Ventilator Timing Control Using End-Expiratory Flow Feedback

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Solution Overview

Problem

Existing ventilators do not efficiently adjust ventilation parameters to ensure gentle and patient-friendly ventilation, particularly in patients with conditions like chronic obstructive pulmonary disease, and often result in unnecessary rapid delivery of respiratory gas during inspiration due to phases of low expiratory gas flow.

Innovation Solution

A ventilator system with a sensor unit, storage unit, and processing unit that measures gas flow-dependent values, adjusts the ratio between inspiratory and expiratory times based on thresholds, and adapts ventilation parameters to maintain a constant respiratory cycle duration, thereby optimizing ventilation modes for patient comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the ventilator delivers respiratory gas rapidly during inspiration, then ventilation efficiency is improved, but patient comfort deteriorates due to high inspiratory gas flow gradient

Engineering Contradiction:
Improveventilation efficiencyVSAvoidinspiratory gas flow gradient
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The ventilator dynamically adjusts the ratio between expiratory time and inspiratory time based on real-time end-expiratory gas flow measurements. When end-expiratory gas flow is low, the system automatically increases expiratory time and decreases inspiratory time, creating a more gradual inspiratory gas flow gradient that improves patient comfort while maintaining ventilation efficiency.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from gas flow sensors to continuously monitor end-expiratory gas flow and adjusts ventilation parameters accordingly. The processing unit receives sensor signals, determines current end-expiratory gas flow, and modifies the time ratio between expiration and inspiration to optimize both efficiency and comfort based on actual patient response.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If the ventilator extends expiratory time to reduce inspiratory gas flow gradient, then patient comfort is improved, but respiratory cycle duration increases

Engineering Contradiction:
Improveinspiratory gas flow gradientVSAvoidrespiratory cycle duration
Core Design Contradiction:
Object-affected harmful factorsVSDuration of action of moving object

Solution Approach 1:

The ventilator dynamically adjusts the ratio between expiratory time and inspiratory time while maintaining a substantially constant respiratory cycle duration. The system achieves this by coordinating changes in both time components so that when expiratory time is extended to reduce gas flow gradient, inspiratory time is相应 reduced, keeping the total cycle length stable.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If the ventilator uses complex hardware adjustments to modify ventilation parameters, then ventilation precision is improved, but device complexity increases

Engineering Contradiction:
Improveventilation parameter adjustment precisionVSAvoidhardware complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical adjustments with a software-based control system. The processing unit modifies ventilation parameters by adjusting the ratio between expiratory and inspiratory times through software algorithms, eliminating the need for complex mechanical hardware while achieving precise control over ventilation characteristics.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4079358B1Ventilation apparatus for mechanical ventilation of a patient
Publication Date: 2025.11.19 DRAGERWERK AG
  • EP4079358B1 patent drawingFigure 1
  • EP4079358B1 patent drawingFigure 2~3
  • EP4079358B1 patent drawingFigure 4~5

AI summary

The invention relates to a ventilator (100) for the mechanical ventilation of a patient (102), comprising at least one sensor unit (110), a storage unit (120), and a processing unit (130). The at least one sensor unit is configured to measure a profile (114) of gas flow-dependent measured values ​​(115) in the ventilation circuit (105) of the ventilator and to output a corresponding sensor signal (116). The storage unit contains a plurality of ventilation parameters (122) of a currently active ventilation mode, wherein these stored ventilation parameters indicate at least one inspiration time (124) of the ventilation currently provided by the ventilator and a subsequent expiratory time (126) for a corresponding respiratory cycle. The processing unit is configured to receive the sensor signal and, based on the profile of the gas flow-dependent measured values, to determine at least one current end-expiratory gas flow (132).The processing unit is further developed to adjust a ratio (136) between inspirational time and expiratory time for the currently present ventilation mode for the ventilation of the patient, depending on a comparison between the determined current end-expiratory gas flow and a lower threshold (134) and/or an upper threshold (135).