternatively, the processing circuitry may be configured to receive data about the secondflow rate based on the setting of the pressure regulator, the pump, or the fan. When thepressure regulator, the pump, or the fan is changed the second flow rate will change anddata about the changed second flow rate may be received by the processing circuitry, sothat a correct oxygen consumption and carbon dioxide production of the patient can bedetermined. The setting of the pressure regulator, the pump, or the fan can be transmittedto the processing circuitry by wire and / or wirelessly and / or typed in manually.It may be possible to set parameters, such as ECMO blood flow (l / min), ECMO gas flow (l / min) and ECMO FiO2 (%) (Fraction of inhaled Oxygen) in an extracorporeal membrane oxygenation device. There is then no need to measure the second flow rate in the presently disclosed system for determining a total energy expenditure.The total oxygen consumption and the total carbon dioxide production can be determinedbased on the first oxygen consumption and the first carbon dioxide production and thesecond oxygen consumption and the second carbon dioxide production. In one embodiment of the presently disclosed system for determining a total energyexpenditure, the system is configured to determine a first energy expenditure based onthe first oxygen consumption and the first carbon dioxide production, and configured todetermine a second energy expenditure based on the second oxygen consumption andthe second carbon dioxide production, and configured to determine the total energyexpenditure as a sum of the first energy expenditure and the second energy expenditure.The first oxygen consumption and the first carbon dioxide production regarding themechanical ventilator can be calculated as shown below, so that the total volume per timeunit consumed oxygen, the total volume per time unit produced carbon dioxide, the totalResting Energy Expenditure (REE), and / or the total Respiratory Quotient (RQ) can bedetermined. The total energy expenditure that is computed by the presently disclosedsystem may be a total resting energy expenditure (REE). The presently disclosed system may be configured to determine a first energy expenditure based on the first oxygen consumption and the first carbon dioxide production, andconfigured to determine a second energy expenditure based on the second oxygen P6990PC00 8 consumption and the second carbon dioxide production, and configured to determine thetotal energy expenditure as a sum of the first energy expenditure and the second energyexpenditure. The following section shows a non-limiting example of how this can be done. The presently disclosed system may be configured to determine a total respiratoryquotient as the total volume produced carbon dioxide divided by the total volumeproduced oxygen. The following section shows a non-limiting example of how this can be done.The first volume of expired oxygen is presented in equations (1) and (2): where FO2 is the fraction of oxygen, sampled at 50 Hz, QATPD is airway flow in l / min,sampled at 50 Hz, fsample is the sample rate of 50 Hz, n is the number of expirations, andthe t0 to t1 is the time interval for the n expirations. In equation (2) the expired first volumeis calculated for seven expirations. Other numbers of expirations and sample rates couldalso be contemplated within the context of the present disclosure.The first volume of inspired oxygen is presented in equations (3) and (4) where FO2, QATPD, and fsample are as presented above. n is the number of inspirations, andthe time interval between t0 to t1 is the corresponding time interval. In equation (4) theinspired first volume is calculated for seven inspirations. Other number of inspirationscould also be contemplated within the context of the present disclosure.The total first volume of oxygen of the mechanical ventilator is presented in equation (5) P6990PC00 9where BreathDuration is the duration in minutes of seven breathings comprising the seveninspirations and the seven expirations. The unit of VO2ventis l / min.The first volume of expired or expelled carbon dioxide is presented in equations (6) and(7): ^^ ^^10 ^^^2 ^^ ^^^^^(^ = ^ ^2 ∗ ^) 60 ∗ ^^(6) ^^^^ ^^^^^^ ^^^2^^^ = ^^^^2^^^ (^)(7) ^^^ 7where FCO2, QATPD, and fsample are as presented above. n is the number of expirations,and the time interval between t0to t1is the corresponding time interval. In equation (7) theexpired or expelled first volume is calculated for seven expirations. Other number ofexpirations could also be contemplated within the context of the present disclosure.The first volume of inspired carbon dioxide is presented in equations (8) and (9): where FCO2, QATPD, and fsample are as presented above. n is the number of inspirations,and the time interval between t0to t1is the corresponding time interval. In equation (4) theinspired first volume is calculated for seven inspirations. Other number of inspirationscould also be contemplated within the context of the present disclosure.The total first volume of carbon dioxide of the mechanical ventilator is presented inequation (10): ^^^^2^^ + ^^^2 ^35 (10) ^^^2 =^^ ^^^^^^^^^^^^ℎ^^^^^^^^where BreathDuration is the duration in minutes of in this case seven breathingscomprising the seven inspirations and the seven expirations. The unit of VCO2ventis l / min. P6990PC00 10The Resting Energy Expenditure (REEvent) for the mechanical ventilator will then be aspresented in equation (11)^^^^^^^ = (3.94 × ^^2^^^^ + 1.11 × ^^^52^^^^) × 1440 (11)The Respiratory Quotient (RQvent) for the mechanical ventilator will then be as presentedin equation The second oxygen consumption and the second carbon dioxide production regarding theECMO can be calculated as shown below.The second volume of expelled oxygen is presented in equation (13): where QexpATPD is the stable flow of the expelled air, and FeO2 is the fraction of expelledoxygen of said expelled air.The second volume of intake oxygen is presented in equation (14): ^^2^^ = ^^^2 ∗ ^^^^^^^(14)where FiO2 is the fraction of intake oxygen, and QinATPD is the stable flow of the intake air.The total second volume of oxygen consumption regarding the ECMO