Randomised trial of epidural bupivacaine and morphine in prevention of stump and phantom pain in lower-limb amputation

Abstract

Background: Epidural analgesia before limb amputation is commonly used to reduce postamputation pain. But there have been no controlled studies with large numbers of patients to prove such a pre-emptive effect. We investigated whether postamputation stump and phantom pain in the first year is reduced by preoperative epidural blockade with bupivacaine and morphine.

Methods: In a randomised, double-blind trial, 60 patients scheduled for lower-limb amputation were randomly assigned epidural bupivacaine (0.25% 4-7 mL/h) and morphine (0.16-0.28 mg/h) for 18 h before and during the operation (29 patients; blockade group) or epidural saline (4-7 mL/h) and oral or intramuscular morphine (31 patients; control group). All patients had general anaesthesia for the amputation and were asked about stump and phantom pain after 1 week and then after 3, 6, and 12 months by two independent examiners. Study endpoints were rate of stump and phantom pain, intensity of stump and phantom pain, and consumption of opioids.

Findings: Two patients in each group were withdrawn before amputation. The groups were well matched in baseline characteristics. Median duration of preoperative saline treatment was 18.5 h (IQR 17-20). Median duration of preoperative epidural blockade in the blockade group was 18 h (15-20.3). The combined median duration of postoperative epidural pain treatment in both groups was 166 h (89.3-308.3). After 1 week, 14 (52%) patients in the blockade group and 15 (56%) in the control group had phantom pain (95% CI - 30.6 to 22.7, p = 0.9). The figures for blockade versus control group were: 14 (82%) vs ten (50%; 4.0 to 60.8, p = 0.09) at 3 months; 13 (81%) vs 11 (55%; -2.7 to 55.3, p = 0.2) at 6 months; and nine (75%) vs 11 (69%; -27.0 to 39.6, p = 1.0) at 12 months. Intensity of stump and phantom pain and consumption of opioids were similar in both groups at all four postoperative interviews.

Interpretation: Perioperative epidural blockade started a median of 18 h (15-20.3) before the amputation and continued into the postoperative period does not prevent phantom or stump pain.