(05-19-2016, 02:57 AM)kwhenrykerr Wrote: I would think that being as air is very compressible increasing the hose volume by adding would lessen the effect of any change in air flow until the increase in volume is overcome. The sensors that record events are going to be set for the expected volume. This longer hose may make the recorded number of triggered events change when in fact they have not.
That said I put a longer hose on my cpap to add a place to hookup the oxygen hose. It makes my numbers look better. I just know that when I use the longer hose and oxygen that the reports are false. But I feel better when it is used. Waking up without a pounding head is nice.
events are measured by monitoring the *flow* of air, you can look at the flow from your machine using sleepyhead.
a longer hose will not affect the flow readings, it will still quite accurately record your inhalations, exhalations and pauses in breathing, (apneas) as well as reductions in flow (hypopneas) those being the events that are recorded.
as mentioned, a longer hose, and thus more resistance to flow will minutely affect the actual pressure experienced at the mask, especially with a bilevel machine, which is why resmed has a setting for the 3 meter (10 foot) hose, so that that the machine can better compensate for this pressure drop.
in other words, the reports are not false.