is presented inequation (15): ^^2^^^^ = ^^2^^ + ^^2^^^ (15)The second carbon dioxide production (VCO2ECMO) can also be determined. The secondvolume of expired carbon dioxide is presented in equation (16): where QexpATPD is the stable flow of the expelled air, and FeCO2 is the fraction of expelledcarbon dioxide of said expelled air. The second volume of inspired carbon dioxide ispresented in equation (17): P6990PC00 11where QinATPD is the stable flow of the intake air, and FiCO2 is the fraction of intake carbondioxide of said intake air. The second carbon dioxide production is presented in equation(18): ^^^2^^^^ = ^^^2^^ + ^^^2^^^(18)The Resting Energy Expenditure (REEECMO) will then be as presented in equation (19):^^^^^^^ = (3.94 × ^^2^^^^ + 1.11 × ^^^2^^^^) × 1440 (19)The Respiratory Quotient (RQECMO) will then be as presented in equation (20) The total volume per time unit consumed oxygen will be as presented in equation (21) ^^2^^^^^ = ^^2^^^^ + ^^2^^^^ (21)The total volume produced carbon dioxide will be as presented in equation (22) ^^^2^^^^^ = ^^^2^^^^ + ^^^2^^^^(22)The total Resting Energy Expenditure (REE) will then be as presented in equation (23):^^^^^^^^ = ^^^^^^^ + ^^^^^^^ 25 (23)The total Respiratory Quotient (RQ) will then be as presented in equation (24) The calculations of REEvent and REEECMO presented above are generally used. However,there are other ways of calculating each of REEvent and REEECMO, which are also contemplated within the context of the present disclosure. The Resting EnergyExpenditure (REEvent) for the mechanical ventilator may e.g. be as in equation (25)^^^^^^^ = (5.5 × ^^2^^^^ + 1.76 × ^^^2^^^^ ) × 1000 − 1.99 ∗ ^^(25)where UN is urinary nitrogen, which may be set to 13 by default. Similar equation(s) canbe applied to REEECMO. With these alternatives, REEvent and REEECMO, the REETotal will bea little different. The calculations of VO2vent, VO2ECMO, VCO2vent and VCO2ECMO presented above are generally used, but there are also alternative ways of calculating VO2vent, VO2ECMO, P6990PC00 12VCO2vent and VCO2ECMO, which will influence VO2Total, VCO2Total, REEvent, REETotal, RQTotal.These alternative calculations of VO2vent, VO2ECMO, VCO2ventand VCO2ECMOare also contemplated within the context of the present disclosure. In one embodiment of the presently disclosed system and method, there are separateprocesses for measuring the first oxygen concentration and first carbon dioxideconcentration and the second oxygen concentration and second carbon dioxideconcentration. Since ECMO has a steady flow, it may be useful to measure the secondoxygen concentration and the second carbon dioxide concentration within the membranegas flow pathway first. For example, measure the second oxygen concentration and thesecond carbon dioxide concentration can be measured until a stable second energyexpenditure has been obtained.In one embodiment the system is configured to measure the second oxygen concentrationand the second carbon dioxide concentration for at least 10 seconds, preferably for atleast 20 seconds, more preferably for at least 30 seconds.Once a stable second energy expenditure has been obtained, the system may proceedwith measuring the first oxygen concentration and the first carbon dioxide concentrationwithin the inhalation and exhalation gas flow pathway. This may typically take longer. Inone embodiment the system is configured to measure the first oxygen concentration andthe first carbon dioxide concentration within the inhalation and exhalation gas flowpathway for at least 5 minutes, preferably for at least 10 minutes, more preferably for at least 30 minutes. The presently disclosed system may comprise one or more oxygen sensors and one ormore carbon dioxide sensors. There are several ways of implementing this, which isdescribed in the following section. According to one embodiment the system comprises a first oxygen sensor configured tomeasure the first oxygen concentration within an inhalation and exhalation gas flowpathway; a first carbon dioxide sensor configured to measure the first carbon dioxideconcentration within the inhalation and exhalation gas flow pathway; a second oxygensensor configured to measure the second oxygen concentration within the membrane gasflow pathway; and a second carbon dioxide sensor configured to measure the secondcarbon dioxide concentration within the membrane gas flow pathway. The sensors can be P6990PC00 13placed at the inhalation and exhalation gas flow pathway and at the membrane gas flowpathway, respectively. It is also possible to use sampling tubes. In such solutions the sensors do not necessarilyhave to be positioned directly in the inhalation and exhalation gas flow pathway and at themembrane gas flow pathway.The system may comprise a module configured to receive an oxygen concentration, acarbon dioxide concentration and a flow rate, the module being further configured tocompute an oxygen consumption and a carbon dioxide production based on the oxygenconcentration, the carbon dioxide concentration and the flow rate.If sampling tubes are used rather than having the sensors positioned directly in theinhalation and exhalation gas flow pathway and at the membrane gas flow pathway, itmay be possible to have only one set of sensors. Accordingly, in one embodiment the one or more oxygen sensors and / or the one or more carbon dioxide sensors are sharedbetween the extracorporeal membrane oxygenation device and the mechanical ventilator.This system may have several advantages. One advantage is that fewer components are needed. Another advantage may be increased accuracy since the system does not haveto be calibrated for differences between the different sets of sensors. In such anembodiment the system may comprise a switch configured to select between samplingthe first oxygen and the second oxygen concentration and / or select between sampling thefirst carbon dioxide concentration and the second carbon dioxide concentration.In order to implement the system, a special device can be provided and connected with anexisting ventilator or integrated into the ventilator and connected with an existing ECMOdevice or integrated into the ECMO device.In one embodiment, the