Disposition of lignocaine for intravenous regional anaesthesia during day-case surgery

Abstract

Lignocaine is a suitable and safe agent for intravenous regional anaesthesia (IVRA) with rapid onset of good surgical anaesthesia. The onset time of the local anaesthetic action of lignocaine was 11.2±5.1 min. Satisfactory surgical conditions, evidenced by good sensory blockade were achieved within 20 min, and no additional analgesics were required. There was no trend towards a fixed sequence, radial, median and ulnar in the development of sensory blockade. No patient exhibited objective symptoms of toxicity, either local or systemic, after release of the tourniquet, nor were there any subjective complaints. No changes in blood pressure, heart rate or oxygen saturation were observed at any time during the procedure, or after deflation of the tourniquet. After releasing the tourniquet lignocaine is rapidly and biexponentially eliminated, with a t_1/2a of 4.3±2.1 min and a t_1/2β of 79.1±31.2 min. Total body clearance was 0.86 ± 0.39L min⁻¹. Eight patients showed rapid release of lignocaine from the exsanguinated area. In two patients the systemic plasma concentration of lignocaine increased more slowly than in the remaining eight. This can be explained by a greater degree of lignocaine absorbtion in the tissues of the arm. Pharmacokinetic constants after rapid and slow absorption were calculated.