Adaptive Base Flow Scheduling for Ventilator Tidal Volume Accuracy
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Solution Overview
Problem
Medical ventilators face challenges in accurately measuring exhaled tidal volume due to uncertainties in flow measurements during exhalation, which can lead to false inspiration triggering and reduced accuracy, especially in neonatal conditions where tidal volumes are smaller.
Innovation Solution
The implementation of adaptive base flow scheduling and inspiratory trigger threshold adjustment during ventilation, where the base flow is increased and the inspiratory trigger threshold is decreased over time to optimize the accuracy of exhaled tidal volume measurement and prevent false triggering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If base flow is increased during exhalation to improve measurement accuracy, then exhaled tidal volume measurement accuracy is improved, but false inspiration triggering increases
Solution Approach 1:
The patent implements dynamic adjustment of both base flow and trigger threshold during the exhalation phase. The base flow increases from an initial lower value to a higher value, while the trigger threshold simultaneously decreases from an initial higher value to a lower value. This dynamic coordination allows the system to maintain measurement accuracy while preventing false triggering, as the changing parameters adapt to the physiological conditions during exhalation.
Solution Approach 2:
The patent changes multiple parameters simultaneously - base flow rate and trigger threshold - to resolve the contradiction. By increasing base flow to improve signal-to-noise ratio for volume measurement while decreasing the trigger threshold to account for the increased base flow, the system achieves both improved measurement accuracy and prevented false triggering. This multi-parameter adjustment strategy directly addresses the technical contradiction.
2Measurement precision
If base flow is increased to reduce uncertainty in flow measurements, then spirometry data accuracy is improved, but device complexity increases
Solution Approach 1:
The system uses dynamic parameter adjustment with predetermined schedules for base flow and trigger threshold changes. Rather than implementing complex real-time adaptive algorithms, the patent employs pre-programmed trajectories that automatically adjust parameters during exhalation phases. This approach improves measurement accuracy while keeping the control system relatively simple through predetermined scheduling rather than complex real-time computation.
3Reliability
If inspiratory trigger threshold is decreased to prevent false triggering, then reliability is improved, but measurement sensitivity is reduced
Solution Approach 1:
The trigger threshold is dynamically adjusted during the exhalation phase, decreasing from an initial higher value to a lower value as exhalation progresses. This time-varying threshold adapts to the changing physiological conditions and base flow levels, maintaining appropriate sensitivity for detecting true inspiratory efforts while preventing false triggers during periods of high base flow. The dynamic nature of the threshold allows it to serve dual purposes at different times.
Solution Approach 2:
The system preliminarily adjusts the trigger threshold before and during early exhalation to higher values when false triggering risk is greatest, then gradually lowers it as exhalation progresses and conditions become more stable. This preliminary protective action prevents false triggering during critical early phases while maintaining measurement sensitivity for later phases when the threshold is lower.
Data Source
AI summary
This disclosure describes systems and methods for providing novel adaptive base flow scheduling during ventilation of a patient to optimize the accuracy of estimated exhaled tidal volume. Further, this disclosure describes systems and methods for providing novel adaptive inspiratory trigger threshold scheduling during the novel adaptive base flow scheduling.