RESUMEN
OBJECTIVES: To examine postoperative serum lidocaine levels in patients with intermittent lidocaine bolus erector spinae plane block (ESPB) catheters after cardiac surgery with or without cardiopulmonary bypass (CPB). DESIGN: A retrospective study. SETTING: Single-center pediatric quaternary teaching hospital. PARTICIPANTS: Patients who received ESPB catheters after congenital cardiac surgery from April 2018 to March 2019. INTERVENTIONS: Postoperative serum lidocaine levels were extracted from the record. MEASUREMENTS AND MAIN RESULTS: Twenty-seven of 40 patients were included in the final analyses (19 with CPB and 8 with no CPB, age 1-47 years, undergoing congenital heart repair). Patients who received ropivacaine or were missing data were excluded. The initial intraoperative bolus of lidocaine ranged from 0- to- 3.72 mg/kg, and the range of postoperative intermittent lidocaine boluses ranged from 0.35- to- 0.83 mg/kg, which were administered every hour. Serum lidocaine levels were measured by the hospital laboratory and ranged from <0.05- to- 3.0 µg/mL in the CPB group and from <0.05- to- 3.2 µg/mL in the no- CPB group. CPB was not associated with differences in lidocaine levels when controlling for time (Pâ¯=â¯0.529). Lidocaine concentrations ranged from 0.50- to- 1.68 µg/mL in the CPB group and 0.86- to- 2.07 µg/mL in the no- CPB group. There was a normally distributed overall mean peak level of 1.818 ± standard deviation of 0.624 µg/mL, with 95% confidence interval of 0.57- to- 3.06 µg/mL. No patients had clinical signs of toxicity. CONCLUSION: Postoperative serum lidocaine concentrations did not appreciably differ due to CPB. Serum lidocaine concentrations did not reach near- toxic doses despite the presence of additional lidocaine in the cardioplegia. The results suggested that lidocaine for ESPBs after cardiac surgery is below systemic toxic range at the doses described.