Epidural ketamine for postoperative analgesia in the elderly

We assessed the epidural use of ketamine in elderly patients undergoing major abdominal surgery.

Patients older than 65 years were randomly allocated to receive preemptive epidural bupivacaine 0.125% (20 ml) combined with either epidural ketamine 40 mg (ketamine group), or epidural morphine 2 mg (morphine group). Postoperatively, boluses of 0.125% bupivacaine (5 ml) supplemented with ketamine (2 mg/ml) or morphine (0.1 mg/ml) were given until a pain score of two was established. Analgesia at rest was assessed by a verbal rating score (0 = no pain, 1 = mild pain, 2 = moderate pain, 3 = severe pain) at 1 h, 2h, 6h, 12h and 24h after surgery. The patient's degree of sedation was assessed using the Ramsay sedation score and episodes of nausea and vomiting (PONV) were recorded.

Patients in the morphine group were more sedated but had significantly lower pain scores and requested less rescue analgesic than patients receiving epidural ketamine (P < 0.05). In the morphine group three patients were treated for PONV while none of the patients in the ketamine group showed PONV.

Epidural ketamine, when compared to epidural morphine, appears to be associated with less sedation and a smaller risk of PONV, but necessitates more frequent or continuous administration to achieve comparable analgesia.