Administration of CPAP treatment pressure in presence of apnea
View Patent ↗A method and CPAP apparatus for automatically adjusting a continuous positive airway treatment pressure delivered to a patient responds in different manners according to the type of breathing problem. If a respiratory event is an apnea at a treatment pressure below a first value, then the treatment pressure is increased in one manner. If the respiratory event is a partial upper airway obstruction at a treatment pressure below a second value, then the treatment pressure is increased in a different manner; where the first pressure value is less than the second pressure value. In particular, obstructive and central apneas are treated differently by the apparatus.
1. A Continuous Positive Airway Pressure device that detects flow limitations and apneas of a patient under treatment during sleep and in response thereto auto-adjusts the treatment pressure comprising:
a breathing tube connectable to a mask for delivery of a supply of air or breathable gas at a treatment pressure to an entrance of the patient's airway;
a motor driven blower adapted to provide the supply of air or breathable gas to the breathing tube at a controllable pressure;
a flow sensor arranged to determine a flow of air to the patient;
a controller adapted to detect flow limitations and apneas from said flow signal, and being further adapted to control the treatment pressure in accordance with an auto-adjusting algorithm;
the auto-adjusting algorithm being characterized in that:
the treatment pressure has a range defined by a minimum pressure and a maximum pressure; and
in response to flow limitations, the treatment pressure is increased to a pressure no higher than the maximum pressure; and
in response to apneas, the treatment pressure is increased to a pressure no higher than an apnea cap pressure, wherein the apnea cap pressure is a pressure that is less than the maximum pressure.
2. The device of claim 1 wherein the minimum pressure is about 4 cmH 2 O.
3. The device of claim 1 wherein the apnea cap pressure is about 10 cmH 2 O.
4. The device of claim 1 wherein the maximum pressure is about 20 cmH 2 O.
5. The device of claim 1 used for treatment of Obstructive Sleep Apnea or Upper Airway Resistance syndrome.
6. The device of claim 1 wherein the auto-adjusting algorithm is further characterized in that the treatment pressure is reduced towards the minimum pressure if apnea is not detected.
7. The device of claim 1 wherein the auto-adjusting algorithm is further characterized in that the treatment pressure is reduced towards the minimum pressure if flow limitation is not detected.
8. The device of claim 1 wherein the auto-adjusting algorithm is further characterized in that the treatment pressure is reduced towards the minimum pressure if apnea and flow limitation are not detected.
9. The device of claim 1 wherein the auto-adjusting algorithm is further characterized in that an increment in pressure in response to an apnea when the treatment pressure is close to the apnea cap pressure is smaller than an increment in pressure in response to an apnea when the treatment pressure is close to the minimum pressure.
10. The device of claim 1 wherein the auto-adjusting algorithm includes a leak compensation procedure.
11. The device of claim 10 wherein the leak compensation procedure comprises adjusting the flow limitation threshold if there is a large leak.
12. The device of claims 1 further adapted to distinguish open airway apneas and closed airway apneas using forced oscillation.