We examined the postoperative analgesia of a controlled delivery ketamine transdermal patch after minor abdominal gynecological surgery using lidocaine epidural blockade. Fifty-two patients were randomized to one of two groups. Epidural anesthesia was performed with 25 mL 2% plain lidocaine. At the end of the surgical procedure, a controlled delivery transdermal patch containing either ketamine (25 mg/24 h) (Ketamine group) or placebo (Placebo group) was applied. Pain and adverse effects were assessed hourly postoperatively for 24 h. IM dipyrone was available at patient request. The two groups were demographically similar. The time to first rescue analgesic was longer in the Ketamine group (230+/-112 min) compared with the Placebo group (94+/-54 min); (P<0.00001). There were more dipyrone dose injections in 24 h in the Placebo group compared with the Ketamine group (P<0.0001). The incidence of adverse effects was similar between groups. We conclude that the transdermal-controlled delivery of ketamine prolonged the duration of analgesia after minor gynecological procedures.
Implications: Transdermal delivery of ketamine was an useful adjuvant to postoperative analgesia after epidural lidocaine blockade in the population studied.