Excessive remifentanil during total intravenous anesthesia is associated with increased risk of pain after robotic thyroid surgery

Association between intraoperative remifentanil use and postoperative hyperalgesia in adolescent idiopathic scoliosis surgery: a retrospective study

BACKGROUND

The liberal use of remifentanil in spine surgery has been associated with an increased incidence of postoperative hyperalgesia. Nevertheless, controversies remain as the existing evidence is inconclusive to determine the relationship between remifentanil use and the development of opioid-induced hyperalgesia. We hypothesized that intraoperative infusion of higher dose remifentanil during scoliosis surgery is associated with postoperative hyperalgesia, manifesting clinically as greater postoperative morphine consumption and pain scores.

METHODS

Ninety-seven patients with adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion surgery at a single tertiary institution from March 2019 until June 2020 were enrolled in this retrospective study. Anesthesia was maintained using a target-controlled infusion of remifentanil combined with volatile anesthetic desflurane in 92 patients, while five patients received it as part of total intravenous anesthesia. Intravenous ketamine, paracetamol, and fentanyl were administered as multimodal analgesia. All patients received patient-controlled analgesia (PCA) morphine postoperatively. Pain scores at rest and on movement, assessed using the numerical rating scale, and the cumulative PCA morphine consumption were collected at a six-hourly interval for up to 48 h. According to the median intraoperative remifentanil dose usage of 0.215 µg/kg/min, patients were divided into two groups: low dose and high dose group.

RESULTS

There were no significant differences in the pain score and cumulative PCA morphine consumption between the low and high dose remifentanil group. The mean duration of remifentanil infusion was 134.9 ± 22.0 and 123.4 ± 23.7 min, respectively.

CONCLUSION

Intraoperative use of remifentanil as an adjuvant in AIS patients undergoing posterior spinal fusion surgery was not associated with postoperative hyperalgesia.

Comparison of remifentanil consumption in pupillometry-guided versus conventional administration in children: a randomized controlled trial

BACKGROUND

Remifentanil is a commonly used opioid analgesic during anesthesia in children. Objective measurement of pain is required for adequate dosing of remifentanil. We investigated whether pupillometry-guided remifentanil administration can reduce intraoperative consumption of remifentanil in children.

METHODS

We performed a single-blinded, prospective, randomized controlled trial from December 2018 through June 2019. Children who were 3-12 years of age and classified as having an American Society of Anesthesiologists physical status I-II and undergoing elective surgery under general anesthesia were included. Fifty-six fulfilled the inclusion criteria, and fifty-four completed the study. Participants were randomly assigned to either a pupillometry or conventional group. Patients in both groups received target-controlled infusion of remifentanil. In the pupillometry group, the adjustment of the remifentanil effect site concentration was determined by the pupillary diameter, whereas in the conventional group, the adjustment was based on the anesthesiologist's experience. Primary outcome was intraoperative remifentanil consumption, divided by patient weight and infusion time (ng kg^-1 min^-1).

RESULTS

Remifentanil consumption was reduced by 25% in the pupillometry group compared to the conventional group (116.7±56.0 ng kg^-1 min^-1 vs. 155.8±64.9 ng kg^-1 min^-1, respectively; P=0.02). There were no differences in intra- and postoperative blood pressure and heart rate. The incidences of postoperative desaturation or nausea/vomiting were not significantly different.

CONCLUSIONS

Pupillometry-guided remifentanil administration in children undergoing general anesthesia can reduce the intraoperative remifentanil consumption.

Remifentanil-Induced Secondary Hyperalgesia Is Not Prevented By Preoperative Acetazolamide Administration In Patients Undergoing Total Thyroidectomy: A Randomized Controlled Trial

Purpose

Acute administration of remifentanil may lead to opioid-induced hyperalgesia (OIH). Studies in mice suggest that OIH is mediated by impaired anionic homeostasis in spinal lamina I neurons due to a down-regulation of the K⁺-Cl⁻ co-transporter KCC2, which was reverted using acetazolamide (ACTZ), a carbonic anhydrase inhibitor. We propose that ACTZ prevents remifentanil-mediated OIH in humans.

Patients and methods

We conducted a randomized, double-blind, placebo-controlled clinical trial between December 2016 and September 2018. Patients were randomly allocated to receive ACTZ (250 mg of ACTZ 2 h before surgery) or placebo. To detect hyperalgesia, mechanical pain threshold (MPT) were measured before and after surgery using hand-held von Frey filaments in the forearm. Anesthesia was maintained with remifentanil at a target effect site of 4.5 ± 0.5 ng/mL, and sevoflurane at an end-tidal concentration of 0.8 MAC corrected for age.

Results

In total, 47 patients completed the study. Both groups were comparable in the baseline characteristics and intraoperative variables. Baseline MPT were similar in both groups. However, MPT in the forearm significantly diminished in the time in both groups. Finally, postoperative pain and morphine consumption were similar between groups.

Conclusion

Both groups developed remifentanil-mediated OIH at 12–18 h after surgery. However, ACTZ did not prevent the MPT reduction in patients undergoing total thyroidectomy.