AHI over 20 at 6000ft altitude?
I was diagnosed with mild OSA (AHI 10.6 in sleep test) in 2015, and have been using a CPAP sporadically since with limited success. Most nights my AHI is in the 2-5 range, though I still don't feel particularly more rested.
I'm spending this month at an altitude of 6200ft, which has been going quite poorly for my sleep. After a few nights without a CPAP, I just got a new Dreamstation Go and was surprised to see my AHI through the roof for a few days with readings of 11.04, 10.30, and 22.34.
I raised my maximum pressure from 13cm to 16cm before that last night, which seems to only have made things worse. I remember waking up quite frequently and being annoyed by my mask going at full blast, though which of those is cause or effect is unclear. The night was going so poorly that I ended up lowering to 14cm around 4am, and down to a pitiful 9cm at 7am in hopes of salvaging at least some sleep.
Clearly something is going quite wrong here, though I can't tell what. Should I raise the pressure higher than 16cm since I was reaching that upper threshold? Lower the pressure since it doesn't seem to be helping and possibly making things worse? Suffer through a full night at 16cm? Anything else?
RE: AHI over 20 at 6000ft altitude?
I would think a few things are against you in this scenario. Higher altitude may be your cause of the CA, which is to the PAP and OSCAR clear airway, medically it's Central Apnea. Neither of your PAP machines can treat these purple CA events. You can try to avoid them by minimizing pressure swings like no flex or EPR. Don't use a ramp. Things of that sort.
Second issue is the travel PAPs like the DreamStation Go aren't as successful at treating Apnea. Your ResMed AirSense likely gives better results to you at higher elevation or at home.
Third issue that complicates all this: your Obstructive Apnea and Hypopnea are needing higher pressure but CA needs lower pressures from the machines you've got in your arsenal. The classic teeter-totter where Obstructive events are on one side and Central are on the other. If you act to push down the one side the other goes up.
You can try minimizing pressure swings to address CA but most likely the already higher Obstructive events go up.
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RE: AHI over 20 at 6000ft altitude?
Have you thought of using a pulse-oximeter to determine if oxygen desaturation is affecting your sleep process as you gasp try to get more air -- and wake up in the process?
Have you considered AMS (Acute Mountain Sickness) which can occur between 6,000 - 8,000 feet? Symptoms include fatigue and sleep disruption? You might want to ask your doctor? BTW, V***** is often used to counter high-altitude pulmonary edema.
"The sensation of disrupted sleep following ascent to high altitude is associated with frequent awakenings, which may reflect sleep disruption due to respiratory dysrhythmia consisting typically of monotonously repetitive periodic breathing. This seems to arise from the combined effects of hypocapnia, which leads to suppression of respiratory effort in NREM sleep, and hypoxia, which stimulates termination of apnea and hyperpnea with consequent hypocapnia, leading to perpetuation of periodicity. Sleep disruption and periodic breathing decrease with time at altitude but may also be considerably reduced by pretreatment with acetazolamide, which may act by correction of alkalosis or through some other mechanism. In long-term residents of high altitude less distinctive, undulating respiratory dysrhythmias are described with unstable and decreased arterial oxygenation."
https://pubmed.ncbi.nlm.nih.gov/2935358/
"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -- Marcus Aurelius
RE: AHI over 20 at 6000ft altitude?
Altitude induced central apnea is more common than you think, and there are two possible solutions. One is to use an ASV machine that actually treats central apnea. The other is Enhanced Expiratory Rebreathing Space that conserves a little CO2 from expiration to help drive respiration. Both are complicated to understand. How deeply do you want to dive into the rabbit hole? So far, your solution of adding pressure is wrong, but there is a better way.
RE: AHI over 20 at 6000ft altitude?
What is your bed and pillow situation when compared to home? In addition to the altitude and new machine induced issues, I see positional apnea increasing your Obstructive events. The first step here is to reduce the height of the pillow you are using. Is the bed 'sagging' more than your at home bed. What do you see, in addition to altitude that is different.
Yes the above comments are all valid.
RE: AHI over 20 at 6000ft altitude?
One thing to consider is that - in my opinion - ResMed and DreamStation score AHI differently from each other. So I don't think the scores should be compared.
I have both a ResMed Airsense 10 Auto and a DreamStation Auto. I sleep well with both of them, with my apnea symptoms abated. My AHI on DreamStation is 2x my AHI on ResMed. It's just a number; I feel equally rested with both.
Not that AHI is not important to consider. But I think it should not be cause for alarm when you see different numbers on the different devices.
