Efficacy of intravenous infusion of prostacyclin (PGI 2) or prostaglandin E 1 (PGE 1) in augmentation of skin flap blood flow and viability in the pig

Abstract

The dose-response effects of 6-h intravenous infusion of PGI 2 (0, 5, 10, 25 or 75 ng/kg/min) or PGE 1 (0, 25, 50, 100 or 300 ng/kg/min) on skin hemodynamics and viability were studied in 4 × 10 cm random pattern skin flaps (n=24) raised on both flanks of the pig. Infusion of PGI 2 or PGE 1 was started immediately after intravenous injection of a loading dose 30 min before skin flap surgery. PGI 2 infusion significantly (P<0.05) increased the total skin flap capillary blood flow at the dose of 10 ng/kg/min, compared with the control. However, the distance of blood flow along the skin flap from the pedicle to the distal end, i.e. perfusion distance, was not increased. Consequently, the length and area of skin flap viability was also not significantly increased. The effect of PGI 2 infusion on skin blood flow was biphasic. Specifically, higher doses (≥ 25 ng/kg/min) of intravenous PGI 2 infusion produced no beneficial effect on the skin flap capillary blood flow. PGI 2 infusion at the dose of 10 or 75 ng/kg/min did not significantly increased plasma renin activities or plasma levels of norepinephrine compared with the control, therefore the biphasic effect of PGI 2 on skin flap blood flow was not related to circulating levels of norepinephrine or angiotensen. Intravenous infusion of PGE 1 did not produce any therapeutic effect on the skin capillary blood flow in the random pattern skin flaps at all doses tested. At the dose of 300 ng/kg/min, the mean arterial blood pressure was 17% lower (P<0.05) than the control, but the skin capillary flow still remained similar to the control. It was concluded that intravenous infusion of PGI 2 or PGE 1 was not effective in augmentation of distal perfusion or length of skin viability in the porcine random pattern skin flaps. Drug treatment modalities for prevention or treatment of skin flap ischemia is discussed.