Effects of prostacyclin injections and infusions on canine femoral hemodynamics

The use of prostacyclin (PGI₂) infusions has been recommended in the management of patients with severe distal arteriopathy, who are not candidates for conventional bypass procedures. Further clarification regarding the route of administration and the optimal dose of this potent vasodilator, however, is needed before controlled clinical trials are initiated. We measured bilateral femoral arterial blood flow electromagnetically in seven anesthetized adult mongrel dogs. Systemic arterial pressure and cardiac output were also measured. Central venous and femoral arterial injections of PGI₂ were administered in five doses ranging from 10^-4 to 10⁰ μg · kg^-1 to study the dose response. PGI₂ was also infused intravenously and intra-arterially for 20 minutes at a dose of 10^-1 μg · kg^-1 · min^-1. Femoral arterial injections of PGI₂ in doses from 10^-4 through 10⁰ μg · kg^-1 caused significant (p < 0.05) and dose-dependent increases in ipsilateral femoral arterial blood flow. Intravenous injections of PGI₂ caused no significant changes in the dose range from 10^-4 to 10^-2 μg · kg^-1 but resulted in a significant (p < 0.05) reduction in femoral arterial flow and systemic arterial pressure at doses of 10^-1 and 10⁰ μg · kg^-1. The femoral arterial infusion of PGI₂ produced a significant and sustained increase in femoral arterial flow that was not observed during the intravenous infusion. Arterial pressure was unchanged with intra-arterial PGI₂ but was significantly reduced during the intravenous infusion. The beneficial hemodynamic effects of intra-arterial PGI₂ suggest that further clinical trials should employ this route of administration. On the basis of these data, intravenous administration of the drug will have limited clinical application.