Effect of pneumoperitoneum on the recovery from intense neuromuscular blockade by rocuronium in healthy patients undergoing laparoscopic surgery

Abstract

Background: This study investigated the effect of pneumoperitoneum on the recovery from intense neuromuscular blockade by rocuronium in healthy patients undergoing laparoscopic abdominal surgery.

Methods: Thirty adult patients undergoing laparoscopic abdominal surgery were studied. Anesthesia was induced with 1.5 mg/kg of propofol, 12 ug/kg of alfentanil and 0.6 mg/kg of rocuronium and maintained with 2 vol% of sevoflurane and 0.05-0.2 µg/kg/min remifentanil. The neuromuscular relaxation was monitored by Train-of-Four (TOF) and post-tetanic count (PTC). Additional rocuronium of 0.2 mg/kg was administered for deep neuromuscular blockade at 30 min after pneumoperitoneum. Before (PPpre) and 30 min after pneumoperitoneum (PPpost), PTC was measured at 6 min intervals. The relationship between PTC and the time interval to reappearance of T1 response was observed.

Results: The mean ± SD of the intervals between the detection of 4 counts of the PTC and the first response to TOF stimulation was 13.0 ± 1.1 min and 16.4 ± 6.3 min PPpre and PPpost, respectively (P = 0.20). There were significant negative relationships between PTC observed and the time interval to reappearance of T1 response (adjusted R(2) = 0.869, P < 0.001 for PPpre data, and adjusted R(2) = 0.561, P < 0.001 for PPpost data). Comparing the difference of regression equation between PPpre and PPpost data using a parallelism test, there was no statistically significant difference (P = 0.193).

Conclusions: This study showed that PP with intra-abdominal pressure at the level of 13-14 mmHg did not affect the recovery from intense neuromuscular blockade by rocuronium in healthy patients undergoing laparoscopic abdominal surgery.

Keywords: Neuromuscular blockade; Neuromuscular monitoring; Pneumoperitoneum; Rocuronium.

Fig. 1

Schematic sample of time course in this study. Trace recording of stabilization period before anesthesia induction and that of data obtained after end of study are truncated. S: the time at which intubating dose of rocuronium is administered. PPpre: the time during obtaining data before pneumoperitoneum. T1: indicates the time at which the first response of train of four (TOF) stimulation is reappeared. RB: the point at which the boost dose of rocuronium is administered. PP: indicates the time of initiation of pneumoperitoneum. PPpost: indicates the time during obtaining data for PPpost (data obtained from 30 minutes after pneumoperitoneum). E: indicates the point of study termination (point at which reappearance of the first response of TOF again). Study time course was scheduled to finish before deflation of peritoneal cavity had made in the middle of surgery.

Fig. 2

The relationship between post-tetanic count (PTC) and the time to the first response to TOF before (PPpre) and 30 min after pneumoperitoneum (PPpost). Exponential fitted curves are shown. Assuming that the regression equation is y=ae^-bx, there is a strong correlation with PTC and T1 reappearance time interval before pneumoperitoneum (adjusted R² = 0.869, P < 0.001) and a weak correlation after pneumoperitoneum (adjusted R² = 0.561, P < 0.001). In a comparison of the differences of regression equation between before and after pneumoperitoneum using parallelism test, there is no significant difference (P = 0.193). PPpre: the time during obtaining data before pneumoperitoneum. PPpost: indicates the time during obtaining data for data obtained from 30 minutes after pneumoperitoneum.