CPC A61M 16/0069 (2014.02) [A61B 5/087 (2013.01); A61B 5/097 (2013.01); A61M 16/0003 (2014.02); A61M 16/024 (2017.08); A61M 16/06 (2013.01); A61M 16/20 (2013.01); A61M 16/0683 (2013.01); A61M 16/107 (2014.02); A61M 16/1055 (2013.01); A61M 2016/003 (2013.01); A61M 2016/0021 (2013.01); A61M 2016/0027 (2013.01); A61M 2205/3317 (2013.01); A61M 2205/3327 (2013.01); A61M 2205/3334 (2013.01); A61M 2205/505 (2013.01); A61M 2205/52 (2013.01); A61M 2230/40 (2013.01)] | 25 Claims |
1. A method of a respiratory treatment apparatus for determining an indication of inspiration or expiration, the method comprising:
measuring current supplied to a blower configured to provide a respiratory treatment;
deriving first and second current signals from the measured current by filtering the measured current, the first derived current signal being a long term measure of current, the second derived current signal being a short term measure of current; and
repeatedly determining, by a processor, indications of inspiration or expiration by comparison of the first derived current signal and the second derived current signal, wherein the comparison generates a control signal to set a speed change of the blower,
wherein a first compensation signal is added to the first derived current signal based on an indication of inspiration of the indications, and a second compensation signal is added to the first derived current signal based on an indication of expiration of the indications, wherein the first compensation signal and the second compensation signal are values of current.
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