Effect of PaCO2 and PaO2 on lidocaine and articaine toxicity.

Abstract

Alterations in arterial PaCO can influence local anesthetic toxicity. The objective of this study was to evaluate the effect of stress-induced changes in PaCO and PaO on the seizure threshold of lidocaine and articaine. Lidocaine (2% with 1:100,000 epinephrine) or articaine (4% with 1:100,000 epinephrine) was administered intravenously under rest or stress conditions to 36 rats separated into 4 groups. Propranolol and prazosin were administered preoperatively to minimize cardiovascular effects of epinephrine. Mean arterial pressure (MAP), heart rate (HR), and arterial pH, PaCO, and PaO were measured. Results showed no differences in MAP, HR, or pH. Stress significantly increased the latency period for the first tonic-clonic seizure induced by a toxic dose of both lidocaine and articaine (P < .05). Seizures were brought on more rapidly by articaine. No significant difference between toxic doses of lidocaine and articaine was noted. Stress raised the seizure threshold dose for both drugs and significantly (P