Patient body temperature control during gas exchange therapy

Abstract

The present disclosure relates to methods for patient body temperature control during gas exchange therapy of a patient (3), such as extracorporeal membrane oxygenator [ECMO] therapy provided by an ECMO device (5) and / or respiratory therapy provided by a mechanical ventilator (7). The method comprises the steps of: determining that the gas exchange is at least one of a carbon dioxide [CO2] exchange and an oxygen [O2] exchange between the oxygen-containing gas and the blood of the patient (3); causing a temperature change in the patient (3); a change in the gas exchange following a change in the temperature of the patient (3) is detected, and the temperature of the patient (3) is automatically controlled on the basis of the detected change in the gas exchange, and / or a user is suggested with respect to a manual adjustment of the temperature of the patient (3) on the basis of the detected change in the gas exchange.

Description

Technical Field

[0001] The present disclosure relates to the field of critical care, and in particular to systems, methods, and computer programs for patient temperature control during extracorporeal membrane oxygenation (ECMO) therapy and / or mechanical ventilation. Background Art

[0002] Mechanical ventilators and medical devices for oxygenating and extracorporeally removing CO2 from human blood are well-known examples of critical care equipment used to provide ventilation support, and sometimes circulatory support, to patients with reduced lung function.

[0003] Mechanical ventilators are used to provide respiratory therapy to a patient by supplying oxygenated breathing gases to the patient's lungs, thereby allowing CO2 to be removed from and oxygen to be added to the patient's circulatory system through gas exchange within the lungs.

[0004] Historically, medical devices for removing CO2 from human blood outside the body are generally referred to as extracorporeal membrane oxygenation (ECMO) devices, which are mainly used to provide ventilation support and circulatory support to patients with reduced lung function and / or heart function when conventional treatment and minimally invasive treatment (such as mechanical ventilation) are insufficient. However, recently, combined treatment with ECMO devices and mechanical ventilators in the treatment of patients with less severe lung diseases has also gained increasing interest from clinicians.

[0005] In an ECMO device, carbon dioxide-rich blood is extracted from a patient and provided to an oxygenator that acts as an artificial lung by removing CO2 and adding oxygen to the blood, and then returns the oxygen-rich blood to the patient's circulatory system. The removal of CO2 and the addition of oxygen are achieved by sweeping a flow of oxygen-containing purge gas through the oxygenator, so that gas exchange between the blood and the purge gas occurs across the oxygenator membrane.

[0006] During ECMO therapy, the blood in the extracorporeal circuit is heated to compensate for the energy lost due to the extracorporeal circulation of the blood. If clinicians do not handle this carefully, the external heating can actually override the patient's own temperature control.

[0007] It is common practice to manually adjust the heating of the blood returning to the patient in order to keep the patient at normal body temperature, ie approximately 37 degrees Celsius.

[0008] In patients who are receiving artificial external heating, it is difficult to detect and discern when a patient has a fever because the body temperature is controlled. When a patient has a fever, the patient's body temperature set point moves upward, and the physiology responds with an increase in metabolic rate in order to raise the actual body temperature. This is sometimes seen as shivering and muscle activity. The perception of a cold (which everyone experiences at the onset of a fever) is also associated with a significant level of discomfort.

[0009] For patients who do not have margin for gas exchange even during rest, any increase in metabolic demand from stress, anxiety, or activity (such as tremor) may cause increased demands on the cardiovascular and pulmonary systems and discomfort / panic in a vicious cycle due to the inability of the cardiovascular and pulmonary systems to compensate for the increased metabolic demand.

[0010] In a similar manner, when a patient stops having a fever, the patient's body temperature set point moves downward, and the physiology responds with a reduction in metabolic rate in order to reduce the actual body temperature. This is sometimes associated with sweating. The perception of being too hot is also associated with a significant level of discomfort. Summary of the invention

[0011] An object of the present disclosure is to propose methods, computer programs and systems for solving or alleviating one or more of the above mentioned problems associated with the prior art.

[0012] It is a particular object of the present disclosure to propose methods, computer programs and systems for improved patient temperature control during gas exchange therapy, such as extracorporeal membrane oxygenation (ECMO) therapy and / or mechanical ventilation.

[0013] These and other objects that will become hereinafter apparent in view of the following detailed description are achieved according to the system, method and computer program as defined in the appended claims.

[0014] According to a first aspect of the present disclosure, a method for controlling the body temperature of a patient during gas exchange therapy, such as ECMO therapy provided by an ECMO device and / or respiratory therapy provided by a mechanical ventilator, is provided. The method comprises the following steps:

[0015] - determining that the gas exchange is at least one of carbon dioxide (CO2) exchange and oxygen (O2) exchange between the oxygen-containing gas and the patient's blood;

[0016] - Cause temperature changes in the patient;

[0017] - Detect changes in gas exchange following changes in the patient's temperature, and

[0018] - automatically controlling the patient's temperature based on detected changes in gas exchange, and / or

[0019] - Proposing to the user a manual control of the patient's temperature based on the detected changes in gas exchange.

