Oxygen consumption and transport in stable patients with chronic obstructive pulmonary disease

We studied the relationship between oxygen consumption and systemic oxygen transport in 30 clinically stable patients with chronic obstructive pulmonary disease (COPD) before and after increasing oxygen transport by passive leg elevation to raise the cardiac output. Results were compared with those observed in 10 patients with silicosis. The effect of leg elevation on oxygen consumption was also studied in 12 normal subjects. Oxygen consumption was measured by a closed circuit system, cardiac output by the direct Fick method, and arterial oxygen content by a cooximeter. Supine oxygen consumption was correlated with oxygen transport in patients with COPD (r = 0.50, p less than 0.01), and with leg elevation transport increased from a mean of 516 +/- 23 (SEM) to 567 +/- 26 ml X min-1 X m-2 and consumption increased from a mean of 136 +/- 3 to 148 +/- 4 ml X min-1 X m-2 (both p less than 0.01). In patients with silicosis, leg elevation raised mean oxygen transport from 620 +/- 40.0 to 745 +/- 54.0 ml X min-1 X m-2 and mean consumption from 161 +/- 6 to 192 +/- 6 ml X min-1 X m-2 (both p less than 0.01). In normal subjects, no change in oxygen consumption was observed with leg elevation (154 +/- 8 to 152 +/- 6 ml X min-1 X m-2).(ABSTRACT TRUNCATED AT 250 WORDS)