Design continuous positive airway pressure machine

Apnea is defined as an absence of respiratory movements for a period of time. These respiratory movements may be categorised as central (no respiratory effort), obstructive (respiratory effort with absent airflow) or mixed (central pause greater than 2 seconds with obstructed respiratory efforts). Sleep Apnea is treated by using a Continuous Positive Airway Pressure (CPAP) machine. The advantages of CPAP are that if tolerated it provides a relatively risk free route symptomatic relief to a serious disorder. CPAP machines have incorporated technology as it has become available to improve the comfort and self- regulating capability to deliver therapy as needed.

The latest CPAP machines modify the pressure they deliver within individual breaths as a function of the instantaneous flow. This will improve pressure induced discomfort, by limiting unnecessary rises in pressure above the prescribed value during expiration The simplest way to accomplish this is to vary the blower speed in response to fluctuations detected in the measured pressure. A constant trade-off exists between the need to optimally set CPAP for a stable physiologic state and the need to respond with a rapid change in CPAP to state changes affecting the airway. The algorithms vary with manufacturer and are proprietary in nature.

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Originally published by Renesas Electronics at www.renesas.com as "Continuous Positive Airway Pressure Machine Reference Design".