Postoperative analgesia after major shoulder surgery with interscalene brachial plexus blockade: etidocaine versus bupivacaine.

Postoperative pain is commonly treated with significant doses of narcotics, occasionally resulting in side effects including nausea, pruritus, and respiratory depression. One potential advantage of regional anesthesia is profound postoperative analgesia that reduces exposure to potent narcotics. To evaluate the efficacy of two long-acting local anesthetics, bupivacaine and etidocaine, in providing pain relief after major shoulder surgery, we randomized 20 patients to receive either bupivacaine or etidocaine for brachial plexus block as the primary anesthetic for shoulder surgery. Surgeons, patients, and the acute pain service were blinded as to drug selection. After the patient was sedated, an interscalene block was placed with the use of a nerve stimulator to facilitate proper needle placement. Forty milliliters of either 0.5% bupivacaine or 0.75% etidocaine containing 5 micrograms/mL epinephrine was injected into the brachial plexus sheath. An additional 8 mL of local anesthetic was administered for superficial cervical plexus blockade. Intraoperative sedation was accomplished with an intravenous infusion of methohexital as needed. After surgery, patients received a standard patient-controlled analgesia protocol providing incremental doses of morphine. 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 intergroup differences either in time of initial use of morphine or in the total dose of morphine required in the first 24 hours. Both etidocaine and bupivacaine provide prolonged analgesia after major shoulder surgery when injected into the brachial plexus. Bupivacaine, however, possesses significant cardiotoxicity and has a relatively delayed onset in peripheral neural blockade. Etidocaine is less cardiotoxic and also has a more rapid onset of effect. Thus etidocaine may be a preferable agent for interscalene block for major shoulder surgery.