processing circuitry may be configured to determine the firstoxygen consumption and the first carbon dioxide production and the second oxygenconsumption and the second carbon dioxide production based also on a third oxygenconcentration and a third carbon dioxide concentration within the membrane gas flow pathway before oxygenation of the blood of the patient in the extracorporeal membrane oxygenation device, wherein the third oxygen concentration and third carbon dioxideconcentration may be accessible to the processing circuitry from a storing unit, or the P6990PC00 14 system may comprise a third oxygen sensor configured to measure the third oxygen concentration within the membrane gas flow pathway before oxygenation of the blood of the patient in the extracorporeal membrane oxygenation device, and a third carbon dioxide sensor configured to measure the third carbon dioxide concentration within the membrane gas flow pathway before oxygenation of the blood in the extracorporealmembrane oxygenation device, and wherein the processing circuitry may be configured toreceive the measured third oxygen concentration and the third carbon dioxide concentration. In addition to the second oxygen concentration and the second carbon dioxideconcentration measured within the membrane gas flow pathway after oxygenation of theblood in the extracorporeal membrane oxygenation device, the second oxygenconsumption and the second carbon dioxide production may also be determined based onthe third oxygen concentration and the third carbon dioxide concentration measured within the membrane gas flow pathway before oxygenation of the blood in the extracorporeal membrane oxygenation device.If composition of the gas flowing through the membrane gas flow pathway is known, thenthe third oxygen concentration and the third carbon dioxide concentration are known, andthe third oxygen concentration and the third carbon dioxide concentration can be madeaccessible to the processing circuitry, so that the second oxygen consumption and thesecond carbon dioxide production can be determined based also on the third oxygenconcentration and the third carbon dioxide concentration. The gas flowing through themembrane gas flow pathway may be air, where the third oxygen concentration and thethird carbon dioxide concentration will be known. The gas flowing through the membranegas flow pathway may be air, at a certain temperature and / or at a certain humidity, so thatthe third oxygen concentration and the third carbon dioxide concentration may be known.The gas flowing through the membrane gas flow pathway may be from a pressure vesselcomprising the pressurized gas with known concentrations of oxygen and carbon dioxide. In that case, the third oxygen concentration and the third carbon dioxide concentration will be known. The system may comprise the third oxygen sensor and the third carbon dioxide sensor configured to measure the third oxygen concentration and the third carbon dioxide P6990PC00 15 concentration, respectively, within the membrane gas flow pathway before oxygenation of the blood of the patient in the extracorporeal membrane oxygenation device, so that the third oxygen concentration and the third carbon dioxide concentration can be determined and used for determining the second oxygen consumption and the second carbon dioxide production, even though the third oxygen concentration and the third carbon dioxide concentration are not known. In one embodiment, the system may comprise a second flow sensor configured to measure the second flow rate through the membrane gas flow pathway, and wherein theprocessing circuitry may be configured to receive the measured second flow rate.The second flow sensor may measure and provide the second flow rate to the processing circuitry, so that the second oxygen consumption and the second carbon dioxideproduction in the extracorporeal membrane oxygenation device can be determined.In one embodiment, the system may comprise a third flow sensor configured to measure a blood flow rate of blood from the patient being oxygenated by the extracorporealmembrane oxygenation device, wherein the processing circuitry may be configured toreceive the measured blood flow rate and to determine the first oxygen consumption andthe first carbon dioxide production and / or the second oxygen consumption and the secondcarbon dioxide production based also on the blood flow rate.In one embodiment, the system may comprise the inhalation and exhalation gas flow pathway comprising the first oxygen sensor, the first carbon dioxide sensor, and the firstflow sensor, wherein the inhalation and exhalation gas flow pathway may be configured tobe connected at one end to the mechanical ventilator and at another end to a respiratorysystem of the patient. The inhalation and exhalation gas flow pathway may be connectable at one end to themechanical ventilator and at the other end to the respiratory system of the patient, so thatthe first oxygen sensor, the first carbon dioxide sensor, and the first flow sensor are able to measure the first oxygen concentration, the first carbon dioxide concentration, and thefirst flow during both when the patient is inhaling and when the patient is exhaling. P6990PC00 16 The inhalation and exhalation gas flow pathway may have a third pathway, through which air exhaled by the patient is let out into the surrounding air. The third pathway may exit in the open air. The inhalation and exhalation gas flow pathway may then have a first oneway valve for preventing the exhaled air to enter the mechanical ventilator and a secondone way valve for preventing the inhaled air to be drawn from the surrounding air. In one embodiment, the system may comprise the membrane gas flow pathway comprising the second oxygen sensor, the second carbon dioxide sensor, and optionally the second flow sensor and / or optionally the third oxygen sensor and the third carbondioxide sensor, wherein the membrane gas flow pathway may be configured to beconnected to the extracorporeal membrane oxygenation device for receiving gas from the extracorporeal membrane oxygenation device after the second oxygen consumption and the second carbon dioxide production.In