the Use of Magnesium Sulfate for Prevention of Postspinal Shivering

Shivering is an unpleasant experience after spinal anesthesia. Shivering is defined as an involuntary, repetitive activity of skeletal muscles. The mechanisms of shivering in patients undergoing surgery are mainly intraoperative heat loss, increased sympathetic tone, pain, and systemic release of pyrogens. Spinal anesthesia significantly impairs the thermoregulation system by inhibiting tonic vasoconstriction, which plays a significant role in temperature regulation. Spinal anesthesia also causes redistribution of core heat from the trunk (below the block level) to the peripheral tissues. These two effects predispose patients to hypothermia and shivering. The median incidence of shivering related to regional anesthesia observed in a review of 21 studies is 64.4%. Shivering increases oxygen consumption, lactic acidosis, carbon dioxide production, and metabolic rate by up to 400%. Therefore, shivering may cause problems in patients with low cardiac and pulmonary reserves. The best way to avoid these intraoperative and postoperative shivering-induced increases in hemodynamic and metabolic demands is to prevent shivering in the first place. Although magnesium is among several pharmacological agents used for the treatment of shivering, its effects on prevention of shivering during central neuraxial blockade have not been evaluated to date. Henceforth, the aim of this study was to evaluate the effect of magnesiume on shivering during spinal anesthesia. Aim: to compare the efficacy of intravenous versus intrathecal magnesium sulphate for prevention of post spinal shivering in adult patients undergoing elective lower limb orthopedic surgeries.