Effects of deep neuromuscular block on surgical pleth index-guided remifentanil administration in laparoscopic herniorrhaphy: a prospective randomized trial

Deep neuromuscular block (NMB) has been increasingly utilized, but its role in reducing intraoperative opioid requirement has yet to be investigated. Surgical pleth index (SPI) quantifies nociception. We investigated the effects of deep NMB on SPI-guided remifentanil administration in laparoscopic herniorrhaphy. Total 128 patients undergoing laparoscopic inguinal herniorrhaphy were randomly allocated to two groups of NMB: deep (n = 64) and moderate (n = 64). The remifentanil dose was assessed during intubation, from skin incision until CO(2) insertion, and pneumoperitoneum. Mean infusion rate of remifentanil during pneumoperitoneum was higher in moderate NMB group than in deep NMB group (0.103 [0.075–0.143] µg/kg/min vs. 0.073 [0.056–0.097] µg/kg/min, p < 0.001). Consequently, median infusion rate of remifentanil during anesthesia was higher in moderate NMB group (0.076 [0.096–0.067] µg/kg/min vs. 0.067 [0.084–0.058] µg/kg/min, p = 0.016). The duration of post-anesthesia care unit stay was longer in the moderate NMB group (40 [30–40] min vs. 30 [30–40] min, p = 0.045). In conclusion, deep NMB reduced the remifentanil requirement compared with moderate NMB in SPI-guided anesthesia for laparoscopic herniorrhaphy.