sleeptech

The lowest pressure any machine can be set at is 4 (with one or two exceptions, but those machines have been out of circulation for over a decade). The ramp can be set to start at any pressure and the time it takes is also adjustable on most models. I think what Gerbil is saying, is that their CPAP is set at 10 and when they press the ramp button it drops to 8. If you have a ResMed S8 or later machine (such as Wiredgeorge) there is no ramp button, but the ramp is activated every time you start it. You should be able to get any CPAP provider to drop your ramp start pressure and probably increase the ramp time (although without knowing the model of your machine it is hard to be definite on the available functions). This does not affect the treatment level, and so it should not require a visit to the doctor (not in Australia any way).

Sometimes, but not often, central apnoea can respond to oxygen therapy, either partially or completely. It does require a proper study with full monitoring (including transcutaneous carbon dioxide monitoring) to make sure the oxygen is not causing any ill effects. Also, in some of our patients central apnoea has reduced one their heart function has improved, and they only need CPAP. Also, the increased mortality for people with low ejection fraction only applies to ASV, not standard BiPAP. Standard BiPAP may very well be effective in treating central apnoea without needing ASV and, indeed, it should be the dsefault choice. ASV was designed specifically for treating Cheynne-Stokes respiration in the setting of hypocapnea, not just as a BiLevel Swiss Army Knife. Although ASV has auto in the name, IT IS NOT and automatic BiPAP and was never designed to be one (I have spoken with the team who first deigned it).

Worth remembering that home studies can be less reliable than a proper, monitored, in-lab study. It mostly depends on which equipment they use. We use 25 sensors to measure at least 19 different parameters (some parameters use 2 sensors). Some home study kits use a few as 3 or 4, and fewer sensors means less data and therefore less reliable results. I not very familiar with healthcare in the US (Where I assume you are), but having a trusted doctor to talk to about it is also very worthwhile, as they can take you entire health history and situation into account. Some of my patients have used Secondwind CPAP with good results.

Which mask are you currently using, and which have you tried? It is a good idea to get a professional to help you with mask fit and adjustment when you first get it, as this can make a difference. My personal favourite full face masks are the Fisher & Paykel Simplus and the Phillips/Respironics Amara View. Getting the right mask and the right size can often mean that it doesn't need to be as tight or uncomfortable, and also remember that a little leak isn't the end of the world if you sleep better. Have you considered a nasal mask and chin strap? Plenty of people with high pressures (such as yours) still use nasal, and it would help with your dry mouth. Another tactic to lower the pressure (and thus improve mask fit and decrease dryness) is to find a way of staying on your side while you sleep, because some people can get away with a lower pressure while on their side. Are you sure that you are using you humidifier correctly? A lot of my patients don't.

I work in a sleep lab, and your AHI of 80 is high, but certainly not record breaking by our standards. We regularly get people with AHIs over 100 ,and I have seen a couple over 200. There is a theoretical maximum based upon the rules for scoring (analysing) sleep studies, but it is not exact. You have to have decreased respiration for at least 10 seconds for it to count (along with either a decrease in oxygen saturation of at least 3% or an observable arousal in EEG). Then, you would require a second or two to take at least one breath for the event to be over before you start the next one. If we call it 2 seconds for a breath, that gives us a theoretical maximum AHI of 300. As Dr Luisi suggested, it's worth remembering that AHI is only part of the picture.