Hyperbaric oxygenation decreases blood flows in normal and septic rats

The purpose of the study reported here was to characterize the effects of acute exposure to 100% oxygen at a pressure of 202.6 kPa on hemodynamics and organ blood flow in antibiotic-controlled bacterial sepsis. An abscess containing known numbers and strains of live Escherichia coli and Bacteroides fragilis was established in the peritoneal cavity of rats. Sham-operated rats were used as controls. Cardiac output, fractional blood flow distribution, and blood flow were calculated from data obtained using the radiolabeled microsphere technique. Myocardial and renal blood flows were decreased (20-30%) in both experimental groups during hyperbaric oxygen (HBO) exposure. Renal blood flow remained diminished for at least 20 min after rats were removed from the hyperbaric chamber. Adrenal gland perfusion in abscess-containing rats was reduced both during and after HBO exposure. Skeletal muscle blood flow (quadriceps and gastrocnemius muscles) was reduced by one third in both experimental groups 20 min after acute exposure to HBO. The results of this study indicate that changes in organ perfusion induced by HBO are similar in abscess-containing and normal rats. We conclude that HBO does not alter the regulation of blood flow in antibiotic-controlled sepsis.