E Ev va al lu ua at ti io on n o of f a an n a au ut to o--n nC CP PA AP P d de ev vi ic ce e b ba as se ed d o onWe observed that a single night of auto-nCPAP improved the apnoea/hypnoea index (AHI) (12±21 vs 51±31 disordered breathing events·h -1 of sleep (mean±SD)), the awakening-arousal index (13±20 vs 40±26 arousals·h -1 of sleep), and duration of slow wave sleep (102±49 vs 71±56 min) but not of rapid eye movement (REM) sleep (55±31 vs 64±38 min). Auto-nCPAP was effective (apnoea/hypopnoea and arousal indices <10 events·h -1 ) in all but three patients. Auto-nCPAP was ineffective in one patient, whose obstructive respiratory events were not preceded by nasal mask pressure vibration detection, and in two patients who were quasi-permanent mouth breathers.Snoring detection may be effective in sleep apnoea syndrome with heavy snoring and without permanent mouth breathing, during the first night of nasal continuous positive airway pressure treatment.

Esophageal pressure amplitude (DeltaPes), inspiratory pulmonary resistance (RLI) and inspiratory flow limitation score (FS) are used as indices of upper airway obstruction for the titration of nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnea syndrome (OSAS). This study was designed to determine whether oscillatory respiratory resistive impedance at 16 Hz (RFO) might be proposed as an alternative index. Eleven OSAS patients were studied during a night of polysomnography-controlled nCPAP titration. Nasal flow (V) and airway opening and esophageal pressures (Pao and Pes, respectively) were continuously measured during nasal breathing, and forced-flow oscillations (FO) were applied for 5 min at each nCPAP level. RLI was calculated by linear regression analysis of resistive pressure versus V over inspiration. R FO was obtained by linear regression analysis of respiratory resistive impedance versus frequency. Application of FO affected neither sleep nor pulmonary mechanics. RFO correlated with RLI in all patients. RFO did not correlate with DeltaPes in two patients, and was not significantly related to FS in five patients. This study demonstrates the applicability of the FO technique in sleeping patients receiving nCPAP, and the reliability of RFO for assessing pulmonary resistance. RFO might therefore be proposed as a quantitative index of airway obstruction for nCPAP titration.

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