Functional Residual Capacity Determination via Nitrogen Washout
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Solution Overview
Problem
Conventional ventilation systems that measure functional residual capacity are unreliable at high oxygen concentrations and require oxygen consumption measurements, which are not feasible in all scenarios, especially for mechanically ventilated patients with reduced functional residual capacity.
Innovation Solution
A system comprising a processor that receives sensor output signals from the airway to determine gas concentrations, identifies inhalation composition changes, calculates alveolar ventilation, and uses a lung model to determine functional residual capacity without measuring oxygen consumption, utilizing a concentration module, composition change module, alveolar volume module, and functional residual capacity module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ventilation systems use oxygen consumption measurements to determine functional residual capacity, then measurement capability is provided, but reliability deteriorates at high oxygen concentrations (greater than 80%)
Solution Approach 1:
The patent extracts the measurement dependency from oxygen consumption and relocates it to nitrogen concentration measurement. By removing the reliance on oxygen consumption measurements and substituting them with nitrogen concentration tracking, the system achieves reliable functional residual capacity determination even at high oxygen concentrations where oxygen-based measurements fail.
Solution Approach 2:
The patent changes the measurement parameter from oxygen consumption to nitrogen concentration. This parameter substitution allows the system to operate reliably across the full range of oxygen concentrations, particularly resolving the unreliability issue at high O2 levels by using nitrogen as the alternative measurement parameter that remains stable and measurable regardless of oxygen concentration.
2Measurement precision
If oxygen consumption measurements are used to determine functional residual capacity, then measurement is possible, but device complexity increases due to integration requirements with ventilation system
Solution Approach 1:
The patent extracts the measurement function from the complex integrated ventilation system and creates a standalone capability using nitrogen concentration measurement. This separation reduces device complexity by making the functional residual capacity determination independent of the ventilation system's oxygen delivery and consumption measurement infrastructure.
Solution Approach 2:
The patent introduces nitrogen concentration as an intermediary measurement parameter that bridges the gap between available sensor data and functional residual capacity determination. This intermediary approach uses existing airway gas composition measurements to derive functional residual capacity without requiring direct integration into the oxygen delivery system, thereby reducing complexity.
3Productivity
If real-time functional residual capacity determination is implemented, then dynamic therapy adjustment is enabled, but measurement feasibility deteriorates without oxygen consumption data
Solution Approach 1:
The patent changes the measurement parameter from oxygen consumption to nitrogen concentration, enabling real-time functional residual capacity determination using gas composition data that is continuously available during mechanical ventilation. This parameter substitution maintains measurement feasibility and reliability in real-time scenarios where oxygen consumption data may be unavailable or unreliable.
Solution Approach 2:
The patent implements a feedback mechanism using nitrogen concentration measurements from exhaled gas analysis. By continuously monitoring nitrogen concentration in exhaled breaths and using this feedback to calculate functional residual capacity in real-time, the system enables dynamic therapy adjustment without requiring oxygen consumption measurements, thereby maintaining both productivity and reliability.
Data Source
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AI summary
A system and method that determine the functional residual capacity of a subject in an automated manner. The determination of the functional residual capacity of the subject is made by analyzing the washout and/or wash-in of one or more molecular species present in gas breathed by the subject. The determination of the functional residual capacity can be made without a determination of oxygen consumption.