Continuous postoperative infusion of a regional anesthetic after an amputation of the lower extremity. A randomized clinical trial.

We performed a prospective, randomized clinical trial to determine whether continuous infusion of bupivacaine hydrochloride decreased the use of narcotics for the relief of pain after an amputation. Twenty-one patients who were to have an amputation of the lower extremity because of ischemic necrosis secondary to peripheral vascular disease were divided into two groups with use of a table of random numbers. Group A (the treatment group) included nine patients who were to have a transtibial amputation, one patient who was to have a disarticulation at the knee, and one patient who was to have a transfemoral amputation. Group B (the control group) included seven patients, two patients, and one patient, respectively. After the amputation had been performed, a Teflon catheter was placed adjacent to the transected end of the sciatic or posterior tibial nerve. Postoperatively, the patients received continuous infusion of either bupivacaine (Group A) or normal saline solution (Group B) for seventy-two hours. Intravenous administration of morphine with use of a patient-controlled pump also was permitted during this period. The amount of morphine that was used was recorded meticulously. The patients in Group A used less morphine during the first and second days after the operation than did those in Group B. There was no difference between the groups with regard to the amount of morphine used on the third postoperative day. Over-all, eleven of fourteen patients who completed questionnaires reported a decrease in pain between the three and six-month evaluations. We concluded that continuous perineural infusion of an anesthetic appears to be a safe, effective method for the relief of postoperative pain but that it does not prevent residual or phantom-limb pain in patients who have had an amputation of the lower extremity because of ischemic changes secondary to peripheral vascular disease.