(08-22-2015, 03:43 PM)richb Wrote: All Hypopnea and periodic breathing at low pressure and nearly all Centrals at higher pressure. I am currently on a ResMed S9 ST machine. My current settings are EPAP 11 IPAP 15 and a backup rate of 8. The backup rate of 8 BPM is at the same pressure as the normal settings. Last night I had an AHI of 9 and felt terrible when I got up this AM. I looked at my waveform and found erratic breathing for most of the night. ( The machine doesn't score a Hypopnea when it is providing backup breaths). I only had about 1 hour of smooth waveform indicating some level of sleep. I am trying to get an ASV machine but am worried that might not work either. I have an appointment with a new sleep center in a month.
During your centrals the ST machine is initiating IPAP for you at the backup rate (8 seems kinda slow, I think the default may be around 15, have you tried 9 or 10?), but with IPAP only 4 higher than EPAP the machine will not be able to keep you adequately ventilated.
I suggest decreasing EPAP by 1 (to 10) for a week. If the obstructive apneas stay low, I suggest lowering EPAP again, to 9 for a week. If you can manage to sleep only on your side(s) you may be able to keep lowering EPAP each week until you see an increase in your obstructive events and know you've backed off EPAP too much.
Each time you decrease EPAP (keeping IPAP unchanged) the Pressure Support (PS is the difference between EPAP and IPAP) will increase, better allowing the machine to keep you adequately ventilated during central events.
If you find you can't lower EPAP to achieve a higher PS, I recommend increasing IPAP 1 cmH2O per week, in order to increase PS.
When the PS gets as high as 8 the machine may be able to keep you adequately ventilated during central events.
But I suggest wearing a recording pulse oximeter at least once a week while experimenting, until things settle down. If your SpO2 is staying at 98% and higher most of the night, I would be concerned. When SpO2 is too high (caused by PS being constantly high) I think this would interfere with prescription meds and would be a high oxidative stress on the body, which could lead to many health problems. The type which is worn on the wrist, with separate finger sensor cup, is more comfortable and more reliable.
When I stop breathing my ASV machine increases the PS to around 8 or 9 or 10, which a big enough difference between EPAP and IPAP to do for me all the work of breathing.
If the CA Index (number of central apneas per hour) is at least 5 and larger than your OA Index then I think you will qualify for an ASV machine.
If you do get an ASV machine, I would suggest the PRS1 BiPAP autoSV Advanced with heated tube. This machine is versatile and can be operated like an ASVAuto, ASV, BiPAP ST, BiPAP Auto, fixed BiPAP, APAP or CPAP machine. (Very much unlike the ResMed AurCurve 10 ASV which can only be operated in a particularly dumb (no CA versus OA detection!) version of basic CPAP therapy mode, or in ASV modes which are restrictive and require the difference between Min PS and Max PS be at least 5.)
In my view, ResMed has shamefully disserved their ASV customers by not including central apnea detection when in CPAP mode (in a machine targeted toward patients with central apnea issues!) and by not including other therapy modes than their restrictive versions of ASV therapy. (But it's all so simple to set up and automatic.... no thanks.)