Endotoxin, prekallikrein, complement and systemic vascular resistance. Sequential measurements in man.

Eighteen patients were studied prior to and again within 6 hours after transurethral resection or cystoscopy. In addition to hemodynamic measurements, detection of endotoxin by limulus assay and bacteriologic sampling; prekallikrein, C3, C3 proactivator and lysosomal enzyme levels were measured. In five patients limulus assays were positive, and in one, gram-positive bacteremia developed but limulus assay remained negative. All six had significant decreases in prekallikrein, C3 or C3 proactivator. Systemic vascular resistance fell in all six. Four additional patients who had a decrease in systemic vascular resistance were not endotoxemic or bacteremic; one of these had a decrease in prekallikrein only. In the remaining eight patients with neither bacteremia nor endotoxemia, systemic vascular resistance did not change or increase after instrumentation. One had a decrease in C3 proactivator, another in prekallikrein. There was no significant difference in age, disease, antibiotic therapy or bactermia in the two groups of patients. Four of the five resectional procedures were performed in the group that showed decreases in systemic vascular resistance. The data suggest that acute endotoxemia or gram-positive bacteremia in man is associated with depletion of prekallikrein, decreased peripheral resistance and, in some instances, activation of the complement system.