Loop Gain Controller for Positive Airway Pressure Ventilation

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Solution Overview

Problem

Current positive airway pressure therapy systems, such as ASV devices, fail to effectively treat ventilation instability in patients with high loop gain, particularly during hyperventilation phases, as they only provide support during reductions in breathing and cannot restrict ventilation when muscle effort exceeds baseline, leading to unstable respiratory patterns in conditions like Cheyne-Stokes respiration and obstructive sleep apnea.

Innovation Solution

A system and method utilizing a loop gain controller with a stability metric module, condition monitoring, loop gain decision, therapy prescription, and pressure delivery modules to modulate gas flow in the airway, adjusting pressure characteristics based on monitored ventilation characteristics and breath features to stabilize ventilation, incorporating a flow-based gain scheduler to oppose unstable breathing efforts and normalize loop gain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If bi-level positive airway pressure therapy is used to support ventilation during hypopnea phases, then ventilation stability improves during low respiratory drive periods, but ventilation becomes unstable during hyperpnea phases where muscle effort exceeds baseline

Engineering Contradiction:

Improveventilation stabilityVSAvoidtherapy response across breathing phases

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts pressure support based on real-time detection of breathing phase and loop gain characteristics. The controller transitions from static bi-level pressure delivery to dynamic proportional pressure support that adapts to waxing and waning respiratory patterns, enabling stable ventilation throughout both hypopnea and hyperpnea phases

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system implements closed-loop feedback control by continuously monitoring ventilation characteristics and using loop gain calculations to determine appropriate pressure support levels. This feedback mechanism allows the system to respond to changing respiratory conditions and maintain stability across varying muscle effort levels

Inventive Principle:

Principle #23Feedback

2Reliability

If machine triggered breaths are delivered during hypopnea intervals, then ventilation support is provided when patient drive is reduced, but the system cannot restrict ventilation when muscle effort exceeds baseline

Engineering Contradiction:

Improveventilation support reliabilityVSAvoidcontrol flexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system inverts the traditional approach by not only providing positive pressure support during low drive periods but also applying negative pressure support or restricting ventilation during high muscle effort phases. This bidirectional control capability allows the system to stabilize ventilation by counteracting both insufficient and excessive respiratory drive

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If CO2 is selectively rebreathed during hyperneic phase, then respiratory drive is modulated to reduce CSR, but additional equipment is required beyond typical ventilator system

Engineering Contradiction:

ImproveCSR treatment effectivenessVSAvoidsystem equipment requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system replaces the mechanical/physiological approach of CO2 rebreathing with a control system approach that uses loop gain calculations and proportional pressure adjustment. This substitution eliminates the need for additional CO2 rebreathing equipment while achieving similar therapeutic effects through intelligent pressure modulation based on real-time ventilation monitoring

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If respiratory rate is increased to reduce CSR, then Cheyne-Stokes respiration is alleviated, but cardiac and respiratory workload proportionally increase

Engineering Contradiction:

ImproveCSR reductionVSAvoidcardiac and respiratory workload

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system changes the control parameter from simple respiratory rate increase to proportional pressure support adjusted according to loop gain and breathing phase. This parameter change allows the system to stabilize ventilation and reduce CSR without the adverse effect of proportionally increasing respiratory rate and associated workload

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12151063B2Utilizing loop gain for positive airway pressure ventilation

Publication Date: 2024.11.26 KONINKLIJKE PHILIPS NV

AI summary

A system for delivering a flow of gas to an airway of a patient respiratory system includes a gas flow generator, a sensor, and a loop gain controller. The loop gain controller selectively controls the flow of gas to the airway according to a positive airway pressure (PAP) therapy mode. The loop gain controller comprises (a) a stability metric module, (b) a condition monitoring module that monitors ventilation characteristics of the flow of gas in the patient respiratory system and provides an output indicative of monitored ventilation characteristics, (c) a loop gain decision module that determines a future ventilation characteristic target and plant gain target, (d) a therapy prescription decision module that determines a therapy command pressure or delivery characteristic, and (e) a pressure delivery module that controls the gas flow generator to deliver the flow of gas at the determined therapy command pressure or delivery characteristic for a future breath.