High dose ropivacaine-induced toxicity after infraclavicular block

Corresponding author: Po Soon Kang, M.D., Department of Anesthesiology and Pain Medicine, School of Medicine, Konyang University, 685, Gasuwon-dong, Seo-gu, Daejeon 302-718, Korea. Tel: 82-42-600-9316, Fax: 82-42-545-2132, E-mail: [email protected] This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. CC Local anesthetic toxicity is an uncommon but welldocumented complication of regional anesthesia. The mechanism of local anesthetic toxicity from a peripheral nerve block can be due to either a direct intravascular injection or from systemic absorption of a toxic dose of local anesthetics. We report two cases of local anesthetic toxicity, including central nervous system toxicity without any cardiac toxicity, following accidental overdose of ropivacaine for infraclavicular block. The first patient was a 36-year-old female (ASA I, 52 kg, and 160 cm), who presented for surgery of the right forearm under infraclavicular block. There was no medical history of neurological or cardiac disease. Physical examination and electrocardiogram (ECG) were unremarkable. The patient did not receive any sedatives before surgery. In the operating room, standard monitoring (pulse oximetry, noninvasive blood pressure cuff, and ECG) was applied. Using an insulated needle (Stimuplex A, B. Braun, Germany) and a nerve stimulator (Stimuplex HNS 12, B. Braun, Germany), a vertical infraclavicular block was performed to provide anesthesia [1]. Once an ulnar nerve response with a current of 0.5 mA was obtained, a total dose of 40 ml of 0.75% ropivacaine (300 mg; 5.77 mg/kg) without epinephrine was slowly injected with negative aspiration in 5 ml increments. Verbal communication was made during injection, and no early signs of systemic toxicity were noted. Ten minutes after the injection, sensory block was complete in the right arm. About twenty minutes after the injection, complete motor block was achieved in the radial, median, ulnar, and musculocutaneous nerves. Twenty-four minutes after the injection, the patient complained of numbness in the tongue, nausea, and dizziness. During this time, her blood pressure, heart rate, and oxygen saturation was 156/102 mmHg, 81 beats/min, and 98%, respectively. No changes were observed on the ECG. Suspecting ropivacaine-induced toxicity, 50 mg of thiopental sodium was administered for seizure prophylaxis, and supplemental oxygen was given via face mask. She recovered over 10 minutes. The patient had no awareness of the incident and was informed. The decision was made to perform surgery and further sedation was given with continuous infusion of propofol. The patient made an uneventful postoperative recovery. The second patient was a 60-year-old female (ASA I, 47 kg, and 142 cm) who was scheduled for surgery of the right forearm under infraclavicular block. She was in good general health, with no significant past medical history and in particular, no history of convulsions or epilepsy. She was taking no medications and had no allergies. No sedation was used for the block placement. A vertical infraclavicular block was performed with the same technique as described in Case 1. At the first attempt, blood was obtained, and the needle was withdrawn. After shifting of the puncture site in a 1 cm lateral direction, an ulnar nerve response of fingers with a current of 0.5 mA was obtained and a total dose of 40 ml of 0.75% ropivacaine (300 mg; 6.38 mg/kg) without epinephrine was slowly injected in 5 ml increments with gentle aspirations between doses. No spontaneous blood return was