Segmented Respiratory Circuit Heating Across Temperature Zones

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Solution Overview

Problem

Existing gas humidification systems struggle to maintain optimal temperature and humidity levels in respiratory circuits when they pass through distinct temperature environments, leading to issues like condensation or overheating.

Innovation Solution

A segmented inspiratory limb with dual heater wire circuits and sensors in each segment, controlled by a controller that switches between heating modes based on feedback from multiple sensors to maintain optimal temperature and humidity levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single heater wire circuit is used throughout the inspiratory limb, then the device complexity is reduced, but the system cannot maintain optimal temperature when passing through distinct temperature environments (e.g., incubator vs. surrounding environment)

Engineering Contradiction:
Improvetemperature control adaptabilityVSAvoidheater circuit complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The inspiratory limb is divided into multiple segments, each with its own heater wire circuit. This segmentation allows independent temperature control of different sections of the conduit, enabling the system to adapt to distinct temperature environments (e.g., warmer incubator environment vs. cooler surrounding environment) without increasing overall system complexity excessively.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each segment of the inspiratory limb is equipped with localized heater wire circuits and temperature sensors, allowing temperature control to be optimized locally at each segment rather than uniformly throughout the entire conduit. This enables precise temperature maintenance in specific zones where condensation or overheating is most likely to occur.

Inventive Principle:
Principle #3Local quality

2Temperature

If heating is applied to maintain temperature in a warm environment (e.g., incubator), then the gas temperature is maintained, but condensation may occur in cooler surrounding environments

Engineering Contradiction:
Improvegas temperature consistencyVSAvoidcondensation
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The heating system is segmented into multiple independent heater wire circuits, each controllable based on local temperature conditions. This allows the system to apply heating only where needed (e.g., in segments passing through cooler environments) while avoiding excessive heating in warmer areas, thereby preventing condensation while maintaining gas temperature consistency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Temperature sensors are positioned at multiple locations along the inspiratory limb to provide feedback on actual temperature conditions. This feedback enables the control system to dynamically adjust heating power in each segment, maintaining optimal temperature without causing condensation in cooler surrounding environments.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If multiple heater wire circuits are added to each segment, then temperature control precision is improved, but the device complexity increases

Engineering Contradiction:
Improvetemperature measurement precisionVSAvoidheater circuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The inspiratory limb is segmented into multiple sections, each with dedicated heater wire circuits and temperature sensors. This segmentation enables precise temperature measurement and control at each location without requiring complex centralized control systems, as each segment operates independently with localized feedback.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each segment receives tailored heating control based on local temperature measurements, allowing precise temperature maintenance without requiring complex overall system architecture. The local quality approach simplifies the system by distributing control functionality rather than using a complex centralized system.

Inventive Principle:
Principle #3Local quality

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 effectively maintains consistent gas temperature and humidity by adaptively adjusting heating in different segments, reducing condensation and overheating, and ensuring safe delivery to the patient.

Implementation Method 1

a first heater wire circuit... a second heater wire circuit... electrical power passes through the intermediate connector to provide power to the first heater wire circuit

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The intermediate connector includes a diode electrically coupled to both the first heater wire circuit and the second heater wire circuit

Methodology Applied
Scientific EffectDiode rectification: Diode

Implementation Method 3

a first sensor circuit having a first sensor positioned at the intermediate connector... a second sensor circuit having a second sensor positioned at a patient-end connector

Methodology Applied
Scientific EffectTemperature sensing: Thermistor

Data Source

PatentEP4218872B1Zone heating for respiratory circuits
Publication Date: 2025.12.24 FISHER & PAYKEL HEALTHCARE LTD
  • EP4218872B1 patent drawingFigure 1
  • EP4218872B1 patent drawingFigure 2
  • EP4218872B1 patent drawingFigure 3A~3B

AI summary

A connector (214) for connecting segments (202a, 202b) of a medical tube (202) in a breathing circuit, the connector (214) comprising: a first connection circuit configured to be electrically coupled to: one or more first heater wires (218, 220), the first connection circuit and the one or more first heater wires (218, 220) forming a first heater wire loop; and, one or more second heater wires (222, 224), the first connection circuit, the one or more first heater wires (218, 220) and the one or more second heater wires (222, 224) forming a second heater wire loop; a second connection circuit configured to be electrically coupled to one or more first sensor wires (228, 230) and to one or more second sensor wires (232, 234); and a first diode (D1) electrically coupled to the first connection circuit, the first diode (D1) being configured to allow current to flow through the first heater wire loop in a first direction and allow current to flow through the second heater wire loop in a second direction.