Background: Spinal surgery is usually performed in the prone position using a posterior approach. However, the prone position may cause venous engorgement in the back and thus increase surgical bleeding with interruption of surgery. The prone position also affects cardiac output since large vessels are compressed decreasing venous return to the heart.
Objective: We hypothesised that deep neuromuscular blockade would be associated with less surgical bleeding during spinal surgery in the prone position.
Design: Randomised, single blinded trial.
Setting: University teaching hospital.
Participants: Eighty-eight patients in two groups.
Interventions: Patients were randomly assigned to moderate neuromuscular blockade or deep neuromuscular blockade. In the moderate neuromuscular blockade group, administration of rocuronium was adjusted such that the train-of-four count was one to two. In the deep neuromuscular blockade group, rocuronium administration was adjusted such that the train-of-four count was zero with a posttetanic count 2 or less.
Main outcome measures: The primary outcome was the volume of intra-operative surgical bleeding. The surgeon's satisfaction with operating conditions, haemodynamic and respiratory status, and postoperative pain scores were evaluated.
Results: The median [IQR] volume of intra-operative surgical bleeding was significantly less in the deep neuromuscular blockade group than in the moderate neuromuscular blockade group; 300 ml [200 to 494] vs. 415 ml [240 to 601]; difference: 117 ml (95% CI, 9 to 244; P = 0.044). The mean ± SD surgeon's satisfaction with the intra-operative surgical conditions was greater in the deep neuromuscular blockade group than in the moderate neuromuscular blockade group; 3.5 ± 1.0 vs. 2.9 ± 0.9 (P = 0.004). In intergroup comparisons of respiratory variables, peak inspiratory pressure was lower in the deep neuromuscular blockade group overall (P < 0.001). The median [IQR] postoperative pain score was lower in the deep neuromuscular blockade group than the moderate neuromuscular blockade group; 50 [36 to 60] vs. 60 [50 to 70], (P = 0.023).
Conclusion: Deep neuromuscular blockade reduced intra-operative surgical bleeding in patients undergoing spinal surgery. This may be related to greater relaxation in the back muscles and lower intra-operative peak inspiratory pressure when compared with moderate neuromuscular blockade.
Trial registration: KCT0001264 (http://cris.nih.go.kr).