[0020] Therefore, the present disclosure proposes a strategy to incorporate changes in the patient's temperature in order to assess whether the patient's current temperature is the optimal temperature based on changes in gas exchange caused by changes in the patient's temperature. For example, if gas exchange decreases in response to changes in the patient's temperature, then the new temperature may be a more optimal temperature and should be maintained, or the temperature should be further adjusted in the direction of the temperature change. The temperature can then be controlled accordingly, and / or a recommendation can be made to the clinician regarding manual patient temperature control.

[0021] According to some embodiments, the method comprises the following steps:

[0022] - detecting a decrease in gas exchange following a temperature change of the patient from an original patient temperature to a new patient temperature, and

[0023] - in response to detecting a reduction in gas exchange, automatically controlling the temperature of the patient such that the temperature of the patient is maintained at the new temperature or is further adjusted in the direction of the induced temperature change, and / or

[0024] - In response to detecting a decrease in gas exchange, making a recommendation to manually adjust the patient's temperature in the direction of the induced temperature change.

[0025] According to some embodiments, the method comprises the following steps:

[0026] - detecting an increase in gas exchange following a change in temperature of the patient from an original patient temperature to a new patient temperature, and

[0027] - in response to detecting an increase in gas exchange, automatically controlling the temperature of the patient such that the temperature of the patient is maintained at the original temperature or is further adjusted in the opposite direction of the induced temperature change, and / or

[0028] - In response to detecting an increase in gas exchange, making a recommendation to manually adjust the patient's temperature in the opposite direction of the induced temperature change.

[0029] According to some embodiments, the method comprises the following steps:

[0030] - obtain the patient's temperature, and

[0031] - automatically controlling the patient's temperature based on both detected changes in gas exchange and the patient's body temperature, and / or

[0032] - Based on both the detected changes in gas exchange and the patient's body temperature, making recommendations to the user regarding manual control of the patient's temperature.

[0033] According to some embodiments, the gas exchange therapy includes ECMO therapy provided by an ECMO device, and the step of causing a change in the patient's temperature and / or the step of automatically adjusting the patient's temperature involves adjusting the temperature of the blood flow recirculated back to the patient after gas exchange between the extracorporeal blood flow and a purge gas flow on the oxygenator.

[0034] According to another aspect of the present disclosure, a computer program for patient temperature control during gas exchange therapy of a patient is provided. The computer program comprises computer readable instructions which, when executed by a control computer, cause the steps of the method described above to be performed.

[0035] According to another aspect of the present disclosure, a computer program product is provided, comprising a data storage medium, such as a non-transitory storage hardware device, storing the above-mentioned computer program for patient temperature control during gas exchange therapy of the patient.

[0036] According to another aspect of the present disclosure, a system for controlling the body temperature of a patient during gas exchange therapy of the patient is provided. The system includes at least one control computer configured to:

[0037] - determining that the gas exchange is at least one of CO2 exchange and O2 exchange between the oxygen-containing gas and the patient's blood;

[0038] - Cause temperature changes in the patient;

[0039] - Detect changes in gas exchange following changes in the patient's temperature, and

[0040] - automatically controlling the patient's temperature based on detected changes in gas exchange, and / or

[0041] - Proposing to the user manual control of the patient's temperature based on detected changes in gas exchange.

[0042] According to some embodiments, the control computer is configured to:

[0043] - detecting a decrease in gas exchange following a temperature change of the patient from an original patient temperature to a new patient temperature, and

[0044] - in response to detecting a reduction in gas exchange, automatically controlling the temperature of the patient such that the temperature of the patient is maintained at the new temperature or is further adjusted in the direction of the induced temperature change, and / or

[0045] - In response to detecting a decrease in gas exchange, making a recommendation to manually adjust the patient's temperature in the direction of the induced temperature change.

[0046] According to some embodiments, the control computer is configured to:

[0047] - detecting an increase in gas exchange following a change in temperature of the patient from an original patient temperature to a new patient temperature, and

[0048] - in response to detecting an increase in gas exchange, automatically controlling the temperature of the patient such that the temperature of the patient is maintained at the original temperature or is further adjusted in the opposite direction of the induced temperature change, and / or

[0049] - In response to detecting an increase in gas exchange, making a recommendation to manually adjust the patient's temperature in the opposite direction of the induced temperature change.

[0050] According to some embodiments, the control computer is configured to:

[0051] - obtain the patient's temperature, and

[0052] - automatically controlling the patient's temperature based on both detected changes in gas exchange and the patient's body temperature, and / or

[0053] - Proposing to the user manual control of the patient's temperature based on both the detected changes in gas exchange and the patient's body temperature.

[0054] According to some embodiments, the system includes an ECMO device, and the control computer is configured to cause a temperature change in the patient and / or automatically adjust the temperature of the patient by causing an adjustment in the temperature of the blood flow recirculated back to the patient after a gas exchange between the extracorporeal blood flow and a purge gas flow on the oxygenator.

[0055] In the following, more advantageous features of the method, computer program and system of the present disclosure will be described in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention will be more fully understood through the detailed description provided hereinafter and the accompanying drawings, which are given by way of non-limiting illustration only. In the different drawings, the same reference numerals correspond to the same elements.

[0057] Figure 1 An exemplary non-limiting embodiment of an ECMO ventilation system for extracorporeal removal of CO 2 from the blood of a patient undergoing mechanical ventilation is shown.

[0058] Figure 2 Shows Figure 1 An exemplary non-limiting embodiment of an ECM device for an ECMO ventilation system in.

