The Effect of Preoperative Maxigesic® on Intraoperative Remifentanil Requirement

Remifentanil is an ultra-short-acting opioid that is useful during surgery because of its fast onset and recovery. However, because of this profile, it is known that the use of high doses of remifentanil during surgery paradoxically increases postoperative pain. It has been reported that intraoperative remifentanil use resulted in higher pain scores 2 hours after surgery compared to intraoperative dexmedetomidine, and that the incidence of hypotension, tremor, and postoperative nausea and vomiting were higher in the remifentanil group. Therefore, minimizing the use of remifentanil during surgery is clinically meaningful.

Nonsteroidal anti-inflammatory drugs (NSAIDs) play an important role in multimodal analgesia, and are known to reduce the use of opioids when used together with opioids in postoperative pain \[3\]. It has also been reported that preoperative administration of ibuprofen reduces postoperative opioid use. Administration of acetaminophen has also been reported to reduce opioid usage. However, there is no study on whether the administration of these NSAIDs and acetaminophen reduces the opioid requirement used during surgery, not after surgery.

The Analgesia nociception index (ANI, MDoloris medical system, France) was developed to measure real-time nociception in patients undergoing surgery under general anesthesia. This index measures parasympathetic nerve activity based on heart rate variability. It is known to be superior in detecting nociceptive stimuli rather than judging only by existing pulse rate and blood pressure. In addition, since information is provided as an objectified numerical value, analgesic drugs can be adjusted during surgery based on this information. This helps to provide an appropriate amount of opioids during surgery when needed, and can prevent overdose. A previous study reported that when ANI-guided remifentanil infusion was performed, the amount of remifentanil used was reduced compared to conventional control of remifentanil only with blood pressure and pulse rate.

Maxigesic® is a combination of acetaminophen and ibuprofen, and is a drug that rapidly relieves various types of pain. It is known to be more effective in relieving postoperative pain than single acetaminophen or ibuprofen. The hypothesis of this study is that administration of Maxigesic®, a combination of acetaminophen and NSAIDs, reduces intraoperative remifentanil requirement. This study aims to investigate whether preoperative Maxigesic® administration can reduce intraoperative remifentanil requirements by performing ANI-guided remifentanil infusion for objective control of remifentanil administration.

• postoperative analgesic requirement [Time frame: 1 hour, while in the recovery room]