Variations of SPI during outpatient laparoscopic cholecystectomy without muscle relaxants using ANI-guided remifentanil.

This study compared ANI and SPI during outpatient laparoscopic cholecystectomy without muscle relaxants. Forty adult patients were included in this prospective observational study. Induction was performed using propofol, ketamine and remifentanil. All patients received bilateral TAP block. Maintenance of anesthesia was performed using remifentanil targeted to ANI 50-80 and desflurane targeted to MAC 0.8-1.2 without muscle relaxants. The ANI and SPI values were collected at different time-points and analyzed using repeated-measures ANOVA. The relationship between ANI and SPI were analyzed by linear regression. All procedures were performed without muscle relaxants. The mean ± SD ANI values significantly decreased from 70 ± 12 at induction to 57 ± 15 at intubation and 56 ± 17 at extubation and were maintained in the 50-80 target range throughout incision to exsufflation. The mean ± SD SPI values significantly decreased from 60 ± 15 at induction to 38 ± 16 at intubation, increased at 73 ± 14 at extubation and were in the 20-50 target range throughout incision to exsufflation. There was a poor but significant negative linear relationship (r = 0.053, p < 0.001) between SPI and ANI values. During laparoscopic cholecystectomy without muscle relaxants, remifentanil titrated to achieve a target ANI range of 50-80 provides SPI values with poor correlation ranging from 20 to 50, corresponding to adequate nociception-antinociception balance. Other studies comparing ANI and SPI guided remifentanil administration are required to determine the effect of each strategy on patient outcomes during laparoscopic cholecystectomy or other types of surgery.