PAP Device Motor Current Sensing for Respiratory Phase Detection
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Solution Overview
Problem
Existing positive airway pressure (PAP) devices for treating respiratory disorders, such as Sleep Disordered Breathing, often require flow or pressure sensors to control pressure settings, which can be cumbersome and less comfortable for patients. Additionally, they struggle to accurately detect transitions between inspiration and expiration phases without additional sensors.
Innovation Solution
A method and apparatus that use motor current measurements to control blower speed and pressure in PAP devices, employing derived current signals from filtering and comparison processes to determine inspiration and expiration phases without the need for flow or pressure sensors, allowing for adaptive pressure adjustments during respiratory cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow or pressure sensors are used to control pressure settings in PAP devices, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces mechanical flow or pressure sensors with an electrical measurement system. Specifically, it uses current measurements from the blower motor to infer respiratory flow and pressure conditions. The controller analyzes motor current characteristics (such as RMS current, peak current, or current derivatives) to determine when to transition between inspiration and expiration phases, eliminating the need for separate flow or pressure sensors while maintaining adequate measurement precision for pressure control.
2Measurement precision
If flow or pressure sensors are used to detect respiratory phases, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the blower motor serve multiple functions: it not only delivers pressurized breaths to the patient but also acts as a sensing element for detecting respiratory phases. By monitoring the motor's current consumption patterns during operation, the controller can detect transitions between inspiration and expiration phases without requiring dedicated flow or pressure sensors. This multi-functional approach reduces device complexity while maintaining adequate detection precision.
3Measurement precision
If additional sensors are added to PAP devices, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent extracts the sensing function from separate flow or pressure sensors and integrates it into the existing blower motor system. By using the motor's electrical characteristics (current measurements) as the sensing mechanism, the invention removes the need for additional sensors that would complicate the device. This simplifies the overall system while maintaining the capability to measure respiratory flow and detect phase transitions with adequate precision.
Data Source
AI summary
A respiratory treatment apparatus generates an indication of inspiration or expiration based on a measure of motor current of a flow generator. In an example, first and second current signals are derived from the measurement. The first derived current signal may be a long term measure or average of current and the second derived current signal may be a short term measure or average of current. A processor 120 determines an indication of inspiration or expiration as a function of the first and second derived current signals. The function of the first derived current signal and the second derived current signal may be a comparison of the derived current signals. The derived signals may be determined by filtering. The indication of inspiration or expiration may serve as a trigger or cycle control for changing treatment pressure in synchrony with patient respiration without measured signals from pressure, flow or speed sensors.