NITRIC-OXIDE SYNTHASE INHIBITION VERSUS NOREPINEPHRINE IN OVINE SEPSIS - EFFECTS ON REGIONAL BLOOD FLOW

Hypotension is a serious problem in septic patients. We investigated r egional perfusion in several organs during treatment of hyperdynamic s epsis in sheep. Sepsis was induced and maintained for the entire exper iment with a continuous infusion of live Pseudomonas aeruginosa, Treat ment with either norepinephrine or the nitric oxide synthase inhibitor L(omega)-mono-methyl-arginine (L-NMMA) was begun after 24 h of sepsis and continued for 24 h, The norepinephrine dosage was adjusted to ach ieve the same increase in mean arterial pressure as that obtained by a fixed dose of L-NMMA (7 mg/kg/h). Blood flows were analyzed by the mi crosphere technique. Both compounds restored blood pressure effectivel y, but only L-NMMA caused a significant increase in systemic vascular resistance, concomitant with a significant fall in cardiac output, Sep sis caused an increase in myocardial blood flow and a redistribution o f blood flow away from the pancreas and the stomach. Renal blood flow was not significantly elevated, During treatment with either compound, renal blood flow remained unchanged, despite a fall in cardiac output in the L-NMMA group. Unchanged renal blood flow combined with the res toration of arterial blood pressure caused a significant increase in u rine output, Both L-NMMA and norepinephrine caused a redistribution of blood flow to the colon. Pancreatic blood flow was further reduced by L-NMMA but the oxygen extraction improved simultaneously, so that oxy gen availability in the pancreas might have been unchanged. Because is chemic pancreatitis in sepsis is likely to trigger multiorgan failure, further investigations in that area are desirable.