Predictors of residual sleepiness in adequately treated obstructive sleep apnoea patients.
Nasal continuous positive airway pressure (nCPAP) usually reduces sleepiness in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). However, even with regular use of nCPAP, some OSAHS patients experience residual sleepiness (RS). The aim of this study was to evaluate the efficacy of adaptive servoventilation (ASV) on RS in OSAHS patients. The Epworth Sleepiness Scale (ESS) score was used for assessment of RS. Following correct application of 1-month auto-CPAP (APAP) treatment and exclusion for other sleepiness-associated disorders, 42 RS patients with severe OSAS were recruited. All of them received 1-week ASV treatment with auto-CS2 ventilator. Comparisons between APAP and ASV treatments were made for the following data: polysomnographic parameters including apnea hypopnea index (AHI), central sleep apnea index (CSAI), micro-arousal index (MAI), minimal pulse oxygen saturation, etc.; daytime ESS score. Compared with the parameters on day 30 of APAP treatment, there was a further significant decrease in AHI, CSAI, MAI, and daytime ESS score (P < 0.01) on day 7 of ASV treatment. ESS score before ASV treatment (10.89 ± 0.40) reduced to normal range (3.98 ± 1.26) on day 7 of ASV treatment (P < 0.01). ASV treatment could significantly improved RS in OSAS patients; the mechanism of such an efficacy might be associated with further declined levels of AHI, CSAI, and arousal index.