Effect of PaCO2 and PaO2 on Lidocaine and Articaine Toxicity

摘要

Alterations in arterial PaCO2 can influence local anesthetic toxicity.The objectivenof this study was to evaluate the effect of stress-induced changes in PaCO2 andnPaO2 on the seizure threshold of lidocaine and articaine. Lidocaine (2% withn1 : 100,000 epinephrine) or articaine (4% with 1 : 100,000 epinephrine) was ad-nministered intravenously under rest or stress conditions to 36 rats separated inton4 groups. Propranolol and prazosin were administered preoperatively to mini-nmize cardiovascular effects of epinephrine. Mean arterial pressure (MAP), heartnrate (HR), and arterial pH, PaCO2,andPaO2 were measured. Results showednno differences in MAP, HR, or pH. Stress significantly increased the latency peri-nod for the first tonic-clonic seizure induced by a toxic dose of both lidocaine andnarticaine (P ,.05).Seizureswerebroughtonmorerapidlybyarticaine.Nosignif-nicant difference between toxic doses of lidocaine and articaine was noted.Stressnraised the seizure threshold dose for both drugs and significantly (P , .01) in-ncreased arterial PaO2 from 94.0 6 1.90 mm Hg to 113.0 6 2.20 mm Hg, andnreduced PaCO2 from 36.0 6 0.77 mm Hg to 27.0 6 0.98 mm Hg. In conclusion,nreduction in PaCO2 and/or increase in PaO2 raised the seizure threshold of lido-ncaine and articaine. This study also confirmed that lidocaine and articaine havenequipotent central nervous system toxicity