Physical Working Capacity in Severe Chronic Obstructive Lung Disease

Abstract

Twenty-five patients (mean age 61±2, range 39–72 years) with severe chronic obstructive lung disease, with a maximum voluntary ventilation (MVV_F), without bronchodilating spray, ≤35% of the individually predicted normal value, were classified into two groups: (1) a group who had suffered from at least one period of absolute respiratory insufficiency (R), with 8 men and 6 women, and (2) a comparison (C) group with the corresponding degree of MVV_F limitation but without any period of absolute respiratory insufficiency, with 10 men and 1 woman. The patients were studied in their habitual state by a standard ergometer-bicycle exercise test. The highest performed work load, near maximal (W_max), was determined, and also the pulmonary gas exchange, arterial-blood (O₂ and CO₂) gas tensions, lactate concentration and acid-base balance under the conditions of maximum work load.

MVV_F and W_max were found to be positively correlated in the R and C groups, but not in the female patients. W_max was also correlated to other factors, namely negatively to resting FRC/TLC and RV/TLC, and to V_D/V_T measured under maximum working conditions. Average W_max was 189 ± 52 in the male R group and 118 ± 37 kpm/min in the female, and in the male C group 256 ± 40 kpm/min. W_max in kpm/min per kg body weight was in the R group 2.63 ± 0.57 and in the C group 4.29 ± 0.65. There was a tendency to lower P_aO₂ and C_aO₂ during maximum work and higher heart rate in relation to work load in the R group than in the C group although this was not statistically significant.