Breathing System Flow Estimation via Compliance
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Solution Overview
Problem
Conventional breathing systems face challenges in accurately measuring gas flow due to compressible internal volumes, leading to potential safety hazards, especially in pediatric patients, and require multiple flow meters which increase complexity and cost.
Innovation Solution
A breathing system that estimates gas flow at a remote location using a relationship between monitored gas flow and compressible gas flow, based on compliance in the gas channel, without the need for flow meters, utilizing pressure sensors to determine estimated pressure and calculate gas flow estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow meters are installed at critical locations to measure gas flow, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical flow meters with a computational approach that uses pressure sensor data and compliance values to calculate gas flow. The flow calculation unit computes flow estimates based on pressure changes and system compliance, eliminating the need for physical flow measurement devices at critical locations.
Solution Approach 2:
The patent introduces compliance as an intermediary parameter that mediates between pressure measurements and flow calculations. By using compliance values (which can be pre-determined or estimated) to relate pressure changes to flow rates, the system achieves accurate flow measurement without direct flow sensing.
2Measurement precision
If flow meters are installed at the y-piece to measure patient flow, then measurement precision is improved, but reliability decreases due to handling difficulties with moisture, mucus, and temperature changes
Solution Approach 1:
The patent substitutes the flow meter at the y-piece with a flow calculation unit that computes flow estimates based on pressure sensor data. This eliminates the flow meter's direct exposure to patient-generated moisture, mucus, and temperature variations, thereby maintaining measurement accuracy while improving reliability.
Solution Approach 2:
Instead of directly measuring flow at the patient interface, the system creates a computational copy of the flow measurement by deriving flow estimates from pressure changes and compliance relationships. This indirect measurement approach avoids the harsh environment at the y-piece while maintaining measurement fidelity.
3Measurement precision
If multiple flow meters are used to compensate for compressible volume effects, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces multiple physical flow meters with a single flow calculation unit that computationally compensates for compressible volume effects. The system uses pressure sensor data combined with compliance values to calculate flow estimates that account for volume changes in the breathing circuit, eliminating the need for multiple measuring points.
Solution Approach 2:
The patent changes the approach from direct physical measurement to parameter-based calculation. By using compliance values (which characterize the compressible volume) and pressure changes, the system dynamically calculates flow estimates that compensate for volume effects without requiring multiple fixed measurement points throughout the circuit.
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
This approach allows for accurate control of inspiratory and expiratory cycles, correct volume delivery, and reduced costs by eliminating the need for flow meters, enhancing patient safety and system reliability.
Implementation Method 1
a compliance (C). The system comprises a flow calculation unit operative to determine a gas flow estimate (Fe) at a flow estimate location in the gas channel. The gas flow estimate is based on a relationship between a monitored gas flow (Fm) in the gas channel and a compressible gas flow (Fc) which depends on the compliance (C) in the gas channel.
Data Source
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AI summary
A breathing system (100, 200, 500) for ventilating a patient is disclosed. The breathing system has a gas channel (101) enclosing a gas channel volume (V), and a compliance (C). The system comprises a flow calculation unit (125) operative to determine a gas flow estimate (Fe) at a flow estimate location (117, 128) in the gas channel. The gas flow estimate (Fe) is based on a relationship between a monitored gas flow (Fm) in the gas channel and a compressible gas flow (Fc) which depends on the compliance (C) in the gas channel. The monitored gas flow (Fm) is a gas flow at a monitoring location (129, 130) in the gas channel and the compressible gas flow (Fc) is a flow of gas in the gas channel between the flow estimate location and the monitoring location, and the flow estimate location is remote from the monitoring location.