Dexmedetomidine dose-dependently enhances local anesthetic action of lidocaine

Synergistic interaction of guanfacine or dexmedetomidine coadministered with lidocaine for cutaneous analgesia in rats

BACKGROUND

This study examined the cutaneous analgesic effects of lidocaine co-injected with guanfacine and its comparison with dexmedetomidine.

METHODS

Cutaneous analgesic effects are quantified through the blocking effects of the cutaneous trunci muscle reflex against skin pinpricks in rats. The dose-response curves of guanfacine, dexmedetomidine, and lidocaine were constructed and drug-drug interactions were analyzed by the ED50 isobologram.

RESULTS

Subcutaneous injections of guanfacine, dexmedetomidine, and lidocaine produced dose-dependently nociceptive/sensory blockade. On the ED50 (50% effective dose) basis, the potency rankings of the drug are dexmedetomidine (0.09 [0.08-0.11] μmol/kg) > guanfacine (3.98 [2.96-5.34] μmol/kg) > lidocaine (25.40 [23.51-27.44] μmol/kg) (p < 0.01). On their equipotent doses (ED25, ED50, and ED75), the duration of sensory blockade induced by guanfacine or dexmedetomidine was longer than lidocaine's (p < 0.01). Both guanfacine and dexmedetomidine showed synergistic effects with lidocaine.

CONCLUSIONS

We showed that guanfacine elicits dose-dependent cutaneous analgesia when administered subcutaneously. Lidocaine is less potent than guanfacine or dexmedetomidine. Both guanfacine and dexmedetomidine enhance the potency and duration of lidocaine. Better synergistic responses we are getting with guanfacine plus lidocaine.

Postoperative Pain Management in Children Undergoing Laparoscopic Appendectomy: A Scoping Review

Laparoscopic appendectomy (LA) is one of the most commonly performed surgical procedures in children and is associated with extreme postoperative discomfort due to peritoneal inflammation and infection. The main objective of this study was to investigate the effects of postoperative pain (POP) in children after laparoscopic appendectomy. Articles describing or evaluating the control of POP in children with LA were considered eligible. All available literature such as randomized controls, prospective controls, retrospective as well as clinical studies were considered. A comprehensive search was performed in PubMed, Medline, Embase, Cochrane Library, Clinical trials.gov, and Google scholar. The initial search took place on 23 April 2021, and was updated on 24 August 2021. There were no language or date restrictions. Each of the included articles was evaluated separately by two independent reviewers. Additional papers were found by searching the reference lists of eligible studies. Eighteen papers were considered. All papers, and many of them used different methods to treat POP in children undergoing LA, such as lidocaine infusion, different analgesic approaches, ultrasound-guided transverse abdominis blockade (UGTAP), ultrasound-guided quadratus lumborum blockade (UGQLB), and comparison of open appendectomy (OA) with local anesthetics in relation to POP management in children. Laparoscopic appendectomy is the surgical procedure preferred by clinicians compared with open appendectomy in children. A multimodal analgesic approach is optimal and efficient surgical techniques such as UGBRSB, UGQLB, and UGTAP block might significantly impact POP in children except that there are contraindications. Dexmedetomidine proved to be an effective adjuvant that can enhance the effect of local anesthetics. The lack of a sufficient number of studies may be a factor affecting our confidence in the results of this study. Therefore, further evidence-based randomized control trials with a large sample size are needed to provide clarity.

Clonidine versus Adrenaline as an Adjunct to Lignocaine on Haemodynamic Parameters during Nerve Block for Third Molar Surgical Removal - A Systematic Review and Meta-Analysis

Background

Adrenaline or clonidine is used as adjuncts in conjunction with lignocaine to improve the depth of local anaesthesia in dental procedures.

Objectives

This systematic review and meta-analysis intends to compare the haemodynamic parameters when clonidine or adrenaline is used in conjunction with lignocaine for third-molar surgical removal.