one embodiment, the processing circuitry may be configured to determine a totaloxygen consumption and a total carbon dioxide production of the patient based on the firstoxygen consumption and the first carbon dioxide production and the second oxygenconsumption and the second carbon dioxide production. In one embodiment, the system may comprise a display unit for displaying the first oxygenconsumption and the first carbon dioxide production and the second oxygen consumptionand the second carbon dioxide production, and / or the total oxygen consumption and the total carbon dioxide production. The display unit may display any of the total energy expenditure, first energy expenditure, second energy expenditure, respiratory quotient (total or individual), first oxygen consumption, first carbon dioxide production, second oxygen consumption, second carbon dioxide production. In one embodiment, the first oxygen sensor may be configured to measure a first series ofoxygen concentrations and the first carbon dioxide sensor may be configured to measurea first series of carbon dioxide concentrations within the inhalation and exhalation gas flowpathway, wherein the first series of oxygen concentrations and the first series of carbondioxide concentrations may comprise measurements during inhalation and exhalation of the patient. P6990PC00 17With the first series of oxygen concentrations and of carbon dioxide concentrations, it willbe possible to detect changes in the first oxygen consumption and the first carbon dioxide production. The first series of oxygen concentrations and of carbon dioxide concentrations may cover several rounds of inhalations and exhalations for determining changes in the first oxygenconsumption and the first carbon dioxide production over time.In one embodiment, the second oxygen sensor may be configured to measure a secondseries of oxygen concentrations and the second carbon dioxide sensor may be configuredto measure a second series of carbon dioxide concentrations within the membrane gasflow pathway after oxygenation of the blood of the patient in the extracorporeal membrane oxygenation device.With the second series of oxygen concentrations and of carbon dioxide concentrations, itwill be possible to detect changes in the second oxygen consumption and the secondcarbon dioxide production over time.The disclosure also relates to a method for determining oxygen consumption and carbondioxide production of a patient connected to an extracorporeal membrane oxygenationdevice and an mechanical ventilator, the method comprises the steps of measuring a firstoxygen concentration within an inhalation and exhalation gas flow pathway between themechanical ventilator and a lung(s) of a patient, measuring a first carbon dioxideconcentration within the inhalation and exhalation gas flow pathway, measuring a first flowrate within the inhalation and exhalation gas flow pathway, and measuring a secondoxygen concentration within a membrane gas flow pathway and / or at a membrane gasflow outlet after oxygenation of the blood of the patient in the extracorporeal membraneoxygenation device, measuring a second carbon dioxide concentration within themembrane gas flow pathway after oxygenation of the blood of the patient in theextracorporeal membrane oxygenation device, determining a first oxygen consumptionand a first carbon dioxide production of the patient through the mechanical ventilator, anda second oxygen consumption and a second carbon dioxide production of the patientthrough the extracorporeal membrane oxygenation device. P6990PC00 18 A person skilled in the art will recognize that the presently disclosed method fordetermining oxygen consumption and carbon dioxide production of a patient connected toan extracorporeal membrane oxygenation device and an mechanical ventilator may beperformed using any embodiment of the presently disclosed system for determining theoxygen consumption and carbon dioxide production of a patient connected to anextracorporeal membrane oxygenation device and an mechanical ventilator, and viceversa.The method may measure the first flow rate, the first oxygen concentration and the firstcarbon dioxide concentration correlated with the patient’s breathing patterns, connected in between the airway system and the endotracheal tube or tracheal tube in patients undergoing ventilatory support. The method may also measure the second oxygen concentration and the second carbon dioxide concentration correlated with the ECMO device which is taken from the gas outlet and / or the gas inlet of the extracorporealmembrane oxygenation device in patients undergoing ECMO support, and can receiveinformation about the second flow rate through the membrane gas flow pathway for determining the total oxygen consumption and the total carbon dioxide production by the patient. Further characteristics and advantages of the present disclosure will become apparentfrom the following illustrations, which are not limiting, description of preferred but notexclusive embodiments of a system or method for measuring the Indirect Calorimetry in apatient receiving mechanical ventilation and extracorporeal membrane oxygenation andmethod for estimating the patients resting energy expenditure and respiratory quotient, as illustrated in the accompanying drawing tables, in which:Fig. 1 shows a schematic view of a mechanical ventilator 2, an extracorporeal membraneoxygenator or an extracorporeal membrane oxygenation device 4, an apparatus 6, suchas an indirect calorimetry apparatus 6, comprising a processing circuitry, an inhalation andexhalation gas flow pathway 8 through which all airway gas from and to a respiratorysystem of a patient 10 is directed and a membrane gas flow pathway 12 through which allgas from the extracorporeal membrane oxygenation device is directed;Fig. 2 shows a detailed schematic view of an example of the Calorimetry apparatus 6 ofFig. 