[Shivering during epidural anesthesia with and without fentanyl: comparative study.].

BACKGROUND AND OBJECTIVES Most studies in the literature correlating epidural opioids to postoperative shivering were carried out with obstetric patients whose thermoregulation center response might be different from non-pregnant patients. Our study aimed at comparing intra and postoperative shivering and other complications of epidural block with and without fentanyl in patients submitted to varicose vein surgery under epidural anesthesia with 0.5% bupivacaine and 1:200,000 epinephrine. METHODS Participated in this study 34 patients, physical status ASA I and II, submitted to lower limbs varicose vein surgery, who were randomly distributed in 2 groups (n = 17) and received intravenous midazolam (0.05 mg.kg-1) followed by lumbar epidural anesthesia. Group S received 20 mL of 0.5% bupivacaine (with epinephrine) associated to 2 mL of 0.9% saline solution, and Group F received 20 mL of 0.5% bupivacaine (with epinephrine) associated to fentanyl (100 microg). Shivering, temperature, meperidine need, nausea and vomiting were evaluated in the following moments: M1 - admission to the operating room; M2 - immediately before anesthesia; M3 - 30 minutes after local anesthetic injection; M4 - 60 minutes after local anesthetic injection; M5 - 90 minutes after local anesthetic injection; M6 - end of anesthesia; M7 - immediately before PACU discharge. RESULTS There have been no statistically significant differences between groups in demographics, physical status, mean anesthesia and surgery duration, patients and operating room temperature, and the incidence of nausea and vomiting. There have been statistically significant differences in shivering occurrence at 60 (M4) and 90 minutes (M5) after epidural block, with higher incidence of shivering in Group S as compared to Group F. A greater demand for meperidine was observed in patients submitted to epidural block without fentanyl. CONCLUSIONS In the conditions of our study, 100 microg fentanyl associated to epidural local anesthetics did not abolish shivering but is able to decrease its incidence without increasing the incidence of nausea and vomiting.