Ventilation Circuit Leak Detection via CO2-O2 Change Curves
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Solution Overview
Problem
Existing methods for detecting leaks in ventilation circuits during mechanical ventilation are unreliable and prone to generating nuisance alarms, particularly when the leak occurs gradually due to material fatigue or incorrect connections, which can distort gas concentration measurements and compromise patient care.
Innovation Solution
A process and system that utilizes a gas sensor array and signal processing unit to analyze the time curves of CO2 and another gas concentration, such as O2, to detect leaks by identifying time periods where the concentration change curves have the same sign, eliminating the need for threshold comparisons and reducing sensitivity to ventilation adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas concentration measurements are performed using a gas sensor array in a ventilation circuit, then gas concentration data can be obtained for automatic ventilation control, but leaks in the fluid connection may cause ambient air to be suctioned in and distort the measurement results
Solution Approach 1:
The system continuously monitors the ventilation circuit by analyzing the temporal relationship between CO2 and O2 concentration changes. When a leak is detected through the feedback analysis of concentration time curves, the system can alert the user or adjust ventilation parameters to compensate for the leak, thereby maintaining measurement precision despite the presence of ambient air ingress.
Solution Approach 2:
The patent introduces an intermediary analysis method that examines the temporal derivative of gas concentration curves. By analyzing the rate of change of CO2 and O2 concentrations over time and comparing their phase relationships, the system creates an intermediate representation that reveals leak conditions without directly measuring pressure differentials or requiring additional sensors in the fluid connection.
2Reliability
If existing leak detection methods are used, then leaks can be detected, but they require predefined thresholds and reference values that may not be accurate for all patient conditions
Solution Approach 1:
The system dynamically adjusts its leak detection methodology by continuously analyzing the temporal derivatives of gas concentration curves. Instead of relying on static predefined thresholds, the system adapts to each patient's breathing pattern and ventilation settings in real-time, making the leak detection equally effective across diverse patient conditions and ventilation modes.
Solution Approach 2:
The patent changes the detection parameter from absolute concentration values or fixed thresholds to the temporal rate of change of concentration curves. By analyzing how quickly CO2 and O2 concentrations change over time and their phase relationship, the system creates a detection method that is inherently adaptable to different patient conditions, ventilation rates, and gas flow rates without requiring re calibration or threshold adjustment.
3Reliability
If the ventilation circuit is monitored continuously, then leaks can be detected immediately, but additional sensors and complex measurement systems are required
Solution Approach 1:
The system achieves multi-functionality by using the existing gas sensor array that measures CO2 and O2 concentrations for ventilation control purposes. The same sensor data is simultaneously analyzed for leak detection through temporal derivative comparison, eliminating the need for separate leak detection sensors or additional measurement systems while enabling immediate leak detection.
Solution Approach 2:
The leak detection system serves itself by using the existing ventilation control measurements to perform leak monitoring. The gas sensor array that is already required for automatic ventilation control based on gas concentration measurements is also utilized for leak detection, making the system self-sufficient and eliminating the need for additional dedicated leak detection hardware.
Data Source
AI summary
A process for monitoring a measuring system (110) for mechanical ventilation of a patient (20) is carried out while a fluid connection (40) is established between the patient (20) and a medical device (100). A gas sample is suctioned from the fluid connection (40) and is sent through a gas sensor fluid-guiding unit (52) to a gas sensor array (50). A time curve of the CO2 concentration and O2 concentration in the suctioned gas sample are determined. A concentration change curve of the change over time of the CO2 concentration and the O2 concentration are calculated. A search is made for a time period in which the two concentration change curves continuously have the same sign. Upon detecting such a time period it is checked whether a predefined first leak criterion is met. When this is the case, an indication of a leak (L) is detected.