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Adventures in AHI
#1
Hello all. I thought I'd start a new thread to describe some interesting things that have gone on recently. Back story: 64 years old, with complex apnea, using a Philips System One ASV. I had been experimenting with manual backup rate settings, instead of auto. That's described in another thread tucked away here somewhere.

Anyway, I was doing very well with PSmin=0, EPAPmin=8.5, BPM=5. My AHI with these setting was consistently around 1.1. Note the past tense.

On December 26, I flew with my family from Philadelphia to Taiwan for a 16-day holiday. I expect a bad night after a long flight, and indeed the first night in Taiwan, my AHI was 5.2. But after that it settled right down. In fact, it stayed at about 0.8 for a week, and I felt fine. Then we took a four-day trip to Tokyo. Interestingly, for all four nights in Tokyo, my AHI was higher, between 4 and 5, with a number of centrals sneaking in. I didn't change the machine settings during any of this. Then we went back to Taiwan for a couple of days before returning to the US. In Taiwan, my AHI dropped back to around 1.0.

I realize we're not talking about a lot of nights, but it's interesting how the AHI changed in Tokyo.

Anyway, upon returning to the US I had to deal with some horrible jet lag for up to a week. For some reason, it's much worse for me when traveling eastward. I've made this trip once before and had the same experience. Back in the States, my AHI rose back up to around 4.5 and stayed there for a while. Even after the jet lag was over, my AHI didn't want to come back down for a while. Gradually, over a period of a month or so, it started to drop back down. As of last week, it was back down to around 1.3. Then I got some kind of head cold with a cough, leading to some high numbers, such as 11.5 last night, and 10.6 two nights ago. I had a hard time getting to sleep last night (unusual for me) due to this dry itchy cough, and I woke up three times feeling like I had a fever.

I realize that AHI numbers are pretty meaningless when you're sick in a way that interferes with normal breathing. What's more interesting to me is the way the travel disrupted my sleep, and how long it took to return to "normal" AHI.

One other thing: A while back, I decided not to check AHI until the end of the day, rather than checking it when I wake up. I discovered that the correlation between AHI and how rested I feel is very weak. In fact, I have to say that the days after a very low AHI night are generally not the days when I feel most rested.
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#2
That's interesting tmoody and I agree with what you have to say about AHI and how you feel. I don't find them proportionate at least not on a daily basis. And isn't it crazy how long our body stays out of sorts when we interupt our routine!
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#3
Welcome back to the Commonwealth.

I've seen many examples posted on Apnea Board of the AHI being below 5, yet the patient claims less restful than at a bit higher AHI. I've had it happen to me; I've gotten a zero AHI or a 0.2 or some such, but wasn't as well rested as I felt on other nights with a bit higher number such as 1.8. Why? I don't have the slightest clue really. The deepest answer I come up with is because life gives us random criteria to deal with so we don't get bored. Even when I was not on PAP therapy, I had good and bad nights of sleep, so I don't think it is only related to AHI and the PAP machine. We just sometimes benefit more from the sleep we got from that night's rest.

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Dave

I'm not a doctor in real or fictional life. My posts include opinions based upon user experience regarding CPAP therapy and should not be considered medically professional direction or advice. Even a 1,000 mile trip requires a good first step. My recommended first steps include getting good walking shoes, 1 great cup of coffee, and a good GPS.

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#4
When I was in the military I always found traveling east was harder to adjust to also. So the take away is, if your going to travel keep heading west and skip Tokyo.
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#5
(03-13-2018, 10:08 AM)Walla Walla Wrote: When I was in the military I always found traveling east was harder to adjust to also. So the take away is, if your going to travel keep heading west and skip Tokyo.

I'll make a note of that.

My only theory about Tokyo--and this is pretty lame--is that it had something to do with altitude. In Taiwan we were consistently near sea level, but in Tokyo our room was pretty high up in a high-rise hotel. 19th floor, I think it was. It was enough that I'd feel the change in pressure when taking the elevator up to the room. I know altitude can affect apnea, especially centrals, but I still think that's kinda far-fetched. It's not like I was up on Mt. Fuji (which I could see from my room!).

And yes, JesseLee, it's eye-opening to see how seemingly minor disruptions in routine can cause major changes in sleep.

As for the lack of correlation between AHI and the feeling of restedness, I have this theory that at least sometimes the low AHI is the product of the machine very aggressively managing things and causing lots of micro-arousals in the process. This is why I started my experiment with the backup rate, in fact.

For over nine years, I used a ResMed S8 set to 11. I had no data, and I also had no sleep problems that I knew about. I felt fine. The fun didn't start until I was put on APAP. I know now that it's very likely that old S8 was not delivering that pressure of 11 during the last part of those nine years. These things don't last forever. But I wonder if there's a way to set the Philips ASV to straight CPAP mode, just for the hell of it.
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#6
Yes, low numbers do not always mean you feel at your best, I was constantly getting 0.0 until I ran into illness.
Then it all went south with the Geese. Now I am starting to recover the numbers have come back to 0.2 from 0.4 and I caan honestly say that since it came down to 0.2 I feel no different than when it was 0.0, however, it was nice to see I could get there, but if I get back to that, that's fine, but 0.2 will do me anyway. There was one night it went way up to 6 and I did feel it after a few nights at that, nothing desperate, but I did feel it. But then I wonder how much feeling unwell didn't help.
By the way, I wouldn't want any of you to get this virus (doctor says it was a virus of some sort) as it knocks you for six and affects your vision and leaves you with no energy! Not surprising that when the old hit these types of viruses some surcome to them. I honestly thought I was touch and go before I got an anti-biotic.

The lowest numbers do not make me feel at my best, but a low number does.

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#7
I have found that getting strenuous exercise for a few days will quickly return my AHI to at or below my normal levels.

Another observation you may want to look at is RDI instead of AHI. Does your machine track RERAs? If so compare RDI numbers by location. I don't know if your machine can track User Flag 1 and 2 events in SH (See CPAP tab under Preferences) but if it does it would be interesting to see how many of those events you had on high or low AHI nights. Then compare to your location.
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#8
I travel a lot for work and even though I have not been on CPAP therapy for very long, I can confirm most of your observations:

1) the first night after travelling my AHI is less good
2) it takes quite some time for the AHI to settle down again
3) altitude makes a significant difference

I have found that the change of bed plays a huge role in the way that I lie while sleeping (posture), which influences my AHI. This seems quite logical, to the point where one easily overlooks it.

We are currently on holiday at the seaside, which one would expect to lead to high levels of relaxation (little to no stress, little "bad" fatigue, etc). BUT, the bed is hard and I am uncomfortable during the night. Due to the hard bed, I seem to "crunch up", compressing my airway/lungs. My pressures are therefore way higher than normal. They were normally around 7 - 11 cmH20, now they are 11 -17 cmH2O. Just for comparison, for two weeks before the holiday I was at the seaside for work and my pressures were still around 7 - 10 cmH2O, BUT the bed was very comfortable.

I guess that we need to adapt to any kind of situations - and the APAP machines will help us to do it. One must HANDLE the changes, but concentrate on the results in your "natural habitat".
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#9
Your BPM is uncommonly low for SV treatment, and that may account for some event getting in that otherwise might not occur. The pressure increases and backup breaths may be more disruptive for you than the apnea. I think you have carefully experimented with pressures and backup rate, so I have no recommendation, other than this might be an area to look at as causative for the increased AHI.
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