Serum and pulmonary angiotensin converting enzyme as a marker of acute lung injury in an experimental model of adult respiratory distress syndrome

OBJECTIVE: To know if the determination of the angiotensin converting enzyme in serum (SACE) and lung (LACE) may be useful as a marker of acute lung injury (ALI) in the adult respiratory distress syndrome (ARDS). METHOD: By reproducing in a experimental model of ALI with oleic acid in dogs which simulate the early stage of ARDS, we have correlated the pathologic and analytical changes observed with the results of the determinations of SACE and LACE. RESULTS: We have found sequential pulmonary lesions (congestion, edema, hemorrhage polynuclear infiltration and thrombosis) and biological alteration (hypoxemia, pulmonary hypertension, early leukopenia and final leukocytosis, thrombopenia and hypofibrinogenemia) that reproduce the typical changes of ARDS, together with the decrease of SACE--slow and progressive--and LACE--abrupt in the onset and maintained during the experiment--. CONCLUSIONS: The LACE is a good marker of the beginning of the lesion because its decrease coincides with the first pathological changes (congestion) and with the hypoxemia, pulmonary hypertension and leukopenia, maintained without changes, during the whole experiment. On the other hand, the SACE corresponds as an inespecifical reactant, marker of acute inflammation and loss of pulmonary endothelium, because its progressive decrease evolutioned with the pathological lesions and the analytical changes. In conclusion, the sequential determination of SACE has a prognostic and evolutive value in comparison with the LACE, which has a diagnostic value from the beginning of the experiment of ALI and maintained throughout.