Cough versus chest physiotherapy. A comparison of the acute effects on pulmonary function in patients with cystic fibrosis.

Vigorous cough was compared with complete chest physiotherapy by functional evaluation in 9 patients with cystic fibrosis who had moderate airways obstruction. Pulmonary function tests were performed before and 1 h after treatment on consecutive mornings. The time spent coughing and in sputum production were equivalent for both treatments. There were no significant differences in functional response to either treatment. Static lung volumes and flows at high lung volumes were not affected. The increases in maximal expiratory flows at 50 and 25% of the vital capacity were 14 +/- 10 SEM% and 22 +/- 11 SEM%, respectively, after cough and 18 +/- 8% and 25 +/- 13% after chest physiotherapy. These responses did not correlate with the volume of sputum produced. Because there was no clear-cut benefit of chest physiotherapy over cough alone, and the latter is easier to perform, cough is an attractive alternate method of treatment.