Catecholamine sensitivity in the rat femoral artery after microvascular anastomosis

Abstract

Tissue can demonstrate vasospastic instability after microvascular anastomosis. This study investigates the in vitro effect of increasing concentrations of phenylephrine on the rat femoral artery after microvascular anastomosis. Bilateral groin flaps based on the inferior epigastric artery were raised on 55 Wistar male rats. On the test side, a microvascular anastomosis was performed, but not on the control side. On days 2–12 postoperatively, the rats were sacrificed and the femoral arteries harvested and suspended in increasing concentrations of phenylephrine. The vascular tone on the test and control sides were recorded and compared. Increased sensitivity was found on the test side as compared with the control side (P = 0.000). This supersensitivity to phenylephrine was blocked by the addition of phentolamine and it is believed to be the result of sympathetic denervation, which occurs when the sympathetic fibers are cut during the harvesting of the flap. The resulting vascular instability is believed to contribute to flap failure. © 2000 Wiley‐Liss, Inc. MICROSURGERY 20:217–220 2000

Effects of Vasopressor Administration on the Outcomes of Microsurgical Breast Reconstruction

“…[5][6][7][8] One study reported a decrease in arterial blood flow to rotational flaps in a porcine model due to systemic phenylephrine administration, while systemic epinephrine increased microvascular perfusion. 5 In a porcine axial myocutaneous flap model, dopamine had no effect on flap perfusion but dobutamine increased flap perfusion.…”

“…A third study reported increased sensitivity to phenylephrine after microsurgical anastomosis in a rat femoral artery model that was hypothesized to cause vascular instability and possible flap failure. 7 Conversely, another pig model study examining free latissimus flaps to the lower extremity demonstrated no deleterious effects of systemic phenylephrine on flap blood flow while increasing mean arterial pressure. 8 The conclusions from these studies are contradictory and their clinical values have not been demonstrated.…”

“…Furthermore, in comparing the 2 studies on muscle free flaps, Gooden et al showed an increase in vasoconstriction with locally administered phenylephrine, whereas Banic et al demonstrated no decrease in flap blood flow with systemic phenylephrine. 7,8 These differences in study design may account for the contradictory results.…”

“…Decreased flap arterial flow has been described with the systemic and topical administration of the vasopressor phenylephrine. [5][6][7] These studies also showed that vasopressors are not universally deleterious as epinephrine, and dobutamine actually increase flap perfusion. 5,6 However, other animal studies show no decrease in perfusion with phenylephrine.…”

The Effect of Intravenous Dopamine and Dobutamine on Blood Circulation During a Microvascular TRAM Flap Operation

“…Animal studies have shown that surgical stripping of adventitia and consequent sympathectomy of the donor vessels of free flaps result in changes in the microcirculation, vasodilatation, increased capillary flow, and hypersensitivity to topical vasoactive agents. 17,18 A prospective clinical study addressed the same issue in noninnervated free latissimus dorsi muscle flaps and demonstrated that blood flow in the pedicle and in the recipient artery of a free muscle flap increases after surgery, while the resistance index decreases. 12 In the present model, however, the pedicle was not cut, so sympathetic tone was present.…”