Capnography System Oxygen Detection via Pressure Differential

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Solution Overview

Problem

Current capnography systems face challenges in accurately detecting the presence of supplemental oxygen, which can lead to inadequate ventilation in patients, especially those on analgesic or sedative medications, due to clinician forgetfulness or inappropriate oxygen administration, causing inaccuracies in capnogram analysis.

Innovation Solution

A capnography system with a controller that determines the concentration and partial pressure of carbon dioxide in a sample gas flow, assesses changes in pressure to identify supplemental oxygen presence, and renders messages or alarms based on patient conditions, using a flow restrictor and sensors to differentiate oxygen provision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If supplemental oxygen is administered to patients at risk of inadequate ventilation, then patient oxygenation is improved, but capnogram accuracy deteriorates making it difficult to analyze breathing adequacy

Engineering Contradiction:

Improvepatient oxygenationVSAvoidcapnogram accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary detection mechanism that measures pressure changes in the sample gas flow caused by supplemental oxygen administration. This intermediary signal allows the system to detect oxygen presence without directly analyzing the capnogram, thereby maintaining capnogram accuracy while still monitoring oxygenation status.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system segments the monitoring function into two independent parts: capnogram analysis for breathing adequacy and pressure change detection for oxygen presence. This segmentation allows both functions to operate independently without interference, resolving the contradiction between oxygenation monitoring and capnogram accuracy.

Inventive Principle:

Principle #1Segmentation

2Reliability

If clinicians administer supplemental oxygen to prevent inadequate ventilation, then patient safety is improved, but clinician forgetfulness or inappropriate administration causes measurement inaccuracies

Engineering Contradiction:

Improvepatient safetyVSAvoidcapnogram information accuracy

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The system provides feedback to clinicians about supplemental oxygen presence through pressure change detection. This feedback mechanism ensures clinicians are aware of oxygen administration status, preventing both forgetfulness and inappropriate administration, while the segmented measurement approach preserves capnogram information accuracy.

Inventive Principle:

Principle #23Feedback

3Reliability

If supplemental oxygen is provided to spontaneously breathing patients, then oxygenation is improved, but detection of oxygen presence becomes difficult affecting ventilation assessment

Engineering Contradiction:

ImproveoxygenationVSAvoidoxygen presence detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces chemical or optical detection methods with a mechanical pressure-based detection system. By measuring pressure changes in the sample gas flow, the system can detect supplemental oxygen presence without complex chemical sensors, simplifying the detection mechanism while maintaining reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively determines supplemental oxygen presence, preventing inadequate ventilation and improving capnogram accuracy by providing clear messages and alarms, ensuring appropriate oxygen administration based on patient needs.

Implementation Method 1

A flow restrictor may be fluidically coupled to the physical interface. The controller may be configured to obtain the sample gas flow through the flow restrictor and determine the change in pressure as a change in differential pressure in the sample gas flow.

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

determine at least one of concentration and partial pressure of carbon dioxide in the sample gas flow during a sampling time interval; determine whether a change in pressure in the sample gas flow during the sampling time interval is equal to or greater than a threshold value

Methodology Applied

Scientific EffectPressure measurement: Pressure Gradient

Data Source

PatentUS10786645B2Capnometry system with supplemental oxygen detection and method of operation thereof

Publication Date: 2020.09.29 KONINKLIJKE PHILIPS NV

AI summary

A capnography system (100, 400), comprising: a controller (110, 410) configured to obtain a sample gas flow from a physical interface (107) for a patient (101); determine a change in a characteristic of the sample gas flow during a sampling time interval; determine whether the change in the characteristic of the sample gas flow during the sampling time interval is equal to or greater than a corresponding threshold value; determine that supplemental oxygen is provided when it is determined that the change in the characteristic of the sample gas flow is equal to or greater than the threshold value; and determine that supplemental oxygen is not provided when it is determined that the change in the characteristic of the sample gas flow is less than the threshold value.