Data Sources

Cochrane, PubMed and Ovid SP databases were searched using "MeSH" terms (((nerve block) OR (IANB)) AND ((clonidine) OR (adrenaline))) AND (lignocaine).

Study Eligibility Criteria

Clinical studies where Clonidine + lignocaine and Adrenaline + lignocaine were compared directly during nerve block administration exclusively for third molar surgical removal were selected.

Participants Study Appraisal

This current systematic review is registered in Prospero database CRD42021279446. Two independent reviewers were involved in collection, segregation and analysis of electronic data. The data were compiled in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Search was conducted till June 2021.

Synthesis Methods

Qualitative analysis of the selected articles was performed for systematic review. Meta-analysis is performed using RevMan 5 Software. Heterogeneity through the I2 statistics. Change in the haemodynamic parameters was the primary outcome evaluated, and secondary outcomes evaluated were onset and duration of anaesthesia in both the groups.

Results

In all databases, 1141 records were screened, out of which a total of 21 articles were included for the evaluation for full-text analysis. Out of these, 16 articles were excluded and 5 articles were included for the final systematic review. Meta-analysis was performed only for 4 studies.

Conclusion

Amongst the evaluated haemodynamic parameters, there was a significant reduction in the heart rate (baseline to intraoperative period) in clonidine and lignocaine groups than in adrenaline and lignocaine groups during nerve block administration for third molar surgical removal. There was no significant difference between other primary and secondary outcomes evaluated.

Limitations

Blinding was not performed in all the studies, randomisation was performed in only three studies. The volume of local anaesthesia deposited varied in the studies (2 mL in three studies and 2.5 mL in two studies). Most of the studies (n = 4) were evaluated on normal adults and only one study evaluated mild hypertensive patients.

Efficacy of adding dexmedetomidine to lidocaine to enhance inferior alveolar nerve block in patients with asymptomatic irreversible pulpitis: double-blind randomized clinical trial

OBJECTIVES

This randomized, double-blind study was to determine whether dexmedetomidine (DEX) helped to improve the inferior alveolar nerve block's (IANB) success in patients with asymptomatic irreversible pulpitis (AIP). We hypothesized that adding DEX to lidocaine enhances the anesthetic effect of lidocaine to a satisfactory level by localizing anesthesia in a safer way.

MATERIALS AND METHODS

Fifty adult volunteers with AIP in a first or second mandibular molar were randomly assigned to two groups to either receive 1.4 ml 2% plain lidocaine or 1.4 ml 2% lidocaine + 0.4 ml (40 μg) DEX, for standard IANB injection. Access cavity preparation initiated 10-15 min postinjection when the patient reported lower lip numbness and had two negative electric pulp tests (EPTs) with 5-min intervals. Heft-Parker visual analog scale (VAS) was used to report pain in three steps: during caries and dentin removal, access cavity preparation, and canal working-length determinations; EPT and VAS were analyzed by Friedman test; and success rates were analyzed by Mann-Whitney and Fisher's exact test using SPSS software version 20.

RESULTS

Successful anesthesia (defined as no or mild pain during any of steps and no need for additional injection) is obtained in 12% of patients in the lidocaine group, while DEX-lidocaine group increased the success rate of IANB to 72% (p-value = 0.0001).

CONCLUSIONS

DEX significantly increases the anesthetic effect of lidocaine in IANB injection in patients with AIP.

CLINICAL RELEVANCE

DEX would be a safe adjunct to lidocaine to increase the success rate in IANB and could be a suitable alternative for conventional vasoconstrictors in sensitive groups.

Levobupivacaine versus levobupivacaine plus dexmedetomidine in transversus abdominis plane block in patients undergoing abdominal aortic surgery

Background:

Severe postoperative pain is a major dilemma for patients undergoing abdominal aortic surgery. Transversus abdominis plane (TAP) block has been described a successful pain management technique after major abdominal surgery. Dexmedetomidine was proved to enhance the analgesic action of local anesthetics.

Aim:

This study was aimed to assess the impact of adding dexmedetomidine to levobupivacaine during TAP block in patients undergoing abdominal aortic operations.

