[Assessment of vigilance for patients with sleep disordered breathing]

Assessment of vigilance for patients with sleep disordered breathing.

Vigilance of the patients referred to sleep study for suspected sleep disorders was evaluated prospectively by a computerized driving simulator SteerClear before (evening) and after (next morning) nocturnal sleep study. The vigilance was quantified by means of the averaged percentages of obstacle hitting made during the evening and the morning driving test, abbreviated as %Hm. Controls included 11 normal volunteers. Kruskal-Wallis ANOVA by Rank was used to compare the %Hm in patients with that in normal controls; Spearman Rank Correlation was used to analyze the relationship between %Hm and parameters obtained from sleep study.

The %Hm in normal subjects and in patients were (expressed as median and range): normal subjects 0.6 (0 - 2.5), n = 11; sleep snoring 1.1 (0.2 - 2.0), n = 7; obstructive sleep apnea syndrome (OSAS) 2.2 (0.2 - 7.7), n = 22; central sleep apnea syndrome (CSAS) 2.7 (0.9 - 5.4), n = 6. The %Hm of the patients with OSAS and CSAS but not the patients with sleep snoring (P > 0.05) was significantly higher than that of normal subjects (P < 0.05). Among the normal subjects, the patients with OSAS or with sleep snoring, there existed a significant correlation between the %Hm and the percentage of cumulated time spent at the oxygen saturation below 90% (r = 0.41, n = 40, P < 0.05), whereas the %Hm was not correlated to apnea/hypopnea index (r = 0.22, n = 40, P > 0.05) nor to arousal index (r = 0.10, n = 17, P > 0.05).

The vigilance of the patients with OSAS or CSAS but not those only with sleep snoring is impaired, the impairment may relevant to the oxygen desaturation during their sleep.