Fig. 6.
In patients presenting BOS, the slope of the alveolar plateau for helium increases as ventilation becomes more heterogeneous and this early marker of BOS becomes abnormal before spirometric criteria for BOS 1 are fulfilled. This figure shows changes in FEV1 and in the slope of the alveolar plateau for helium obtained during a single-breath washout test (She) in one heart-lung transplant recipient. In the upper panel, the dashed line corresponds to 100% of the two best postoperative values and the continuous line indicates a 20% decrease (BOS stage 1). In the lower panel, the dashed line corresponds to the average of the two lowest postoperative values, and the continuous line is the upper limit of the 97.5% CI computed from data obtained in 10 stable transplant patients. Note that a significant change in She is observed 631 days before the 20% drop in FEV1.
(From Van Muylem A, Knoop C, Estenne M. Early detection of chronic pulmonary allograft dysfunction by exhaled biomarkers. Am J Respir Crit Care Med 2007;175:731–6; with permission.)