My brother also needs a sleep study big-time. He fell asleep at the wheel while driving us a few years ago. Hit the curb but no damage. He will also fall asleep while talking to you. Yet he is very active, Vice Commodore of his yacht club, and into all sorts of civic duties. His wife says he splutters and snores all night long.
The problem is that they both live on the other side of the world - my new avatar gives you a clue where. There is one sleep clinic in the city where they live, and it has a waiting list over a year long. Next time I visit I'll take my apap and do a self-titration with them. Better than nothing at all...
What is going on???
How about talking them into getting their doctors to at least screen with overnight pulse oximetry? My understanding is this apnea screening method has only mediocre sensitivity but good specificity for those yielding "apnea positive" results. Then an AutoPAP screening/titration test after that.
Another interesting observation about the pressure at which your AHI happens to increase: very close to that "statistically magic" 10 cm at which central apneas begin to pressure induce across the patient population as a whole. That "statistically magical" 10 cm is the command-on-apnea pressure limit at which the adjustable 420e is defaulted and the Spirit is actually "hard-limited" or "hard coded".
Another interesting observation about the pressure at which your AHI happens to increase: very close to that "statistically magic" 10 cm at which central apneas begin to pressure induce across the patient population as a whole. That "statistically magical" 10 cm is the command-on-apnea pressure limit at which the adjustable 420e is defaulted and the Spirit is actually "hard-limited" or "hard coded".
SWS - The problem with an oximetry only test is that some folks don't desat very much, but are very much symptomatic. He is more than likely not one of them, but it wouldn't help if he did that and came up empty handed...
At the lecture in DC, Dr. Rappoport talked about a patient that was the opposite, he desat to 60% and was totally without symptoms.
Kinda leads you to believe that there is something missing in the measurements...
At the lecture in DC, Dr. Rappoport talked about a patient that was the opposite, he desat to 60% and was totally without symptoms.
Kinda leads you to believe that there is something missing in the measurements...
That's primarily what makes the sensitivity of pulse oximetry as an apnea screening test so mediocre: quite a few apneics simply don't present significant desaturations. They can still have apnea and suffer because of excessive apnea-based cortical arousals. Yet, the specificity of pulse ox as an apnea screening test is actually pretty good----meaning that if a patient desaturates by night and not by day, there's an excellent chance that they have a sleep disordered breathing condition. That mediocre apnea sensitivity makes pulse oximetry a very bad tool for ruling apnea out, but the good specificity makes pulse oximetry a great tool for ruling apnea in----especially when PSG sleep studies are not available. Those who test "apnea positive" with pulse oximetry probably have apnea because of oximetry's high apnea specificity; those who test "apnea negative" with pulse oximetry may or may not have apnea because of oximetry's very mediocre apnea sensitivity.Mikesus wrote: The problem with an oximetry only test is that some folks don't desat very much, but are very much symptomatic.
Yes, Mike. I think that's precisely the connotation the medical industry implies when pulse oximetry is referred to as an "apnea screening tool" versus a definitive "apnea diagnostic tool". When a doctor out in the sticks has limited access to PSG beds, a screening tool with very high apnea specificity comes in downright handy. I don't think the medical community ever views any screening tool of any sort as definitive diagnostic means, however.
In this scenario a doctor in the sticks would be able to sort out quite a few "apnea positives" and promote them to the head of the waiting line for PSG beds or even AutoPAP titration. Those testing or screening "apnea positive" on pulse oximetry would also have compelling reason to travel to the nearest big city for definitive apnea diagnostics, if that were the only means of follow up. Those testing "apnea negative" are not off the hook because of such low apnea sensitivity.
And as you said, desaturations should be compared during both sleep and wake cycles to keep the apnea screening specificity high.
In this scenario a doctor in the sticks would be able to sort out quite a few "apnea positives" and promote them to the head of the waiting line for PSG beds or even AutoPAP titration. Those testing or screening "apnea positive" on pulse oximetry would also have compelling reason to travel to the nearest big city for definitive apnea diagnostics, if that were the only means of follow up. Those testing "apnea negative" are not off the hook because of such low apnea sensitivity.
And as you said, desaturations should be compared during both sleep and wake cycles to keep the apnea screening specificity high.