[0059] Figure 3 is a flow chart illustrating an exemplary, non-limiting embodiment of a method for gas exchange determination.

[0060] Figure 4 An exemplary non-limiting embodiment of a mechanical ventilation system is shown. DETAILED DESCRIPTION

[0061] The present disclosure relates to the field of extracorporeal blood gas exchange using an oxygenator for extracorporeal removal of carbon dioxide (CO2) from a patient's blood. In particular, the present disclosure relates to methods, computer programs and systems for improved control of CO2 removal by an oxygenator by adding CO2 to a purge gas flow passing through the oxygenator.

[0062] The present invention will be described below in the context of a combined system for extracorporeal blood gas exchange via an extracorporeal membrane oxygenator (ECMO) during lung protective ventilation of a patient using a mechanical ventilator. Such a combined system including both an ECMO device and a mechanical ventilator will be referred to herein as an ECMO ventilation system. However, it should be understood that the principles of the present disclosure are equally applicable to an independent ECMO device and an independent mechanical ventilator.

[0063] Figure 1 A system 1 for combined mechanical ventilation of the lungs of a patient 3 and for extracorporeal removal of CO2 from the blood of the patient 3 is shown. The system 1 will be referred to hereinafter as the ECMO ventilation system. ECMO (extracorporeal membrane oxygenation) is one of several terms used for extracorporeal blood gas exchange, in which blood is pumped outside the body of the patient being treated to a device sometimes called a heart-lung machine, which removes CO2 and returns oxygen-rich blood to the patient. Other terms often used in the art for the same or similar treatments are ECLA (extracorporeal lung assist), ECCO2R (extracorporeal removal of CO2), ECLS (extracorporeal life support), and ECGE (extracorporeal membrane gas exchange), all of which are included in the term ECMO as used herein.

[0064] The ECMO ventilation system 1 includes an apparatus 5 for extracorporeally removing CO 2 from the blood of a patient 3 (hereinafter referred to as an ECMO apparatus) and a mechanical ventilator 7 for mechanically ventilating the patient 3 by supplying breathing gas to the patient's lungs.

[0065] The ventilator 7 comprises or is connected to a source of pressurized breathing gas (not shown), which is supplied to the patient 3 via a patient circuit 9. In this example, the patient circuit 9 comprises an inspiratory line 11 for delivering a flow of breathing gas to the patient 3 and an expiratory line 13 for delivering a flow of expiratory gas exhaled by the patient away from the patient. The inspiratory line 11 and the expiratory line 13 are connected to each other via a so-called Y-piece 15, which in turn is connected to the patient 3 via a common line 17.

[0066] The ECMO device 5 is configured to: provide ECMO therapy to patient 3 by generating an extracorporeal blood flow from patient 3; oxygenate the blood through extracorporeal blood gas exchange in which CO2 is removed from the extracorporeal blood flow and oxygen (O2) is added to the extracorporeal blood flow; and return the oxygen-rich blood to patient 3.

[0067] In order to generate blood flow to and from the patient 3, the ECMO device 5 may include a blood flow generator (not shown), typically in the form of one or several rollers, turbines and / or centrifugal pumps. The blood flow generator generates blood flow through a tubing system forming a blood flow channel 19 of the ECMO device 5, where parts of the channel may be heated and / or cooled to maintain a desired temperature of the blood when the blood returns to the patient 3.

[0068] Blood gas exchange including blood oxygenation and CO2 removal occurs in the membrane oxygenator 21 of the ECMO device 5, in which a purge gas flow containing oxygen interacts with the blood in the blood flow channel 19 via a membrane 23 of the oxygenator 21. The membrane 23 acts as a gas-liquid barrier capable of transferring CO2 and O2 content between the blood flow flowing through the oxygenator 21 on the liquid side of the membrane 23 and the purge gas flow flowing through the oxygenator 21 on the gas side of the membrane 23.

[0069] The purge gas flow is generated by a purge gas generator 25 connected to one or more purge gas sources, which typically include one or both of an oxygen source and a compressed air source. According to the principles of the present disclosure, the purge gas generator 25 is also connected to a CO2 source so as to control the degree of CO2 removal on the oxygenator 21 by adding CO2 to the purge gas flow. The purge gas generator 23 is configured to deliver a controllable purge gas composition to the oxygenator 21 at a controllable purge gas flow rate.

[0070] The composition and optionally the flow rate of the purge gas generated by the purge gas generator 23 may be automatically controlled by a controller or control computer 27 of the ECMO apparatus 5 based on set target values ​​and sensor data obtained by various sensors 29, 31 of the ECMO apparatus 5. In particular, the control computer 27 of the ECMO apparatus 5 may be configured to automatically control the addition of CO2 to a purge gas flow comprising either or both of oxygen and air based on a set target for measurement of CO2 removal by the oxygenator 21.