1, provided with a first embodiment of an apparatus for measuring the Indirect P6990PC00 19Calorimetry in a patient receiving mechanical ventilation and extracorporeal membraneoxygenation and for estimating the patient’s oxygen consumption VO2, carbon dioxide production VCO2, resting energy expenditure REE and respiratory quotient RQ according to the present disclosure;Fig.3 shows an example of a flowchart of the presently disclosed method for determininga total energy expenditure. Gas, such as air, oxygen, oxygenated air, or a mixture of oxygen and atmospheric air, tothe respiratory system 102 of the patient 10 and from the mechanical ventilator 2 maypass through the inhalation and exhalation gas flow pathway 8 during the inhalation intothe respiratory system, as shown in the example of fig.1. The gas that has providedoxygen to the lungs is exhaled by the patient through the inhalation and exhalation gasflow pathway 8 to the mechanical ventilator 2 or out into the surrounding air through anexhaust valve (not shown). The exhaust valve may be a one-way valve or a controlledvalve for only letting exhaled air out. The gas flow pathway 8 may comprise a first oxygensensor 120 and a first carbon dioxide sensor 121, wherein the first oxygen sensor 120 isconfigured to measure a first oxygen concentration within the inhalation and exhalationgas flow pathway between the mechanical ventilator 2 and one lung or both lungs of thepatient 10, and wherein the first carbon dioxide sensor 121 is configured to measure a firstcarbon dioxide concentration within the inhalation and exhalation gas flow pathway. Themeasured first oxygen concentration and / or the measured first carbon dioxideconcentration is / are transferred to the processing circuitry wirelessly or by a first wire 104as shown in Fig. 1. It is also possible to have a sampling tube instead of a wire and havethe sensors connected to the sampling tube.In the example of fig. 1 there is a first oxygen sensor 120, a first carbon dioxide sensor121, and a first flow sensor 122 within the inhalation and exhalation gas flow pathway.There is also a second oxygen sensor 123 and a second carbon dioxide sensor 124 at the membrane gas flow outlet. In the apparatus 6 there is a module 125 configured to receivean oxygen concentration, a carbon dioxide concentration and a flow rate. There is also aswitch 126 configured to select between sampling the first oxygen and the second oxygenconcentration and / or select between sampling the first carbon dioxide concentration andthe second carbon dioxide concentration. P6990PC00 20 If 18 and 104 are instead thought of as sampling tubes the sensors may be located in theapparatus 6 and the switch 126 may be configured to select between sampling the firstoxygen and the second oxygen concentration and / or select between sampling the firstcarbon dioxide concentration and the second carbon dioxide concentration using thesampling tubes 104 and 118. The inhalation and exhalation gas flow pathway 8 may also comprise a first flow sensor122 for measuring a first flow rate between the patient 10 and the mechanical ventilator 2and / or the exhaust valve. During a breathing cycle of the patient, the first flow rate willchange direction and quantity. Preferably, the first flow sensor, and any of the othersensors, has a sampling rate so that the first flow rate is measured many times during thebreathing cycle. Blood from the patient may be transported to the extracorporeal membrane oxygenation device 4 through a blood extracting tube 112 for being oxygenated by the extracorporeal membrane oxygenation device and the oxygenated blood may then be transported back to the patient through a blood returning tube 114. The extracorporeal membrane oxygenation device 4, the blood extracting tube 112 or the blood returning tube 114 may comprise a blood pump (not shown) for pumping the blood from the patient through the blood extracting tube 112, through the extracorporeal membrane oxygenation device 4,and back to the patient through the blood returning tube 114. The extracorporealmembrane oxygenation device may be provided with gas, such as air, oxygen, oxygenated air, or a mixture of oxygen and atmospheric air by a gas source (not shown), wherein the gas source can e.g. be ^a pressure vessel comprising the pressurized gas, wherein the pressure vesselmay comprise a pressure regulator for providing a constant pressure and / or flow independent on the pressure in the pressure vessel, ^a cryogenic storage dewar comprising the liquified gas, wherein the cryogenicstorage dewar may comprise a pressure regulator for providing a constant pressure and / or flow independent on the pressure in the pressure vessel, ^a pump for pumping gas like e.g. air through the extracorporeal membraneoxygenation device, or ^a fan for blowing gas like e.g. air through the extracorporeal membraneoxygenation device. P6990PC00 21 The gas for the extracorporeal membrane oxygenation device will be let into the extracorporeal membrane oxygenation device through an inlet (not shown) for oxygenating the blood in the extracorporeal membrane oxygenation device provided from the blood extracting tube 112. The gas after having oxygenated the blood and removed CO2 from the blood in the extracorporeal membrane oxygenation device will be let outthrough an extracorporeal membrane oxygenation device outlet 116 and through themembrane gas flow pathway 12. The membrane gas flow pathway may comprise asecond oxygen sensor 123 configured to measure a second oxygen concentration withinthe membrane gas flow pathway after oxygenation of the blood of the patient in theextracorporeal membrane oxygenation device, and a second carbon dioxide sensor 124 configured to measure a second carbon dioxide concentration within the membrane gas flow pathway after oxygenation of the blood of the patient in the extracorporeal membraneoxygenation device. The measured second oxygen concentration and / or the measuredsecond carbon dioxide concentration may be transferred to the processing circuitrywirelessly or by a second wire 118 as shown in Fig.1. It is also possible to have asampling tube instead of a wire and have the sensors connected to the sampling tube.The extracorporeal membrane oxygenation device may blow a gas of a knowncomposition at a known second flow rate through the extracorporeal membraneoxygenation device, or a gas of a known composition at a known second flow rate is blown passed the extracorporeal membrane