Ventilator Exhalation Flow Estimation During Sensor Failure
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Solution Overview
Problem
Conventional medical ventilators cease ventilation when exhalation flow is unreliable or undeterminable, such as during malfunctions or sensor removals, leading to disrupted patient-ventilator synchrony and impaired breathing support.
Innovation Solution
The system estimates exhalation flow using monitored exhalation pressure and auxiliary pressure, allowing for continued ventilation through a backup trigger mechanism, enabling the ventilator to maintain synchrony and deliver breaths even when exhalation flow is unknown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ventilator uses monitored exhalation flow for triggering inspiration, then the patient-ventilator synchrony is maintained, but the ventilation stops when exhalation flow becomes unreliable or undeterminable
Solution Approach 1:
The system performs preliminary calibration to establish a relationship between exhalation pressure, auxiliary pressure, and exhalation flow before the flow sensor becomes unreliable. This pre-established relationship enables the system to switch to estimation mode when the flow sensor fails, maintaining ventilation continuity without interruption.
Solution Approach 2:
The system uses exhalation pressure and auxiliary pressure as intermediary variables to estimate exhalation flow when the direct flow measurement becomes unreliable. These pressure measurements serve as mediators that allow the ventilator to continue triggering inspiration based on estimated flow rather than requiring direct flow sensor input.
2Measurement precision
If the ventilator ceases ventilation when exhalation flow is unreliable, then measurement accuracy is maintained, but patient breathing support is interrupted
Solution Approach 1:
The system accepts reduced measurement precision from pressure-based flow estimation as a acceptable trade-off compared to the alternative of complete ventilation interruption. The estimation method provides sufficient accuracy for triggering inspiration even though it is less precise than direct flow sensor measurements.
Solution Approach 2:
The system converts the potentially harmful condition of sensor malfunction into a beneficial estimation mode. By detecting when the flow sensor becomes unreliable, the system automatically switches to using pressure measurements to estimate flow, transforming a failure condition into an alternative operational mode that maintains patient support.
3Reliability
If the ventilator switches to estimated exhalation flow, then ventilation continuity is maintained, but device complexity increases
Solution Approach 1:
The pressure sensors serve multiple functions: they monitor exhalation pressure for normal ventilation control, provide auxiliary pressure measurements, and enable flow estimation when the flow sensor fails. This multi-functionality reduces the need for additional dedicated components for the estimation mode.
Solution Approach 2:
The system merges the flow estimation function with the existing pressure monitoring system. Rather than creating a separate estimation subsystem, the patent combines the estimation algorithm with the existing pressure sensor data processing, reducing overall system complexity.
Data Source
AI summary
Systems and methods for ventilation that allows the patient to trigger or initiate the delivery of a breath are provided. Further, systems and methods for triggering ventilation when exhalation flow is unknown or unreliable by the ventilator are provided.