Effect of S-ketamine on the intraoperative Surgical Pleth Index in patients undergoing video-assisted thoracoscopic surgery: a single-center randomized controlled clinical trial

OBJECTIVE: To investigate whether S-ketamine affects the Surgical Pleth Index (SPI) during video-assisted thoracoscopic surgery. METHODS: Eighty-four patients undergoing video-assisted thoracoscopic lung lobectomy were enrolled. They were randomly assigned to an S-ketamine group (group S) and an equivalent normal saline group (group N). SPI values were recorded; and pain score on a numerical rating scale (NRS), the consumption of opioids, rescue analgesia, and post-operative nausea and vomiting (PONV) were evaluated. RESULTS: The SPI and heart rate of the S-ketamine group were significantly lower 30 minutes after the start of surgery and at the end. The NRS score was lower in the S-ketamine group 6 and 12 hours postoperatively, but there were no differences in mean blood pressure or the NRS score 24 and 48 hours postoperatively. Rescue analgesia was required less frequently by the S-ketamine group, but the incidence of PONV did not differ between the groups. CONCLUSIONS: S-ketamine was associated with lower intraoperative SPI 30 minutes after the start and at the end of surgery. It also reduced opioid use intraoperatively and the NRS scores 6 and 12 hours postoperatively. Trial registration: Chinese Clinical Trial Registry (ChiCTR2000040012), 18/11/2020.