Abstract: Objective To explore the efficacies and compliances during the treatment of continuous positive airway pressure (CPAP) or auto-continuous positive airway pressure (Auto-CPAP) in patients with severe obstructive sleep apnea-hypopnea syndrome (OSAHS).Methods A total of 116 individuals were enrolled in this study, of which, 60 patients with severe OSAHS diagnosed by the whole night polysomnography (PSG) were randomly divided into CPAP group and Auto-CPAP group(n=30,each). And 56 persons with normal PSG were selected as controls. Both groups were given a pulmonary function test(PFT). Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1%, FEV1/FVC, ratio of total lung capacity(TLC) measured value to predicted value, closing capacity (CC)/functional residual capacity (FRC%), ratios of peak expiratory flow (PEF50) measured value to predicted value[PEF50, maximum midexpiratory flow (MMEF), carbon monoxide diffusing capacity(DLCO), airway resistance 5 (R5)] were obtained. Differences in those indexes between two groups were compared. With a computer-assistant diagnostic system, PSG parameter changes in CPAP group and Auto-CPAP group were monitored at 1 month,3 months,6 months. The effect of treatment were evaluated by comparison of sleep latency (SL), sleep efficiency (SE), the number of wake after sleep onset (WASO), time of Ⅰ+Ⅱ over TST, time of Ⅲ+Ⅳ and rapid eye movement (REM) over total sleep time (TST), apnea-hypopnea index (AHI), nighttime mean pulse oxygen saturation (M SaO₂) and nighttime the lowest pulse oxygen saturation (L SaO₂), as well as the mean effective pressure required for ventilation treatment, the ventilator average time nightly, Epworth Sleepiness Scale (ESS), and the PFT parameter changes.Results The differences in FVC, FEV1, FEV1%, FEV1/FVC, ratios of measured value to predicted value(TLC, DLCO, R5) were not statistically significant. The differences in CC/FRC% (P=0.038), ratio of PEF50 measured value to predicted value(P=0.041, ratio of MMEF measured value to predicted value(P=0.037) were statistically significant. At the 1 month,3 months,6 months of treatment, differences in AHI, M SaO₂, L SaO₂, SL, SE, FVC, FEV1, FEV1%, FEV1/FVC,ratios of measured value to predicted value (TLC, PEF50, MMEF, DLCO, R5),CC/FRC% and ESS were not significant differences between CPAP group and Auto-CPAP group(P>0.05 for all of above). The number of WASO, time of Ⅰ+Ⅱ over total sleep time and the effective pressure required for ventilation treatment in Auto-CPAP group were less than those in CPAP group, while the time of Ⅲ+Ⅳ and REM over total sleep time and the ventilator average time nightly in Auto-CPAP group were more than those in CPAP group(P<0.05). Parameters such as AHI, WASO, time of Ⅰ+Ⅱ over total sleep time and ESS at the 1 month, 3 months, 6 months were all lower than those before therapy, while M SaO₂, L SaO₂, time of Ⅲ+Ⅳ and REM over total sleep time were all higher than those before therapy in these two groups(P<0.05),SL and SE were slightly higher than those before treatment, but there were no significant difference(P>0.05). PFT parameters such as FVC,FEV1, FEV1%, FEV1/FVC, ratios of measured value to predicted value(TLC, PEF50, MMEF, DLCO, R5),CC/FRC% at 1 month, 3 months, 6 months showed no significant difference to those before therapy in these two groups(P>0.05). No adverse events were reported during this study.Conclusion Early pulmonary function damage in patients with severe OSAHS is mainly irreversible small airway disease. CPAP and Auto-CPAP are similar in efficacy and safety for OSAHS treatment. Patients under Auto-CPAP treatment showed a better compliance and would benefit more for sleep structure.

Key words: obstructive sleep apnea-hypopnea syndrome, continuous positive airway pressure (CPAD), Auto-CPAP, Z polysomnography, pulmonary function test