ANGIOTENSIN-CONVERTING ENZYME BEI ADULT RESPIRATORY DISTRESS SYNDROME

Abstract

Angiotensin-converting enzyme (ACE) is present in high concentration in pinocytotic vesicles of the inner walls of the capillary endothelial cells of the lungs. Since a lesion of these endothelial cells is considered to be a major pathogenetic factor in adult respiratory distress syndrome (ARDS), the question arises whether serum ACE could be used as a marker enzyme in the course of ARDS to assess the syndrome's development and prognosis. The authors examined 28 patients with ARDS, 14 of whom survived acute respiratory failure. The serum ACE was determined every 48 hours. In addition, daily determination was carried out of AaDO2, pulmonary shunt perfusion (Qs/Qt) and thoraco-pulmonary compliance. In 9 of the surviving ARDS patients control serum ACE levels of lung function tests were performed half a year after recovery. 60 healthy volunteers served as controls. Definitely reduced serum ACE levels were found both in the surviving (17.1 ± 6.9 U/ml) and dead (17.6 ± 8.7 U/ml) ARDS patients. However, since the values for both groups are practically identical it can be assumed that determining the ACE level alone is probably not of prognostic value in acute respiratory failure. Patients who have survived ARDS show a significantly positive correlation between serum ACE and AaDO2, whereas in the patients who died a significantly negative correlation between serum ACE, AaDO2 And Qs/Qt was found. The combination of low AaDO2 and high serum ACE in ARDS, or conversely, high AaDO2 with simultaneously very low serum ACE, would, therefore, have to be regarded as prognostically unfavourable. With normalization of lung function a marked increase of serum ACE was noted in the surviving group.