ANI-Guided Fentanyl Infusion During Living Donor Liver Resections

Monitoring nociception accurately during general anaesthesia has presented a long-standing difficulty. Typically, anaesthesiologists rely on changes in the autonomic nervous system, such as heart rate, blood pressure, and sweating, to help determine the need for pain relief medication. Analgesia nociception index (ANI) is a noninvasive tool for monitoring the intraoperative state of the autonomic nervous system, particularly the parasympathetic nervous system. During the long-lasting high nociceptive surgery, the infusion of fentanyl was used at our institution. Opioids can lead to postoperative nausea, vomiting, and other complications when an overdose occurs. Fentanyl dosage changes significantly after hours of infusion due to context-sensitive halftime. It is practically impossible to adjust an infusion dose with the subjective evaluation of standard monitoring, such as heart rate and blood pressure. Doses of opioids that we use in our daily practice, e.g. mcg.kg-1, are unpredictable and vary between individuals due to pharmacogenetics and pharmacokinetic reasons. The best method to exclude pharmacokinetic peculiarities and predict the subsequent dose is to directly measure analgesic agents' concentration in the blood, though it is practically impossible. This study aimed to assess whether intraoperative analgesia nociception monitoring (ANI) could have an impact on the average intraoperative dose of fentanyl and on the occurrence of postoperative nausea and vomiting.