Lidocaine Concentration in Oral Tissue by the Addition of Epinephrine
The vasoconstrictive effect due to the addition of epinephrine to local anesthetic has been clearly shown by measuring blood-flow volume or blood anesthetic concentration in oral mucosal tissue. However, there are no reports on the measurement of anesthetic concentration using samples directly taken from the jawbone and oral mucosal tissue. Consequently, in this study, the effect of lidocaine concentration in the jawbone and oral mucosal tissue by the addition of epinephrine to the local anesthetic lidocaine was considered by quantitatively measuring lidocaine concentration within the tissue. Japanese white male rabbits (n = 96) were used as test animals. General anesthesia was induced by sevoflurane and oxygen, and then cannulation to the femoral artery was performed while arterial pressure was constantly recorded. Infiltration anesthesia was achieved by 0.5 mL of 2% lidocaine containing 1 : 80,000 epinephrine in the upper jawbone (E+) and 0.5 mL of 2% of epinephrine additive–free lidocaine (E0) under the periosteum. At specified time increments (10, 20, 30, 40, 50, and 60 minutes), samples from the jawbone, oral mucosa, and blood were collected, and lidocaine concentration was directly measured by high-performance liquid chromatography. No significant differences in the change in blood pressure were observed either in E+ or E0. In both E+ and E0 groups, the serum lidocaine concentration peaked 10 minutes after local anesthesia and decreased thereafter. At all time increments, serum lidocaine concentration in E+ was significantly lower than that in E0. There were no significant differences in measured lidocaine concentration between jawbone and mucosa within either the E+ or the E0 groups at all time points, although the E0 group had significantly lower jawbone and mucosa concentrations than the E+ group at all time points when comparing the 2 groups to each other. Addition of epinephrine to the local anesthetic inhibited systemic absorption of local anesthetic into the blood such that a high concentration could be maintained in the tissue. Epinephrine-induced vasoconstrictive effect was observed not only in the oral mucosa but also in the jawbone.
Method of general anesthesia. General anesthesia was induced by oxygen 5 L/min and 5% sevoflurane, and then a tracheotomy was performed, after which general anesthesia was maintained at oxygen 3 L/min and 3% sevoflurane. A cannula was inserted into the femoral artery, and arterial pressure was continuously recorded throughout the experiment using a polygraph and a pressure transducer.
Location of infiltration anesthesia: 0.5 mL of 2% of lidocaine containing 1 : 80,000 epinephrine or 0.5 mL of 2% of epinephrine additive-free lidocaine was infused into the right maxillae for 20 seconds. Injection site was the buccal side of the third molar on both sides (white arrow). Subperiosteal infiltration anesthesia was performed by touching the needle tip to the jawbone surface under the periosteum.
Chromatogram of lidocaine concentration from oral mucosa in rabbit in one case.
Change of mean arterial pressure before and after infiltration anesthesia. No significant difference was observed.
Change of blood lidocaine concentration after infiltration anesthesia. At all time points, blood lidocaine concentration in epinephrine addition group (E+) was significantly lower than that in epinephrine additive–free group (E0). ** P < .01 E+ versus E0. * P < .05 E+ versus E0.
Change of lidocaine concentration in jawbone after infiltration anesthesia. At all time points, lidocaine concentration in jawbone in epinephrine addition group (E+) was significantly higher than that in epinephrine additive–free group (E0). ** P < .01 E+ versus E0. * P < .05 E+ versus E0.
Change of lidocaine concentration in oral mucosa after infiltration anesthesia. At all time points, lidocaine concentration in oral mucosa in epinephrine addition group (E+) was significantly higher than that in epinephrine additive–free group (E0). ** P < .01 E+ versus E0. * P < .05 E+ versus E0.
Change of lidocaine concentration in jawbone and oral mucosa in epinephrine addition group after infiltration anesthesia. Lidocaine concentration in jawbone was lower than that in oral mucosa at all time points, and no significant difference was observed between the concentration values of both groups.
Change of lidocaine concentration in jawbone and oral mucosa in epinephrine additive–free group after infiltration anesthesia. Lidocaine concentration in jawbone was lower than that in oral mucosa only at the 10-minute time point. Values thereafter were reversed, and no significant difference was observed between the 2 concentration values of both groups.
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