[Cohort study of remifentanil-induced hyperalgesia in postoperative patients].

OBJECTIVE

To investigate the incidence of remifentanil-induced hyperalgesia and screen for the relevant influencing factors in the post-operative patients.

METHODS

A total of 1620 patients from June 2008 to December 2008 in our hospital undergoing general anesthesia with remifentanil and whose length of operative incision was less than 4 cm were enrolled. The incidence of postoperative hyperalgesia was investigated and recorded at the timepoints of staying at post-anesthesia care unit (PACU), 4 h and 24 h postoperation respectively. The unconditional statistical analysis of Logistic regression was used to explore such possible influencing factors as age, gender, methods of general anesthesia, operative duration, operative sites and remifentanil dose.

RESULTS

The incidence of postoperative remifentanil-induced hyperalgesia was 16.1% (n = 261). The incidence of postoperative hyperalgesia was significantly increased in patients < 16 yrs (25.9%) vs ≥ 16 yrs (15.6%) (P < 0.05), males vs females (20.8% vs 13.0%, P < 0.01), operative duration > 2 h (32.7%) vs ≤ 2 h (9.9%) (P < 0.01) and remifentanil dose > 30 µg/kg (41.8%) vs ≤ 30 µg/kg (4.8%) (P < 0.01). And the incidence of limb protective action, touch and cold-induced allodynia were the two highest indicators (39.0%, 34.5%). Analysis of Logistic regression showed that ages under 16 years old, operative duration > 2 h and remifentanil dose > 30 µg/kg were relevant with hyperalgesia (all P < 0.05).

CONCLUSION

Ages under 16 years old, operative duration and remifentanil dose are the risk factors for postoperative remifentanil-induced hyperalgesia. Neither methods of general anesthesia nor operative sites has any effect on the occurrence of hyperalgesia.