[Changes in cardiopulmonary functional reserve after thoracic surgery assessed by treadmill exercise test]

Abstract

The authors evaluated the effect of thoracic surgery on cardiopulmonary functional reserve using a three-minute incremental test on treadmill before and after operation in 148 patients undergoing thoracic surgery. Patients were divided into two groups according to the presence or absence of respiratory symptoms during the exercise test. In all patients, the number of cases with hypoxemia induced by exercise test increased postoperatively including all cases with pneumonectomy. The number of patients who halted the test because of respiratory symptoms (Group A) increased after operation (45 cases before (30.4%), 82 cases after (55.4%)). Most of them showed at least 10 Torr lower PaO2 levels than their basal levels during exercise. Before operation, patients in Group A (n = 45) showed significantly lower FEV1.0% than those who halted the test because of other symptoms (Group B, n = 103) (68.0 +/- 12.5% vs 76.0 +/- 9.7%, mean +/- S.E. p less than 0.05, Student's t-test). After operation, patients in Group A (n = 82) showed a significantly lower %DLco than those in Group B (n = 66) (71.4 +/- 14.3% vs 88.6 +/- 16.8%, p less than 0.05). Preoperative %DLco did not differ between the two groups. Consequently, postoperative decrease in %DLco was characteristic for patients with respiratory symptoms, suggesting that hypoxemia during exercise induced by reduction in diffusion capacity may be responsible for their respiratory symptoms. The anaerobic threshold (AT), and index of aerobic capacity, and symptomlimited maximal oxygen consumption (VO2 max (s.l)), VO2 at the end of exercise, fell to 78.4% and 79.1% of preoperative levels respectively one month after operation. Both indices recovered to 85% of preoperative levels at six months after operation. AT and VO2 max (s.l) values were expressed as a percent of predicted maximal VO2 values for age, body weight and sex (%AT, %VO2 (s.l)). The %VO2 max (s.l) was significantly lower in patients with pneumonectomy (n = 8) as compared with that in patients with lobectomy (n = 55) (51.1 +/- 6.4% vs 60.6 +/- 11.4%, p less than 0.05). Patients with thoracotomy (n = 35) only showed significantly higher %VO2 max (s.l) values (70.5 +/- 12.1%) than those of patients with lobectomy (p less than 0.05). The %AT did not show significant differences among different operative procedure groups. Despite a good preoperative correlation (r = 0.725) between %VO2 max (s.l) and %AT in all patients, there was no correlation between the indices postoperatively.(ABSTRACT TRUNCATED AT 400 WORDS)