Effect of manually assisted cough and mechanical insufflation on cough flow of normal subjects, patients with chronic obstructive pulmonary disease (COPD), and patients with respiratory muscle weakness

Background-It has been suggested that cough effectiveness can be improved b y assisted techniques. The effects of manually assisted cough and mechanica l insufflation on cough how physiology are reported in this study. Methods-The physiological actions and patient self-assessment of manually a ssisted cough and mechanical insufflation were investigated in 29 subjects (nine normal subjects, eight patients with chronic obstructive pulmonary di sease (COPD), four subjects with respiratory muscle weakness (RMW) with sco liosis, and eight subjects with RMW without scoliosis). Results-The peak cough expiratory flow rate and cough expiratory volume wer e not improved by manually assisted cough and mechanical insufflation alone or in combination in normal subjects. The median increase in peak cough ex piratory flow in subjects with RIMW without scoliosis with manually assiste d cough alone or in combination with mechanical insufflation of 84 l/min (9 5% confidence interval (CI) 19 to 122) and 144 l/min (95% CI 14 to 195), re spectively, reflects improvement in the expulsive phase of coughing by thes e techniques. Manually assisted cough and mechanical insufflation in combin ation raised peak expiratory flow rate more than either technique alone in this group. The abnormal chest shape in scoliotic subjects and the fixed in spiratory pressure used made effective manually assisted cough and mechanic al insufflation difficult in this group and no improvements were found. In patients with COPD manually assisted cough alone and in combination with me chanical insufflation decreased peak expiratory how rate by 144 l/min (95% CI 25 to 259) and 135 l/min (95% CI 30 to 312), respectively. Conclusions-Manually assisted cough and mechanical insufflation should be c onsidered to assist expectoration of secretions in patients with RMW withou t scoliosis but not in those with scoliosis.