oxygenation device. That the gas has aknown composition may mean that a third oxygen concentration and / or a third carbondioxide concentration of the gas are known before the gas passes the extracorporealmembrane oxygenation device.Alternatively, the extracorporeal membrane oxygenation device or the membrane gas flowpathway 12 may have a second flow sensor (not shown) for measuring the second flow rate. Whether the second flow rate is known or measured, the second flow rate may be provided to the apparatus 6.Alternatively, the extracorporeal membrane oxygenation device 4 may have a thirdoxygen sensor (not shown) for measuring the third oxygen concentration in the gasentering the extracorporeal membrane oxygenation device and the third carbon dioxidesensor (not shown) for measuring a third carbon dioxide concentration in the gas entering the extracorporeal membrane oxygenation device. P6990PC00 22 Whether the third oxygen concentration and / or the third carbon dioxide concentration are known or measured, the third oxygen concentration and / or the third carbon dioxide concentration may be provided to the apparatus 6.The measured first oxygen concentration and / or the measured first carbon dioxideconcentration and / or the measured first flow rate may be received by the apparatus 6through the first wire 104 and / or a first inlet 202 as shown in Fig. 2. It is also possible tohave a sampling tubes instead of wires and have the required sensors connected to the sampling tube.The measured second oxygen concentration and / or the measured second carbon dioxideconcentration may be received by an apparatus 6, such as an indirect calorimetryapparatus 6, through the second wire 118 and / or a second inlet 204. The known ormeasured second flow rate, third oxygen concentration and / or the known or measuredthird carbon dioxide concentration may also be received by the apparatus 6 through thesecond wire 118 and a second inlet 204. If the second flow rate, the third oxygenconcentration and / or the third carbon dioxide concentration are known the second flowrate, the third oxygen concentration and / or the third carbon dioxide concentration may bealready stored in the apparatus 6, so that the known second flow rate, third oxygenconcentration and / or third carbon dioxide concentration do not need to be transferred tothe apparatus 6.The apparatus 6, which may be an indirect calorimetry apparatus 6, may compriseprocessing circuitry, where the measured first oxygen concentration and / or the measuredfirst carbon dioxide concentration and / or the measured first flow rate as well as themeasured second oxygen concentration and / or the measured second carbon dioxideconcentration are received by a controller 205.Fig.2 shows an apparatus 6 with a structure that may be only for illustration purposes.Other designs of the apparatus 6 are contemplated within the scope of the present disclosure, e.g. where at least one processing circuit determines the oxygen consumptionand the carbon dioxide production based on the measured or known data e.g. received bythe first inlet 202 and the second inlet 204, and / or the known data e.g. stored on theprocessing circuitry or on a storage available to the processing circuitry. P6990PC00 23 The measured first flow rate may be received from the controller 205 and the measured first flow rate may be provided by a first flow analyser processing circuit 206 in a format readable by a data processor circuit 208.The measured first oxygen concentration may be received from the controller 205 and themeasured first oxygen concentration may be provided by a first oxygen analyserprocessing circuit 210 in a format readable by the data processor circuit 208.The measured first carbon dioxide concentration may be received from the controller 205and the measured first carbon dioxide concentration may be provided by a first carbondioxide analyser processing circuit 212 in a format readable by the data processor circuit208.The measured second oxygen concentration may be received from the controller 205 andthe measured second oxygen concentration may be provided by a second oxygenanalyser processing circuit 214 in a format readable by the data processor circuit 208.The measured second carbon dioxide concentration may be received from the controller205 and the measured second carbon dioxide concentration may be provided by a secondcarbon dioxide analyser processing circuit 216 in a format readable by the data processorcircuit 208. The measured second flow rate may be received from the controller 205 and the measured second flow rate may be provided by a second flow analyser processing circuit218 in a format readable by the data processor circuit 208. Alternatively, the second flowrate may be known and stored in a format readable by the data processor circuit 208, so that the second flow analyser processing circuit 218 is not necessary. The controller 205 may receive the data received by the first inlet 202 and the second inlet 204 and distribute each data to the relevant analyser processing circuit. Since the data processor circuit 208 has all necessary data available, the data processor circuit 208 can determine or calculate the total oxygen consumption and the total carbondioxide production, as well as the total energy expenditure and / or the total respiratory P6990PC00 24quotient, of the patient based on both the first oxygen consumption and the first carbondioxide production and the second oxygen consumption and the second carbon dioxideproduction.The apparatus 6 may comprise a display unit 220, like a screen, for displaying any of thetotal energy expenditure, first energy expenditure, second energy expenditure, respiratory quotient (total or individual), first oxygen consumption, first carbon dioxide production,second oxygen consumption, second carbon dioxide production of the patient based onboth the first oxygen consumption and the first carbon dioxide production and the secondoxygen consumption and the second carbon dioxide production and / or for displaying thefirst oxygen consumption and the first carbon dioxide production and the second oxygenconsumption and the second carbon dioxide production, separately.

