Background: During laparotomy, surgeons may experience difficult surgical conditions if the patient's abdominal wall or diaphragm is tense. Deep neuromuscular block (NMB), defined as a post-tetanic-count (PTC) between 0-1, paralyses the abdominal wall muscles and the diaphragm. We hypothesized that deep NMB (PTC 0-1) would improve subjective ratings of surgical conditions during upper laparotomy as compared with standard NMB.

Methods: This was a double blinded, randomized study. A total of 128 patients undergoing elective upper laparotomy were randomized to either continuous deep NMB (infusion of rocuronium 2 mg ml -1 ) or standard NMB (bolus of rocuronium 10 mg or increased depth of anaesthesia). Surgical conditions were evaluated using a 5-point subjective rating scale (1: extremely poor, 5: optimal) every 30 min. Primary outcome was the average of scores for a patient's surgical conditions. Other outcomes were surgical rating score during fascial closure, episodes of a need to optimize surgical conditions, occurrence of wound dehiscence, and wound infection.

Results: Deep compared with standard NMB resulted in better ratings of surgical conditions; median 4.75 (range 3-5) compared with 4.00 (range 1-5) ( P <0.001), respectively. Deep compared with standard NMB resulted in better ratings of surgical conditions during fascial closure ( P <0.001), fewer episodes of need to optimize surgical conditions ( P <0.001), and fewer incidents with sudden movements ( P <0.001). No differences in operating time, occurrence of wound infection, and wound dehiscence were found.

Conclusions: Deep NMB compared with standard NMB resulted in better subjective ratings of surgical conditions during laparotomy.

Clinical trial registration: NCT02140593.