Kentaro Ouchi

Dexmedetomidine dose-dependently enhances local anesthetic action of lidocaine.

PURPOSE The combination of α2-adrenoceptor agonists, such as dexmedetomidine (DEX) and clonidine, with local anesthetics has been found to extend the duration of peripheral nerve blocks, probably owing to the resultant local vasoconstriction in the peripheral nerves. However, because the clear elucidation of the effect of DEX requires examination of the local anesthetic effect with DEX alone and the combination of various concentrations of DEX with local anesthetics, we evaluated the local anesthetic effect of various concentrations of DEX alone and with a local anesthetic. MATERIALS AND METHODS The present study assessed the tail-flick (TF) latencies after injection of the appropriate drug in male Sprague-Dawley rats, using an epidural model that allowed constant pain stimulation intensity, dispersion of the anesthetic, and a precise injection site and dose. Lidocaine alone, lidocaine with 2.5-ppm DEX, lidocaine with 5.0-ppm DEX, lidocaine with 7.5-ppm DEX, and DEX alone were administered at the predetermined dose. The TF latency changes over time were compared using repeated measures analysis of variance (ANOVA). Comparisons among the groups were analyzed using ANOVA followed by a post hoc Dunnetts multiple comparison test or Tukeys multiple comparison test. RESULTS The addition of DEX to lidocaine increased the TF latency and dose-dependently prolonged its duration as follows: 0-ppm DEX, 20 minutes; 2.5-ppm, 40 minutes; 5.0-ppm, 40 minutes; and 7.5-ppm, 50 minutes. DEX alone did not change the TF latency. CONCLUSIONS Our results have demonstrated that DEX dose-dependently enhances the local anesthetic action of lidocaine in a rat TF model.

Dexmedetomidine Dose Dependently Enhances the Local Anesthetic Action of Lidocaine in Inferior Alveolar Nerve Block: A Randomized Double-Blind Study.

Background and Objectives Dexmedetomidine (DEX) dose dependently enhances the local anesthetic action of lidocaine in rats. We hypothesized that the effect might also be dose dependent in humans. We evaluated the effect of various concentrations of DEX with a local anesthetic in humans. Methods Eighteen healthy volunteers were randomly assigned by a computer to receive 1.8 mL of 1 of 4 drug combinations: (1) 1% lidocaine with 2.5 ppm (parts per million) (4.5 &mgr;g) DEX, (2) lidocaine with 5.0 ppm (9.0 &mgr;g) DEX, (3) lidocaine with 7.5 ppm (13.5&mgr;g) DEX, or (4) lidocaine with 1:80,000 (22.5 &mgr;g) adrenaline (AD), to produce inferior alveolar nerve block. Pulp latency and lower lip numbness (for assessing onset and duration of anesthesia) were tested, and sedation level, blood pressure, and heart rate were recorded every 5 minutes for 20 minutes, and every 10 minutes from 20 to 60 minutes. Results Pulp latency of each tooth increased compared with baseline, from 5 to 15 minutes until 60 minutes. There were no significant intergroup differences at any time point. Anesthesia onset was not different between groups. Anesthesia duration was different between groups (that with DEX 7.5 ppm was significantly longer than that with DEX 2.5 ppm and AD; there was no difference between DEX 2.5 ppm and AD). Blood pressure decreased from baseline in the 5.0 and 7.5 ppm DEX groups at 30 to 60 minutes, although there was no hypotension; moreover, heart rate did not change in any group. Sedation score did not indicate deep sedation in any of the groups. Conclusions Dexmedetomidine dose dependently enhances the local anesthetic action of lidocaine in humans. Dexmedetomidine at 2.5 ppm produces similar enhancement of local anesthesia effect as addition of 1:80,000 AD.

Intravenous General Anesthesia for Patients with Neurological Disorders

In dental practice, intravenous general anesthesia is useful for patients who are difficult to treat when not sedated such as those with neurological disorders

Remifentanil não aumenta a diurese durante cirurgia oral, contrariamente ao seu efeito durante outras cirurgias – Estudo de coorte

BACKGROUND An increase in urine output by remifentanil injection during laparoscopic procedures and surgeries such as cardiac and gynecological procedures, due to suppression of the stress response to surgery, has been reported. The aim of our prospective, observational, cohort study was to assess the effect of remifentanil analgesia on urine output during dental and minor oral surgery by comparing intraoperative urine output under defined infusion volumes with and without the use of remifentanil. METHODS Dental patients aged 16 years or older, American Society of Anesthesiologists physical status 1, with no renal diseases or abnormal blood values of serum creatinine and BUN, not on treatment with diuretic drugs, and undergoing minor oro-maxillofacial surgery or dental treatment under inhalation general anesthesia were included in this study. Urethral catheterization was performed after anesthesia induction, and urine output was measured every 30minutes. We measured urine volume (mL) and rate of urine output (mL.kg-1.h-1) intraoperatively, and compared these parameters between patients who did and did not receive remifentanil during the intraoperative period. RESULTS Eighty-seven patients were categorized into the remifentanil group (n=43) or remifentanil non-use group (n=44). Both volume of urine (mL) and rate of urine output (mL.kg-1.h-1) were not significantly different between the two groups (remifentanil group, 372.3±273.5mL, 1.8±1.1mL.kg-1.h-1; remifentanil non-use group, 343.3±283.3mL, 1.9±1.2mL.kg-1.h-1; p=0.63; 0.57). CONCLUSION Our results show that use of remifentanil during dental and minor oral surgeries does not increase urine output.