Comparision of Nalbuphine versus Ketamine for treating post anaesthtic shivering after spinal anaesthesia in patients undergoing infra umbilical surgeries

Introduction and Need for the study:

Shivering is known to be a frequent complication, reported in 40 to 70 % of patients undergoing surgery under regional anesthesia.(1,2) Post-anesthetic shivering is spontaneous involuntary, rhythmic, oscillating, tremor-like muscle hyperactivity that increases metabolic heat production up to 600% after general or regional anesthesia .(3) Post anesthetic shivering may cause discomfort to patients, and aggravate wound pain by stretching incisions and increase intracranial (4) and intraocular (5) pressure. Various methods are available for control of shivering; these may be non pharmacological or pharmacological methods using drugs which have anti-shivering properties.

Nalbuphine, a semisynthetic opioid related to both Naloxone and Oxymorphone, has the characteristics of μ-antagonist and κ-agonist activities. It has a high affinity for κ-opioid receptors in the central nervous system. Therefore, Nalbuphine got a significant effect on post spinal anesthesia shivering. But Nalbuphine associated with many side effects like respiratory depression, urinary retention, nausea, vomiting, sedation and pruritus (6-9)

Ketamine has also been used as an anti-shivering drug. It is a non-competitive N-methy-D-aspartate (NMDA) receptor antagonist. Ketamine increases arterial pressure, heart rate, and cardiac output because of direct central sympathetic stimulation and inhibition of norepinephrine uptake into postganglionic sympathetic nerve endings, and may decrease core-to-peripheral redistribution of heat(10). Thus helps in prevention of shivering.

It is used as antishivering agent in dose of 0.5-0.75mg kg-1 IV. But even in these doses it causes side effects i.e. drowsiness, hallucination and delirium.(11-14)

So we conducted the present study to evaluate and compare the relative efficacy and safety of low dose Ketamine (0.25 mg/kg) and Nalbuphine (0.1mg/kg) for prevention of shivering in ASA 1 and 2 patients during spinal anaesthesia.

Objectives:

1) Primary objective- To evaluate and compare the relative efficacy and safety of low dose Ketamine (0.25 mg/kg) and Nalbuphine (0.1mg/kg) for prevention of shivering in ASA 1 and 2 patients during spinal anaesthesia.

2) Secondary objective- To assess any side effects like respiratory depression, urinary retention, nausea, vomiting, sedation and pruritus due to Nalbuphine and drowsiness, hallucination and delirium due to Ketamine .