Lidocaine in del Nido cardioplegia solution prolongs the refractory period of cardiomyocytes, yielding a longer arrest per dose. Serum lidocaine concentrations >8 mg/L are associated with seizure and cardiotoxicity. We evaluated serum lidocaine concentrations in patients receiving del Nido solution during cardiac surgery.

Forty consecutive patients undergoing cardiac surgical procedures with del Nido cardioplegia were selected for serum lidocaine concentration measurements determined immediately after aortic cross-clamp removal. Variables included weight, body surface area, operation, cardiopulmonary bypass time, aortic cross-clamp time, and total volume of del Nido solution. The primary outcome was serum lidocaine concentration relative to total volume of del Nido solution. Descriptive statistics and Pearson correlations were computed.

Median weight was 78.3 kg (range, 43-132.4 kg), and mean body surface area was 1.9 ± 0.2 m². Operations included coronary artery bypass grafting (n = 26 [65%]), a combination procedure (n = 5 [12.5%]), isolated mitral valve repair or replacement (n = 4 [10%]), isolated aortic valve replacement (n = 3 [7.5%]), and aortic repair or replacement (n = 2 [5%]). Median total volume of del Nido solution was 1870 mL (range, 800-5800 mL). Mean serum lidocaine concentration was 2.2 ± 0.6 mg/L. Serum lidocaine concentration was weakly correlated with del Nido solution volume (R² = 0.21). The highest total volume of del Nido solution (5800 mL) did not yield the highest serum lidocaine concentration of 3.5 mg/L.

Serum lidocaine concentration during cardiac surgical procedures weakly correlates with the volume of del Nido solution used and does not reach toxic levels even at high doses of del Nido solution. The results of this study may help alleviate concerns for lidocaine toxicity with high doses of del Nido solution.