Summary

Background and objectives: Central sensitization is an important process for the maintenance of pain after trauma. Ketamine is an NMDA receptors antagonist, and can inhibit this sensitization. The aim of this study was to evaluate the analgesic effect S(+) ketamine by epidural route after lower limbs orthopedic surgery. Method: Twenty patients submited to epidural anesthesia with pain in postoperative period received 25 mg of S(+)ketamine + saline (total 5ml). Analgesic complementation was made with epidural 0.25% bupivacaine + 50 mg of fentanyl (total 5ml); if necessary the complementation before 4h was with 1g of IV dipirone. There were evaluated: pain intensity after 15, 30, 60, 120, 180 and 240min; the number of analgesic complementation and side effects. Results: The pain intensity by numerical scale reduced after 15 (2.1 ± 2,9); 30 (2.4 ± 2.6); 60 (2.8 ± 2.9); 120 (1.4 ± 2.2); 180 (1.5 ± 1.8); and 240 min (2.1 ± 2.5) when compared with the beginning of the study (6.0 ± 3.2), ANOVA p=0,0003. There was increase of percentage of patients with mild and no pain after 15 (75%), 30 (70%), 60 (70%), 120 (84.2%), 180 (89.5%) and 240 min (88.2%) when compared with the beginning of the treatment (25%); Chi-SquareTest. The side effects were: blurring of vision (80%); dizziness (80%), nausea (5.26%) and hallucination (5.26%). Three patients (15%) required complementary epidural solution after 30 min; 5 (25%) after 1 h and 3 (15%) after 3 h. Dipirone was used in 2 patients, and tramadol in 1 patient. Conclusion: Epidural 25 mg of S(+)ketamine provided analgesic effect without complementation in 50% of patients submited to lower limbs orthopedic surgery.