Comparative assessment of Clonidine and Tramadol on controlling post-spinal anaesthesia shivering.

Spinal anaesthesia is widely used as a safe anaesthetic technique for both elective and emergency operations. Shivering is a frequent complication following spinal anaesthesia, affecting between 40% and 60% of patients who receive a subarachnoid block This high rate of post-spinal shivering (PSS) is largely due to hypothermia that develops during surgery. The spinal block causes blood vessels to dilate and inhibits the body’s natural ability to constrict them for temperature regulation below the block level, leading to a shift of heat from the core to the body’s extremities. Shivering is a potentially serious complication, resulting in increased metabolic rate, increased oxygen consumption (up to 100-600%) along with raised carbon dioxide (CO2) production, ventilation and cardiac output, adverse postoperative outcomes such as wound infection, increased surgical bleeding, and morbid cardiac events. It causes arterial hypoxemia, lactic acidosis, increased intraocular pressure (IOP), increased intracranial pressure (ICP) and interferes with pulse rate, blood pressure (BP) and electrocardiographic (ECG) monitoring. Different drugs like Pethidine, Clonidine, Ketamine, Tramadol, Butorphanol, Dexmedetomidine, Nalbuphine and Nefopam have been evaluated for the prevention and treatment of peri operative shivering. They are simple, cost effective and readily available. Among the various drugs for controlling shivering, Pethidine has been shown to be effective with a minimum dose of 0.35mg per kg body weight. However, it is associated with many undesirable side effects including post-operative nausea and vomiting and respiratory depression. Tramadol on the other hand at a dose of 1mg per kg body weight had also been shown to be effective in the treatment of post-anaesthetic shivering but the incidence of nausea and vomiting was high. Clonidine at a dose of 1mcg per kg body weight is also effective in controlling the shivering post-spinal anaesthesia, however there are incidences of Hypotension and decreased heart rate in the patients. Hence, the aim of the present study is to compare the efficacy of Clonidine an alpha 2-agonist with that of Tramadol, a non-opioid analgesic for control of shivering after spinal anaesthesia in patients undergoing lower abdominal and lower limb surgeries. In the present study we hypothesise that Clonidine is more efficacious than Tramadol in controlling the post-spinal anaesthesia shivering.