EFFECTS OF NOREPINEPHRINE ON REGIONAL BLOOD-FLOW AND OXYGEN EXTRACTION CAPABILITIES DURING ENDOTOXIC-SHOCK

We explored the effects of norepinephrine on blood flow distribution a nd oxygen extraction capabilities during hyperdynamic endotoxic shock. Twelve anesthetized and mechanically ventilated dogs received 2 mg/kg of Escherichia coli endotoxin followed by a general saline infusion a nd were then randomly divided into two groups: six received norepineph rine (1 mu g/kg/min), and six served as control subjects. The norepine phrine group maintained higher mean arterial pressure, cardiac index, left ventricular stroke work index, and hepatic arterial blood flow wi thout altering blood flow to portal, mesenteric, and renal beds. When cardiac tamponade was induced to study tissue oxygen extraction capabi lities, the norepinephrine group had a lower critical oxygen delivery in whole body (11.5 +/- 5.2 versus 14.3 +/- 1.4 ml/kg/min, p < 0.05) a nd in liver (25.0 +/- 11.3 versus 38.0 +/- 9.0 ml/min, p NS) and a hig her critical oxygen extraction ratio in whole body (53.8 +/- 17.7 vers us 32.0 +/- 6.1%, p < 0.05), and in liver (57.0 +/- 11.9 versus 35.2 /- 4.3%, p < 0.05). We conclude that during endotoxic shock in dogs, n orepinephrine hardly influences blood flow distribution and could even increase hepatic artery blood flow, and it can also improve whole bod y and liver oxygen extraction capabilities.