Patients and Methods:

We included 114 patients in this prospective trial, and they were enrolled into two groups; the L group received levobupivacaine only, and the LD group received levobupivacaine plus dexmedetomidine. The block was performed before anesthetic induction. Postoperative pain score was our main outcome.

Statistical Analysis:

The collected data were tabulated and analyzed through the SPSS software program IBM's Statistical Package for the Social Sciences (SPSS) statistics for Windows (version 25, 2017) (IBM Corporation, Armonk, NY, USA). The categorical data were expressed as numbers and percentages and then compared using the Chi-square test. The continuous data were expressed as mean and standard deviation if normally distributed, or median and range if abnormally distributed. The former data were compared through the one-way ANOVA, while the latter were compared through the Kruskal–Wallis test. Any P < 0.05 was considered statistically significant.

Results:

Group LD showed significantly earlier sensory blocks compared to the other group. Postoperative pain scores were comparable between the two groups for the initial 4 h following the surgery. Adjuvant dexmedetomidine was associated with better pain scores for the subsequent 12 h compared to Group L. The duration till the first analgesic request showed a significant increase in the LD group (13.3 vs. 11.09 h in Group L). In addition, the same group showed a significant decline in their opioid consumption after the operation (48.95 μg vs. 72.63 μg in the other group). Postoperative nausea and vomiting were significantly increased in Group L.

Conclusion:

Adjuvant dexmedetomidine has a significant beneficial impact on postoperative analgesic profile. Its use as an adjuvant to peripheral and neuraxial nerve blocks should be recommended in pain management practice.

A clinical comparative study of dexmedetomidine as an adjuvant to 2% plain lignocaine and 2% lignocaine with 1:200,000 adrenaline as local anesthetic agents for surgical removal of impacted mandibular third molars

Introduction

Dexmedetomidine is a selective alpha-2 adrenoceptor agonist. It is conventionally used as a sedative in the intensive care unit. However, recently, the application of dexmedetomidine as an adjuvant to a local anesthetic agent has been studied. The present study intends to evaluate the effectiveness of dexmedetomidine as an adjuvant to 2% plain lignocaine for surgical removal of impacted mandibular third molar and to compare the efficacy of dexmedetomidine with 2% plain lignocaine with 2% lignocaine and 1:200000 adrenaline.

Materials and Methods

A total of 80 patients who required surgical removal of impacted mandibular third molar extraction were included in the study. Patients were randomly divided into two groups using a computer-generated table. Patients in the study group received 2% plain lignocaine with 1 mcg/ml dexmedetomidine. Patients in the control group received 2% lignocaine with 1:200000 adrenaline. The parameters evaluated were onset and duration of action, pulse rate, blood pressure, oxygen saturation, and blood loss.

Results

Onset of action was faster and the duration of action was longer when dexmedetomidine was used with lignocaine as a local anesthetic agent. The vital parameters in both the groups were stable. Bleeding at the surgical site was less in the dexmedetomidine group.

Conclusion

The study concluded that the combination of dexmedetomidine with lignocaine enhances the local anesthetic potency of lignocaine when injected for nerve blocks.

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.

Calcium channel blockers, angiotensin II receptor antagonists and alpha-blockers accentuate blood pressure reducing caused by dental local anesthesia

OBJECTIVE

The primary aim of this study was to investigate the effect associated with patients' factor such as systemic disease on the blood pressure of patients in dental procedure. The secondary aim of this study was to investigate the effect associated with systemic disease and antihypertensive on the blood pressure changes with local anesthesia.

METHODS

The blood pressure was measured before and after local anesthesia injection for dental treatment. The effect associated with patients' factor such as systemic disease on the blood pressure and the effect on blood pressure changes of the type of antihypertensive drugs and the systemic disease were analyzed using a multivariate analysis of variance test.

