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.

Keywords: Laparoscopy; Neuromuscular blockade; Pneumoperitoneum; Rocuronium.