Importance

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Abstract

A directional sensor for the detection of a very feeble effort to breathe on the part of a patient whose breathing needs are under the influence and control of a mechanical ventilator. A self-heated thermistor assembly is mounted in a small diameter sensor tube. A diaphragm and chamber arrangement provides a low volume flow of air in the sensor tube past the thermistor assembly at a high velocity, so that a very small effort to breathe will draw a limited volume of air past the thermistor assembly at a high velocity, causing rapid cooling. The air will flow past the thermistor assembly in a first direction in response to an inhalation effort, and in a second direction in response to an exhalation effort. A heating element is arranged in the tube so that a first temperature-related voltage change is produced across the thermistor assembly when air flow is in the first direction, and a second such temperature-related voltage change is produced when air flow is in the second direction. The first voltage change resulting across the thermistor assembly is utilized to signal a patient effort to inhale and to command the ventilator to furnish an appropriate response, while the second voltage change, signaling an exhalation effort, is used to block such a response.

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First Claim