ROLE OF CARDIOPULMONARY EXERCISE TESTING AND THE CRITERIA USED TO DETERMINE DISABILITY IN PATIENTS WITH SEVERE CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

The aim of this study was to evaluate the precision and variability wi th which resting pulmonary function tests (resting PFTs) can be used t o predict the capacity in exercise, and the usefulness of the differen t measurements of pulmonary function in the evaluation of impairment/d isability in patients with chronic obstructive pulmonary disease (COPD ). We studied 78 patients with stabilized COPD (FEV, 45.1 +/- 17.1%). Of these, 39 suffered severe impairment according to the resting PFTs. Both the group with severe impairment (maximal oxygen consumption [VO 2,max]: 16.22 +/- 5 ml/kg/min; maximal minute ventilation [VEmax]: 31. 87 +/- 7.1 L/min; maximal heart rate [HRmax]: 133.8 +/- 10.9 beats/min ) and the group with nonsevere impairment according to the resting PFT s (VO(2)max: 22.55 +/- 7.9 ml/kg/min; VEmax: 42.11 +/- 10.9 L/min; HRm ax: 138 +/- 13.7 beats/min) showed ventilatory limitation during exerc ise. FEV(1) was the most prevalent criterion for the determination of severe impairment (FEV(1) < 40%), and was the variable best correlated to VO(2)max (r = 0.52 with VO(2)max as absolute value and r = 0.54 wi th VO(2)max expressed as a percentage of the reference value), but the resting PFTs were not predictive of exercise performance including pa tients with severe COPD. Evaluation of working capacity (based on VO(2 )max) revealed a significant number of inaccurate predictions among th e results of the resting PFTs. Sensitivity and specificity analysis we re used to compare the different criteria used to evaluate the severit y of disability. They reveal that the classification will be different according to the criteria used. The criteria that classified more pat ients similarly were VO(2)max < 60% of the reference values (sensitivi ty of 64.1% and specificity of 66.6%) and VO(2)max < 15 ml/kg/min (sen sitivity of 41% and specificity of 79.5%). The impairment rating whene ver the theoretical energy requirements of the job exceeded 40% of the patients' VO(2)max (handicap) was contradicted by other exercise crit eria. A combination of exercise testing results and job energy require ment may be necessary for an accurate determination of impairment/disa bility for the individual subject.