[0071] In the following, the purge gas flow upstream of the oxygenator 21 (i.e., before the oxygenator from the perspective of the purge gas) will be referred to as the input purge gas flow or the pre-oxygenator purge gas flow, and the purge gas flow downstream of the oxygenator 21 (i.e., after the oxygenator from the perspective of the purge gas) will be referred to as the output purge gas flow or the post-oxygenator purge gas flow. The input purge gas flow flows from the purge gas generator 25 to the oxygenator 21 via the purge gas inlet line 33a of the ECMO device 5, and the output purge gas flow flows from the oxygenator 21 to the atmosphere or to an evacuation or recirculation system via the purge gas outlet line 33b. In most configurations, the ECMO system is an open system, which means that the post-oxygenator purge gas flow is allowed to escape to the environment. In some cases, especially when anesthetic agents are added to the purge gas flow, a closed or semi-closed (purge) gas control system can be envisioned, similar to the gas control systems commonly used in anesthesia machines.

[0072] Likewise, the blood flow upstream of the oxygenator 21 (i.e., before the oxygenator from the perspective of blood flow) may be referred to as the input blood flow or the pre-oxygenator blood flow hereinafter, and the blood flow downstream of the oxygenator 21 (i.e., after the oxygenator from the perspective of blood flow) may be referred to as the output blood flow or the post-oxygenator blood flow. The input blood flow flows from the patient 3 to the oxygenator 21 via the blood flow inlet line 19a of the ECMO device 5, and the output blood flow flows from the oxygenator 21 and returns to the patient 3 via the blood flow outlet line 19b of the ECMO device 5.

[0073] Now refer to Figure 2 , the sensors 29, 31 of the ECMO device 5 may include:

[0074] - A pre-oxygenator flow rate sensor 29a, which is used to measure the input purge gas flow The pre-oxygenator flow rate sensor 29a is a mainstream flow sensor, which means that it is configured to measure the flow rate of the purge gas flowing in the purge gas inlet line 33a. The pre-oxygenator flow measurement value obtained by the pre-oxygenator flow rate sensor 29a occurs at the pre-oxygenator flow measurement point indicated as P1 in the purge gas inlet line 33a.

[0075] - a pre-oxygenator gas analyzer 29b for measuring at least the fraction FCO2 of CO2 in the input purge gas flow in . The pre-oxygenator gas analyzer 29b may also be configured to measure the fraction of one or more additional gases selected from the group consisting of oxygen (O2), nitrogen (N2), and anesthetic agents. In this exemplary embodiment, the pre-oxygenator gas analyzer 29b is a so-called sidestream gas analyzer configured to extract a purge gas sample from the purge gas inlet line 33a and measure the fraction of CO2 and, optionally, the fraction of at least one additional gas in the purge gas sample at a pre-oxygenator CO2 measurement point denoted as P2. The pre-oxygenator CO2 measurement point P2 is separated in distance from the pre-oxygenator purge gas flow rate measurement point P1 by at least the length of the pre-oxygenator sample line 34a. In other embodiments, the pre-oxygenator gas analyzer 29b may be a so-called mainstream gas analyzer configured to measure the fraction of CO2 and, optionally, the fraction of at least one additional gas within the purge gas inlet line 33a. In some embodiments, the pre-oxygenator gas analyzer includes at least a CO2 sensor and an O2 sensor for measuring the fraction of CO2 and O2 in the purge gas sample, respectively. In some embodiments, the CO2 sensor is a non-dispersive infrared (NDIR) CO2 sensor. In some embodiments, the O2 sensor is a paramagnetic or electrochemical O2 sensor.

[0076] - a pre-oxygenator temperature sensor 29c, which is used to measure the temperature T of the input purge gas in,gas .

[0077] a pressure sensor 29d for measuring a purge gas circuit pressure P which corresponds substantially to the purge gas pressure in the gas inlet line 33a gas .

[0078] - A post-oxygenator flow rate sensor 31a, which is used to measure the flow rate of the output purge gas flow The post-oxygenator flow rate sensor 31a is a mainstream flow sensor, which means that it is configured to measure the flow rate of the purge gas flowing in the purge gas outlet line 33b. The post-oxygenator flow measurement obtained by the post-oxygenator flow rate sensor 31a occurs at a post-oxygenator flow measurement point denoted as P3 in the purge gas outlet line 33b.

[0079] - a post-oxygenator gas analyzer 31b for measuring at least the fraction FCO2 of CO2 in the output purge gas flow out. The post-oxygenator gas analyzer 31b may also be configured to measure the fraction of one or more additional gases selected from the group consisting of oxygen (O2), nitrogen (N2) and anesthetic agents. In this exemplary embodiment, the post-oxygenator gas analyzer 31b is a so-called sidestream gas analyzer configured to extract a purge gas sample from the purge gas outlet line 33b and measure the fraction of CO2 and, optionally, the fraction of at least one additional gas in the purge gas sample at a post-oxygenator CO2 measurement point denoted as P4. The post-oxygenator CO2 measurement point P4 is separated in distance from the post-oxygenator purge gas flow rate measurement point P3 by at least the length of the post-oxygenator sample line 34b. In other embodiments, the post-oxygenator gas analyzer 31b may be a so-called mainstream gas analyzer configured to measure the fraction of CO2 and, optionally, the fraction of at least one additional gas within the purge gas outlet line 33b. In some embodiments, the post-oxygenator gas analyzer includes at least a CO2 sensor and an O2 sensor for measuring the fraction of CO2 and O2, respectively, in the purge gas sample. In some embodiments, the CO2 sensor is an IR spectrometer for IR spectroscopy, such as IR absorption spectroscopy. In some embodiments, the O2 sensor is a paramagnetic O2 sensor.

