Comparative Study between Intrathecal Dexmedetomidine and Intrathecal Magnesium Sulfate for the Prevention of Post-Spinal Anesthesia Shivering in Lower Limb Orthopedic Surgeries. A Randomized Controlled Trial

Abstract

hivering is a common and unpleasant perioperative event following general as well as neuraxial anesthesia. It has been reported in 40-70% of regionally anesthetized patients. Shivering is a physiological compensatory response to core hypothermia precipitated by anesthetic induced thermoregulatory impairment, exposure to a cool environment, infusion of unwarmed fluids and evaporation from exposed surfaces. However, some shivering like tremors is not thermoregulatory. Post-spinal shivering presents by different degrees ranging from piloerection in the mild form up to generalized skeletal muscle contraction in the severe form that interferes with pulse rate, blood pressure and electrocardiographic (ECG) monitoring. Shivering increases the metabolic rate, the oxygen consumption and carbon dioxide production with lactic acidosis which is hazardous in patients with poor cardiac and/or respiratory reserves. It also increases intraocular and intracranial pressures and leads to hypertension, tachycardia, patient discomfort, increased wound pain, delayed wound healing, and delayed discharge from the post-anesthetic care unit (PACU). That is why its primary prevention and prompt control are warranted.