Investigation On Association Between Residual Sleepiness And Central Sleep Apnea Events In Patients With Obstructive Sleep Apnea Syndrome

Objective To investigate the possible association between residual sleepiness(RS)and central sleep apnea events in patients with obstructive sleep apnea syndrome(OSAS)following continuous positive airway pressure(CPAP)treatment,as well as the effects of adaptive servo-ventilation(ASV)on their RS.Methods Following correct application of CPAP treatment and exclusion for other sleepiness-associated disorders,50 patients with moderate-to-severe OSAS were recruited,of whom were 26 patients with RS(RS group)and 24 patients without RS(control group).The treatments of one month's auto-CPAP(AutoCPAP)followed by one week's ASV with autoCS2 ventilator were performed.Comparisons were made separately before treatment,on AutoCPAP and ASV treatments in both groups concerning the following parameters:polysomnographic parameters including central sleep apnea index(CSAI),micro-arousal index(MAI),etc;daytime Epworth sleepiness score(ESS);and possibly sleepiness-associated factor,i.e.,plasma tumor necrosis factor-α(TNF-α). Plasma TNF-αlevels were measured by enzyme linked immunosorbent assay(ELISA).Results Before treatment there was no significant difference between two groups in apnea hypoapnea index(AHI),MAI,minimal pulse oxygen saturation(miniSpO₂),ESS and plasma TNF-αlevels(all P＞0.05). However,the CSAI in RS group was significantly higher than that in control group(7.19±1.75 vs 3.37±1.04,P＜0.05).Compared with before treatment,on the one month's AutoCPAP treatment there was a significant decrease in AHI,CSAI,miniSpO₂,MAI and daytime ESS on the both groups(all P＜0.05),but there was a significantly higher CSAI., MAI and ESS in RS group than those in control group(CSAI:7.19±1.75 vs 3.37±1.04,P＜0.05;MAI:9.00±1.95 vs 2.36±0.66,P＜0.05;ESS: 9.54±0.51 vs 5.42±1.32,P＜0.05).On one weeks' ASV treatment there was such a further significant decrease in CSAI,MAI and daytime ESS in RS group and control group.In addition,compared with the plasma TNF-αlevel before treatment in RS group,there was no statistical difference on AutoCPAP treatment but a significant decrease on ASV treatment.Plasma TNF-αlevels were positively correlated with ESS (r=0.503,P＜0.01)and MAI(r=0.545,P＜0.01).Conclusion RS in OSAS patients following CPAP treatment was associated with their CSAI before and during treatment.By effectively eliminating CSA events with ASV,RS was significantly improved,which suggested that ASV was effective in treatment of RS.The elevation of plasma TNF-αlevel was correlated with the severity of sleepiness and may be associated with the pathogenesy of RS.