Effects of perioperative S (+) ketamine infusion added to multimodal analgesia in patients undergoing ambulatory haemorrhoidectomy

Abstract: Background and objective: Perioperative low-dose ketamine has been useful for postoperative analgesia. In this study we wanted to assess the analgesic effect and possible side-effects of perioperative low-dose S (+) ketamine when added to a regime of non-opioid multimodal pain prophylaxis. Methods: Seventy-seven patients scheduled for haemorrhoidectomy were enrolled in this randomized, double-blind, controlled study. They received oral paracetamol 1–2g, total intravenous anaesthesia, intravenous 8mg dexamethasone, 30mg ketorolac and local infiltration with bupivacaine/epinephrine. Patients randomized to S (+) ketamine received an intravenous bolus dose of 0.35mgkg−1 S (+) ketamine before start of surgery followed by continuous infusion of 5μgkg−1 min−1 until 2min after end of surgery. Patients in the placebo group got isotonic saline (bolus and infusion). BIS™ monitoring was used. Pain intensity and side-effects were assessed by blinded nursing staff during PACU stay and by phone 1, 7 and 90 days after surgery. Results: In patients randomized to S (+) ketamine emergence from anaesthesia was significantly longer (13.1min vs. 9.3min; p <0.001). BIS values were significantly higher during anaesthesia (maximal value during surgery: 62 vs. 57; p =0.01) and when opening eyes (81 vs. 70, p <0.001). Pain scores (NRS and VAS) did not differ significantly between groups. Conclusions: The addition of perioperative S (+) ketamine for postoperative analgesia after haemorrhoidectomy on top of multimodal non-opioid pain prophylaxis does not seem to be warranted, due to delayed emergence and recovery, more side-effects, altered BIS readings and absence of additive analgesic effect. [Copyright &y& Elsevier]