Intraperitoneal ketamine versus bupivacaine for postoperative pain control after laparoscopic cholecystectomy – a double-blind randomized controlled trial

Intraperitoneal instillation of local anesthetics is commonly used to manage pain associated with laparoscopic surgeries. Few studies have compared intraperitoneal instillation of ketamine with bupivacaine for postoperative pain control in patients undergoing laparoscopic cholecystectomy (LC). This study aimed to compare the effects of intraperitoneal instillation of ketamine versus bupivacaine on postoperative pain control following LC. This double-blind randomized controlled trial was conducted by the Department of Anesthesiology, Critical Care, and Pain Management at Liaquat National Hospital. Patients were divided into Group K and Group B. Group K received ketamine at a dose of 0.25 mg/kg diluted in 40 ml of saline intraperitoneally, while Group B received 2 mg/kg bupivacaine diluted in 40 ml of saline. Pain scores were assessed using the Numeric Rating Scale at 5 min, 15 min, 6 h, 12 h, and 24 h postoperatively. A total of 46 patients in each group were studied. At 5 min, the average pain score was 2.1 ± 0.5 in Group K and 2.8 ± 0.7 in Group B (p < 0.001). At 15 min (1.5 ± 0.2 versus 3.6 ± 0.4), 6 h (2.5 ± 0.5 versus 4.8 ± 0.4), 12 h (3 ± 1.1 versus 4.5 ± 0.7), and 24 h (1.8 ± 0.8 versus 4.1 ± 1.2), the mean pain score was significantly lower in Group K than in Group B. Analgesia requirement was significantly higher in the bupivacaine group, whereas the mean time to seek the first rescue analgesia was longer in the ketamine group. No adverse events other than postoperative nausea and vomiting were observed. The present study found that in elective LC, intraperitoneal instillation of ketamine at a dose of 0.25 mg/kg was superior to bupivacaine alone in reducing postoperative pain and analgesic demand from initial 6 to 24 h after surgery, without any safety concerns. This trial was retrospectively registered on January 29, 2025, in clinicaltrials.gov with trial number ‘NCT06807554’.