Effects of thromboxane synthetase inhibition on postburn mesenteric vascular resistance and the rate of bacterial translocation in a chronic porcine model.

It is known that thromboxane (TX)B2, the metabolite of the potent vasoconstrictor TXA2, is elevated markedly in the serum of the patients immediately postburn. We had shown that extensive thermal injury causes a reduction in mesenteric blood flow that can lead to bacterial translocation from the intestine. In this study, we tested the hypothesis that the TX synthetase inhibitor, OKY-046, prevents increased mesenteric vascular resistance (MVR) and decreases the rate of translocation of bacteria seen after extensive thermal injury. Pigs in groups 1 (n = 6) and 2 (n = 6) had third degree burns of 40 per cent total body surface area under general anesthesia and were resuscitated according to the Parkland formula. Pigs in group 2 received 10 milligrams per kilogram of OKY-046 as a bolus just before the burn and 10 grams per kilogram per minute for 16 hours as a continuous infusion. Pigs in group 3 (control, n = 6) underwent general anesthesia only and received daily maintenance fluids of lactated Ringer's solution, 2 milliliters per kilogram per hour. OKY-046 prevented the significant increase in MVR seen during the first eight hours after burn. The total peripheral resistance (TPR) showed an early increase and a late decrease in the burn group, while the cardiac index (CI) and temperature (T) significantly increased after 24 hours. Administration of OKY-046 kept TPR, Cl, and T remarkably stable. OKY-046 reduced the rate of translocation of bacteria seen in the burn group from 67 to 17 per cent. Our results show that the blockade of thromboxane synthesis by OKY-046 prevented the early mesenteric vasoconstriction and the late hyperdynamic response seen after thermal injury and was useful in reducing the incidence of postburn translocation of bacteria.