Hello Guest, Welcome to Apnea Board !
As a guest, you are limited to certain areas of the board and there are some features you can't use.
To post a message, you must create a free account using a valid email address.

or Create an Account

New Posts   Today's Posts

Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
I’m a new member, and very regretful that I only recently discovered this site. My brief time here has convinced me that I have much to learn.

To a considerable extent the reason for my ignorance is that I was skeptical that I had sleep apnea; I thought my fatigue must be due to another cause. (When I googled fatigue, I got dozens of possible causes.) My initial sleep study ((9/2011, overnight in my local hospital) found no evidence of obstructive sleep apnea. It showed an AHI of 2.4 with 7 obstructive, 1 central, 0 mixed and 3 hypopneas. It did note snoring and severe periodic limb movements (PLMAI of 28.7.)

When my condition persisted (after trying Ritalin for a while), I had a second sleep study (this time an unattended portable polysomnography) in May, 2012, with quite different results. My AHI was 18, with 132 hypopneas, 6 obstructive apneas, and 9 central apneas; the doctor’s conclusion—moderate obstructive apnea. Although I was confused by the conflicting reports and suspected that the more elaborate overnight test was more reliable, I went ahead with the recommended CPAP therapy. After 6 weeks of conscientious use with no noticeable improvement (and with a trip to Hawaii about to commence), I decided to discontinue the CPAP (and concluded that the initial sleep study had been validated). My doctor made no protest that I should persist.

To break the tie, I have now had a third sleep study (1/2013). Again, it was an unattended portable polysomnography, and the results were very similar to the second test—AHI—21, 5 obstructive, 10 central, and 147 hypopneas. (FWIW, the the SaO2 nadir was 83 in one and 84 in the other, and less than 90% for about an hour in each.)

So my questions:

Is 6 weeks and adequate trial for CPAP therapy?

What is the reason for the significantly different results in my tests? (My doctor said no supine sleep was recorded in the lab test, but both my spouse and I THINK I am primarily a side-sleeper.) How reliable are attended and unattended tests? Is my condition just deteriorating rapidly?

P.S., I’m now scheduled to try a dental appliance.
Post Reply Post Reply

Donate to Apnea Board  
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
Ross, there is not an easy, or one answer to your question. Sometimes it does take longer that six weeks to receive optimal benefits from therapy. My doctor gives me longer to adjust. I would guess your unattended tests were accurate. How do you sleep? I used to think all you had to do was strap on the mask, turn on the machine 100% of sleep time and everything would fall into place. Compliance is an important part of the equation. You won't get better if you don't use the machine 100% of sleep time. But, if you are not getting good sleep- into REM and deep stages of sleep your body cannot repair the damage from the day. As you found out there are a lot of causes for fatigue. CPAP therapy takes a big committment- 100% of sleep time. For some of us it takes three months to feel better. Good luck with the dental device. You will need another sleep study to determine if it is effective.
Post Reply Post Reply
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
No, 6 weeks is not enough. Not for many people.

Your sleep study at home was the more accurate for several reasons:
your own bed
your own pillow
your own bedroom
the sounds, smells, etc that you are familiar with

A sleep study in a formal environment such as a sleep lab is very important. It can detect things that a home study cannot. Such as the PLMD. But it's weakness is that it is just one night in a strange environment. Home tests are best for some people who cannot sleep well or sleep abnormally away from home. The ideal situation would be for everyone to have a night or two with a home test then have a formal sleep test if the results were very high or were otherwise wonky.

It is possible that the pressure you were given was not correct. That happens. It is possible that you had a lot of leaks, which also happens.

My suggestion to you, to both help your sleep apnea and satisfy your need for answers, is to get data capable autoPAP. An APAP adjusts the pressure to your needs during the night vs maintain a single pressure, no matter what your body is requiring. Use one for at least two weeks, preferably longer. Then look at the data. You can do this yourself or trust your doc to do it for you. You can also note the AHI on the screen of most APAPs.

What that will tell you is the minimum and maximum pressure you require. You can then either pick a number in between to use as a regular CPAP or continue using the APAP using those pressure numbers as the range.

