Excessively high plasma bupivacaine concentrations after tonsillar bed and adenoidal injection of 0.25% bupivacaine

The injection of local anaesthetics into the tonsillar bed has gained acceptance in the United States as a method for providing postoperative pain relief. A clinical trial was devised in which the tonsillar bed was injected at the upper and lower poles subsequent to the removal of each tonsil. In addition, a small amount of local anaesthetic was sprayed topically by the nares onto the adenoidal beds subsequent to adenoidectomy to alleviate pain from this area. Bupivacaine was used as the local anaesthetic because of its long duration of action. Despite extreme care in the performance of this study, one patient developed ventricular tachycardia subsequent to the injection of bupivacaine. Plasma bupivacaine levels were obtained after tonsillar bed infiltration and nasal instillation post tonsillectomy and adenoidectomy in each of the patients, and though most levels were below toxic ranges, one patient had high serum levels. This high serum level coincided with the development of ventricular tachycardia. On the basis of this finding, we have abandoned this technique for postoperative pain management after tonsillectomy.