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No effect of oral high frequency oscillation combined with forced expiration manoeuvres on tracheobronchial clearance in chronic bronchitis.

This study compared the effect of oral high frequency oscillation (OHFO) with the effect of the forced expiration technique (FET) on tracheobronchial clearance. Eight patients with chronic bronchitis were investigated (mean age 60 +/- 10 yrs, mean forced expiratory volume in one second (FEV1) 68 +/- 27% predicted, mean sputum production 33 +/- 9 g.day-1). OHFO was applied at the respiratory system resonant frequency of each patient (range 9.2-25 Hz) and combined with huffing. FET included breathing exercises, huffing and postural drainage. Duration of both OHFO and FET was 30 minutes. Tracheobronchial clearance was measured by means of a radio-aerosol technique. At 60 mins after start of the treatment mean tracheobronchial retention was 70 +/- 26% after OHFO, 54 +/- 26% after FET and 76 +/- 18% in the control run, which included huffing only. OHFO was not significantly different from control. FET was significantly different (p less than 0.02) from both OHFO and control. It is concluded that OHFO has no effect on tracheobronchial clearance in chronic bronchitis.