Effect of Expiratory Positive Airway Pressure on Sleep Disordered Breathing

• Published in: Sleep (New York, N.Y.) N.Y.), 2008-03, Vol.31 (3), p.429-432
• Main Authors: HEINZER, Raphael, WHITE, David P, MALHOTRA, Atul, LO, Yu L, DOVER, Louise, STEVENSON, Karen E, JORDAN, Amy S
• Format: Article
• Language: English
• Subjects: Adult; Airway Resistance - physiology; Behavioral psychophysiology; Biological and medical sciences; Body Mass Index; Expiratory Reserve Volume - physiology; Female; Functional Residual Capacity - physiology; Fundamental and applied biological sciences. Psychology; Humans; Male; Medical sciences; Middle Aged; Oxygen - blood; Pneumology; Polysomnography; Positive-Pressure Respiration; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Respiratory system : syndromes and miscellaneous diseases; Short Note; Sleep Apnea, Obstructive - diagnosis; Sleep Apnea, Obstructive - physiopathology; Sleep Apnea, Obstructive - therapy; Tidal Volume - physiology
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleep/31.3.429

We sought to determine the effect of expiratory positive airway pressure on end expiratory lung volume (EELV) and sleep disordered breathing in obstructive sleep apnea patients. Observational physiology study We studied 10 OSA patients during sleep wearing a facial mask. We recorded 1 hour of NREM sleep without treatment (baseline) and 1 hour with 10 cm H2O EPAP in random order, while measuring EELV and breathing pattern. The mean EELV change between baseline and EPAP was only 13.3 mL (range 2-25 mL). Expiratory time was significantly increased with EPAP compared to baseline 2.64 +/- 0.54 vs 2.16 +/- 0.64 sec (P = 0.002). Total respiratory time was longer with EPAP than at baseline 4.44 +/- 1.47 sec vs 3.73 +/- 0.88 sec (P = 0.3), and minute ventilation was lower with EPAP vs baseline 7.9 +/- 4.17 L/min vs 9.05 +/- 2.85 L/min (P = 0.3). For baseline (no treatment) and EPAP respectively, the mean apnea+hypopnea index (AHI) was 62.6 +/- 28.7 and 56.8 +/- 30.3 events per hour (P = 0.4). In OSA patients during sleep, the application of 10 cm H2O EPAP led to prolongation of expiratory time with only marginal increases in FRC. These findings suggest important mechanisms exist to avoid hyperinflation during sleep.