[0080] - A post-oxygenator temperature sensor 31c for measuring the temperature of the output purge gas.

[0081] In some embodiments, the ECMO device 5 may also include or be connected to a device for measuring the partial pressure PCO2 of at least CO2 in the input blood flow. in The pre-oxygenator blood gas analyzer 32 can also be configured to measure the partial pressure PO2 of O2 in the input blood flow. in The pre-oxygenator blood gas analyzer 32 may also be configured to measure the hemoglobin content Hb in the input blood stream. in In some embodiments, the blood gas analyzer 32 is not incorporated into the ECMO apparatus 5, but is arranged to form part of another medical device connected to the ECMO apparatus 5 so that the ECMO apparatus 5 receives measurements obtained by the blood gas analyzer. For example, the blood gas analyzer may form part of a stand-alone blood gas analyzer unit, commonly referred to as a BGA, which is typically used for intermittent blood gas analysis during ECMO therapy.

[0082] In accordance with the principles of the present disclosure, ECMO device 5 and / or mechanical ventilator 7 may include functionality for patient temperature control during gas exchange therapy of patient 3 .

[0083] In some embodiments, the control computer 27 is configured to:

[0084] - determining that the gas exchange is at least one of a CO2 exchange and an O2 exchange between the oxygen-containing gas and the blood of the patient 3;

[0085] - inducing a temperature change in the patient 3 to assess any changes in gas exchange that occur in response to the temperature change;

[0086] - detecting changes in gas exchange following changes in temperature of the patient 3, and

[0087] - automatically controlling the temperature of the patient 3 based on detected changes in gas exchange, and / or

[0088] - Proposing to a user, such as a clinician or operator of the ECMO device 5 and / or the mechanical ventilator 7, a manual control of the temperature of the patient 3 based on the detected changes in gas exchange.

[0089] Therefore, the present disclosure proposes a strategy for incorporating a change in the patient's temperature in order to assess whether the patient's current temperature is an optimal temperature based on the change in gas exchange caused by the change in the patient's temperature. For example, if gas exchange (e.g., total gas exchange of CO2 elimination and O2 uptake, or O2 uptake by patient 3) decreases in response to a change in the patient's temperature, then the new temperature (after the change) may be a more optimal temperature and should be maintained, or the temperature should be further adjusted in the direction of the temperature change. The control computer 27 can then control the temperature accordingly and / or, for example, make a recommendation to the clinician on a monitor of the system regarding manual patient temperature control.

[0090] Thus, gas exchange is typically one of the patient's 3 O2 uptake and the patient's 3 total gas exchange of CO2 elimination and O2 uptake.

[0091] The metabolic rate that changes with body temperature has a local minimum at the patient's optimal body temperature or near the optimal body temperature, which can depend on the patient's physiological state. The optimal body temperature of healthy humans is usually in the range of 36 degrees Celsius to 38 degrees Celsius. More specifically, according to, for example, age, time of day, individual differences and the way to measure temperature, the optimal body temperature of healthy humans is usually in the range of 36.1 degrees Celsius to 37.8 degrees Celsius. On both sides of the local minimum at the optimal body temperature or near the optimal body temperature, in the range that can be called the normal body temperature range, the body reacts to temperature changes by increasing metabolic rate and increasing O2 intake. This means that, within the normal body temperature range, if the patient has a body temperature higher than the optimal body temperature, the body increases metabolic rate in response to a further increase in body temperature, and reduces metabolic rate in response to a reduction in body temperature. Similarly, if within the normal body temperature range, the patient has a body temperature lower than the optimal body temperature, the body increases metabolic rate in response to a further reduction in body temperature, and reduces metabolic rate in response to an increase in body temperature. Thus, within the normal body temperature range, a decrease in gas exchange in response to a temperature change (indicating a reduced metabolic rate) indicates that the temperature change has brought the patient's body temperature closer to the patient's optimal body temperature, and therefore the new temperature should be maintained or further changed in the same direction. In this context, the normal body temperature range is generally about 35 degrees Celsius to 41 degrees Celsius.

[0092] On the other hand, when the body temperature is outside the normal temperature range, such as in the case of a patient suffering from hypothermia or hyperthermia, the body's ability to regulate temperature and oxygen uptake is generally impaired. In these abnormal hypothermic and hyperthermic temperature ranges, the body's response to temperature changes is somewhat different. For example, in the hypothermic temperature range (i.e., a temperature range below the normal temperature range), a further decrease in temperature results in a decrease in metabolic rate, while an increase in temperature results in an increase in metabolic rate.

[0093] Considering the above, it may be important to know the patient's body temperature in order to understand how to interpret the response of gas exchange to temperature changes.

[0094] Thus, in some embodiments, the control computer 27 may be configured to:

[0095] - Obtaining the temperature of patient 3;

[0096] - inducing a temperature change in the patient 3 to assess any changes in gas exchange that occur in response to the temperature change;

[0097] - detecting changes in gas exchange following changes in temperature of the patient 3, and

[0098] - automatically controlling the temperature of the patient 3 based on detected changes in gas exchange and the body temperature of the patient 3, and / or

[0099] - Proposing to a user, such as a clinician or operator of the ECMO device 5 and / or the mechanical ventilator 7, a recommendation regarding manual control of the temperature of the patient 3 based on both the detected changes in gas exchange and the patient's body temperature.

