Maximal expiratory flows after postural drainage.

Flows measured from maximal expiratory flow-volume (MEFV) curves were used to evaluate 
the efficacy of postural drainage in improving ventilatory function acutely. Maximal 
expiratory flow-volume curves were obtained for 9 cystic fibrosis subjects and 
10 subjects with chronic bronchitis before and 5, 15, and 45 
min after a 30-min session of postural drainage with percussion, vibration, 
and coughing. Forced vital capacity (FVC) was significantly increased 45 min 
after drainage for the combining group. Flows at high lung volumes 
were different for the 2 subgroups. Subjects with cystic fibrosis demonstrated 
a significant increase in peak expiratory flow rates 45 min after 
drainage and an increase in forced expiratory volume in one sec 
at all time intervals. The subjects with chronic bronchitis had a 
decreased peak expiratory flow rate 5 min after drainage, but by 
45 min, it had returned to baseline. There was no significant 
change in one-sec forced expiratory volume at any time interval for 
the chronic bronchitis subgroup. Changes in flows at low lung volumes 
were similar for the 2 subgroups. Forty-five min after drainage there 
was an increase in flow rates near 50 per cent of 
FVC. Flows near 25 per cent of FVC were increased 15 
and 45 min after drainage. This study demonstrated that postural drainage 
with coughing resulted in significant improvement in flows at low lung 
volumes. Changes in flows at high lung volumes were less consistent. 
