Shivering is recognized as an undesirable effect of spinal anesthesia. Patients undergoing gynecological surgeries may experience increased physiological stress due to perioperative shivering. This condition can lead to serious complications such as increased oxygen consumption, resulting in hypoxemia, lactic acidosis, and elevated carbon dioxide production. Additionally, shivering may cause increased intraocular and intracerebral pressure and can interfere with monitoring techniques like pulse oximetry, blood pressure, and electrocardiography. If not treated, shivering can negatively impact patient outcomes, prolong recovery times, and extend hospital stays. The use of opioids has shown effectiveness in treating shivering. Based on the existing literature, it is hypothesized that there is no difference in the efficacy of nalbuphine and ketamine in controlling perioperative shivering in patients undergoing gynecological surgery under spinal anesthesia. Therefore, the study aims to investigate and compare the effectiveness of nalbuphine and ketamine in managing post-spinal shivering in these patients, focusing on i) incidence of shivering, ii) severity of shivering in both groups, iii) complications such as vomiting and sedation, and iv) the need for rescue medication. Preventing and managing shivering is crucial for successful surgical outcomes. To date, no comparative study has evaluated the intravenous efficacy of these two drugs in this patient population for post-spinal shivering control. This will be a double-blind, randomized controlled trial conducted in the Anesthesiology Department at DHQ Teaching Hospital Sargodha. A total of 90 gynecological patients will be enrolled and divided equally into two groups: Group N receiving nalbuphine and Group K receiving ketamine. Parameters such as heart rate, systolic and diastolic blood pressure, temperature, oxygen saturation, incidence and grade of shivering, complications like sedation and vomiting, and the need for rescue medication will be recorded. The study may face limitations due to the lack of advanced monitoring equipment for assessing parameters like core body temperature at the study site. Evaluations of cognitive and psychomotor functions cannot be conducted due to resource constraints. The use of a non-probability convenience sampling method, while practical, may introduce bias. Additionally, precise blinding may not be achievable due to limited technical personnel, and financial constraints prevent increasing the sample size.

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:

1. Incidence of shivering in both study groups
2. Determine the grades of shivering
3. Complications of study drugs such as vomiting and sedation
4. 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.

Female patients undergoing gynecological surgery under spinal anesthesia will be recruited for the study.

Your study is a single-center anesthesia comparison trial.

There is no requirement to share individual participant data (IPD).

Unless you have a formal data-sharing mechanism (repository, request process, timelines), selecting Yes will create extra mandatory fields.

An independent outcome assessor was blinded to group allocation. This assessor was not involved in administering the anesthesia and had no knowledge of whether the participants received nalbuphine or ketamine. Incidence and grades of shivering, complications of study drugs such as vomiting and sedation, and the need for rescue drugs were evaluated by this blinded assessor to minimize bias.