Longitudinal evaluation of cardiopulmonary performance during exercise after bone marrow transplantation in children.

Abstract

Abnormalities in cardiopulmonary performance during exercise have been reported in children after bone marrow transplantation (BMT). We sought to study changes in exercise performance over time in pediatric BMT survivors. We retrospectively reviewed the results of serial cardiopulmonary exercise tests performed by patients who had undergone BMT at our institution. Four measurements of cardiopulmonary function are reported: maximum cardiac index (MCI), maximal oxygen consumption (Max VO(2)), oxygen consumption at ventilatory threshold (VO(2) at VT), and maximum work (Max Work) performed. A linear mixed-effects model was fitted to assess changes in these parameters over time. Thirty-three patients performed 96 cardiopulmonary exercise tests. MCI and VO(2) at VT were depressed at initial testing and did not change over time. Max VO(2) increased by 4% per year to 69% predicted, and Max Work increased to 77% predicted at 6 years after BMT. In spite of an impaired cardiovascular response to exercise as indicated by the persistently low MCI, aerobic and physical working capacity increase. Improved Max VO(2) suggests that oxygen extraction at the musculoskeletal level becomes more efficient with recovery from BMT. This may represent a compensatory response to an impaired ability to increase cardiac output.