Comparison of lidocaine with and without bupivacaine for local dental anesthesia.

The purpose of this study was to investigate the effectiveness of a combination of bupivacaine and lidocaine and that of lidocaine alone for local dental anesthesia. First, on different days, healthy volunteers were given 2% lidocaine with 1/80,000 epinephrine or 2% lidocaine with 1/80,000 epinephrine + 0.5% bupivacaine, after which pain was produced with a pulp tester. No difference was found in the time until onset of anesthetic effect between the preparations. However, the duration of anesthetic effect was longer with both lidocaine and bupivacaine than with lidocaine alone. Next, patients undergoing dental surgery were given one of the anesthetic preparations, after which serum concentrations of the anesthetics and epinephrine were measured. The maximal serum concentration of lidocaine was higher and was reached sooner after injection in patients receiving lidocaine alone (1.74 microgram/ml after 5 min) than in patients receiving both anesthetics (0.85 microgram/ml after 3 min). The mean maximal serum concentration of lidocaine was higher in patients receiving lidocaine alone (1.77 +/- 0.03 microgram/ml) than in those receiving both anesthetics (0.99 +/- 0.45 microgram/ml). Furthermore, the mean plasma concentration of epinephrine 1 min after injection was significantly higher in patients receiving lidocaine alone (0.671 ng/ml) than in patients receiving both lidocaine and bupivacaine (0.323 ng/ml). The results of this study suggest that the combination of lidocaine with epinephrine and bupivacaine produces lower systemic levels of the anesthetic and epinephrine and a longer duration of activity than lidocaine with epinephrine alone for local dental anesthesia.

[Intravenous anesthesia by continuous administration of midazolam and fentanyl].

We examined the amount and method of administration of midazolam and fentanyl for intravenous anesthesia. Intravenous anesthesia was induced by intravenous administration of fentanyl 0.2-0.3 mg, followed by a minimal sleeping-inducing dose of midazolam, and then an additional 0.2 mg of fentanyl before starting the operation. To maintain anesthesia, a half dose of the first dose of midazolam was administered every hour, and a continuous intravenous injection of fentanyl at 0.08 microgram-1. kg-1.min-1 was also performed. It is suggested that these doses are the most suitable for obviating the use of antagonist. Also, by using a continuous administration, the dose of fentanyl can be reduced, and it is possible to stabilize circulation. Without the use of nitrous oxide during intravenous anesthesia, it is necessary to double the dose of fentanyl administered.

Timing and side effects of flumazenil for dental outpatients receiving intravenous sedation with midazolam.

We studied the timing and side effects of flumazenil treatment for 10 healthy volunteers and 46 dental outpatients who received intravenous sedation with midazolam. For the volunteers, vital signs were monitored before and after intravenous injection of midazolam and flumazenil. In addition, grip strength, signs and symptoms, and performance on the Romberg's test and addition tests were evaluated 30 min and 60 min after midazolam injection as well as after flumazenil injection. There were no significant changes in vital signs before, immediately after, or 50 min after injection of flumazenil, the latter time corresponding to the half-life of the drug. Thus, awakening from sedation was associated with no effects on the cardiovascular or respiratory systems. Distinct effects of flumazenil were demonstrated by the Romberg's test and the assessment of sedation status. Flumazenil had no effect on the outcome of the addition test. For the outpatients, sedation status and signs and symptoms were studied in patients undergoing procedures lasting 30 min or less (group S) and those undergoing procedures lasting 31 to 60 min (group L). Three patients in group S and one in group L had signs and symptoms of resedation. After treatment with flumazenil, abnormalities such as excitability and nausea were reported by only two patients in group L. One patient in group S had drowsiness that did not resolve after injection of flumazenil and continued until the following day. Our results indicate that flumazenil should be given at least 60 min after intravenous sedation with midazolam in dental outpatients. Moreover, caution should be exercised with regard to the potential side effects of flumazenil.

Effects of clonidine on intravenous sedation with midazolam.

The effect of clonidine, an alpha 2-adrenoceptor agonist, on intravenous (IV) sedation with midazolam was studied. Subjects were eight healthy adults; IV sedation was performed twice on each subject. In the control (CO) group, midazolam alone was administered. In the clonidine (CL) group, the subjects were given about 5 micrograms/kg of clonidine orally 2 hr before the initiation of sedation with midazolam. The following parameters were determined: dose of midazolam, changes in vital signs, recovery time, amnesia, and side effects. The average sedating dose of midazolam was 0.078 and 0.043 mg/kg in the CO and CL groups, respectively. Recovery times determined by stabilometry were 150 and 120 min in the CO and CL groups, respectively. Based on these results, the combined use of clonidine can reduce the dose of midazolam and shorten the recovery time. It is suggested that clonidine may be useful in IV sedation with midazolam.