Clonidine Versus Granisetron for Shivering Prevension

Shivering is one of the most important periperative complications seen in clinical practice. Several mechanisms have been postulated for its pathogenesis. Anesthetic-induced inhibition of thermoregulation resulting in hypothermia is an important cause of post anesthesia shivering, uncontrolled spinal reflexes, and cutaneous vasodilation are the other suggested mechanisms involved in the pathogenesis of shivering. Opioid receptors, α2 receptors, and serotonergic receptors also are involved of shivering. Various drugs were studied for their potential role in prevention of peri-operative shivering such as tramadol, dexmedetomidine, ondansetron, ketamine, and pethidine. We decided to perform a well-designed study to compare clonidine and granisetron which has been recently introduced as drugs for prevention and control of shivering after spinal anesthesia.