EFFECTS OF THE STABLE PROSTACYCLIN ANALOG ILOPROST ON MESENTERIC BLOOD-FLOW IN PORCINE ENDOTOXIC-SHOCK

Objective: To determine the effects of the stable prostacyclin analog, iloprost, in a porcine model of endotoxin-induced mesenteric ischemia . Design: Prospective, experimental, randomized, controlled study. Set ting: Animal research laboratory at a university medical center. Inter ventions: Pigs were randomized to receive a constant infusion of ilopr ost (0.18 mu g/kg/min) or an equivalent amount of carrier solution (no rmal saline) 30 mins before being infused with endotoxin (100 mu g/kg over 1 hr). The infusion with iloprost or carrier solution was continu ed for the duration of the experiment. Measurements and Main Results: Twelve pigs (six per group), weighing between 20 and 22 kg, underwent laparotomy during which a magnetic flowprobe was placed around the sup erior mesenteric artery and an ileal tonometer was inserted. Thirty mi nutes before they were infused with endotoxin, the animals were random ized to receive intravenous iloprost or normal saline. Endotoxin was i nfused centrally over a 60-min period. Animals received normal saline at a rate of 1.2 mL/kg/min which was begun at the start of the endotox in infusion. Data were measured at the end of the endotoxin infusion ( E-60) and 1 hr later (E-120). Mean arterial pressure was not affected by the dosage of iloprost used in this experiment. After resuscitation , the cardiac output returned to baseline in the iloprost-treated grou p but remained decreased in the control group (2.6 +/- 0.5 vs. 1.6 +/- 0.4 L/min). Superior mesenteric blood flow increased 34% above baseli ne levels in animals pretreated with iloprost (from 363 +/- 85 to 485 +/- 81 mL/min). The superior mesenteric Pco(2) was significantly highe r (53 +/- 9 vs. 40 +/- 5 torr; 7.1 +/- 1.2 vs. 5.3 +/- 0.7 kPa) and th e ileal intramucosal pH was significantly lower (7.07 +/- .28 vs. 7.44 +/- .23) in the control group than in the iloprost-treated group. Con clusions: Pretreatment with intravenous iloprost effectively increased intestinal blood flow in this model of endotoxin-induced mesenteric i schemia. This action of the drug resulted in an attenuation of ileal i ntracellular acidosis. Since low-dose iloprost had no effect on mean a rterial pressure, it may be a useful adjunct in the treatment of sepsi s and septic shock.