CPAP during MSLT?

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How do you feel about CPAP use during MSLTs?

Poll ended at Sat Aug 09, 2014 3:59 pm

CPAP should always be used during naps
CPAP should never be used during naps
No votes
MWTs are more appropriate for compliant well treated CPAP users
No votes
Total votes : 11

CPAP during MSLT?

Postby Jayhawkhenry » Thu Jul 10, 2014 3:59 pm

An interesting question has come up in our labs concerning the use of CPAP during MSLTs. One physician feels it should always be used, another physician does not what CPAP used. Our ensuing discussion in the lab has been on the validity of using CPAP during MSLT naps.
If a patient’s OSA is well treated and the patient is very compliant, how would the use of CPAP effect sleep latency? It could be argued that putting a patient to bed in a darkened room with CPAP is like ringing the bell for Pavlov's dog. The use of CPAP is a trigger to sleep. Should naps be conducted without that trigger?
Another argument is that the well treated patient, would not be lying down with CPAP, but would be up and functioning. Therefore, the MWT would better assess the patient’s sleepiness.
What do you think?
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Re: CPAP during MSLT?

Postby somnonaut » Thu Jul 10, 2014 6:45 pm

It is not that CPAP facilitates sleep, it is that non-use of CPAP provides artificial stimulation to stay awake. If CPAP had been used regularly and the patient is still reporting EDS, then the use of CPAP is what constitutes the proper milieu for the patient. Its use is mandated, since removing it would be tantamount to having someone waking the patient every 30 sec, artificially stimulating them.
It is not that when I wear CPAP it artificially makes me sleepy. If I do not wear my CPAP I know my naps will be artificially aborted from my untreated apneas, curtailing my sleep. So, any test of my daytime sleep should be with whatever I use to make my body able to freely sleep.
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Re: CPAP during MSLT?

Postby MrBig » Thu Jul 10, 2014 9:33 pm

Every lab I've done MSLTs in, pts wore PAP if they were current PAP users. Somno's answer pretty much explains why.
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Re: CPAP during MSLT?

Postby zack » Thu Jul 10, 2014 10:09 pm

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Re: CPAP during MSLT?

Postby bduce » Fri Jul 11, 2014 1:34 am

My two cents worth...
The first thing would be for the Physicians to clarify what question are they trying to answer when requesting a MSLT or MWT. This is often the first thing that some physicians get wrong.
Question 1. Are they able to maintain vigilance in sleep inducing conditions? This is basically the crux of the MWT. This sorts out if their current treatment of their sleep disorder is adequate and they can demonstrate that they can stay awake in these conditions. This is useful for commercial license drivers etc. This test seeks to measure inappropriate sleepiness.

Question 2. If they are on CPAP and using it well with no technical issues and current pressures are adequate to control for obstructive events BUT are still quite hypersomnolent, then you would look at a MSLT with CPAP to determine if there is another cause of this hypersomnolence (ie a hypersomnia of central origin - narcolepsy etc). Remember Narcolepsy and OSA are quite often comorbid. In this case you are actually wanting to put them in a sleep-inducing environment to see (a) how quickly they get to sleep and (b) what happens when they get to sleep (ie SOREMPs). This test seeks to measure sleepability and the possible underlying causes. With this test you actually want to encourage them to go to sleep - this as Somno has already said, is the reason why you will have your CPAP patients on CPAP during the MSLT. Arousals may prevent the transition into REM for potential narcoleptics.

As an aside if they are looking at comparing the effectiveness of treatments for OSA, meta-analysis of studies demonstrates that the MSLT appears to show very little change in Mean Sleep Latency while the MSL in the MWT increases and corresponds with a decrease in the ESS. Sangal et al looked at MWT and MSLT in the same patients and showed in 15% of his population the MSL in the MSLT was low while the MSL in the MWT was high ie they could go to sleep quickly but stay awake when required. This indicates that the MSLT and MWT would be measuring slightly different processes. Thus it is important to clarify what question you are wanting to ask before you choose either of this tests.
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Re: CPAP during MSLT?

Postby respbarb » Mon Jul 14, 2014 7:23 pm

Exactly, bduce.
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Re: CPAP during MSLT?

Postby SCNVsleep » Tue Jul 15, 2014 1:27 am

bduce and Somnonaut nailed the nail on the head.
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