The Effect of Alpha‐Adrenergic Stimulation and Blockade on Perfusion of Myocutaneous Flaps

Abstract

A porcine myocutaneous flap model was utilized to assess the development of denervation adrenergic hypersensitivity and to determine the effects of the alpha-adrenergic blocking agent--phenoxybenzamine--on flap blood perfusion. During intravenous administration of norepinephrine, blood flow to the flaps and control skin was monitored simultaneously, using laser Doppler velocimetry and dermofluorometry. A relative decrease in myocutaneous flap blood flow, as compared to control skin in response to norepinephrine infusion, was observed at between 2 and 7 days following flap elevation. This is the same time period during which norepinephrine content of skin flaps is diminished, and suggests development of an increased sensitivity to adrenergic stimulation. Administration of phenoxybenzamine blunted norepinephrine-induced pressor responses and blocked development of adrenergic hypersensitivity in the porcine myocutaneous flap model. Phenoxybenzamine significantly increased flap blood perfusion (as measured by dermofluorometry).

A literature review and meta‐analysis of outcomes in microsurgical reconstruction using vasopressors

“…This renders the vasculature of the flap less responsive to systemically administered vasoconstrictive agents (Lecoq, Joris, Nelissen, Lamy, & Heymans, ; Lorenzetti, Salmi, Ahovuo, Tukiainen, & Asko‐Seljavaara, ). Animal models have demonstrated that this transient nonresponsiveness is replaced by a heightened vasoconstrictor sensitivity, which may begin as early as 2 days postoperatively (Banbury, Siemionow, Porvasnik, Petras, & Browne, ; Banbury, Siemionow, Porvasnik, Petras, & Zins, ; Banic et al, ; Bickel, Axelrod, Schmelz, Marthol, & Hilz, ; Godden, Little, Weston, Greenstein, & Woodwards, ; Moore et al, ; Rizzoni et al, ). Thus, even if safety of intraoperative vasopressor usage is demonstrated, postoperative complications are still feared.…”

“…When performing microsurgical reconstruction, there has been a hesitancy to use vasopressors, both intraoperatively and postoperatively, for the fear of causing vessel spasm leading to decreased inflow, which may or may not be reversible. This reluctance is mainly based on animal studies demonstrating decreased flap inflow secondary to vasopressor usage (Banic, Krejci, Erni, Wheatley, & Sigurdsson, ; Cordeiro, Santamaria, Hu, & Heerdt, ; Moore, Trachy, & Cummings, ; Sun, Kuo, & Yang, ). In contrary to these findings, literature reviews have largely demonstrated that no deleterious effects were associated with perioperative vasopressor utilization (Hand et al, ; Haughey et al, ; Ibrahim, Kim, Rabie, Lee, & Lin, ; Swanson et al, ).…”

Vasopressors and Reconstructive Flap Perfusion

“…However, when sodium nitroprusside is given in a dose causing a 30% reduction in systemic vascular resistance and thereby decreasing arterial pressure, there is a great reduction in free f lap blood f low although cardiac output is maintained. The administration of vasopressors in microsurgical breast reconstruction was explored by Chen et al 12 18 Pigs Orthotopic groin free flap Lidocaine, bupivacaine f laps, free transverse rectus abdominis myocutaneous f lap, and muscle-sparing free transverse rectus abdominis myocutaneous f lap operations. One-hundred two patients (140 f laps) received phenylephrine and/or intraoperative ephedrine, whereas 85 patients (118 f laps) did not.…”

Comparison of Topical Anti-ischemic Agents in the Salvage of Failing Random-Pattern Skin Flaps in Rats

“…Although the mechanisms for random-pattern skin flap ischemia have yet to be fully elucidated, surgically induced adrenergic vasoconstriction is believed to play a major role in the reduction of nutrient capillary blood flow. 2,[7][8][9] Various pharmacologic agents that diminish sympathetic tone or promote arteriolar smooth muscle relaxation have been shown to improve skin flap perfusion and survival, lending support to this proposed pathophysiologic mechanism. 10 One such group of vasoactive drugs is the calcium channel blockers.…”