Patent Number: 6,332,463

Title: Flow estimation and compensation of flow-induced pressure swings in CPAP treatment and assisted respiration

Abstract: A method of flow estimation during CPAP treatment is disclosed and involves measuring turbine (32) speed by means of the motor's Hall-effect sensors (80). The equivalent pressure, p.sub.est, that would be developed by the turbine (32) for the measured speed if the flow were zero is estimated using a predetermined mathematical function. Coincidentally with the speed measurement and pressure estimation, the delivery tube pressure, p.sub.act, is measured by the pressure transducer (42), and from p.sub.act together with p.sub.est, the difference between the two pressures is calculated, representing an estimation of flow, f.sub.est. The flow estimation value can be linearised by the square root device (86), and then filtered by the combination of low pass and high pass filters (90, 92) to derive a filtered flow estimate value, that has the non-respiratory components removed. A method of flow compensation of flow-induced pressure swings also is disclosed.

Inventors: Farrugia; Steven Paul (Bexley, AU), Finn; Shane Darren (North Rocks, AU)

Assignee: ResMed Limited

International Classification: F04D 27/00 (20060101); A61M 16/00 (20060101); G01F 1/34 (20060101); G01F 1/42 (20060101); G01F 15/02 (20060101); G01F 15/00 (20060101); G01F 1/50 (20060101); A61M 016/00 ()

Expiration Date: 12/25/2018