RESULTS

We analyzed 1306 patients scheduled for the dental procedure. Age and some systemic diseases such as hypertension and angina pectoris affected blood pressure before local anesthesia. On the other hand, age and systemic diseases did not affect blood pressure changes. And, some antihypertensive affected systolic blood pressure changes.

CONCLUSIONS

The blood pressure change with local anesthesia was not associated with systemic diseases and age but was associated with antihypertensive agents. In particular, calcium channel blockers, angiotensin II receptor antagonists and alpha-blockers accentuate blood pressure reducing caused by local anesthesia.

CLINICAL RELEVANCE

The blood pressure change with local anesthesia was associated with antihypertensive agents. This study was registered with the University Hospital Medical Information Network Clinical Trials Registry (number UMIN000030695).

Comparison of intraperitoneal ropivacaine and ropivacaine-dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy

OBJECTIVE

To investigate the intraperitoneal (IP) administration of ropivacaine or ropivacaine-dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomized, blinded, positively controlled clinical study.

ANIMALS

A total of 45 client-owned cats were enrolled.

METHODS

The cats were administered intramuscular (IM) meperidine (6 mg kg^-1) and acepromazine (0.05 mg kg^-1). Anesthesia was induced with propofol and maintained with isoflurane. Meloxicam (0.2 mg kg^-1) was administered subcutaneously in all cats after intubation. After the abdominal incision, the cats were administered one of three treatments (15 cats in each treatment): IP instillation of 0.9% saline solution (group Control), 0.25% ropivacaine (1 mg kg^-1, group ROP) or ropivacaine and dexmedetomidine (4 μg kg^-1, group ROP-DEX). During anesthesia, heart rate (HR), electrocardiography, noninvasive systolic arterial pressure (SAP) and respiratory variables were monitored. Sedation and pain were assessed preoperatively and at various time points up to 24 hours after extubation using sedation scoring, an interactive visual analog scale, the UNESP-Botucatu multidimensional composite pain scale (MCPS) and mechanical nociceptive thresholds (MNT; von Frey anesthesiometer). Rescue analgesia (morphine, 0.1 mg kg^-1) IM was administered if the MCPS ≥6. Data were analyzed using the chi-square test, Tukey test, Kruskal-Wallis test and Friedman test (p < 0.05).

RESULTS

HR was significantly lower in ROP-DEX compared with Control (p = 0.002). The pain scores, MNT, sedation scores and the postoperative rescue analgesia did not differ statistically among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

As part of a multimodal pain therapy, IP ropivacaine-dexmedetomidine was associated with decreased HR intraoperatively; however, SAP remained within normal limits. Using the stated anesthetic protocol, neither IP ropivacaine nor ropivacaine-dexmedetomidine significantly improved analgesia compared with IP saline in cats undergoing ovariohysterectomy.

The impact of dexmedetomidine added to ropivicaine for transversus abdominis plane block on stress response in laparoscopic surgery: a randomized controlled trial

BACKGROUND

Intravenous dexmedetomidine is known to attenuate stress response in patients undergoing laparoscopic surgery. We investigated whether the addition of the highly selective alpha-2 adrenergic agonist dexmedetomidine into ropivacaine for ultrasound-guided transversus abdominis plane block could inhibit stress response during laparoscopic surgery, and determined the optimal dose of dexmedetomidine in it.

METHODS

One hundred and twenty-five patients undergoing laparoscopic gynecological surgery were included in this prospective and randomized double-blind study. Patients received general anesthesia with or without a total of 60 ml of 0.2% ropivacaine in combination with low (0.25 μg/kg), medium (0.50 μg/kg) or high dose (1.0 μg/kg) of dexmedetomidine for the four-quadrant transversus abdominis plane block (n = 25). The primary outcomes were stress marker levels during the operation.

RESULTS

One hundred and twenty patients completed the study protocol. Dexmedetomidine added to ropivacaine for transversus abdominis plane block significantly reduced serum levels of cortisol, norepinephrine, epinephrine, interleukin-6, blood glucose, mean arterial pressure and heart rate in a dose-dependent manner (P < 0.05), accompanied with decreased anesthetic and opioid consumption during the operation (P < 0.05), but the high dose of dexmedetomidine induced higher incidences of bradycardia than low or medium dose of dexmedetomidine (P < 0.05).

