CA-3024430-C - VENTILATION DEVICE FOR CARDIOPULMONARY RESUSCITATION WITH DISPLAY OF THE CO2 TREND

CA3024430CCA 3024430 CCA3024430 CCA 3024430CCA-3024430-C

Abstract

The invention relates to a respiratory assistance apparatus for providing a respiratory gas, such as air, to a patient during cardiopulmonary resuscitation (CPR) comprising a source (1) of breathing mixture, a means for measuring CO2 (4), and signal processing and control means (5). The signal processing and control means (5) are configured to process the CO2 content measurement signals corresponding to measurements made by the CO2 content measuring means (4) for a given period of time (dt) and extracting a plurality of CO2 content values, selecting the maximum value (Vmax) of CO2 content from said plurality of CO2 content values, repeating these steps to obtain a plurality of successive maximum CO2 content values (Vmax) measured over a time window (Ft) comprising several successive time periods (dt), calculating at least one average value (Vmoy) of CO2 content from the maximum values (Vmax) of CO2 content obtained over the time window (Ft), and transmit said at least one average value (Vmoy) of CO2 content to the graphical user interface (7) which displays it.

Inventors

Jean-Christophe Richard
Marceau RIGOLLOT
Bilal Badat

Assignees

AIR LIQUIDE MEDICAL SYSTEMS

Dates

Publication Date: 20260505
Application Date: 20181115
Priority Date: 20180111

Claims (1)

Claims 1. A respiratory support device for supplying respiratory gas to a patient during cardiopulmonary resuscitation (CPR) comprising: - a source (1) of respiratory gas for supplying respiratory gas to said patient during cardiopulmonary resuscitation (CPR), - CO2 content measurement means (4) for performing measurements of CO2 concentration produced by the patient, and providing CO2 content measurement signals to signal processing and control means (5), - the signal processing and control means (5) configured to process the CO2 content measurement signals from the CO2 content measurement means (4), and - at least one graphical user interface (7), characterized in that: - the signal processing and control means (5) are configured to: a) process the CO2 content measurement signals corresponding to measurements performed by the CO2 content measurement means (4) during a given time period (dt), and extract a plurality of CO2 content values, b) select the maximum value (Vmax) of CO2 content from said plurality of CO2 content values measured during said given time period (dt), c) repeat steps a) and b) to obtain several successive maximum values (Vmax) of CO2 content measured over a time window (Ft) comprising several successive time periods (dt), d) calculate at least one average value (Vmoy) of CO2 content from the maximum values (Vmax) of CO2 content obtained over the time window (Ft), and e) transmit said at least one average value (Vmoy) of CO2 content to the graphical user interface (7), and - the graphical user interface (7) is configured to display said at least one average value (Vmoy) of CO2 content. 2. Device according to claim 1, characterized in that the signal processing and control means (5) are configured to repeat steps a) to e) so as to obtain several successive average values (Vavg) of CO2 content calculated from maximum values (Vmax) of CO2 content obtained over successive time windows (Ft). 3. Device according to claim 1 or claim 2, characterized in that the signal processing and control means (5) are configured to repeat steps a) to e) so as to obtain several successive average values (Vavg) of CO2 content calculated from maximum values (Vmax) of CO2 content obtained over a sliding time window (Ft). 4. Device according to any one of claims 1 to 3, characterized in that the time window (Ft) is between 20 seconds and 10 minutes. 5. Device according to any one of claims 1 to 4, characterized in that the time window (Ft) is between 30 seconds and 5 minutes. 6. Device according to any one of claims 1 to 5, characterized in that the graphical user interface (7) is configured to display said at least one average value (Vavg) of CO2 content in the form of a graphical representation or a numerical value. 7. Device according to any one of claims 1 to 6, characterized in that the graphical user interface (7) is configured to display at least some of the successive average values (Vavg) of CO2 content calculated in the form of: - a curve formed by a succession of graphical symbols, each graphical symbol corresponding to one value among said at least one average value (Vavg) of CO2 content, - or a bar graph comprising several bars, each bar of said bar graph corresponding to one value among said at least one average value (Vavg) of CO2 content. 27. 8. Apparatus according to any one of claims 1 to 7, characterized in that the signal processing and control means (5) comprise at least one microprocessor. 9. Apparatus according to any one of claims 1 to 8, characterized in that the CO2 content measurement means (4) comprise a capnometer. 10. Apparatus according to any one of claims 1 to 9, characterized in that the respiratory gas source (1) is in fluidic communication with a gas conduit (2), the gas conduit (2) being in fluidic communication with a respiratory interface (3). 11. Apparatus according to claim 10, characterized in that the respiratory interface (3) is selected from an endotracheal intubation tube, a face mask, or a laryngeal mask. 12. Apparatus according to any one of claims 1 to 11, characterized in that the CO2 content measurement means (4) are arranged: - either upstream and in the immediate vicinity (18) of the breathing interface (3), - or within the apparatus, connected to a gas sampling site (18) located upstream and in the immediate vicinity of the breathing interface (3). 13. Apparatus according to any one of claims 1 to 12, characterized in that the given time period (dt) is between 2 and 10 seconds. 14. Apparatus according to any one of claims 1 to 13, characterized in that the given time period (dt) is between 3 and 6 seconds. 15. Apparatus according to any one of claims 1 to 14, characterized in that the CO2 content measurement means (4) are configured to perform continuous measurements. 16. A device according to any one of claims 1 to 15, characterized in that it comprises storage means (8) cooperating with signal processing and control means (5) to store the CO2 concentration values measured during each given 28-minute period (dt) and the maximum CO2 concentration values (Vmax) calculated for each time window (Ft). 17. A device according to any one of claims 1 to 16, characterized in that the graphical user interface (GUI) comprises a digital display. 18. A device according to claim 17, characterized in that the digital display is a touchscreen. 19. A device according to any one of claims 1 to 18, characterized in that the signal processing and control means (5) are configured to control the breathing gas source (1) and deliver the breathing gas according to ventilation cycles comprising two pressure levels. 20. Apparatus according to claim 19, characterized in that the source (1) of breathing gas comprises a motorized micro-blower.

