Prise en charge anesthésique en chirurgie microvasculaire

Transfer of free flaps is a routine procedure but despite improved surgical skills, a significant proportion of free flaps ultimately fail due to insufficient blood perfusion. Problems during free flap surgery include prolonged procedures, large open wounds and extensive, often underestimated, blood and fluid loss. Thus, the patient may become both hypothermic and hypovolemic resulting in generalised vasoconstriction and diminished blood flow to the flap. The following is recommended: 1) maintain normal blood volume and blood pressure; 2) maintain normal body temperature; 3) avoid using systemically vasodilators that may cause a steal of blood flow from the free flap; 4) prefer general anesthesia to regional anesthesia that makes perfusion dependent on arterial pressure due to vasodilatation; 5) use crystalloids for replacement of insensible fluid loss and colloids for plasma substitution; 6) use invasive monitoring of arterial blood pressure and in high risk patients cardiac output monitoring as well; 7) use invasive monitoring of arterial blood pressure and in high risk patients monitor central venous pressure and cardiac output as well; 8) monitor blood flow in the flap. Clinical monitoring may be sufficient in skin flaps provided the observer is experienced but buried flaps may need hand held Doppler or implantable Doppler ultrasonography. Laser Doppler and spectrophotometry are alternative monitoring methods that have been fairly well documented in free flap surgery.