Background: Previous studies have reported that deep neuromuscular block (posttetanic-count 1 to 2 twitches) improves surgical conditions during laparoscopy compared with moderate block (train-of-four count: 1 to 2 twitches). However, comparisons of surgical conditions were made using different scales and assessment intervals with variable results.
Objective: To explore the heterogeneity of previous comparisons between deep and moderate neuromuscular block.
Design: Systematic review and meta-analysis of randomised controlled trials (RCTs).
Data sources: Medline, EMBASE and Cochrane Central Register of Controlled Trials were searched from inception to October 2017.
Eligibility criteria: Our meta-analysis included RCTs comparing the effects of deep with moderate neuromuscular block on surgical field conditions during laparoscopic surgery. The frequency of excellent or good operating conditions on a surgical rating scale was compared. Heterogeneity was assessed by subgroup analyses.
Results: Eleven RCTs involving 844 patients were included. On the surgical rating scale, the frequency of excellent or good operating conditions was higher with deep block compared with a moderate block (odds ratio 2.83, 95% confidence interval 1.34 to 5.99, P = 0.007, I = 59%). We analysed surgical rating according to the number of assessments made. There was a significant difference in surgical rating with multiple assessments, but no difference when the assessment was made on only one occasion. A significant difference in rating was noted with variable abdominal pressures; there was no significant difference with the same fixed abdominal pressure. Trial sequential analysis demonstrated that the cumulative z-curve crossed the O'Brien-Fleming significance boundary. However, required information size was not achieved.
Conclusion: Deep block was associated with excellent or good surgical rating more frequently than moderate block. However, this finding was not consistent on subgroup analyses based on frequencies of assessment of surgical conditions and abdominal pressure. Further studies are required to address the heterogeneity and power shortage demonstrated by the trial sequential analysis.