Limitations of spirometry in detecting rejection after single-lung transplantation

Pulmonary function testing has been extensively studied in the heart-lung transplant (HLT) population and has been advocated as a screening test for rejection or infection; however, few data are available in the single-lung transplant (SLT) population. The effect of acute episodes of infection, rejection, and bronchiolitis on the pulmonary function of 30 SLT patients with varying underlying disease states was prospectively evaluated. The native disease process was obstructive in 17 (SLT-OBS), restrictive in six (SLT-IPF), and pulmonary vascular in seven (SLT-PVD). Rejection was associated with a drop in FVC from 71 +/- 15 to 62 +/- 14% of predicted, with a significant drop seen in all three subgroups. Statistically significant drops in FEV1 were also seen in the SLT-OBS and SLT-PVD subgroups but not in the SLT-IPF subgroup. A drop in FEV25-75% was seen only in SLT-PVD. The greatest fall in FVC, FEV1, and FEF25-75% was seen with bronchiolitis, followed by acute rejection. The sensitivity and specificity of spirometry as a predictor of infection or rejection were significantly lower than those previously reported for HLT, with SLT-PVD having the most and SLT-OBS the least clinically useful values. We conclude that a fall in spirometry is seen in infection and rejection in SLT and that the underlying disease state has a significant influence on the diagnostic utility of specific spirometric indices.