title: Effect of expiratory positive airway pressure on sleep disordered breathing.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Observational physiology study
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors: Sleep Medicine Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. rheinzer@post.harvard.edu
authors: Raphael
authors: R
authors: Heinzer
authors: David P
authors: DP
authors: White
authors: Atul
authors: A
authors: Malhotra
authors: Yu L
authors: YL
authors: Lo
authors: Louise
authors: L
authors: Dover
authors: Karen E
authors: KE
authors: Stevenson
authors: Amy S
authors: AS
authors: Jordan
mesh_terms: D000328:Adult; D000403:Airway Resistance / Q000502:physiology; D015992:Body Mass Index; D005105:Expiratory Reserve Volume / Q000502:physiology*; D005260:Female; D005652:Functional Residual Capacity / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D011175:Positive-Pressure Respiration; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D013990:Tidal Volume / Q000502:physiology
chemical_list: D010100:Oxygen