Claims

P6990PC00 25 Claims1. A system for determining a total energy expenditure of a patient (10) connected to anextracorporeal membrane oxygenation device (4) for oxygenation of blood of the patient and a mechanical ventilator (2), the system comprises^ one or more oxygen sensors configured to measure a first oxygenconcentration within an inhalation and exhalation gas flow pathway (8) between the mechanical ventilator (2) and a lung(s) of the patient (10) and a secondoxygen concentration within a membrane gas flow pathway (12) and / or at amembrane gas flow outlet of the oxygenation of the blood of the patient in theextracorporeal membrane oxygenation device, ^one or more carbon dioxide sensors configured to measure a first carbondioxide concentration within the inhalation and exhalation gas flow pathway between the mechanical ventilator (2) and a lung(s) of the patient (10) and asecond carbon dioxide concentration within the membrane gas flow pathway(12) of the oxygenation of the blood of the patient in the extracorporealmembrane oxygenation device, ^a first flow sensor configured to measure a first flow rate within the inhalationand exhalation gas flow pathway between the mechanical ventilator (2) and alung(s) of a patient (10), and ^processing circuitry configured to determine based on the first oxygenconcentration, the first carbon dioxide concentration, the first flow rate, the second oxygen concentration, the second carbon dioxide concentration, and a second flow rate through the membrane gas flow pathway received by the processing circuitry ^a first oxygen consumption and a first carbon dioxide production of thepatient (10) through the mechanical ventilator (2), and^ a second oxygen consumption and a second carbon dioxide productionof the patient through the extracorporeal membrane oxygenation device(4), wherein the system is further configured to determine a total energyexpenditure based on the first oxygen consumption and the first carbondioxide production and the second oxygen consumption and the second carbon dioxide production.P6990PC00 262. The system according to claim 1, wherein the system is configured to determine afirst energy expenditure based on the first oxygen consumption and the firstcarbon dioxide production, and configured to determine a second energy expenditure based on the second oxygen consumption and the second carbondioxide production, and configured to determine the total energy expenditure as asum of the first energy expenditure and the second energy expenditure.

3. The system according to claim 2, wherein the system is configured to measure thesecond oxygen concentration and the second carbon dioxide concentration withinthe membrane gas flow pathway until a stable second energy expenditure hasbeen obtained.

4. The system according to claim 2, wherein the system is configured to measure thesecond oxygen concentration and the second carbon dioxide concentration for atleast 10 seconds, preferably for at least 20 seconds, more preferably for at least 30 seconds.

5. The system according to any one of claims 2-4, wherein the system is configuredto measure the first oxygen concentration and the first carbon dioxideconcentration within the inhalation and exhalation gas flow pathway (8) for at least 5 minutes, preferably for at least 10 minutes, more preferably for at least 30 minutes.

6. The system according to any one of the preceding claims, wherein the systemcomprises a first oxygen sensor configured to measure the first oxygenconcentration within an inhalation and exhalation gas flow pathway; a first carbon dioxide sensor configured to measure the first carbon dioxide concentration withinthe inhalation and exhalation gas flow pathway; a second oxygen sensor configured to measure the second oxygen concentration within the membrane gasflow pathway; and a second carbon dioxide sensor configured to measure the second carbon dioxide concentration within the membrane gas flow pathway.

7. The system according to any one of the preceding claims, comprising a moduleconfigured to receive an oxygen concentration, a carbon dioxide concentration anda flow rate, further configured to compute an oxygen consumption and a carbon dioxide production based on the oxygen concentration, the carbon dioxide concentration and the flow rate.P6990PC00 278. The system according to any one of the preceding claims, wherein the one ormore oxygen sensors and / or the one or more carbon dioxide sensors are shared between the extracorporeal membrane oxygenation device and the mechanical ventilator.

9. The system according to claim 8, wherein the system comprises a switchconfigured to select between sampling the first oxygen and the second oxygenconcentration and / or select between sampling the first carbon dioxideconcentration and the second carbon dioxide concentration.

10. The system according to any one of the preceding claims, wherein the total energyexpenditure is a total resting energy expenditure (REE).

