APAP based question on reliability of Sleep Lab titrations.

I've only had eight nights on AutoPAP, but already observations on my nightly performance lead me to question the reliability of single night, or split study, titatrations that lead to prescriptions for CPAP. Maybe I'm not typical, but I have seen wide variation in the APAP levels from night to night. For example:

Day 3: 90 percentile pressure 7.1 cm H2O. AHI = 0.7 (zero apneas)
Day 8: 90 percantile pressure 13.9 cm H2O. AHI = 0.7 (zero apneas)

Big difference in pressures for the same AHI! So let's ask the question - what would have happened if I had gone to the Sleep Lab on Day 3, versus Day 8 (last night)? Would I have walked out with two very different prescriptions, and suffered with either too high or too low pressure on CPAP until another sleep study, possibly years from now?

In other words I am questionning the statistical reliability of a single night's study at predicting the true CPAP requirements of an individual, based on my own variability (which may not be typical). Is this a reason why some people are not getting relief with CPAP (titrated too low), and others are struggling with compliance (perhaps titrated too high)?

Maybe, after the titration, the patient should be sent home for a week with an AutoPAP to check for variability, and a final prescription delayed until the home data is analyzed. Or maybe the patient should be sent home with an AutoPAP - period!

Vive l'AutoPAP...
derek

Great point Derek,

A spot check with an auto is not a bad way to go.

When thinking of how your night went in the sleep lab, you must take into concideration that all sleep is effected by time of year, job stress, relationship stress and a host of other factors. This is true of breathing folks and pap folks.

Even now with an auto, I bet you have different quality of sleep during the week. That is a strong argument for the use of an auto.

Regards,

Ted

derek,

This is the way I see it. I think you are correct in your questioning of the statistical reliabilty of the Sleep Lab titration, but I don't think that the magnitude of the inaccuracy is as great as you suspect. I say this because of two reasons. One, the Sleep Lab uses much more accurate monitoring devices to detect actual events, plus in the lab the detection is augmented by the much more sophisticated algorithm that is the human brain. Two, I have found the the algorithm of the REMstar auto tends to attempt to proactively prevent potential events by reacting to mask/mouth leaks and snores by ramping up the pressure on occasion higher than is ultimately necessary. As a result on some nights the reported 90 percentile pressure is most likely higher than was in reality required. In defense of the auto, in the long run you will find the average pressure to be approximately 30% lower than using a fixed pressure machine. FYI, in my case the two auto machines I've used, the Puritan Bennett 420E and the REMstar Auto w/C-flex, over a number of months have more frequently settled on a 90 percentile pressure exacly at my 7cm Lab titrated pressure. That being said I've also experienced a similar range of fluctuation in pressure on occasion that you have.

we're all works in progress and take ea. night's data individually. It's good to know an overall average (don't I sound like I know what I'm talking about-lol) I finally got my silverlining downloaded and was pleasantly surprised and happy to learn I've been doing in the 90%'tile's also. Minimal leaks, etc. Better than I thought. But I ''feel'' better overall. Not like running a race, but better. So ea. day's perspective I guess is based on many factors, how long you sleep, quality, snoring. I was surprised to find out I still snore with all the beasts on my head/face, I would have expected ZERO. I'm not going to stress, so long as my overall ap/hypop's are down/to/low/to none, I'm content.

Bigger pic, Does anyone ever truly eliminate aps, hypop's, ever?

I don't think so in my case, but any improvement is a good start on the road to better overall health.

I think the sleep lab tiration study is so skewed, it's just really a thumbnail summary for the doc to scribble you a scrip and OUT YOU GO. My doc did not go thru the entire loose leaf binder (as I watched him before he came in) he strictly read the 2 pg summary which I forced them to copy a cy for me, and read the "recommendation" section,a nd was reaching for his prescription pad to write me a straight CPAP at 12, when I whipped out my APAP request, he just basically was leaving the room. SO I had to go round and round with is RT to change it, she sighed and flummoxed around, but I persisted.

If Liam wants I'll go get his scrip, they'll give it to me to just shut me the heck up...!!

go APAP. IMHO
Oh, and I forgot in my summary of the last 3 wks on apap, I averaged about a 10.5. The CPAP was for 12, and then they changed it to 14. So if I was on straight CPAP, by now my sinuses would be blown out of town....

Beauty of apap, gives what you need, when you need it,and when you don't, it doesn't. simple really.

Keep hosing...

derek wrote:I've only had eight nights on AutoPAP, but already observations on my nightly performance lead me to question the reliability of single night, or split study, titatrations that lead to prescriptions for CPAP. Maybe I'm not typical, but I have seen wide variation in the APAP levels from night to night. For example:

Day 3: 90 percentile pressure 7.1 cm H2O. AHI = 0.7 (zero apneas)
Day 8: 90 percantile pressure 13.9 cm H2O. AHI = 0.7 (zero apneas)

Big difference in pressures for the same AHI! So let's ask the question - what would have happened if I had gone to the Sleep Lab on Day 3, versus Day 8 (last night)? Would I have walked out with two very different prescriptions, and suffered with either too high or too low pressure on CPAP until another sleep study, possibly years from now?

In other words I am questionning the statistical reliability of a single night's study at predicting the true CPAP requirements of an individual, based on my own variability (which may not be typical). Is this a reason why some people are not getting relief with CPAP (titrated too low), and others are struggling with compliance (perhaps titrated too high)?

Maybe, after the titration, the patient should be sent home for a week with an AutoPAP to check for variability, and a final prescription delayed until the home data is analyzed. Or maybe the patient should be sent home with an AutoPAP - period!

Vive l'AutoPAP...
derek

Hi,

Ok...in addition to sleep apnea I'm now addicted to posting on CPAPTALK!

My sleep doctor wrote a Rx of 8-12 based on my sleep study.

Then...was set-up with a APAP for 3 weeks.

My RT came, went over the data with me, and set a pressure for me based on the data. (within the range set by the doc's rx)

So, I'm using a Respironics CPAP with Flex, set at 8. After reading about the love affair many have here with APAPs i'm wondering why I didn't get one, especially given that my insurance covers the cost. I will ask my RT, but so far, 8 isn't so high and not causing me any problems. But I agree with the original post, that one night is not enough to go on.

Darren

VancouverBreeze wrote:Ok...in addition to sleep apnea I'm now addicted to posting on CPAPTALK!

Wow, it's like crack cocaine. 5 posts, and he's ALREADY addicted. I guess that makes me an old crack ho, and Wader and rested gal life-long heroin addicts.



Welcome, VB, I totally feel your "pain".

Liam, might as well face it you're addicted to cpaptalk.com.

Liam,

It's your humor that we are all addicted to.

I have been wondering about the accuracy also. I have yet to have a night at my titrated pressure 10(always higher). As of late it seems I could even go to 15 or 16 on the high end . Overall 12.5 seems to be the average.

Hi all,

I have been on my PB420E for 8 days with a range of 10-16.5 (recently)and IFL1 turned off. My average pressure seems to run about 12, but my 90% pressure is 15-16, which is above my titrated pressure of 14. The indexes are low, with the possible exception of the acoustical vibrations, so I think that it is working better than my CPAP, and I am sleeping well and feeling better.

I am not sure what the significance of this is (or if it is normal). I have not waded through all the manuals yet -- I've been on vacation and really busy after getting back home! If anyone would like to help me out understanding the software results better, I would be grateful!

Thanks,

Jane