Anesthesia in outpatient facilities

Dexmedetomidine 2 ppm Is Appropriate for the Enhancement Effect of Local Anesthetic Action of Lidocaine in Inferior Alveolar Nerve Block: A Preliminary, Randomized Cross-over Study

OBJECTIVE

Local anesthesia is essential for pain management in dentistry. The duration of anesthetic action of the addition of 5.0 and 7.5 ppm of dexmedetomidine (DEX) was significantly longer than the addition of adrenaline, and the mean duration of anesthetic action of the addition of 2.5 ppm DEX was also longer than the addition of adrenaline. We hypothesized that it is possible to safely achieve an equal local anesthesia effect as with 1:80,000 adrenaline, without using adrenaline or felypressin, by the addition of <2.5 ppm DEX to the local anesthetic solution.

MATERIALS AND METHODS

Nineteen healthy volunteers were randomly assigned by a computer to receive 1.8 mL of 1 of 3 drug combinations (1.8% lidocaine with 1.0 ppm [1.8 μg] DEX, lidocaine with 2.0 ppm [3.6 μg] DEX or lidocaine with 1:80,000 [22.5 μg] adrenaline), 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 2 minutes for 10 minutes, every 5 minutes from 10 to 20 minutes, and every 10 minutes from 20 to 60 minutes.

RESULTS

Pulp latency increased compared with the baseline, from 4 minutes until 60 minutes; there were no significant intergroup differences at any timepoint. Anesthesia onset did not differ between groups. Anesthesia duration did not differ between groups. Blood pressure and heart rate did not change in any group. Sedation score did not indicate deep sedation in any of the groups.

DISCUSSION

DEX at a concentration of 1.0 to 2.0 ppm enhances the local anesthetic action of lidocaine. DEX at 2.0 ppm produces similar enhancement of local anesthesia effect as the addition of 1:80,000 adrenaline.

Serious Cardiovascular Adverse Events Reported with Intravenous Sedatives: A Retrospective Analysis of the MedWatch Adverse Event Reporting System

BACKGROUND

Serious cardiovascular adverse events (SCAEs) associated with intravenous sedatives remain poorly characterized.

OBJECTIVE

The objective of this study was to compare SCAE incidence, types, and mortality between intravenous benzodiazepines (i.e., diazepam, lorazepam, and midazolam), dexmedetomidine, and propofol in the USA over 8 years regardless of the clinical setting where it was administered.

METHODS

The Food and Drug Administration's MedWatch Adverse Event Reporting System was searched between 2004 and 2011 using the Evidex^® platform from Advera Health Analytics, Inc. to identify all reports that included one or more of ten different SCAEs (package insert incidence ≥ 1%) and where an intravenous benzodiazepine, dexmedetomidine, or propofol was the primary suspected drug.

RESULTS

Among the 2326 Food and Drug Administration's MedWatch Adverse Event Reporting System cases reported, 394 (16.9%) were related to a SCAE. The presence of a SCAE (vs. a non-SCAE) is associated with higher mortality (34 vs. 8%, p < 0.001). The percentage of cases with one or more SCAE, the case mortality rate (%), and the incidence of each SCAE (per 10⁶ days of sedative exposure), respectively, were benzodiazepines (14, 26, 13) [diazepam (13, 23, 31); lorazepam (15, 43, 14); midazolam (14, 20, 11)]; dexmedetomidine (40, 15, 13); and propofol (17, 39, 7). Propofol (vs. either a benzodiazepine or dexmedetomidine) was associated with more total SCAEs (268 vs. 126, p < 0.001) but a lower incidence (per 10⁶ days of sedative exposure) of SCAE (7 vs. 13, p = 0.0001) and cardiac arrest [6.3 (benzodiazepine) vs. 6.7 (dexmedetomidine) vs. 1.4 (propofol), p < 0.0001].

CONCLUSIONS

Serious cardiac adverse events account for nearly one-fifth of intravenous sedative Food and Drug Administration's MedWatch Adverse Event Reporting System reports. These SCAEs appear to be associated with greater mortality than non-cardiac serious adverse events. Serious cardiac events may be more prevalent with either benzodiazepines or dexmedetomidine than propofol.

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 μg) DEX, (2) lidocaine with 5.0 ppm (9.0 μg) DEX, (3) lidocaine with 7.5 ppm (13.5μg) DEX, or (4) lidocaine with 1:80,000 (22.5 μg) 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.

Capnography Prevents Hypoxia during Sedation for Dental Treatment: A Randomized Controlled Trial

Intravenous sedation is useful for dental treatment in patients with intellectual disabilities. However, it is often necessary to manage such patients with deep sedation because their cooperation cannot be obtained. During deep sedation, undetected hypoventilation can lead to severe complications, such as hypoxia. Recently, capnographic monitoring has been advocated as a useful technique for preventing hypoxia during sedation. This randomized control trial evaluated whether the use of capnography reduces the incidence of hypoxia during the deep sedation of patients for dental treatment. This study involved patients with intellectual disabilities who underwent dental treatment under sedation. The subjects were randomized to the intervention group (I-group) or control group (C-group). All of the patients underwent routine monitoring, as well as bispectral index (BIS) and capnographic monitoring; however, only an independent observer had access to the patients’ capnographic data during the dental procedures. Sedation was maintained at a BIS of 50 to 70 by administration of propofol. In the I-group, the independent observer signaled to the dental anesthesiologist if the capnogram indicated that the patient had been suffering from alveolar hypoventilation or apnea for >15 s. In the C-group, the observer signaled to the dental anesthesiologist if the capnogram indicated that the patient had been suffering from alveolar hypoventilation or apnea for >60 s. In both groups, the dental anesthesiologists responded to the signals using appropriate airway management strategies. The primary endpoint of this study was the incidence of hypoxia during dental treatment, which was defined as oxygen saturation of <95%. Hypoxemic episodes occurred in 13.4% and 34.8% of cases in the I-group and C-group, respectively. The incidence of hypoxia was significantly lower in the I-group. These results suggest that capnographic monitoring during deep sedation for dental treatment prevents hypoxemic episodes by allowing the early detection of hypoventilation.

Knowledge Transfer Statement: This is the first randomized controlled trial to examine whether the use of capnography reduces the incidence of hypoxia during deep sedation for dental treatment. The findings of this study can be used by clinicians to aid decision-making regarding dental sedation standards at individual clinics. Moreover, they can be used as high-level evidence during the production or updating of clinical guidelines for dental sedation by leading associations.

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 Dunnett's multiple comparison test or Tukey's 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.