PERIOPERATIVE BLOOD LOSS AND ITS REDUCTION THE ROLE OF THE ANAESTHETIST

Abstract

Perioperative blood loss & its reduction is considered one of the most important topics in modern surgery not only for the surgon but also for the anaesthesiologist and the search is still continued for the best safe & effective methods that reduce the blood loss. There is no ideal technique for deliberate hypotension. This leads to suggesting multiple methods each of which has advantages & Dis advantages: The physiological methods of bleeding reduction includes patient positioning, mechanical ventilation with intennittent positive pressure ventilation, IPPV, positive end oxpiratory pressure (PEEP), control of oxygen & C02 tension in blood & good and smooth anaesthesia. Mechanical methods include arteriotomy, torniquet & local infiltration with sympathomimetic amines. Pharmacological methods include agents & drugs that either decrease total peripheral resistane (TPR) or cardiac output (CO) peripheral vascular resistance can be reduced by blocking the sympathetc. Reflex arc at multiple sites at the barcreceptors as halothane at the vasomotor center (VMC) as AH general anaesthetics, at the preganglionic sympathetic nerve as spinal anaesthesia, at sympathetic ganglia as ganglion blockers, at alpha adrergic receptors as alpha 2 antagonists and alpha agonists or at the vessel wall as vasodilators. Cardiac output can be reduced either by beta blockers & volatil anaesthetics. Complication of deliberate hypetonsion includes reactionary haemorrhage, haematoma formation and complications of decreased blood flow to vital organs as brain, heart, lungs, kidney & the liver.