[Characteristics of mepivacaine axillary brachial plexus block performed at 2800 m of altitude].
OBJECTIVE: We evaluated the feasibility and pharmacodynamic profile of axillary brachial plexus nerve blocks performed in high altitude. STUDY DESIGN: A prospective study was performed in healthy volunteers. PATIENTS AND METHODS: Ten male volunteers received 20 ml of 1.5% mepivacaine on radial and median nerves (total 40 ml), first at altitude of 150 then at 2877 m. Onset and offset times for sensory, motor and sympathetic blocks were recorded. Blood was sampled up to 60 min after injection to measure plasma concentrations of mepivacaine. RESULTS: At 150 and 2877 m of altitude, onset times for blocks were similar. Duration of sensory and motor blocks was not different at low and high altitude (193+/-35 min and 180+/-47 min; and 237+/-32 min and 217+/-44 min, respectively). Plasma mepivacaine concentrations were significantly lower at 20 minutes in high altitude (p<0.05). At higher altitude, one patient showed clinical signs of neurological toxicity, with plasma concentrations of mepivacaine ranging from 0.94 to 1.21 mug/ml. CONCLUSION: At altitude of 2877 m, axillary brachial plexus block with 1.5% mepivacaine is feasible, with onset and offset times for sensory and motor effects similar to those performed at 150 m.