An AHI is the number of events (obstructive, central, and hypopnea) divided by the number of hours slept to get an average. Assuming you slept 8hrs on that last test, that means you had 168 events. The AHI of 21 means that each hour, you stopped breathing or had restricted breathing 21 times. And an event is not noted unless it lasts 10 seconds or more. For every 3 minutes, you had an event. For ten seconds, you stopped breathing or was basically choking. Your blood O2 dropped. Your brain panicked. To try to wake you, it made you twitch (that's the PLMD). Every 3 minutes, at least once, this happened. All night. Since no two nights are the same, sure, maybe some nights you don't have as many events, but with two studies with 20something each time, you can bet that's your usual night.

What most likely happened with the CPAP you tried is this: your body and brain are used to being woken every 3 minutes. Then now it suddenly got to experience real sleep. Some people, their body fights it, and demands the "normal" back. Some people, their body says WAY FREAKIN' COOL! and enjoys the sleep too much. Either way, they are still tired despite the treatment. Then there's the phenomenon called "sleep debt" that we all have to catch up on.

So give it another try. If you use the dental device, use it for a few weeks then do the home study again to ensure it is working (which it probably won't). Otherwise, you have no idea if it is working. When it comes to your health, assumptions are not a good thing.

Take a deep breath and count to zen.

Post Reply Post Reply
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
Yes, Ross. What Paula said.
I have been "on the hose" since October (5 months) and I am now starting to see changes for the better.

Just do it. Smile

"With ordinary talent and extraordinary perseverance, all things are attainable." - Thomas Foxwell Buxton

Post Reply Post Reply

Donate to Apnea Board  
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
What Paula said!

Every night is different for all of us. Some nights I have an AHI of 0.1, other nights I have an AHI of 3.0. Same bed, same machine, same everything. If you had the two sleep studies at home with the higher numbers, those are most likely your norm.

BTW, it took almost two months with my new prescription (previous fixed pressure of 6; now in auto mode 6-12) to eliminate the daytime sleepiness and the need for a nap in the afternoon. And that was after my AHI went from a "normal" range of 7-24 to averaging 1.2 for the last two months.
Post Reply Post Reply
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
100% agreement with what Paula and others have posted.

Best out of three puts the odds on the apnea diagnosis. I also put more stock in the home tests than the lab tests because the lab tests don't really test how you sleep, they test how you sleep in a strange, uncomfortable environment while being watched by strangers.

You ask if six weeks is enough and the answer is "probably not".

Reasons being:

-How do you know your pressure is at the proper setting for therapy to be working? I'm assuming you haven't had a titration since your lab study was seemingly unsuccessful. Did you have a home titration with an auto-titrating data capable machine? Are you using an auto-adjusting machine? Who decided what pressure or pressure range you use for therapy? Was it just a guess? Did they just hand you an auto and say "don't let the door hit you on the way out"?

PAP therapy needs to be personalized, it isn't one size fits all. No diligence in finding the right pressure with CPAP is kind of like handing a diabetic a vial of insulin and saying, "here you go, inject some of that", without knowing what blood sugar levels are.

-Are you wearing it every time you sleep? Have you gotten unintentional leaks under control? Are you sure you're using it properly?

Not using it is an obvious problem; even perfect therapy doesn't work if you don't use it.

Bad leaks are pretty much the same...the pressure won't do any good if a lot if it isn't making it to your airway.

Proper use is like this also. If you are using a nasal mask or pillows and allowing your mouth to open at night, for instance, then the therapy will escape out your mouth instead of helping you breath.

I would strongly suggest getting at least a data capable machine (if you don't already have one). This will let you see what your AHI is at the therapy level you are using every time you sleep. This will let you know, and show your doctor, if your pressure levels are inadequate. It will also show you if you are having leaks and how bad they are as well as a wealth of other info.

Even better, in my opinion, would be a data capable auto-adjusting/auto titrating machine (once again, if you don't already have one). If your pressure isn't set right, you can let the auto find the right pressure. Some folks leave autos on "wide open" and let it find the right pressure every night, others look at trends over long periods and narrow the range down to only what's needed. I prefer narrowing down, because it helps the body get used to the pressure, helps with mask fit issues etc.; but I strongly feel that an auto set to "wide open" is still much better than a static pressure PAP set to the WRONG pressure as long as you can get used to the pressure swings etc. or an auto machine set to a bad pressure range.

