Variable Oxygen Flow Delivery System for Apnea Detection
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Solution Overview
Problem
Current breathing detection systems during procedural sedation are inadequate, particularly in differentiating between true apnea and oxygen delivery device displacement, and fail to accurately measure the fraction of inhaled oxygen, leading to inefficiencies and potential hazards due to reliance on unreliable methods like transthoracic bioimpedance and capnometry.
Innovation Solution
A system that utilizes a processor to analyze breathing pressure values and oxygen flow rates, distinguishing between patient breathing and apnea by comparing these values to ambient pressure, and adjusting oxygen delivery through a flow control valve to optimize oxygen inhalation, incorporating differential-type pressure analyzers and heated wire anemometers for precise measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If fixed flow rate oxygen is delivered continuously through nasal cannula or mask, then oxygen is always available to the patient, but the majority of supplemental oxygen is wasted as the patient is breathing out (exhaling)
Solution Approach 1:
The system uses periodic action by detecting patient inhalation through pressure sensor signals and delivering oxygen in synchronized pulses during inhalation phases only. The flow control valve receives periodic control signals that open the valve during detected inhalation events and close it during exhalation, converting continuous oxygen delivery into periodic delivery that matches patient respiratory cycles, thereby reducing waste while maintaining reliability
Solution Approach 2:
The system implements feedback by using a pressure sensor to detect patient breathing patterns and feed this information back to the flow control valve. The pressure sensor generates signals in response to patient inhalation, which are processed by a processor that then sends control signals to adjust the flow control valve, creating a closed-loop feedback system that dynamically adjusts oxygen delivery based on actual patient needs
2Reliability
If high oxygen flow is given to hypoxic patients, then oxygenation is improved, but the signal is degraded when high oxygen flow is given because increased oxygen flow dilutes the exhaled carbon dioxide
Solution Approach 1:
The system uses an intermediary approach by switching from direct capnometry (which measures CO2 concentration) to pressure-based breathing detection. The pressure sensor acts as an intermediary that detects breathing patterns through pressure changes in the airway, providing reliable breathing detection that is not degraded by high oxygen flow dilution of CO2
Solution Approach 2:
The system replaces the chemical measurement system (capnometry measuring CO2 concentration) with a mechanical measurement system (pressure sensing). The pressure sensor detects breathing events through mechanical pressure changes in the airway, substituting the CO2-based chemical detection method with a pressure-based physical detection method that is not affected by oxygen dilution
3Reliability
If transthoracic bioimpedance is used to monitor respiration rate, then respiration monitoring is provided, but it is often unreliable and cannot detect airway obstruction since the patient's chest still moves during an attempt to force gas through an obstructed airway
Solution Approach 1:
The system extracts the detection function from indirect chest movement measurement (bioimpedance) and places it directly at the airway level. By positioning the pressure sensor in the airway, the system directly measures pressure changes caused by breathing, extracting the essential detection function from the unreliable indirect method and placing it where it can directly observe airway conditions
Solution Approach 2:
The system replaces the electrical measurement system (bioimpedance measuring electrical impedance changes) with a mechanical measurement system (pressure sensing). The pressure sensor directly measures mechanical pressure changes in the airway, substituting the electrical impedance method with a direct mechanical detection method that reliably detects both normal breathing and obstructions
4Measurement precision
If capnometry is used to detect breath attempts, then breath detection is provided, but it is expensive and cannot distinguish between true breaths and other respiratory events
Solution Approach 1:
The system uses a low-cost pressure sensor instead of expensive capnometry equipment. The pressure sensor is a simpler, more affordable device that provides sufficient functionality for breath detection without the high cost of capnometry systems, achieving reliable detection at a fraction of the expense
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
This system enhances breathing detection accuracy, reduces oxygen wastage by delivering variable oxygen flows based on patient inhalation patterns, and provides alarms for apnea and oxygen delivery device issues, ensuring safer and more efficient oxygen therapy.
Implementation Method 1
a pressure sensor to detect the patient's breathing pressure
Implementation Method 2
measuring the oxygen flow rate with a differential-type pressure analyzer
Implementation Method 3
measuring the oxygen flow rate with a heated wire, or heated film, type anemometer
Data Source
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AI summary
A method and apparatus to deliver a variable flow of oxygen to a patient is described. The apparatus may include a flow control valve, a pressure sensor to detect a patient's breathing pressure and ambient pressure, an oxygen flow analyzer to measure oxygen flow to the patient, and a processor to analyze the breathing pressure values, ambient pressure value, and oxygen flow rate values and to determine when a patient is inhaling. When the processor determines the patient is inhaling, the processor calculates an optimal oxygen flow rate to deliver to a patient, which may depend on a pre-selected flow rate and an oxygen backlog, and the processor sends a signal to the flow control valve to deliver the optimal oxygen flow rate to the patient.