CPAP technology is based on positive air pressure. The air pressure is intended to keep your airway open rather than the condition which causes sleep apnea events. The technology is often very effective in reducing these events but zero is seldom the result. I suspect one of the main medical issues caused by these events is that when you stop breathing, blood oxygen level can get very low. A second major issue is that sleep never reaches its deepest state where you feel rested. Someone mentioned 5 events per hour as normal and while five or less per hour may be the technical definition, I would not be comfortable with breathing stoppage that frequently. It is certainly better to have an AHI of 5 rather than 55 but to stop breathing five times per hour would concern me; especially if blood oxygen level dipped low at those points. I track my AHI history using the Resmed.com/myair app on my computer and I have had 3 nights of sleep out of the last 14 days where there were zero AHI and the others have been less than 1 per hour. I am not sure WHY there are any with positive air pressure but I am guessing it is normal to have some. How to get to zero on a continuing basis is something a med professional would have to elaborate on I guess and I am not sure a person who doesn't suffer from sleep apnea is at zero. Just don't know.
Hey Orphan I am currently running at around 0.8 at worst, 0.48 average and an occasional 0 too usually once a week at the moment. 10 years I was 8 to 10 and stopped breathing for sustained periods and I am pretty sure I never had a 0 in the first years. I am beginning to think that the latest technology is capable of keeping you really low and potentially at near 0 and almost trains you to be better. Either that or they intervene (if autoset) earlier, stay at the necessary level to avoid repeats.
I have Autoset/autopap and that literally means that some nights the machine doesn't even crank up. When I take off the nasal mask (which I sometimes do for a couple of hours in the morning, when I wake up after 6 to 7 hours of sleep, if I happen to fall back asleep I do snort and wake up suddenly so there is little doubt I still have apnea. The machine is controlling and minimising it.
Thank you for the response
The part I am currently have trouble understanding is the correlation between my sinus problems and my apnea and whether one affects the other and which way round.
I have my first month checkup at the hospital this week and the technician told me the machine I use and the data it records is too complicated to explain and I should contact the manufacturer if I want more guidance. I am totally appalled at her response and how unhelpful it was.
I am also interested to know how a home sleep study records ahi versus the cpap machine as the later is obviously recording all the events so seems far more efficient at the calculations than the home study
Can't speak to the home study but I do know it involves equipment. It is a viable means of getting useful sleep/apnea info I think. The sinus thing is easy. If you have sinus issues, that means breathing through your nose is more difficult at times and I suspect that will affect your therapy strategy. You should talk with an ENT to help resolve the sinus stuff as it would make PAP therapy a lot more simple. As far as the "technician" who told you that you just are not capable of interpreting data; well, I would ignore the person, gather data and start self educating cuz it just ain't rocket science once you get by some of the scientific jargon. If they put the results into English, anyone could understand most, if not all. You have to sit down and look up words to find out they are often not complicated concepts just medical training has to pin these concepts to $3 words. Keep after the self education and I bet you are farther along than the therapist at some point.
I shall try to cover the various queries in this post as succinctly as possible, but I may get lost. CPAP is supposed to lower AHI, but the AHI on your download will rarely be zero. On a download, and AHI of 5 or less is generally considered good because of the the machine measures data. It detects events using only pressure. If your are breathing well, the pressure fluctuation created by your inhalation and exhalation is very regular. When it changes at all your CPAP machine is inclined to count this an event. The manufacturers say that they have some fancy software to refine things, but generally speaking, if your breathing changes they count it. Now, this may be due to an apnoea or hypopnoea, but it may also be because you cough, roll over, twitch or anything else which causes a slight change in your breathing pattern. For this reason, the AHI stated on a CPAP download will always be an overestimate and so most people will never get zero, which is why we have the idea of anything less than 5 being OK. People with Periodic Limb Movement Disorder (similar to restless leg syndrome) will almost always have a very high AHI because they twitch a lot. For this reason they can't use an auto CPAP because it thinks the twitches are apnoeas and maxes out the pressure in an effort to stop them.
In a sleep study, apnoeas and hypopnoeas are detected by a range of sensors. It involves a drop in air flow (detected by nasal pressure and a thermister) accompanied by a decrease on oxygen saturation (detected by an oximeter) or a change in brain activity (measured by an EEG). This adds up to a bare minimum of 4 wires. However, in order to classify the type of event, the effort of your breathing muscles is measured (requiring a strap around your stomach, chest or both which is cheerfully called an inductance plethismograph - say that without your teeth in). This allows us to tell if the events are obstructive or central. Limb movements should also be measured on order to eliminate changes in breathing which are caused by leg twitches (as mentioned above). Overall, this is a lot more detailed and sensitive than just using air pressure as a guide, so this is why a proper sleep study is always considered more reliable than the download data from your CPAP machine.
OrphanAnnie, I am rather surprised that your technician told you that the data your machine records is too complicated. The software can be a bit of a mess, but the data is quite simple and not that hard to understand. I can only suggest that you call the hospital, speak to someone else who works at the sleep lab and ask them to explain the results to you. Having said that, there's not much to explain from a download, but they should still be able to answer your questions about it. That's what I do all the time at work.
Regarding your sinus problems, it will probably affect which mask you use, whether you use a humidifier and such, but it is totally independent of your sleep apnoea. Your sinuses are between your nose and mouth, but obstruction due to sleep apnoea happens at the back of your throat, so they are in separate parts of your head.