Analgesia Nociception Index (ANI) as a monitor of peri-operative nociception-antinociception balance in paediatric craniotomies: a prospective observational study

IntroductionAnalgesia Nociception Index (ANI) as a monitor of peri-operative nociception-anti-nociception balance has not been studied in paediatric neurosurgery. The objectives were to study the correlation between ANI (Mdoloris Education system) and revised FLACC (r-FLACC) score for the prediction of acute postoperative pain in paediatric population undergoing elective craniotomies and to compare the changes in ANI values with heart rate (HR), mean arterial pressure (MAP) and surgical plethysmographic index (SPI) during various time points of intraoperative noxious stimulation and before and after opioid administration.MethodsThis prospective observational pilot study included 14 patients between 2 and 12 years of age undergoing elective craniotomies. HR, MAP, SPI, ANI instantaneous (ANIi) and ANI mean (ANIm) values were recorded intraoperatively and before and after opioid administration. Postoperatively HR, MAP, ANIi and ANIm, and pain scores (r-FLACC scale) were recorded.ResultsThere was a statistically significant negative correlation between ANIi and ANIm with r-FLACC during the time course of PACU stay (r = - 0.89, p < 0.001 and r = - 0.88 and p < 0.001 respectively). Intraoperatively, in patients with ANIi values < 50, with additional fentanyl administration, there was an increasing trend in values beyond 50, which was statistically significant (p < 0.05) at 3, 4, 5 and 10 min. The trend in changes of SPI after opioid administration was not found to be significant for patients irrespective of the baseline SPI values.ConclusionThe ANI is a reliable tool for objective assessment of acute postoperative pain as assessed by r-FLACC in children undergoing craniotomies for intracranial lesions. It may be used as a guide to nociception-antinociception balance during the peri-operative period in this population.