Incidence of local anesthetic systemic toxicity and postoperative neurologic symptoms associated with 12,668 ultrasound-guided nerve blocks: an analysis from a prospective clinical registry.

BACKGROUND AND OBJECTIVES There are varying reports on the incidence of major morbidity associated with peripheral regional anesthesia. Our objective was to contribute to the knowledge regarding the incidence of local anesthetic systemic toxicity and postoperative neurologic symptoms in the setting of ultrasound-guided peripheral regional anesthesia. METHODS During an 8-year period, 12,668 patients undergoing peripheral regional anesthesia were evaluated. Using a clinical registry, incidence rates of postoperative neurologic symptoms, local anesthetic toxicity, pneumothorax, and vascular trauma were calculated. Univariate analysis was used to identify risk factors for postoperative neurologic symptoms. We defined postoperative neurologic symptoms as any sensory or motor dysfunction present for more than 5 days and anatomically consistent with the possibility of contribution from the nerve block. RESULTS The incidence (per 1000 blocks) of adverse events across all peripheral regional anesthetics was 1.8 (95% confidence interval [CI], 1.1-2.7) for postoperative neurologic symptoms lasting longer than 5 days, 0.9 (95% CI, 0.5-1.7) for postoperative neurologic symptoms lasting longer than 6 months, 0.08 (95% CI, 0.0-0.3) for seizure, 0 (95% CI, 0-0.3) for pneumothorax, 0.6 (95% CI, 0.2-1.2) for unintended venous puncture, 1.2 (95% CI, 0.7-2.0) for unintended arterial puncture, and 2.0 (95% CI, 1.2-3.0) for patients having unintended paresthesia during block placement. There were no cardiac arrests. CONCLUSIONS In the setting of a surgical procedure, ultrasound-guided regional anesthesia is associated with the risk of long-term postoperative neurologic symptoms. Local anesthetic systemic toxicity, however, is extremely uncommon.