[0100] The temperature may be the original temperature of the patient before the temperature change, or the temperature may be the temperature of the patient after the temperature change. The temperature, temperature changes, and gas exchange response to the temperature change may be used by the control computer 27 to identify where along the temperature metabolic rate curve the patient's temperature is, and therefore whether the patient's temperature should be maintained, increased, or decreased.

[0101] However, in most cases, it can be assumed that the patient's body temperature is within the normal body temperature range, and thus the control computer 27 can be configured to:

[0102] - detecting a decrease in gas exchange following a temperature change of patient 3 from an original patient temperature to a new patient temperature, and

[0103] - in response to detecting a reduction in gas exchange, automatically controlling the temperature of the patient 3 such that the temperature of the patient 3 is maintained at the new temperature or is further adjusted in the direction of the induced temperature change, and / or

[0104] - In response to detecting a decrease in gas exchange, making a recommendation to manually adjust the temperature of the patient 3 in the direction of the induced temperature change.

[0105] Likewise, the control computer 27 may be configured to:

[0106] - detecting an increase in gas exchange following a temperature change of patient 3 from an original patient temperature to a new patient temperature, and

[0107] - in response to detecting an increase in gas exchange, automatically controlling the temperature of the patient 3 such that the temperature of the patient 3 is maintained at the original temperature or is further adjusted in the opposite direction of the induced temperature change, and / or

[0108] - In response to detecting a reduction in gas exchange, making a recommendation to manually adjust the temperature of the patient 3 in the opposite direction of the induced temperature change.

[0109] In some embodiments, the control computer 27 can be configured to determine whether the patient's body temperature is within the normal body temperature range based on the obtained body temperature of the patient 3, and only respond to the reduction or increase of gas exchange in the manner described above if the patient's body temperature is within the normal body temperature range.

[0110] In some embodiments, the control computer 27 can be configured to determine that the patient's body temperature is within the hypothermic body temperature range based on the obtained body temperature of the patient 3, and increase the body temperature until it falls within the normal body temperature range.

[0111] Likewise, in some embodiments, the control computer 27 may be configured to determine, based on the obtained body temperature of the patient 3, that the patient's body temperature is within the hyperthermia range, and to lower the body temperature until it falls within the normal body temperature range.

[0112] Thus, the control computer 27 of the present disclosure is configured to detect the response of gas exchange to the induced temperature changes and, based on the response, to change the patient's body temperature so as to push the patient's body temperature in the direction of the patient's optimal body temperature, which corresponds to a local minimum in metabolic rate as it varies with body temperature.

[0113] In embodiments where the gas exchange therapy includes ECMO therapy provided by the ECMO device 5, the control computer 27 can be configured to cause a temperature change in the patient 3 and / or automatically adjust the body temperature of the patient 3 by adjusting the temperature of the blood flow recirculated back to the patient 3 after gas exchange between the extracorporeal blood flow and the purge gas flow on the oxygenator 21.

[0114] The temperature change may be either an increase or a decrease in temperature.

[0115] Monitored changes in gas exchange can also be used for other purposes besides immediate temperature control. For example, the control computer 27 can be configured to predict future changes in the patient's temperature based on current changes in gas exchange. If metabolic demand changes in an otherwise stable patient, the change may be an indication of a fever and an impending infection, or other changes in the patient's clinical state. Therefore, changes in gas exchange that are indicative of future changes in the patient's body temperature can be used to predict changes in the patient's clinical state, thereby enabling the clinician to take preventive measures and administer appropriate treatment to the patient.

[0116] To assist the clinician in this regard, the control computer 27 may be configured to:

[0117] - monitoring gas exchange is at least one of CO2 exchange and O2 exchange between the oxygen-containing gas and the blood of the patient 3;

[0118] - detect changes in gas exchange,

[0119] - predicting future changes in the patient's temperature based on the detected changes in gas exchange, and

[0120] - providing information to the user regarding the predicted change in the patient's temperature, and / or

[0121] - automatically adjusting ongoing treatment of patient 3 based on predicted changes in patient temperature, and / or

[0122] - As described above, the user is advised on executing a strategy involving inducing a temperature change in the patient and monitoring a response of gas exchange.

[0123] CO2 exchange and / or O2 exchange can be determined using any known technique for determining CO2 and O2 exchange. There are many known techniques for determining CO2 elimination and O2 uptake in a patient connected, for example, to an ECMO device and / or a mechanical ventilator.

[0124] For example, Figure 3 As shown in the flowchart in FIG. , CO2 exchange on the oxygenator 21 of the ECMO device 5 can be performed by using a net CO2 exchange The calculation method is determined, including the following steps:

[0125] S1) For example, the pre-oxygenator fraction (FCO2) of CO2 in the purge gas flow upstream of the oxygenator 21 is measured by means of the pre-oxygenator gas analyzer 29b. in );

[0126] S2) For example, by means of the pre-oxygenator flow rate sensor 29a, the pre-oxygenator purge gas flow rate of the purge gas flow upstream of the oxygenator 21 is measured.

