This randomized controlled trial aims to compare the analgesic efficacy of dexmedetomidine infusion versus low-dose ketamine infusion as adjuvants in bariatric surgery. The study includes 90 patients undergoing bariatric surgery at Menoufia University Hospital, randomized into three groups: dexmedetomidine, ketamine, and control (placebo). Primary outcomes include total morphine consumption intra- and post-operatively. Secondary outcomes include postoperative pain scores, total analgesic consumption, time to first analgesic request, hemodynamic parameters, and patient satisfaction. This study seeks to explore safer, more effective pain management strategies to minimize opioid use in bariatric surgery patients.

This study is a prospective, randomized controlled interventional trial evaluating the analgesic efficacy and opioid-sparing effects of dexmedetomidine and low-dose ketamine as adjuvants in bariatric surgery. Ninety patients meeting the inclusion criteria will be enrolled and randomized into three groups:

• Dexmedetomidine Group: Patients will receive a bolus dose of dexmedetomidine (0.5 µg/kg) followed by a continuous infusion (0.5 µg/kg/h) until 10 minutes before the end of surgery.
• Ketamine Group: Patients will receive a bolus dose of ketamine (0.3 mg/kg) followed by a continuous infusion (0.3 mg/kg/h) until 10 minutes before the end of surgery.
• Control Group: Patients will receive an equal volume of normal saline as a placebo.

Objectives

The primary objective is to compare intra- and postoperative morphine consumption between groups. Secondary objectives include:

• Pain assessment using the Numeric Rating Scale (NRS) at multiple time points postoperatively.
• Time to first request for rescue analgesia.
• Hemodynamic stability (heart rate and mean arterial pressure).
• Patient satisfaction assessed using a 5-point scale.
• Incidence of adverse effects such as nausea, vomiting, bradycardia, and respiratory depression.

Study Protocol All patients will undergo standard preoperative assessments, including history, physical examination, and laboratory investigations. General anesthesia will be induced and maintained per institutional protocols. Postoperatively, pain management will follow a stepwise approach, with intravenous paracetamol as rescue analgesia.

Significance Given the high prevalence of obesity-related comorbidities, bariatric surgery patients are at increased risk for postoperative complications, particularly with opioid use. This study addresses the need for opioid-sparing pain management strategies, potentially reducing the risks of opioid-related adverse effects and improving patient outcomes.

Inclusion Criteria:

• Patients aged 18-60 years.
• Both sexes.
• Body mass index (BMI) > 35 kg/m², scheduled for bariatric surgery.
• American Society of Anesthesiologists (ASA) physical status I-II.

Exclusion Criteria:

• History of hypersensitivity to dexmedetomidine or ketamine.
• History of substance abuse or chronic opioid use.
• American Society of Anesthesiologists (ASA) physical status III or IV.
• Severe hepatic or renal impairment.
• Cardiopulmonary disorders.
• Severe diabetes mellitus.
• Psychiatric disorders, seizures, uncontrolled hypertension (systolic ≥ 140 mmHg or diastolic ≥ 90 mmHg), or heart block.

IPD and supporting information will be available starting 6 months after publication of the study results and will remain accessible for 5 years.

Access to IPD and supporting information will be provided to qualified researchers upon reasonable request. Requests should include a proposal outlining the intended research objectives, ethical approval, and a data-sharing agreement. Access will be granted via secure data transfer or repository.

The allocation will be concealed using sequentially numbered, sealed envelopes. A nurse not involved in patient care will open the envelope after induction of anesthesia to assign patients to groups.