Segmented Inspiratory Limb Heating for Condensation Control

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Solution Overview

Problem

Existing respiratory humidification systems face challenges in maintaining optimal temperature and humidity levels when gas conduits pass through distinct temperature environments, leading to condensation or overheating issues.

Innovation Solution

A segmented inspiratory limb with dual heater wire circuits and an intermediate connector that allows independent control of heating modes based on sensor feedback, enabling differential heating across segments to maintain desired gas properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single heater circuit is used in the inspiratory limb, then the device complexity is reduced, but the ability to maintain optimal temperature in segments passing through distinct temperature environments deteriorates

Engineering Contradiction:
Improveheater circuit configurationVSAvoidgas temperature control
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The inspiratory limb is divided into multiple segments (first segment and second segment), each with its own heater wire circuit. This segmentation allows independent temperature control of each segment, enabling the system to maintain optimal gas temperature even when segments pass through distinct temperature environments such as inside/outside an incubator or under/over a blanket.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each segment of the inspiratory limb is equipped with localized heating capability through dedicated heater wire circuits. The intermediate connector provides selective electrical connection, allowing the controller to activate heating in specific segments based on their local environmental conditions, thus achieving local quality control for temperature management.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If heater power is increased to prevent condensation in cold environments, then condensation prevention is improved, but the risk of overheating gas increases

Engineering Contradiction:
Improvecondensation preventionVSAvoidgas temperature
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The system dynamically adjusts heater power based on real-time environmental conditions and gas flow parameters. The controller monitors the distal end environment and selectively activates heater circuits in different segments, modulating power delivery to prevent condensation in cold segments while avoiding overheating in segments with higher ambient temperatures or higher gas flow rates.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters (heater power level, which segment heaters are active) based on detected environmental conditions. When condensation risk is detected in a segment, the controller increases power to that segment's heater; when gas flow is high or ambient temperature is high, the controller reduces or disables heating in that segment, thus adapting parameters to prevent both condensation and overheating.

Inventive Principle:
Principle #35Parameter changes

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

Effectively prevents condensation and ensures optimal gas temperature delivery by adaptively adjusting heating based on sensor feedback, improving thermal management in respiratory circuits.

Implementation Method 1

The inspiratory limb includes a first heater wire circuit and a second heater wire circuit, wherein the first and second heater wire circuits are configured to heat the humidified gas

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4674458A1Zone heating for respiratory circuits
Publication Date: 2026.01.07 FISHER & PAYKEL HEALTHCARE LTD
  • EP4674458A1 patent drawingFigure 1
  • EP4674458A1 patent drawingFigure 2
  • EP4674458A1 patent drawingFigure 3A~3B

AI summary

Some embodiments provide for an inspiratory limb for a breathing circuit that includes a first segment that comprises a first heater wire circuit and a second segment that comprises a second heater wire circuit. The inspiratory limb can include an intermediate connector that includes a connection circuit that electrically couples the first heater wire circuit to the second heater wire circuit. The inspiratory limb can be configured to operate in two modes wherein, in a first mode, electrical power passes through the first electrical connection to provide power to the first heater wire circuit without providing power to the second heater wire circuit, and in a second mode, electrical power pass through the first electrical connection to provide power to both the first heater wire circuit and the second heater wire circuit.