Peripheral resistance changes and blood pooling after endotoxin in eviscerated dogs.

Studies were performed on eviscerated dogs maintained with a constant cardiac inflow with and without injections of lethal amounts of E. coli endotoxin. Continuous recordings of mean arterial blood pressure and total venous return permitted determination of changes in total peripheral resistance and extent of vascular pooling. A significant fall in mean arterial blood pressure occurs within 30 minutes after endotoxin in the eviscerated dog with constant cardiac inflow. There is therefore a decrease in total peripheral resistance. There is also a small but significant increase in vascular pooling exceeding that seen without endotoxin but much reduced from that observed in noneviscerated animals given endotoxin. It is concluded that a decrease in vascular tone occurs after endotoxin and that it probably plays a significant role in the later phase of endotoxin shock in the dog.