Anestesia e retalhos microvascularizados

Abstract

Background and objectives: Head and neck reconstructive surgery represents a major challenge facing the need to achieve a good cosmetic and functional outcome. Anesthesia may be an important and determining factor in the technique success due to its role in hemodynamic stability and regional blood flow. On the other hand, regional anesthesia, changes in blood volume, and vasoactive drugs may influence blood flow in the flap. Thus, due to the lack of recommendations based on evidence, the anesthetic technique of these procedures is most often inspired in pathophysiological considerations. The aim of this paper is to review relevant aspects regarding anesthetic practice in these cases.

The Adrenergic System in Plastic and Reconstructive Surgery

“…Laminar flow through a vessel is influenced by its radius, the pressure gradient at the ends of the vessel, the length of the vessel, and viscosity of traveling fluid as per the Hagen-Poiseuille Law 11,12 . As blood flow is proportional to the radius of the vessel to the fourth power, the adrenergic system thereby influences blood flow by altering the luminal size of the vessel via constriction and dilation, reducing and increasing flow, respectively 1,11 …”

“…Laminar flow through a vessel is influenced by its radius, the pressure gradient at the ends of the vessel, the length of the vessel, and viscosity of traveling fluid as per the Hagen-Poiseuille Law. 11,12 As blood flow is proportional to the radius of the vessel to the fourth power, the adrenergic system thereby influences blood flow by altering the luminal size of the vessel via constriction and dilation, reducing and increasing flow, respectively. 1,11 Vascular smooth muscle tone in the tunica media dictates vessel diameter and therefore local blood flow and is autoregulated under the influence of α 1 and α 2 plus β 2 receptors in the endothelium and smooth muscle of vessels found in the skin and mucosa.…”

“…11,12 As blood flow is proportional to the radius of the vessel to the fourth power, the adrenergic system thereby influences blood flow by altering the luminal size of the vessel via constriction and dilation, reducing and increasing flow, respectively. 1,11 Vascular smooth muscle tone in the tunica media dictates vessel diameter and therefore local blood flow and is autoregulated under the influence of α 1 and α 2 plus β 2 receptors in the endothelium and smooth muscle of vessels found in the skin and mucosa. 1 α 1 Receptors are G q protein-coupled receptors, which facilitate the enzymatic conversion of phosphatidyl diphosphate into inositol triphosphate (IP 3 ) diacylglycerol (DAG) downstream pathways.…”