Description

1. VENTILATION DEVICE FOR CARDIOPULMONARY RESUSCITATION WITH CO2 TREND DISPLAY. The invention relates to a respiratory support device, i.e., a medical ventilator, connected to a patient receiving cardiopulmonary resuscitation (CPR), i.e., a patient in cardiac arrest undergoing cardiac massage with alternating chest compressions and decompressions, with a display of at least one average CO2 concentration value obtained, over a given time window, from a plurality of successive maximum CO2 concentration values. 10. Medical mechanical ventilation devices, also called respiratory support devices or medical ventilators, are commonly used to provide respiratory gas, for example, oxygen-enriched or oxygen-free air, to certain patients suffering from respiratory disorders. The supply of respiratory gas to the patient is commonly operated by means of a motorized and piloted micro-15 blower, as described in particular by EP-A-3093498, EP-A-2947328, EP-A-2986856, EP-A-2954213 or EP-A-2102504. It is known to monitor the gaseous compounds present in the gas administered to patients, particularly in the gases exhaled by patients which contain CO2 resulting from pulmonary gas exchange, i.e. CO2 produced by the patient's metabolism, transported to the lungs via the bloodstream and then expelled during the patient's expiration. Thus, etCO2 for fnd Iidal CO2 or CO2 at the end of expiration, corresponds to the measurement of the fraction of CO2 at the end of expiration in the gases collected during the expiration of an individual, whether their inspiration is natural or assisted, that is to say obtained by mechanical ventilation. Under mechanical ventilation, different techniques allow analysis by spectrophotometry of the CO2 fraction of exhaled gases. To do this, the gas present in the expiratory circuit can be: - either aspirated and then analyzed by an analysis cell at a site away from the respiratory circuit. This method of operation is called sidestream or secondary flow, i.e. "sidestream" in English, - meaning analysis near the patient, preferably at the level of a room Y arranged in the respiratory circuit near the patient. This method of operation is called mainstream. 2 During cardiopulmonary resuscitation (CPR) performed on a person in cardiac arrest, alveolar CO2 depends on the amount of CO2 generated by cellular metabolism, cardiac output, and pulmonary ventilation/perfusion ratios. In theory, the more effective CPR is, the more cellular metabolism is preserved and the greater the cardiac output generated by chest compressions, the greater the amount of CO2 brought back to the lungs. For these reasons, EtCO2 monitoring is recommended to guide cardiopulmonary resuscitation (CPR). Figure 1 is a capnogram which is a graphical representation of the variations in CO2 content in a patient's respiratory gases over time (in seconds). This type of 1° capnogram is observed in ventilated patients outside of situations of cardiac arrest. As we can see, it is divided into four successive phases: - Phase I: it represents the inspiratory baseline which must be stable at zero. - Phase II: it is the ascending part of the capnogram and corresponds to the appearance of CO2 in the exhaled gases, at the beginning of the patient's expiration, by emptying the best ventilated alveoli. In reality, exhalation begins slightly before this phase because the exhaled gas at the beginning of exhalation is devoid of CO2, as it has not participated in gas exchange due to instrumental and anatomical dead spaces. The increase in CO2 is slower the more inhomogeneous the lung and the longer the alveoli have time constants. - Phase III: This corresponds to the alveolar plateau phase, which corresponds to the CO2-rich gas coming from the alveoli with well-ventilated hands. The maximum value at the end of the plateau (PetCO2) corresponds to the value of etCO2. - Phase IV: it corresponds to the decrease in CO2 concentration caused by the start of spontaneous or assisted (i.e. mechanical) inspiration. However, during Cardiopulmonary Resuscitation (CPR) on a patient in cardiac-respiratory arrest, the capnogram is very different for several reasons, including: - chest compressions (CT) generate displacements of small volumes of gas. These volumes, close to the instrumental and anatomical space, disrupt the capnogram between two ventilatory cycles by a CO2 washing effect. Oscillating traces are often observed because the maximum CO2 value on each chest compression (30) constantly varies. 3 - The dynamic opening and closing behavior of small airways during CPR has recently been reported. This phenomenon compromises the movement of exhaled gases and therefore the interpretation of CO2 concentrations during CPR. We understand, therefore, that etCO2 as it is currently measured, i.e. during each chest compression, does not allow us to obtain a reliable approximation of the alveolar CO2 content. However, this alveolar CO2 content is important for healthcare personne