Role of Ketamine in Multimodal Analgesia Protocol for Bariatric Surgery

Background and Objectives: Acute postoperative pain is one of the most undesirable experiences for a patient in the postoperative period. Many options are available for the treatment of postoperative pain. One of the methods of multimodal analgesia is a combination of opioids and adjuvant agents, such as ketamine. The aim of this study was to evaluate the effect of a pre-incisional single injection of low-dose ketamine on postoperative pain after remifentanil infusion in patients undergoing laparoscopic gastric bypass or gastric plication surgery. Materials and Methods: The prospective, randomized, double-blinded and placebo-controlled trial took place at the Hospital of the Lithuanian University of Health sciences KaunoKlinikos in 2015-2017. A total of 32 bariatric patients (9 men and 23 women) were randomly assigned to receive a single pre-incisional injection of ketamine (0.15 mg/kg (LBM)) (ketamine, K group) or saline (placebo, S group). Standardized protocol of anesthesia and postoperative pain management was followed for all patients. Postoperative pain intensity, postoperative morphine requirements, incidence of side effects and patients' satisfaction with postoperative analgesia were recorded. Results: Thirty-two patients undergoing bariatric surgery: 18 (56.25%; gastric bypass) and 14 (43.75%; gastric plication) were examined. Both groups did not differ in demographic values, duration of surgery and anesthesia and intraoperative drug consumption. Postoperative pain scores were similar in both groups (p = 0.105-0.941). Morphine consumption was 10.0 (7.0-12.5 mg) in group S and 9.0 (3.0-15.0 mg) in group K (p = 0.022). The incidence of side effects was similar in both groups (p = 0.412). Both groups demonstrated very high satisfaction with postoperative analgesia. Conclusions: Pre-incisional single dose ketamine reduces postoperative opioids consumption, but does not have an effect of postoperative pain intensity and side effects after remifentanil infusions. Very high patient satisfaction is achieved if standard multimodal analgesia protocol with an individual assessment of pain and dosage of medications is followed.