[0127] S3) For example, the post-oxygenator fraction (FCO2) of CO2 in the purge gas flow downstream of the oxygenator 21 is measured by means of the post-oxygenator gas analyzer 31b. out );

[0128] S) For example, by measuring the post-oxygenator purge gas flow rate of the purge gas flow downstream of the oxygenator 21 with the aid of the post-oxygenator flow rate sensor 31a as well as

[0129] S5) Based on the measured FCO2 in , FCO2 out as well as Calculate the membrane 23

[0130]

[0131] Since the pre-oxygenator gas analyzer 29b and the post-oxygenator gas analyzer 31b are configured for both CO2 measurement and O2 measurement, the same principle can be used to measure O2 exchange on the oxygenator 21. The functionality for determining gas exchange on the oxygenator 21 can exist in the ECMO device 5 or in another device to which the ECMO device 5 is connected.

[0132] Figure 4 A more detailed view of the mechanical ventilator 7 included in the ventilation system 100 is shown. The ventilation system 100 comprises a device configured for mainstream capnography and arranged to measure the fraction of carbon dioxide (FCO2 main )'s first gas analyzer 103.

[0133] The first gas analyzer 103 is a capnometer arranged for mainstream (i.e., non-steered) capnography, which means that the capnometer is configured to measure CO2 at a sample location. The first gas analyzer 103 is typically positioned at or near the airway of the patient 3. For example, the first gas analyzer 103 can be positioned in the common line 17 of the breathing circuit 9, very close to the Y-piece 15. The first gas analyzer 103 is configured to measure at least the fraction of CO2 in the exhaled gas exhaled by the patient 3. Typically, the first gas analyzer 103 is configured to measure the fraction of CO2 also in the respiratory gas inhaled by the patient 3.

[0134] The system may also include at least one second gas analyzer 105. The at least one second gas analyzer 105 may include an O2 sensor for measuring the fraction of O2 in exhaled gas exhaled by the patient, which measurement may be used with flow measurements and / or information about ventilator minute ventilation to determine a measure of O2 uptake in the lungs of a ventilated patient.

[0135] In this exemplary embodiment, at least one second gas analyzer 105 is configured to measure the fraction of CO2 and the fraction of O2 in exhaled gas exhaled by the patient 3. The second CO2 measurement (the first CO2 measurement being obtained by the first gas analyzer 103) can be used to determine a second measure of CO2 elimination of the patient, which can be compared to the first measure of CO2 elimination determined from mainstream capnography measurements obtained by the first gas analyzer 103 in order to verify or compensate for the measure of O2 uptake determined from the O2 measurement obtained by the second gas analyzer 105.

[0136] The at least one second gas analyzer 105 can be a single multi-gas analyzer for measuring both CO2 and O2, or the at least one second gas analyzer 105 can be two separate gas analyzers for measuring CO2 and O2, respectively. In one example, the at least one second gas analyzer 105 is a single gas analyzer including a non-dispersive infrared (NDIR) CO2 sensor for CO2 measurement and a paramagnetic or electrochemical O2 sensor for O2 measurement. The at least one second gas analyzer 105 is different from the first gas analyzer 103. As will be discussed in more detail below, for example, the at least one second gas analyzer 105 can be arranged to measure CO2 and O2 in exhaled gas mixed in a mixing chamber coupled to the exhalation line 13, or a sidestream gas analyzer arranged to sample exhaled gas from, for example, a common line 17.

[0137] The control computer 27' may be integrated into the ventilator 7, or the control computer 27' may be a stand-alone computer or a computer of any other device to which the ventilator 7 is connected. The control computer 27' is coupled to the ventilator 7, the first gas analyzer 103 and the at least one second gas analyzer 105, and is configured to receive measurements obtained by the first gas analyzer 103 and the at least one second gas analyzer 105, as well as various ventilation-related data including current ventilator settings and sensor data obtained by other sensors (not shown) of the ventilation system 1. Among other things, the ventilation-related data may include data regarding a set fraction of inspired O2 (FiO2), a set or measured minute ventilation, and flow measurements obtained by various flow sensors of the ventilation system 1, which data may be used by the control computer 27' together with the CO2 and O2 measurements in calculations of CO2 elimination and O2 uptake.

[0138] The control computer 27' is configured to determine a first measure of carbon dioxide elimination of the patient 3 based on the CO2 measurement obtained by the first gas analyzer 103. This can be achieved by the control computer 27 by integrating the continuously measured or estimated flow of exhaled gas through the mainstream gas analyzer 105 with the continuously measured fraction of CO2 in the exhaled gas flowing through the mainstream gas analyzer 105.

[0139] The control computer 27 is further configured to determine a second measure of CO 2 elimination by the patient 3 , and a measure of O 2 uptake by the patient 3 , based on the measurements obtained by the at least one second gas analyzer 105 .

[0140] The above examples are merely examples of how CO 2 elimination and O 2 uptake in the ECMO oxygenator 21 and the patient's lungs may be determined, and the present disclosure is not limited to any particular manner of doing so.

