title: Effects of positive end-expiratory pressure on oscillated volume during high frequency chest compression in children with cystic fibrosis.
abstract: OBJECTIVE
  To investigate the effects of positive end-expiratory pressure (PEEP) on end-expiratory lung volume (EELV) and mean oscillated volume (V(osc)) during high frequency chest compression (HFCC).
  
  
  METHODS
  A clinic-based prospective intervention study.
  
  
  METHODS
  Pulmonary function laboratory, University of Alberta, Edmonton, Alberta.
  
  
  METHODS
  Nine children with cystic fibrosis with little or no obstructive airway disease who were selected from the outpatient Cystic Fibrosis and Pediatric Pulmonary Clinics at the University of Alberta Hospital, Edmonton, Alberta.
  
  
  METHODS
  Each child received HFCC alone (at 10 Hz with chest wall pressure of 8 cm H2O) and HFCC plus PEEP. A closed circuit spirometry system was used to measure HFCC- and PEEP-induced changes in EELV, expressed as per cent baseline functional residual capacity (FRC) measured using helium dilution. An isothermic chamber permitted measurement of V(osc).
  
  
  RESULTS
  HFCC caused a significant 9% decrease in EELV. Adding 2.0 +/- 0.3 cm H2O of PEEP increased EELV back to at least the FRC level. With HFCC alone, Vosc was significantly lower during spontaneous expiration than during spontaneous inspiration, but adding PEEP to HFCC increased V(osc), especially during spontaneous expiration.
  
  
  CONCLUSIONS
  Adding PEEP during HFCC prevents the decrease in EELV and increases V(osc). Therefore, PEEP may improve HFCC-induced mucus clearance in children with cystic fibrosis.
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, Canada. c.dosman@utoronto.ca
authors.forename: Cara F
authors.initials: CF
authors.lastname: Dosman
authors.forename: Peter C
authors.initials: PC
authors.lastname: Zuberbuhler
authors.forename: Joan I
authors.initials: JI
authors.lastname: Tabak
authors.forename: Richard L
authors.initials: RL
authors.lastname: Jones
mesh_terms: D000293:Adolescent; D035641:Chest Wall Oscillation; D002648:Child; D003550:Cystic Fibrosis / Q000175:diagnosis / Q000628:therapy*; D005105:Expiratory Reserve Volume; D005260:Female; D006801:Humans; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods*; D011379:Prognosis; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D014109:Total Lung Capacity; D016896:Treatment Outcome