Angiotensin-converting enzyme activity in serum and bronchoalveolar lavage fluid after damage to the alveolo-capillary barrier in the human lung

Abstract

Objective: Angiotensin-converting enzyme (ACE) is considered as a possible marker for endothelial cell damage in serum or bronchoalveolar lavage fluid. This hypothesis was tested during cardiac surgery and during the adult respiratory distress syndrome.

Design: We used patients with an expected different degree of endothelial cell damage. ACE levels in serum and bronchoalveolar lavage fluid were compared with indirect markers of alveolo-capillary barrier integrity.

Setting: Interdisciplinary team in a university hospital.

Methods: 13 Cardiac surgery patients received no glucocorticoids and 13 others received 2 g methylprednisolone before extracorporeal circulation. Thirteen patients were used as controls and 15 patients had nonseptic adult respiratory distress syndrome. All underwent bronchoalveolar lavage for ACE determination.

Results: At different times during surgery serum angiotensin-converting enzyme levels were not significantly different between the two groups. In post-operative bronchoalveolar lavage fluid, angiotensin-converting enzyme levels were significantly higher in patients who received corticoids (27.8 +/- 1.7 U/l, mean +/- SEM), compared to patients without corticoids (19.8 +/- 1.4 U/l), control patients (18.2 +/- 1.3 U/l) or patients with full blown non-septic adult respiratory distress syndrome (18.8 +/- 1.1 U/l). There were no correlations between lavage angiotensin-converting enzyme and other parameters for alveolo-capillary membrane integrity in the lavage fluid such as the number of neutrophil cells, albumin or protein concentration, and between lavage angiotensin-converting enzyme and PaO2/FIO2 ratio during lavage.

Conclusion: Angiotensin-converting enzyme activity in serum or bronchoalveolar lavage fluid does not reflect damage of endothelial cells or damage of alveolocapillary integrity in acute pulmonary disease.