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Do Not Sleep w/CPAP For Two Nights Before New Sleep Study ?????
Someone in another forum who has been on CPAP faithfully every night at 11 cms for 5 years had gained some weight and was brought in for a new sleep study. This person had been told to NOT use their CPAP for TWO nights before the new sleep test but continued to use their CPAP anyway those two nights..
The test was a split night. 3 hours after starting this person was switched to using CPAP and mask. The new setting was 7 cms. But this person couldn't sleep at 7 cms and felt like not getting enough air and couldn't breathe so reset pressure back to 11 cms.
Did continuing to use the CPAP the two nights before the split night study skew their split night titration? I've read of one other person going in for a new evaluation and titration being told NOT to use their CPAP the night before their new study.
What is the basis for this not using CPAP before a new PSG? Is it valid? Does using CPAP the night(s) before a repeat PSG really affect test results??
The test was a split night. 3 hours after starting this person was switched to using CPAP and mask. The new setting was 7 cms. But this person couldn't sleep at 7 cms and felt like not getting enough air and couldn't breathe so reset pressure back to 11 cms.
Did continuing to use the CPAP the two nights before the split night study skew their split night titration? I've read of one other person going in for a new evaluation and titration being told NOT to use their CPAP the night before their new study.
What is the basis for this not using CPAP before a new PSG? Is it valid? Does using CPAP the night(s) before a repeat PSG really affect test results??
Views: 27
Replies to This Discussion
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Permalink Reply by sleepycarol on
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Interesting. I have heard this from others, but don't see how using your cpap affects your data during a sleep study so am very interested in the answers.
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Permalink Reply by amott1973 on
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Interesting. I'd never heard of this, and they didn't ask me to do that before my last sleep study when they tried to do a split night study. I had a horrible time even falling asleep without my mask during the split night study and hence they weren't actually able to do it. Maybe if I'd "practiced" sleeping without my mask for a few nights I'd have fallen asleep easier? That's the only reason I can think of to ask someone to do without it before a study.
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Permalink Reply by Daniel on
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If they are doing a new diagnostic study, or the first half of a split night, tthe results can be skewed by the residual effect of using a CPAP. At one point, Stanford advised staying off CPAP for a week prior to the test. Remember, this test is to determine whether or not you have sleep apnea and how severe it is.
In the case of someone who is being retitrated, I don't see that it would make a difference. The fact that you have sleep apnea has already been established. You are merely redetermining pressure settings. However, if the reason for the repeat study is because a patient has lost significant weight, it would make sense to redo the diagnostic part of the study, since the patient might conceivably not need CPAP anymore. If that patient used CPAP right up until the night of the study, it is possible to get a false negative, and think that s/he doesn't need CPAP anymore, when there may still be a need.
I hope that explanation made some sense...
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Permalink Reply by RockRpsgt on
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I have never heard of this. I would guess it would be to build up some sleep debt, and to get used to sleeping without it so that a split study could be performed.
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Permalink Reply by Judy on
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Residual effects of using CPAP???? THAT I do NOT understand. Or maybe I was just too gullible when I was told repeatedly and read in the support forums repeatedly that we NEED to use our xPAPs EVERY time we sleep, that even one nap w/o CPAP was going back to square one like we'd never used CPAP as far as SDB was concerned. Too much for my beady ole brain to wrap around.
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I see the problem. A person whom has not yet been diagnosed with apnea should not have a CPAP machine.
Daniel said:If they are doing a new diagnostic study, or the first half of a split night, tthe results can be skewed by the residual effect of using a CPAP. At one point, Stanford advised staying off CPAP for a week prior to the test. Remember, this test is to determine whether or not you have sleep apnea and how severe it is.
In the case of someone who is being retitrated, I don't see that it would make a difference. The fact that you have sleep apnea has already been established. You are merely redetermining pressure settings. However, if the reason for the repeat study is because a patient has lost significant weight, it would make sense to redo the diagnostic part of the study, since the patient might conceivably not need CPAP anymore. If that patient used CPAP right up until the night of the study, it is possible to get a false negative, and think that s/he doesn't need CPAP anymore, when there may still be a need.
I hope that explanation made some sense...
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I think this is a wierd rule. Most labs reduce the split titration protocols for pts that are already on PAP therapy. Unless someone can explain it to me better I see no reason for this practice. I have worked at 2 different labs for 8 different sleep doctors and have never once heard of this.
Rock Hinkle said:I see the problem. A person whom has not yet been diagnosed with apnea should not have a CPAP machine.
Daniel said:If they are doing a new diagnostic study, or the first half of a split night, tthe results can be skewed by the residual effect of using a CPAP. At one point, Stanford advised staying off CPAP for a week prior to the test. Remember, this test is to determine whether or not you have sleep apnea and how severe it is.
In the case of someone who is being retitrated, I don't see that it would make a difference. The fact that you have sleep apnea has already been established. You are merely redetermining pressure settings. However, if the reason for the repeat study is because a patient has lost significant weight, it would make sense to redo the diagnostic part of the study, since the patient might conceivably not need CPAP anymore. If that patient used CPAP right up until the night of the study, it is possible to get a false negative, and think that s/he doesn't need CPAP anymore, when there may still be a need.
I hope that explanation made some sense...
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This discussion seems to be moving in two directions simultaneously.
1) I agree that it seems bizarre to do a split night study when it is already an established fact that the patient has sleep apnea. Why not do a full night titration?
2) There can be a residual effect to using CPAP. It varies greatly from person to person. For some people, one night without a CPAP and it's right back to square one. For others, it's as if the muscles of the upper airway have been strengthened by dealing with pressurized air. For a couple of nights, there is muscle tone, but it gradually decays back to pre-CPAP levels.
For me personally, I was working at a company that used at-home diagnostic equipment. My diagnostic AHI was 38. I had been on CPAP successfully for about 2 years. One night, I didn't use the CPAP and tested myself. It came back with an AHI of 1.3. I figured it had to be a mistake, so two nights later, I tried again. This time, it came backk 2,1. Was I cured of sleep apnea? I talked to my sleep doctor, who explained the residual effect. He pointed out that I had lost 10% of my body weight and that I had learned to sleep on my side. He suggested I go three weeks without CPAP and see how I felt. I made it a week and a half before I was dragging around terribly. I can remember saying to myself, "Oh yeah, this is how I used to feel all the time." I took one more diagnostic test and sure enough, my AHI was back around 38. The next night, I was back on my CPAP, and I have been using it every night since then for the last seven years.
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Okay, I bow to superior heads than mind. However, one thing jnk said makes LOTS OF SENSE to me.
" I would consider a titration to be MORE valuable when a patient is already used to CPAP and has used it right up to the titration night. That titration would better reflect what the patient needs long-term-- again, in my opinion."
Bold emphasis is mine.
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