Significance of bronchial mucosal blood flow for the monitoring of acute rejection in lung transplantation.

Abstract

Bronchial mucosal blood flow (BMBF) was measured with a laser-Doppler flowmeter in a canine model (n = 20), and the measurement was evaluated to see if it was a useful method for diagnosing allografted lung rejection. The ratio of the value of BMBF at the level of the donor second carina against that at the level of carina (the L/C ratio, an index of BMBF of donor bronchus) decreased in accordance with the extent of lung rejection, and it increased and entered the normal range with the reversal of lung rejection. Compared with the L/C ratio and the rejection grade by histologic changes in open-lung biopsy, the L/C ratio at grade 0 (latent phase) was 0.91 +/- 0.07; at grade Ia (early vascular phase), 0.86 +/- 0.05; at grade Ib (late vascular phase), 0.68 +/- 0.10; at grade II (early alveolar phase), 0.60 +/- 0.14; and at grade III (late alveolar phase), 0.50 +/- 0.15. A significant difference was noted between grades Ia and Ib (p less than 0.01) and between grades Ib and III (p less than 0.01). The sensitivity and the specificity in the detection of early rejection before grade Ib were 96% and 92%, with only one false-negative and two false-positives resulting from 51 measurements of BMBF. In three cases of serious lung infections, the L/C ratio did not fall, and the rejection could be distinguished from infection. These results suggest that measurement of the BMBF is useful for detecting the early rejection of transplanted lungs.