Closed-Loop Pressure Driver for Stable CPAP Delivery
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Solution Overview
Problem
Existing CPAP ventilation systems face challenges with pressure variations due to leakage and disconnections, which are not detectable by non-adjustable manual flow control valves, leading to unstable pressure delivery to patients.
Innovation Solution
A closed-loop control system with a patient pressure sensor providing feedback to an inspiration flow control valve, combined with a flow generator and oxygen mixer, to maintain stable pressure and detect leakage or disconnections, using a voltage-sensitive orifice valve and safety features for responsive pressure adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a manual flow control valve is used to control pressure at the patient, then the device is simple in structure, but pressure variations occur due to leakage and disconnections that cannot be detected or corrected
Solution Approach 1:
The patent implements a closed-loop feedback control system where a pressure sensor continuously monitors actual pressure at the patient interface and feeds this information back to a controller. The controller compares actual pressure with desired pressure and adjusts the flow control valve accordingly to maintain stable pressure, thereby resolving the contradiction between reliability and complexity by introducing intelligent control.
Solution Approach 2:
The patent replaces the purely manual mechanical flow control valve with an electronically controlled valve that responds to feedback signals from the pressure sensor. This substitution transforms the mechanical system into an electromechanical system, enabling automatic pressure regulation and leakage detection while maintaining reasonable device complexity.
2Loss of information
If the flow control valve is placed between the gas source and the patient, then pressure can be controlled, but it cannot detect leakage or disconnections at the patient circuit
Solution Approach 1:
The patent introduces a pressure sensor as an intermediary element placed at the patient interface to detect pressure changes caused by leakage or disconnection. This intermediary provides critical information about system status without requiring complex sensor arrays, enabling leakage detection while keeping device complexity manageable.
Solution Approach 2:
The pressure sensor provides feedback information about actual pressure conditions at the patient interface, enabling the controller to detect leakage or disconnection events. This feedback mechanism transforms the system from one that cannot detect losses to one that can identify and respond to them, resolving the contradiction between detection capability and system complexity.
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 ensures accurate and stable positive airway pressure delivery, detects and compensates for leakage and disconnections, and gradually reduces oxygen dependency as the patient recovers, enhancing respiratory support.
Implementation Method 1
A voltage-sensitive orifice valve may be used for controlling a flow of pressurized gas to the patient
Implementation Method 2
A patient pressure sensor may be disposed at the patient airway and which is operative to measure pressure thereat for feedback to a flow control valve
Data Source
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AI summary
A pressure driver for a ventilation system comprises a gas source, an inspiration flow control valve and a patient pressure sensor to form a closed loop control system. The inspiration flow control valve may be mounted within a housing and is operative to open and close in response to patient pressure measurements in order to produce a desired pressure at the patient. The pressure driver may further include a mixture control for allowing selective adjustment of the oxygen concentration in pressurized gas delivered to the patient. An oxygen mixer is connected between the gas source and the mixture control and is operative to deliver the desired mixture of oxygen and air to the inspiration flow control valve for delivery to the patient. An oxygen sensor monitors the oxygen concentration in the gas provided by the oxygen mixer.