CONCLUSION

The addition of dexmedetomidine at the dose of 0.5 μg/kg into ropivacaine for ultrasound-guided transversus abdominis plane block is the optimal dose to inhibit stress response with limited impact on blood pressure and heart rate in patients undergoing laparoscopy gynecological surgery.

TRIAL REGISTRATION

This study was registered at www.chictr.org.cn on November 6th, 2016 (ChiCTR-IOR-16009753).

Haemodynamic changes and incisional bleeding after scalp infiltration of dexmedetomidine with lidocaine in neurosurgical patients

BACKGROUND

The purpose of this randomised controlled study is to compare the haemodynamic changes and the degree of incisional bleeding after scalp infiltration of lidocaine and dexmedetomidine versus lidocaine and epinephrine for patients with hemi-facial spasm undergoing microvascular decompression.

METHODS

Fifty-two patients were injected with 5 mL of 1% lidocaine with either dexmedetomidine (2 μg/mL) or epinephrine (1:100,000 dilution) to reduce scalp bleeding. Mean blood pressure and heart rate were recorded every minute for 15 minutes after scalp infiltration. The primary outcome was the incidence of predefined hypotension, which was treated with administration of 4 mg ephedrine as often as needed. The number of administrations and total amount of ephedrine administered were also recorded as a measure of the severity of hypotension. The neurosurgeon scored incisional bleeding by numeric rating scale from 0 (worst) to 10 (best).

RESULTS

The incidence of hypotension (68% vs. 34.8%, P = 0.02) and the frequency (P = 0.02) and total dose (P = 0.03) of ephedrine administered were lower in the dexmedetomidine group than in the epinephrine group. In addition, there was no difference in mean blood pressure between the two groups but heart rates were lower in the dexmedetomidine group (P = 0.01). Incisional site bleeding was better with epinephrine (median [interquartile range] of the numeric rating Score: 6 [4] in the dexmedetomidine group and 8 [2] in the epinephrine group; P < 0.001).

CONCLUSION

The dexmedetomidine-lidocaine combination may be recommended as a substitute for epinephrine-lidocaine for scalp infiltration in neurosurgical patients, especially neurologically compromised patients.

Dexmedetomidine as an Additive to Local Anesthesia: A Step to Development in Dentistry

PURPOSE

The study aimed to compare the effect of dexmedetomidine added to lidocaine against epinephrine added to lidocaine on local anesthetic potency and to look for future prospects of dexmedetomidine as an additive to local anesthesia in dentistry.

MATERIALS AND METHODS

The study included 25 healthy volunteers in whom extraction of all first premolars was scheduled as part of their orthodontic treatment plan. In this split-mouth, double-blind, crossover, randomized controlled trial, patients were randomized into 2 groups: Group 1 received injection lidocaine plus dexmedetomidine, and group 2 was administered lidocaine plus epinephrine. Patients were assessed for the onset of action of anesthesia, duration of analgesia, pain perception, and vital signs.

RESULTS

The mean values (±standard deviations) for the onset of anesthetic action in groups 1 and 2 were 113 ± 24.9 and 141 ± 34.8 seconds, respectively, for the mandible. For the maxilla, the mean values were 113 ± 24.9 seconds for group 1 and 165 ± 43.8 seconds for group 2. The duration of anesthesia was longer in group 1 (lidocaine plus dexmedetomidine), in which the requirement for the first analgesic on request was seen after a longer time interval, when compared with group 2 (lidocaine plus epinephrine). Pain perception elicited statistically significant results with less perception of pain in group 1 (lidocaine plus dexmedetomidine). The vital parameters remained stable, and the results were not statistically significant.

