Plasma concentrations of lignocaine after thoracic paravertebral blockade in infants and children.

Abstract

Plasma concentrations of lignocaine were determined in six ASA 1 children treated with thoracic paravertebral blockade. Peak concentrations ranged between 1.7 and 3.0 micrograms.ml-1 after a bolus injection of lignocaine 0.5 ml.kg-1 (lignocaine 10 mg.ml-1 with adrenaline 5 micrograms.ml-1) and peak plasma concentrations were reached 15-30 min after injection. Two hours after the initial bolus a continuous infusion of the same lignocaine solution was started (0.25 ml.kg-1.h-1). Steady state levels of lignocaine were reached 8-10 h after the start of the infusion and ranged from 2.1-3.2 micrograms.ml-1. This regimen for paravertebral block in children resulted in moderate plasma concentrations of lignocaine, well below those which might result in side effects or systemic toxicity.