Non-Invasive Ventilator CO2 Measurement via EPAP Adjustment

Solution Overview

Problem

Non-invasive ventilator systems face challenges in accurately measuring CO2 levels due to high leaks around the mask seal, which lead to erroneous measurements as exhaled gas with CO2 escapes, diluting the sample and reducing the amount reaching the CO2 sensor.

Innovation Solution

The system temporarily lowers the expiratory positive airway pressure (EPAP) to a lower level for a predetermined number of breaths to allow for accurate CO2 measurement by the sensor, then returns to the original EPAP setting, using a controller to manage this process and ensure precise CO2 monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If non-invasive ventilation is used with a mask seal, then patient comfort is improved and invasive procedures are avoided, but measurement precision of CO2 levels deteriorates due to gas leaks around the mask

Engineering Contradiction:

Improvepatient comfortVSAvoidCO2 measurement precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system dynamically adjusts the EPAP parameter by temporarily lowering it during measurement cycles to improve CO2 detection accuracy, then restoring it to maintain therapeutic effect. This dynamic parameter adjustment resolves the contradiction between maintaining comfortable non-invasive ventilation and achieving precise CO2 measurements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The ventilator implements periodic measurement cycles where EPAP is temporarily reduced for a predetermined number of breaths to enable accurate CO2 sampling, then returns to the therapeutic setting. This periodic action allows the system to alternate between measurement optimization and therapeutic maintenance, resolving the measurement precision issue without compromising overall patient comfort.

Inventive Principle:

Principle #19Periodic action

2Stress or pressure

If EPAP is maintained at a higher level to compensate for mask leaks, then positive airway pressure support is improved, but CO2 measurement precision deteriorates as more exhaled gas escapes before reaching the sensor

Engineering Contradiction:

Improveexpiratory positive airway pressureVSAvoidCO2 measurement precision

Core Design Contradiction:

Stress or pressureVSMeasurement precision

Solution Approach 1:

The system dynamically adjusts the EPAP parameter by temporarily lowering it during measurement cycles to improve CO2 detection accuracy, then restoring it to maintain therapeutic effect. This dynamic parameter adjustment resolves the contradiction between maintaining comfortable non-invasive ventilation and achieving precise CO2 measurements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs preliminary action by temporarily lowering EPAP before CO2 measurement to ensure adequate exhaled gas reaches the sensor, then restores the therapeutic pressure afterward. This preliminary adjustment of pressure conditions enables accurate measurement without compromising the overall therapeutic pressure support.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If EPAP is temporarily lowered to improve CO2 measurement, then measurement precision is improved, but ventilator support effectiveness deteriorates during the measurement period

Engineering Contradiction:

ImproveCO2 measurement precisionVSAvoidventilator support effectiveness

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The ventilator implements periodic measurement cycles where EPAP is temporarily reduced for a predetermined number of breaths to enable accurate CO2 sampling, then returns to the therapeutic setting. This periodic action allows the system to alternate between measurement optimization and therapeutic maintenance, resolving the measurement precision issue without compromising overall patient comfort.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the EPAP parameter by temporarily lowering it during measurement cycles to improve CO2 detection accuracy, then restoring it to maintain therapeutic effect. This dynamic parameter adjustment resolves the contradiction between maintaining comfortable non-invasive ventilation and achieving precise CO2 measurements.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10869978B2Method of CO<sub>2 </sub>measurement during non-invasive ventilation

Publication Date: 2020.12.22 KONINKLIJKE PHILIPS NV

AI summary

A method for measuring a patient's expired CO2 level in a non-invasive ventilator system while maintaining a positive inspiratory pressure. The method includes the steps of: receiving, by the non-invasive ventilator system, a signal comprising an instruction to obtain a CO2 measurement from a patient; lowering, by the non-invasive ventilator system in response to the signal, the expiratory positive airway pressure from a first, higher level to a second, lower level for a first time period comprising one or more breaths; obtaining, by a CO2 sensor, a CO2 measurement during the first time period; and returning, after the first time period, the expiratory positive airway pressure to the first, higher level.