Claims

1. A method for controlling the body temperature of a patient (3) during gas exchange therapy, such as extracorporeal membrane oxygenation [ECMO] therapy provided by an ECMO device (5) and / or respiratory therapy provided by a mechanical ventilator (7), comprising the following steps: - determining that the gas exchange is at least one of carbon dioxide [CO2] exchange and oxygen [O2] exchange between the oxygen-containing gas and the blood of the patient (3); - causing a temperature change in the patient (3); - detecting changes in gas exchange following changes in temperature of the patient (3), and - automatically controlling the temperature of the patient (3) based on detected changes in gas exchange, and / or - Proposing to the user a manual control of the temperature of the patient (3) based on the detected changes in gas exchange.

2. The method according to claim 1, comprising the steps of: - detecting a decrease in gas exchange following a temperature change of the patient (3) from an original patient temperature to a new patient temperature, and - in response to detecting a reduction in gas exchange, automatically controlling the temperature of the patient (3) such that the temperature of the patient (3) is maintained at a new temperature or is further adjusted in the direction of the induced temperature change, and / or - in response to detecting a reduction in gas exchange, making a recommendation to manually adjust the temperature of the patient (3) in the direction of the induced temperature change.

3. The method according to claim 1, comprising the steps of: - detecting an increase in gas exchange following a temperature change of the patient (3) from an original patient temperature to a new patient temperature, and - in response to detecting an increase in gas exchange, automatically controlling the temperature of the patient (3) such that the temperature of the patient (3) is maintained at the original temperature or is further adjusted in the opposite direction of the induced temperature change, and / or - In response to detecting an increase in gas exchange, making a recommendation to manually adjust the temperature of the patient (3) in the opposite direction of the induced temperature change.

4. The method according to any one of claims 1 to 3, comprising the following steps: - obtaining the body temperature of the patient (3), and - automatically controlling the temperature of the patient (3) based on both the detected changes in gas exchange and the body temperature of the patient (3), and / or - Proposing to the user a recommendation regarding manual control of the temperature of the patient (3), wherein the recommendation is based both on the detected changes in gas exchange and on the patient's body temperature.

5. A method according to any one of the preceding claims, wherein: The gas exchange therapy comprises extracorporeal membrane oxygenator [ECMO] therapy provided by an ECMO device (5), and wherein the step of causing a change in the temperature of the patient (3) and / or the step of automatically regulating the temperature of the patient (3) involves regulating the temperature of the blood flow recirculated back to the patient (3) after gas exchange between the extracorporeal blood flow and a purge gas flow on an oxygenator (21).

6. A computer program for patient temperature control during gas exchange therapy of a patient (3), the computer program comprising computer readable instructions which, when executed by a control computer (27, 27'), cause the method according to any of the preceding claims to be performed.

7. A computer program product comprising a non-volatile memory hardware device (39) storing a computer program for patient temperature control during gas exchange therapy of a patient (3), the computer program comprising computer readable instructions which, when executed by a control computer (27; 27'), causes the method according to any one of claims 1 to 5 to be performed.

8. A system (1; 100) for patient temperature control during gas exchange therapy of a patient (3), comprising at least one control computer (27, 27'), the at least one control computer (27, 27') being configured to: - determining that the gas exchange is at least one of carbon dioxide [CO2] exchange and oxygen [O2] exchange between the oxygen-containing gas and the blood of the patient (3); - causing a temperature change in the patient (3); - detecting changes in gas exchange following changes in temperature of the patient (3), and - automatically controlling the temperature of the patient (3) based on detected changes in gas exchange, and / or - Proposing to the user a manual control of the temperature of the patient (3) based on the detected changes in gas exchange.

9. System (1; 100) according to claim 8, wherein: The control computer (27, 27') is configured to: - detecting a decrease in gas exchange following a temperature change of the patient (3) from an original patient temperature to a new patient temperature, and - in response to detecting a reduction in gas exchange, automatically controlling the temperature of the patient (3) such that the temperature of the patient (3) is maintained at a new temperature or is further adjusted in the direction of the induced temperature change, and / or - in response to detecting a reduction in gas exchange, making a recommendation to manually adjust the temperature of the patient (3) in the direction of the induced temperature change.

10. The system (1; 100) according to claim 8, wherein: The control computer (27, 27') is configured to: - detecting an increase in gas exchange following a temperature change of the patient (3) from an original patient temperature to a new patient temperature, and - in response to detecting an increase in gas exchange, automatically controlling the temperature of the patient (3) such that the temperature of the patient (3) is maintained at the original temperature or is further adjusted in the opposite direction of the induced temperature change, and / or - In response to detecting an increase in gas exchange, making a recommendation to manually adjust the temperature of the patient (3) in the opposite direction of the induced temperature change.

11. A system according to any one of claims 8 to 10, wherein: The control computer (27, 27') is configured to: - obtaining the body temperature of the patient (3), and - automatically controlling the temperature of the patient (3) based on both the detected changes in gas exchange and the body temperature of the patient (3), and / or - Proposing to the user a manual control of the temperature of the patient (3) based both on the detected changes in gas exchange and on the patient's body temperature.

12. The system (1; 100) according to any one of claims 8 to 11, wherein: The system comprises an ECMO device (5), and the control computer (27, 27') is configured to cause a change in the temperature of the patient (3) and / or automatically regulate the temperature of the patient (3) by causing regulation of the temperature of the blood flow recirculated back to the patient (3) after a gas exchange between the extracorporeal blood flow and a purge gas flow on an oxygenator (21).

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