DIAPHRAGMATIC BREATHING REDUCES EFFICIENCY OF BREATHING IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

The effects of diaphragmatic breathing learning on chest wall motion, mechanical efficiency of the respiratory muscles, breathing pattern, a nd dyspnea sensation were studied in seven patients with severe chroni c obstructive pulmonary disease (COPD) (FEV, 34 +/- 7% of the predicte d value) during loaded and unloaded breathing. Chest wall motion was s tudied focusing on amplitude and phase relation of rib cage and abdomi nal motion. Mechanical efficiency was defined as the ratio of added ex ternal power output and added oxygen consumption during inspiratory th reshold loading (40% maximal inspiratory pressure [PImax]). After 2 wk run-in, all subjects participated in a diaphragmatic breathing progra m for 3 wk. Variables obtained during diaphragmatic breathing were com pared with those obtained during natural breathing. During diaphragmat ic breathing the ratio of rib cage to abdominal motion decreased signi ficantly during unloaded (0.86 versus 0.37; p < 0.01) as well as durin g loaded breathing (0.97 versus 0.50; p < 0.01). Chest wall motion bec ame more asynchronous during diaphragmatic breathing in the unloaded c onditions (mean phase difference for natural breathing 3.5 versus 10.4 % for diaphragmatic breathing; p < 0.02) and loaded conditions (mean p hase difference for natural breathing 6 versus 11.4% for diaphragmatic breathing; p < 0.02). Surprisingly, mechanical efficiency decreased s ignificantly during diaphragmatic breathing (2.57 +/- 0.76%) in compar ison with natural breathing (3.35 +/- 1.48%; p < 0.01). Tidal volume, respiratory frequency, and duty cycle did not change significantly dur ing diaphragmatic breathing. Dyspnea sensation tended to increase duri ng diaphragmatic breathing. We conclude that diaphragmatic breathing i n patients with severe COPD detrimentally affected coordination of che st wall motion as well as mechanical efficiency, while dyspnea sensati on tended to increase. Consequently, we question the usefulness of thi s technique in the rehabilitation of COPD patients.