CPR Ventilator Mode Switching for Cardiac Massage and ROSC

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Solution Overview

Problem

Conventional medical ventilators malfunction or trigger false alarms during cardiopulmonary resuscitation due to inappropriate ventilation settings, particularly during the transition from cardiac arrest to return of spontaneous circulation (ROSC), and fail to adapt ventilation parameters effectively.

Innovation Solution

A medical ventilator with a motorized blower and control system that switches between two ventilation modes: one for cardiac massage and another for ROSC, adjusting pressures and rates based on patient CO2 levels to avoid alarms and ensure safe ventilation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional medical ventilators are used during CPR with chest compressions, then ventilation can be provided to the patient, but the ventilator may sound alarms and/or malfunction due to inappropriate ventilation settings

Engineering Contradiction:

Improveventilator operation stabilityVSAvoidventilation settings appropriateness

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The ventilator dynamically adapts its ventilation settings based on the detected CPR phase (cardiac arrest or ROSC). The system automatically adjusts pressure limits, respiratory rate, and tidal volume according to real-time detection of chest compression status, transforming a static ventilator into a dynamic system that responds to changing physiological conditions during resuscitation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The ventilator implements distinct ventilation parameters for different CPR phases: during cardiac arrest, it uses higher pressure support and higher respiratory rate to compensate for reduced chest compliance; during ROSC, it transitions to lower pressure and rate to match improved lung mechanics, thereby preventing alarms and malfunctions caused by inappropriate fixed settings

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If ventilation is delivered excessively during cardiac arrest, then oxygen supply is improved, but circulation generated by chest compressions is detrimental to gas exchange

Engineering Contradiction:

Improveoxygen supplyVSAvoidcirculation interference

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The ventilator precisely controls ventilation parameters including tidal volume, pressure support level, and respiratory rate based on the cardiac arrest phase detection. By adjusting these parameters to optimal levels during CPR, the system provides sufficient oxygenation without excessive ventilation that would interfere with chest compression-generated circulation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system incorporates detection means that monitor ventilation effectiveness and circulation status during CPR, using this feedback to automatically adjust ventilation settings. This closed-loop control ensures oxygen supply meets metabolic demands while avoiding harmful over-ventilation effects on compression circulation

Inventive Principle:

Principle #23Feedback

3Quantity of substance

If FiO2 is maintained at maximum during cardiac arrest, then oxygenation is optimized, but hyperoxia occurs during ROSC causing potential harm

Engineering Contradiction:

Improveinspired oxygen fractionVSAvoidhyperoxia

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The ventilator dynamically adjusts the fraction of inspired oxygen (FiO2) based on detected CPR phase. During cardiac arrest, FiO2 is maintained at 100% to maximize oxygenation when circulation is compromised; upon detection of ROSC, the system automatically reduces FiO2 to appropriate lower levels to prevent hyperoxia, transforming a static oxygen delivery system into an adaptive one

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements distinct FiO2 settings for different physiological phases: maximum oxygen concentration during cardiac arrest to compensate for poor perfusion, and reduced oxygen concentration during ROSC when circulation is restored, thereby optimizing oxygenation while avoiding harmful hyperoxia

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If the ventilator switches between ventilation modes during CPR, then ventilation adapts to patient condition, but false alarms may be triggered during mode transition

Engineering Contradiction:

Improveventilation adaptationVSAvoidalarm accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The ventilator performs preliminary detection of CPR phase (cardiac arrest or ROSC) before switching ventilation modes. By detecting the physiological state in advance and preparing the appropriate ventilation parameters, the system smoothly transitions between modes without abrupt changes that would trigger false alarms, ensuring both adaptability and alarm reliability

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4450103B1Medical ventilator with ventilatory modes suitable for cardiac massage

Publication Date: 2026.03.04 AIR LIQUIDE MEDICAL

Figure 1~2
Figure 3

AI summary

The invention relates to a medical ventilator (1) configured to provide respiratory assistance to a person in cardiac arrest, comprising a motorized blower (2), a gas circuit (3), and means for storing ventilation modes (MV1, MV2) to be implemented during or when cardiac massage is not being performed, particularly during ROSC. Ventilation mode selection means (5; 5.1, 5.2) allow a user to select one of the stored ventilation modes, and control means (6) control the motorized blower (2) in response to the user's selection of one of said ventilation modes (MV1, MV2), to supply gas at the desired low and high pressures.