COMPARISON OF THE 4 RESPIRATORY DETERMINA TION METHODS FOR THE ANAEROBIC THRESHOLD

We analyzed 128 cardiopulmonary exercise tests (CPX), performed in nor mal subjects (n = 31), in patients with coronary artery disease (n = 4 1), with chronic heart failure before (n = 14) and after (n = 14) appl ication of oral PDE-inhibitors and in patients with HIV-infection on a bicycle-ergometer in semi-supine position using a ramp-program (depen dent on study-population with 15, 20 or 35 Watt/min increases) with re spect to the ability to determine the respiratory anaerobic threshold non-invasively, using the main criteria described by Wasserman et al.: the V-slope-method according to Beaver [1], the increase of the venti latory equivalent for O-2 (V-E/VO2). the increase of the end-tidal PO2 (PETO(2)) and the increase of the respiratory quotient (RQ) during ex ercise. In the different study-populations we calculated the detection rates of the AT for each criteria separately. The typical changes in the endtidal PO2 (124/128 = 96.9%) and the V-slope-method (119/128 = 9 2.9%) were the most reliable parameters to detect the anaerobic thresh old. The characteristic changes of the ventilatory equivalent for O-2( V-E/VO2) and of the respiratory quotient (RQ) we found in 100/128 (= 7 8.1%) and in 107/128 (= 83.6%) of the tests respectively. 86/128 tests (67.2%) showed typical changes in all four mentioned criteria. In ano ther 24/128 tests (19.8%) three of four criteria were fulfilled. There fore, our investigations showed that in 110/128 cases (85.9%) the AT c ould be determined by typical changes by means of at least three of th e four described parameters. In 15/128 (11.7%) tests only two of four criteria we were able to detect the anaerobic threshold in 100% of our tests.