Bman, there is a chance that the Spirit's algorithm may not be best suited for you. However, that statement is true of any AutoPAP model with respect to any patient who is not receiving satisfactory results. My understanding is that the Spirit, in particular, is highly intolerant of these three physical faults: 1) condensation build-up, or any blockage, of the sensor line, 2) humidifier over-fill, and 3) excessive air leaks anywhere in the circuit, mask seal, or even an open mouth. Users have repeatedly posted that any of those three physical conditions can skew their sleep-event detection and/or consequent delivered pressure (which tends to elevate). So consider avoiding those three fault conditions to be absolute prerequisites to success with the Spirit.bman wrote: my ahi 5-10, ai 2-3
reading other postings, ?others have better results
my 95th is about 12, I wondered this is actually my fixed pressure settings.
I actually tried different settings:
5-15, results as above
5-10, more sleep apnoea
5-12, feeling less easy to start cos of low pressure
5, shocking apnoea, went over the limit
7.2 -12.6, more pressure to start with and then just high enough to stop apnoea
With a pressure range of 5 to 15, you typically achieve an AHI of 5-10 and an AI of only 2 to 3. That implies an AHI that is primarily comprised of hypopneas. Bear in mind that the Spirit will trigger on sleep events and compounded sleep events with a pressure response that is commensurate with the detected sleep-event severity (as defined by the A10 algorithm). However, you should also know that the Spirit will not trigger on any hypopneas unless those hypopneas are concomitant with either snore or flow limitation. In my guesstimation, this is the Spirit's statistically-based risk-avoidance strategy with respect to hypopneas that may or may not be central in nature. Hypopneas that are concimitant with lesser obstructive events by contrast have much less inherent statistical risk of being central in nature. The Spirit's A10 algorithm thus can and will trigger on those concomitant hypopneas with a statistical probability of safety in mind (regarding avoidance of pressure induced "runaway" central events). Also bear in mind that the Spirit is in no way neglegent with non-concomitant hypopneas as the A10 algorithm will try to leverage as much of its obstructive treatment toward proactive pressure as possible (versus exclusive delivery of reactive pressures)
While the Spirit's A10 algorithm seems to fit the apneic patient population rather well, some unfortunate hypopnea patients will have fair numbers of obstructive hypopneas that are not concomitant with either snore or flow limitation. These patients may end up with unusually high numbers of hypopneas on their overnight sleep charts (since the Spirit elects to not trigger on these non-concomitant hypopneas on a statistically-sound basis). Some of these patients will have to try another AutoPAP's algorithm or convert to using fixed pressure. However, many or perhaps even most of these non-concomitant hypopneic patients can try lowering their AutoSet's bottom pressure to proactively address many of these non-concomitant hypopneas. If those hypopneas were central in nature, you might expect your HI numbers to stay the same or even increase. If those hypopneas were purely obstructive, on the other hand, you would hope to see those elevated HI numbers decrease a bit---it really depends on how much pressure those particular hypopneas require, and whether your AutoSet bottom pressure happens to meet ot exceed that value.
