Determinants of Daytime Sleepiness in Obstructive Sleep Apnea: Determinants of EDS

Determinants of EDS
Comparison between Multiple Sleep Latency Test-Defined Groups. We first subdivided our population into three groups according to mean MSLT scores: population A (n = 24), “non-sleepy” with a mean MSLT >8 min; population C (n = 28), “mildly sleepy” with a mean MSLT <8 to >5 min; and population D (n = 48), “severely sleepy” with a mean MSLT <5 min. An analysis of variance disclosed that no variable was significantly different. We then compared population.

A with population D. The only significant variables were mean percentage of nocturnal SI (p<0.01), significantly higher in population D, and mean percentage of nocturnal S3-4 (p<0.05), significantly higher in population A. There were other trends: nocturnal TST^ tended to be longer in the alert population A (X = 393 ±63.6 min) than in population D (X=379 ±57.2 min). The severely sleepy group D had a greater number of “awakenings,” with a mean total of 43.6±30.3 vs 32.2±16.4 for population A. But once again, none of these changes was significant. Overall, population D experienced the greatest sleep fragmentation and the largest amount of light sleep associated with the longest nocturnal TST and highest percentage of nocturnal REM sleep. Their BMI and Sa02 indices were not significantly different.
We next subdivided subjects with a mean MSLT score >8 min into a “non-sleepy” group A (identical to our original group A, n = 24) and subjects with a mean MSLT score <8 min (n = 76) into a “sleepy” group B (Table 2). Group B, combining our original C and D groups, did not differentiate between degrees of sleepiness. As seen in Table 2, group A differed from group B to a statistically significant degree for several variables, especially for RDI, percentage of SI, percentage of S3-4, percentage of REM sleep, and total number of awakenings during nocturnal sleep. The nocturnal sleep disturbances were more pronounced and the RDI higher in the “sleepy” group. None of the other variables was significantly different, particularly BMI, the Sa02 indices, age, nocturnal TST or time spent awake during nocturnal sleep.
Table 2—Mean and Standard Deviations of Polygraphic Variables Measured on Patients with a Mean Sleep Latency^ 8 Minutes

Variable* MSLT ^8 Min (Mean ± SD) MSLT >8 Min (Mean ± SD) p Value fromt
M-W Student t test
RDI 53.8±25.4 37.6 ± 18.7 0.027 0.001
SI 41.8 ±22.2 25.5 ±13.9 0.002 <0.001
S2 40.7 ± 19.7 46.1 ±13.7 0.477 0.217
S3-4 4.4±7.4 3.6±9.9 0.002 N/A
REM 13.0±6.5 16.3 ±7.1 0.004 0.036
Awakenings (n) 47.1 ±31.3 32.2 ±16.4 0.091 0.003
% T<90% Sa02 27 ±30.3 20±21.3 0.758 N/A
02-80-I 9.0± 16.7 3.8±8.5 0.413 N/A
This entry was posted in Sleep Apnea and tagged daytime sleepiness, obstructive sleep apnea, respiratory.