POSTOPERATIVE ANALGESIA AFTER MAJOR SHOULDER SURGERY WITH INTERSCALENE BRACHIAL-PLEXUS BLOCKADE - ETIDOCAINE VERSUS BUPIVACAINE

Postoperative pain is commonly treated with significant doses of narco tics, occasionally resulting in side effects including nausea, pruritu s, and respiratory depression. One potential advantage of regional ane sthesia is profound postoperative analgesia that reduces exposure to p otent narcotics. To evaluate the efficacy of two longacting local anes thetics, bupivacaine and etidocaine, in providing pain relief after ma jor shoulder surgery, we randomized 20 patients to receive either bupi vacaine or etidocaine for brachial plexus block as the primary anesthe tic for shoulder surgery. Surgeons, patients, and the acute pain servi ce were blinded as to drug selection. After the patient was sedated, a n interscalene block was placed with the use of a nerve stimulator to facilitate proper needle placement. Forty milliliters of either 0.5% b upivacaine or 0.75% etidocaine containing 5 mu g/mL epinephrine was in jected into the brachial plexus sheath. An additional 8 mL of local an esthetic was administered for superficial cervical plexus blockade. In traoperative sedation was accomplished with an intravenous infusion of methohexital as needed. After surgery, patients received a standard p atient-controlled analgesia protocol providing incremental doses of mo rphine. The degree of postoperative analgesia resulting from residual local anesthetic effect was expressed as the time until first morphine requirement and the total dose of morphine required during the first 24 hours postoperatively. We found no statistically significant interg roup differences either in time of initial use of morphine or in the t otal dose of morphine required in the first 24 hours. Both etidocaine and bupivacaine provide prolonged analgesia after major shoulder surge ry when injected into; the brachial plexus. Bupivacaine, however, poss esses significant cardiotoxicity and has a relatively delayed onset in peripheral neural blockade. Etidocaine is less cardiotoxic and also h as a more rapid onset of effect. Thus etidocaine may be a preferable a gent for interscalene block for major shoulder surgery.