Impact of different doses of remifentanil on postoperative pain and hyperalgesia: a prospective randomized controlled study and genotypic analysis.

BACKGROUND

Remifentanil is commonly used for perioperative analgesia, but its role in postoperative pain and hyperalgesia is still debated. This study investigated the effect of different remifentanil doses on postoperative pain and hyperalgesia and the influence of SCN9A genetic variants on these outcomes.

METHODS

A total of 268 patients who underwent laparoscopic surgery were included in the study. Eligible patients were randomly assigned to one of three groups: a high dose of remifentanil (Group H), a low dose of remifentanil (Group L), or no remifentanil (Group N). Postoperative pain intensity and mechanical pain thresholds were assessed after surgery, and side effects were recorded during follow-up. The single-nucleotide polymorphisms of SCN9A, rs16851799 and rs6746030, were also analyzed.

RESULTS

There were no differences in postoperative pain scores among the three groups with different remifentanil doses (P = 0.969). However, the mechanical pain thresholds were significantly lower in Group H compared with the other groups postoperatively (P < 0.001). The A allele of rs6746030 was associated with higher pain scores (P = 0.002) and increased postoperative analgesic requirements (P = 0.013).

CONCLUSIONS

While high doses of remifentanil significantly induced detectable hyperalgesia in a laboratory phenomenon, RIH had zero clinical impact on the patient's actual pain experience or analgesic requirements after surgery. Additionally, the exploratory findings revealed that rs6746030 in SCN9A was a genetic marker for severe postoperative pain.