Systemic Absorption of Lidocaine from Continuous Erector Spinae Plane Catheters After Congenital Cardiac Surgery: A Retrospective Study

Abstract

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 (P = 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.

Keywords: Cardiopulmonary bypass (CPB); Erector spinae plane block (ESPB) catheters; Serum lidocaine.