Hemodynamic responses to exercise after lung transplantation.

A reduced exercise tolerance, maximum oxygen uptake (VO2max), and anaerobic threshold have been reported after lung transplantation (LT). We prospectively assessed the hemodynamic responses to incremental cycle ergometry before and after LT in eight recipients. All recipients underwent a 6-week formal exercise training program. The VO2max increased after versus before LT (13.4 +/- 0.8 vs 9.2 +/- 0.8 ml/min/kg) (p < 0.01). No transition thresholds by analysis of arterial standard bicarbonate were discerned before LT, while the thresholds after LT were abnormally low (VO2 = 9.4 +/- 0.6 ml/min/kg or 35 +/- 3 percent of predicted maximum VO2). An early rise in arterial lactate was similarly observed after LT. Maximum stroke volume index increased in six of seven patients after versus before LT (51 +/- 4 vs 37 +/- 2 ml/beat/m2) (p < 0.05). Three patients demonstrated an increased mean pulmonary arterial pressure at rest, while pressures during exercise were elevated in six. Pulmonary vascular resistance was mildly elevated after LT but decreased appropriately during incremental exercise and was associated with normal cardiac output responses. We conclude that pulmonary vascular abnormalities occurred during hemodynamic exercise testing in the majority of LT recipients; however, exercise limitation was primarily attributed to cardiovascular limitation or to deconditioning in five of the recipients. In the remaining three, the exercise study was considered to be submaximal by virtue of low peak heart rates. A persistent state of deconditioning may have important implications with respect to exercise training regimens after LT.