ACTIVITY OF SERUM ANGIOTENSIN-CONVERTING ENZYME IN SEPTIC PIGS TREATED WITH INTRAPULMONARY CORTICOSTEROID

Objective: To evaluate serum angiotensin converting enzyme activity (S -ACE) in sepsis, its association with haemodynamics and pulmonary func tion, and the influence of intrapulmonary corticosteroid on its activi ty in serum. Design: Randomised, blind, placebo controlled experiment. Setting: Trauma research laboratory. Material: Sixteen juvenile pigs. Interventions: Mechanical ventilation and continuous light anaesthesi a. Brief infusion of live Staphylococcus aureus (4 x 10(10) colony for ming units) followed by inhalation of nebulised beclomethasone dipropi onate 50 mu g/kg (n = 8) or placebo (n = 7) 30 and 360 minutes after t he start of the septic challenge.Measurements and results: S-ACE activ ity, vascular pressures, lung mechanics arterial oxygen tension, and g lobal oxygen extraction were measured and calculated at regular interv als. One animal was withdrawn because of pulmonary arterial hypertensi on at the start of the experiment. The 15 remaining pigs were studied for 12 hours. The septic challenge induced a significant but transient increase in S-ACE activity in 13 animals (mean (SEM) +0.19 (0.06) mu kat/1). There were no significant differences in S-ACE between the gro ups. Terminal S-ACE correlated with oxygen extraction (r = -0.76, p < 0.01), mean arterial pressure (r = 0.69, p < 0.01), arterial oxygen te nsion (r = 0.59, p < 0.05) and change in lung/thorax compliance (r = 0 .63, p < 0.02). Conclusion: S-ACE activity increases in response to a Gram positive septic challenge. This is followed by a gradual decline which reflects to some extent the degree of septic lung injury. S-ACE activity is not influenced by intrapulmonarily administered corticoste roid.