• Cara F Dosman, Peter C Zuberbuhler, Joan I Tabak, and Richard L Jones.
• Department of Pediatrics, University of Alberta, Edmonton, Canada. c.dosman@utoronto.ca
• Can. Respir. J. 2003 Mar 1; 10 (2): 94-8.

ObjectiveTo 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).DesignA clinic-based prospective intervention study.SettingPulmonary function laboratory, University of Alberta, Edmonton, Alberta.PopulationNine 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.MethodsEach 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).ResultsHFCC 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.ConclusionsAdding 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.

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