Comparison of the oxygen cost of breathing exercises and spontaneous breathing in patients with stable chronic obstructive pulmonary disease

Background and Purpose. The oxygen demand of breathing exercises and the clinical implications have not been studied in detail. In this study, the oxygen cost,of 3 common breathing exercises believed to reduce oxygen cost (ie, work of breathingy was compared with that of spontaneous breathing in patients with chronic obstructive pulmonary disease (COPD). Subjects. Thirty subjects with stable moderately severe COPD participated. Methods. Oxygen consumption ((V)over doto(2)) and respiratory rate (RR) during spontaneous breathing at rest (SB) were recorded for 10 minutes. Subjects then performed 3 breathing exercises in random order, with a rest between exercises: diaphragmatic, breathing (DB), pursed-lip breathing (PLB), and a combination of DB and PLB (CB). Oxygen consumption and RR were measured. Results. Mean (V)over doto(2) (+/-SD) was lower during the breathing exercises (165.8 +/- 22.3 mL O-2/min for DB, 164.8 +/- 20.9 mL, O-2/min for PLB, and 167.7 +/- 20.7 mL O-2/min for CB) compared with SB (174.5 +/- 25.2 mL O-2/min), Correspondingly, mean RR (+/-SD) was higher during SB (17.3 +/- 4.23 breaths/min), followed by OB (15.0 +/- 4.32 breaths/min,), PLB (12.8 +/- 3.53 breaths/min), and CB (11.2 +/- 2.7 breaths/min),., Discussion and Conclusion. Given that patients do not-spontaneously p adopt the breathing pattern with the least (V)over doto(2) and the lowest RR, the 2 results suggest that determinants of the breathing pattern other than metabolic demand warrant being a primary focus in patients with COPD.