If you let us know what make and model of machine you have been using the members here will be better able to help you. And if you tell us what the settings are and why (for instance - pressure is set to 8cmH2O because that's where the resp. therapist set it) and AHI statistics if they are available, that will help us help you even more - even more if you can provide leak statistics. Also, if you tell us what mask/mask type you are using and how well it is working for you, we can try to help with that too.

There are lots of other things that can be suggested to help figure things out, but it is always best to cover the basics first.

Post Reply Post Reply
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
Hi Ross,
WELCOME! to the forum.!
What everyone has said so far.
Six weeks is not a long enough trial because it can take longer than that to get used to it; don't give up so quickly on CPAP therapy.
What kind of machine and mask do you have?
Best of luck to you.
Post Reply Post Reply

Donate to Apnea Board  
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
(03-05-2013, 12:43 PM)Ross Wrote: Is 6 weeks and adequate trial for CPAP therapy?
As long as it takes. It does not matter how long it take, By using CPAP you,re making a positive contribution to your health and well being.

CPAP is a treatment, not a cure. Unless it's on your nose or over your face, it's not going to be helping you when you're sleeping.

The most important finding a mask that you like and feel comfortable to keep on all night every night and the right machine is important too

Machines that provide you with information about AHI, mask leakage, time on machine etc .. for past night, or week will encourage you to be involved with the treatment

Sleep Apnea and Heart Failure: http://www.healthcare.philips.com/pwc_hc...984200.pdf

Consequences if OSA is Left Untreated:
• Hypertension
• Cardiac Arrhythmias
• Myocardial Ischemia
• Myocardial Infarction
• Stroke
• Motor vehicle and work-related accidents
due to sleepiness
• Decreased quality of life

Post Reply Post Reply
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
Ross-- My experience demonstrated, as others have said, that sleep lab results can be less accurate than home results.
My recent overnight lab results called for a pressure of 13cm to stop my obstructive apnea events. Not long after when I became aware that all was not well, a loaner auto-PAP machine (ResMed S9 Autoset) found that I actually required about 6cm higher pressure than what the lab found to truly get my apnea under control!
Neither the doctor nor I know why the sleep lab was so far off. The doc told me he spoke with the lab tech to see if I was sleeping on my back there as I do at home. I was.
Post Reply Post Reply
RE: Conflicting sleep study results. /Is 6 weeks an adequate CPAP trial?
Thanks for all the responses; you are very generous with your time. I feel more confident of my diagnosis and equipped to interact with my doctor now. I will share your thoughts and advice with him.

jgjones and trish asked about the equipment I used. My rental agreement is not easy to read for someone unfamiliar with the technology, but it appears (it’s a bit faint) to be:



S9 (hand written)
MODEL #: 1037688 (stricken out)
MANUF: RESPIRONICS (stricken out)

MODEL#: DS6H (stricken out) S9-H5i (hand written)
Post Reply Post Reply

Donate to Apnea Board  

Possibly Related Threads...
Thread Author Replies Views Last Post
  Two weeks on APAP and trying to understand Gtobot 12 695 3 hours ago
Last Post: Crimson Nape
  [CPAP] OSCAR results ovmeadows 26 379 6 hours ago
Last Post: OpalRose
  Understanding Results (OSCAR) Wperrott92 0 89 Yesterday, 07:46 PM
Last Post: Wperrott92
  Need help understanding my results Mysti 0 64 Yesterday, 02:10 PM
Last Post: Mysti
Sad Please help me change my life and interpret my OSCAR results Koalamanx 2 151 07-05-2022, 07:55 AM
Last Post: Sleeprider
  Self-Treating Sleep Apnea | First Night with CPAP = 0,87 AHI | Central Apnea? Dumdi 12 873 07-03-2022, 09:41 AM
Last Post: OpalRose
  New to forum, got some questions about results woodepgh 7 291 07-02-2022, 11:59 AM
Last Post: woodepgh

New Posts   Today's Posts

About Apnea Board

Apnea Board is an educational web site designed to empower Sleep Apnea patients.