Effect of Single Dose Intravenous Magnesium Sulfate on Postoperative Analgesic Consumption in Patients Undergoing Laparoscopic Cholecystectomy

This study describes a meticulous randomized controlled trial designed to investigate the "Effect of single dose intravenous magnesium sulfate on postoperative analgesic consumption in patients undergoing laparoscopic cholecystectomy." The study addresses a critical clinical need, as laparoscopic cholecystectomy, despite being a minimally invasive procedure, often leads to significant postoperative pain. This pain traditionally necessitates opioid analgesics, which, while effective, come with a host of undesirable side effects such as nausea, vomiting, constipation, dizziness, and even respiratory depression. The study aims to explore multimodal analgesia (MMA) by specifically examining magnesium, a known NMDA receptor antagonist with analgesic properties, as a means to reduce opioid dependency and improve patient recovery.

The central research question revolves around whether a single intravenous dose of magnesium sulfate can effectively reduce postoperative analgesic consumption in this patient population. The null hypothesis posits that intravenous magnesium sulfate will decrease analgesic consumption, while the alternate hypothesis suggests no such effect.

The primary objective is to quantify the reduction in postoperative morphine consumption in the magnesium group compared to the placebo. Secondary objectives are comprehensive, including the evaluation of pain intensity using the Visual Analogue Scale (VAS), the time until patients require rescue analgesia, an assessment of hemodynamic stability, the impact on neuromuscular blockade, and the incidence of any other adverse events.

Methodologically, it will be a parallel, two-arm randomized controlled trial. Eligible participants will be adult patients (18-65 years) classified as ASA Physical status I or II, scheduled for elective laparoscopic cholecystectomy. Stringent exclusion criteria are in place to ensure patient safety and data integrity, covering factors like patient refusal, high BMI, obstructive sleep apnea, significant organ dysfunction, certain medication use, substance abuse, psychiatric illness, specific surgical durations, or conversion to open surgery.

Patients will be randomly assigned to one of two groups: the Magnesium Sulfate Group (M), receiving 30 mg/kg intravenous magnesium sulfate diluted in 100 ml Normal Saline at the induction of anesthesia, or the Normal Saline Group (S), receiving an equivalent volume of Normal Saline. Both groups will also receive standard multimodal analgesia with intravenous Diclofenac (75 mg) and Paracetamol (1 gm) at the time of port closure. Rescue analgesia, in the form of Morphine (3-4 mg), will be administered if a patient's VAS score is ≥ 4. Extensive intraoperative and postoperative monitoring will be conducted to track various physiological parameters and pain-related outcomes. A robust sample size of 117 patients (53 per arm, adjusted for a 10% attrition rate) has been determined to ensure sufficient statistical power (90%) to detect a 30% reduction in morphine use, with a two-sided significance level of 5%. Data analysis will be performed using SPSS, employing descriptive statistics, Chi-square tests for categorical variables, and independent samples t-tests or Mann Whitney U-tests for continuous variables, with a P-value < 0.05 considered statistically significant.