Comparison of Two Drugs ,i.e., Nalbuphine Vs Ketamine at Low Doses for the Peri-Operative Shivering Control in Patients Undergoing Gynaecological Surgery Under Spinal Anaesthesia

Shivering, a repetitive involuntary muscular activity, is the most common problem during and after spinal anesthesia. The spinal anesthesia not only causes vasodilation, resulting in rapid loss of heat, but it also causes redistribution of heat in the peripheral areas, resulting in hypothermia and, eventually, shivering. Although it does not result in death, complications can arise in patients with a history of cardiorespiratory diseases, endangering the patients' safety. These complications include hypoxemia with increased lactic acidosis and carbon dioxide, increased oxygen consumption, increased intraocular and intracerebral pressure resulting in aggravation of post-operative pain and increased surgical bleeding that interferes with pulse rate and ECG monitoring.

Various treatments are currently available to control shivering in patients following spinal anesthesia. These include both pharmacological and non-pharmacological methods. Non-pharmaceutical methods are effective but expensive. A variety of pharmacological methods for controlling post-spinal anesthesia shivering have been suggested, including ketamine and nalbuphine as well as many others that are inexpensive and easy to use. Ketamine, a competitive receptor antagonist of N-methyl D-aspartate (NMDA), is known to reduce regional anesthesia by 70% and postoperative shivering by impairing thermoregulatory controls. It causes vasoconstriction in patients at risk of hypothermia. Ketamine controls shivering through non-shivering thermogenesis, either through the β-adrenergic effect of norepinephrine or through the hypothalamus. Nalbuphine, a semi-synthetic "class B" opioid analgesic, has both K-agonist and µ-antagonist properties. It has a high affinity for K-opioid receptors in the central nervous system. In the hypothalamus, the temperature regulation threshold is lowered by it for vasoconstriction during shivering due to the presence of high-density a2 adeno-receptors. The anti-shivering effects of intravenous ketamine and nalbuphine are poorly understood. Therefore, a double-blind, placebo-controlled, randomized study has been designed to compare the potency and efficacy of ketamine with nalbuphine and investigate the possible control mechanisms in patients undergoing gynecological surgery receiving spinal anesthesia.

The objectives of this study are to investigate and compare the effects of nalbuphine and ketamine in patients undergoing spinal anesthesia for gynecological surgeries in terms of:

• Incidence of shivering in both study groups
• Determine the grades of shivering
• Complications of study drugs such as vomiting and sedation
• Need of Rescue drug (injection of Tramadol IV 0.5 mg/kg)

Inclusion criteria

i. Female patients of age between 18 and 40 years undergoing gynecological surgeries (total abdominal hysterectomy, ovarian cystectomy, vaginal hysterectomy, myomectomy).

ii. ASA 1 and 2.

Exclusion criteria

i. ASA 3 and onwards as per the classification of the American Society of Anesthesiologists.

ii. Obstetric patients

iii. Patients who are allergic to study drugs.

iv. Patients undergoing general anesthesia.