Effect of depth of neuromuscular blockade on the abdominal space during pneumoperitoneum establishment in laparoscopic surgery

Abstract Study Objective To evaluate the effect of neuromuscular blockade (NMB) upon the abdominal space during pneumoperitoneum establishment in laparoscopic surgery, comparing moderate NMB and deep NMB. Design Prospective, randomized, crossover clinical trial. Setting Operating room. Patients Seventy-six American Society of Anesthesiologists 1 to 2 patients scheduled for elective laparoscopic surgery. Interventions Two independent evaluations were performed at the establishment of pneumoperitoneum for a preset intraabdominal pressures (IAPs) of 8 and 12 mm Hg, both during moderate NMB (train-of-four count, 1-3) and deep NMB (posttetanic count, < 5). Rocuronium was used to induce NMB, and sugammadex was used for reversal. Measurements We evaluated (i) the volume of CO2 introduced in 41 patients and (ii) the skin-sacral promontory distance in 35 patients, at pneumoperitoneum establishment. Results Compared to moderate NMB, deep NMB increased, in a significant manner, both the intraabdominal volume of CO2 insufflated (mean [SD], 2.24 [1.10] vs 2.81 [1.13] L at 8 mm Hg IAP, P < .001, and 3.52 [1.31] vs 4.09 [1.31] L at 12 mm Hg IAP, P < .001) and the skin-sacral promontory distance (11.78 [1.52] vs 12.16 [1.51] cm at 8 mm Hg IAP, P = .002, and 13.34 [1.87] vs 13.80 [1.81] cm at 12 mm Hg IAP, P < .001). Increase in intraabdominal volume after inducing deep NMB was observed in 88% and 81.7% of patients at 8 and 12 mm Hg pneumoperitoneum, with a volume increase of mean of 36.8% (95% confidence interval [CI], 22.8-50.8) and 25% (95% CI, 13.7-36.4), respectively ( P = .003). Increase in distance was observed in 61% and 82% of patients at 8 and 12 mm Hg pneumoperitoneum, with a mean distance increase of 3.3% (95% CI, 1.3-5.4) and 3.6% (95% CI, 1.9-5.2), respectively ( P = .840). Conclusions Deep NMB, in comparison to moderate NMB, increased in a significant manner the abdominal space at pneumoperitoneum establishment. However, the effective increase in the abdominal cavity dimensions could be low, the increase showed a great interindividual variability, and it was not observed in every patient. Clinical significance of this increase on surgical conditions is yet to be demonstrated.