Plasma prilocaine concentrations after three techniques of brachial plexus blockade.

Brachial plexus blockade (n = 30: 10 axillary, 10 perivascular subclavian, 10 interscalene) was performed on 28 patients, using 35 ml of 1.5% prilocaine in plain solution. Plasma prilocaine concentrations were measured at intervals over the following 60 min. There was no significant difference in the prilocaine concentrations between the three groups. One asymptomatic patient in the interscalene group had a peak prilocaine concentration greater than the accepted threshold for toxic symptoms.