Cardiopulmonary exercise testing after single and double lung transplantation

The cardiopulmonary response to exercise was investigated in six single and six double lung transplant recipients using a three-minute incremental work rate protocol on a cycle ergometer. Maximum V̇O₂ averaged 44.2 ± 9.2 percent and 48.5 ± 5.0 percent of predicted maximal V̇O₂ in the single and double lung transplant groups, respectively. No evidence of ventilatory limitation to exercise was found in either group. Circulatory factors that may have limited exercise capacity included anemia and submaximal heart rates. There was a strong correlation between V̇O₂/kg at venous blood lactate level of 2.2 mEq/L and vital capacity/body surface area in the single, but not in the double, lung recipients. Maximum V̇O₂ in these lung transplant recipients was comparable to previously published values in heart-lung transplant recipients. The factors that limit maximum exercise capacity after lung transplantation deserve further study.