11. The system according to any one of the preceding claims, wherein the processingcircuitry is configured to determine the first oxygen consumption and the first carbondioxide production and the second oxygen consumption and the second carbondioxide production based also on a third oxygen concentration and a third carbondioxide concentration within the membrane gas flow pathway (12) before oxygenationof the blood of the patient in the extracorporeal membrane oxygenation device (4),wherein ^the third oxygen concentration and third carbon dioxide concentration areaccessible to the processing circuitry from a storing unit, or^ the system comprises^ a third oxygen sensor configured to measure the third oxygenconcentration within the membrane gas flow pathway beforeoxygenation of the blood of the patient in the extracorporeal membrane oxygenation device (4), and^ a third carbon dioxide sensor configured to measure the third carbondioxide concentration within the membrane gas flow pathway before oxygenation of the blood of the patient in the extracorporeal membrane oxygenation device, and wherein the processing circuitry is configured to receive the measured thirdoxygen concentration and the third carbon dioxide concentration.P6990PC00 2812. The system according to any one of the preceding claims, wherein the systemcomprises a second flow sensor configured to measure the second flow rate throughthe membrane gas flow pathway (12), and wherein the processing circuitry isconfigured to receive the measured second flow rate.

13. The system according to any one of the preceding claims, wherein the systemcomprises a third flow sensor configured to measure a blood flow rate of blood fromthe patient (10) being oxygenated by the extracorporeal membrane oxygenation device (4), wherein the processing circuitry is configured to receive the measuredblood flow rate and to determine the first oxygen consumption and the first carbondioxide production and the second oxygen consumption and the second carbondioxide production based also on the blood flow rate.

14. The system according to any one of the preceding claims, wherein the systemcomprises the inhalation and exhalation gas flow pathway (8) comprising the firstoxygen sensor, the first carbon dioxide sensor, and the first flow sensor, wherein the inhalation and exhalation gas flow pathway is configured to be connected at one endto the mechanical ventilator (2) and at another end to a respiratory system of thepatient (10).

15. The system according to any one of the preceding claims, wherein the systemcomprises the membrane gas flow pathway (12) comprising^ the second oxygen sensor,^ the second carbon dioxide sensor, and^ optionally the second flow sensor and / or^ optionally the third oxygen sensor and the third carbon dioxide sensor,wherein the membrane gas flow pathway is configured to be connected to theextracorporeal membrane oxygenation device (4) for receiving gas from theextracorporeal membrane oxygenation device after the second oxygen consumptionand the second carbon dioxide production.

16. The system according to any one of the preceding claims, wherein the processingcircuitry is configured to determine a total oxygen consumption and a total carbondioxide production of the patient (10) based on the first oxygen consumption and theP6990PC00 29 first carbon dioxide production and the second oxygen consumption and the secondcarbon dioxide production.

17. The system according to any one of the preceding claims, wherein the systemcomprises a display unit (220) for displaying the first oxygen consumption and the firstcarbon dioxide production and the second oxygen consumption and the secondcarbon dioxide production, and / or the total oxygen consumption and the total carbon dioxide production.

18. The system according to any one of the preceding claims, wherein^ the first oxygen sensor is configured to measure a first series of oxygenconcentrations, and ^the first carbon dioxide sensor is configured to measure a first series of carbondioxide concentrations within the inhalation and exhalation gas flow pathway (8), wherein the first series ofoxygen concentrations and the first series of carbon dioxide concentrations comprise measurements during inhalation and exhalation of the patient (10).

19. The system according to any one of the preceding claims, wherein^ the second oxygen sensor is configured to measure a second series of oxygenconcentrations, and ^the second carbon dioxide sensor is configured to measure a second series ofcarbon dioxide concentrations within the membrane gas flow pathway (12) after oxygenation of the blood of thepatient in the extracorporeal membrane oxygenation device (4).

20. A method (300) for determining a total energy expenditure of a patient (10) connectedto an extracorporeal membrane oxygenation device and an mechanical ventilator (2),the method comprises the steps of: ^measuring (301) a first oxygen concentration within an inhalation andexhalation gas flow pathway (8) between the mechanical ventilator (2) and alung(s) of a patient (10),P6990PC00 30^ measuring (302) a first carbon dioxide concentration within the inhalation andexhalation gas flow pathway between the mechanical ventilator (2) and alung(s) of a patient (10),^ measuring (303) a first flow rate within the inhalation and exhalation gas flowpathway between the mechanical ventilator (2) and a lung(s) of a patient (10),and^ measuring (304) a second oxygen concentration within a membrane gas flowpathway (12) and / or at a membrane gas flow outlet of the oxygenation of theblood of the patient in the extracorporeal membrane oxygenation device,^ measuring (305) a second carbon dioxide concentration within the membranegas flow pathway of the oxygenation of the blood of the patient in theextracorporeal membrane oxygenation device,^ determining (306)^ a first oxygen consumption and a first carbon dioxide production of thepatient (10) through the mechanical ventilator (2),^ a second oxygen consumption and a second carbon dioxide productionof the patient (10) through the extracorporeal membrane oxygenationdevice, and ^determining a total energy expenditure based on the first oxygenconsumption and the first carbon dioxide production and the second oxygen consumption and the second carbon dioxide production.

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