CONCLUSIONS

In this study, we observed that the addition of dexmedetomidine to lidocaine for maxillary and mandibular nerve blocks significantly prolonged the block duration and shortened the onset of action, as well as improved postoperative analgesia in terms of the need for fewer analgesics in the postoperative period. Furthermore, the vital parameters remained stable and no complications were encountered. The findings were supportive of the use of dexmedetomidine as an adjunct to local anesthetics in dental procedures.

omparative Evaluation of the Intranasal Spray Formulation of Midazolam and Dexmedetomidine in Patients Undergoing Surgical Removal of Impacted Mandibular Third Molars: A Split Mouth Prospective Study

Purpose

The purpose of this prospective randomized single blinded split mouth study was to conduct a comparative evaluation of the efficacy of intranasal atomised spray formulation of Dexmedetomidine with Midazolam in patients undergoing surgical removal of bilaterally impacted mandibular third molars.

Methods

This prospective study was conducted in twenty volunteers. Each volunteer underwent the surgical removal of an impacted mandibular third molar at two separate appointments at an interval of two weeks. The first third molar surgery was conducted using either intranasal Midazolam (Group M) or intranasal Dexmedetomidine (Group D). At the second appointment the surgical procedure was performed using the sedative agent not used at the first appointment. The primary testing outcome variables were Plasma oxygen saturation (SpO2), pulse and blood pressure and Modified Observer's Assessment of Alertness/Sedation (OAA/S) scale. These were recorded at predetermined intervals starting 10 min before the administration of local anaesthesia and continued up to 10 min after completion of the procedure. In addition surgeon's opinion regarding the patient cooperation, event amnesia, post operative nausea & vomiting were obtained.

Results

The sample composed of twenty patients (M = 9 and F = 11). There was statistically no significant difference between Group M and Group D with respect to mean SpO2. Minor differences were however noted at 20 and 30 min after sedation. There was no significant difference between the groups with respect to mean pulse rate, blood pressure, OAA/S, event amnesia, post operative nausea and vomiting and patient cooperation.

Conclusion

We conclude that Midazolam and Dexmedetomidine are equivalent and can be used in minor oral surgery with minimal complications. These drugs can be used intranasally using nasal atomization device in routine outpatient basis in otherwise normal healthy but anxious patients. All procedures must however be performed in the presence of an anaesthesiologist and with ready availability of emergency drugs and equipment.

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.

Dexmedetomidine as an adjuvant to local anesthetics in brachial plexus blocks: A meta-analysis of randomized controlled trials

BACKGROUND

Brachial plexus block (BPB) for upper extremity surgery provides superior analgesia, but this advantage is limited by the pharmacological duration of local anesthetics. Dexmedetomidine (DEX) as a local anesthetics adjuvant for BPB has been utilized to prolong the duration of the nerve block in some randomized controlled trials (RCTs) but is far from unanimous in the efficacy and safety of the perineural route. Hence, an updated meta-analysis was conducted to assess the efficacy and safety of DEX as local anesthetic adjuvants on BPB.

METHODS

A search in electronic databases was conducted to collect the RCTs that investigated the impact of adding DEX to local anesthetics for BPB. Sensory block duration, motor block duration, onset time of sensory and motor block, time to first analgesic request, the common adverse effects were analyzed.

RESULTS

Eighteen trails (1014 patients) were included with 515 patients receiving perineural DEX. The addition of DEX prolonged the duration of sensory block (WMD 257 minutes, 95%CI 191.79-322.24, P < 0.001), motor block (WMD 242 minutes, 95%CI 174.94-309.34, P < 0.001), and analgesia (WMD 26 6 minutes, 95%CI 190.75-342.81, P < 0.001). Perineural DEX also increased the risk of bradycardia (OR=8.25, 95%CI 3.95-17.24, P < 0.001), hypotension (OR = 5.62, 95%CI 1.52-20.79, P < 0.01), and somnolence (OR = 19.67, 95%CI 3.94-98.09, P < 0.001). There was a lack of evidence that perineural DEX increased the risk of other adverse events.

CONCLUSIONS

DEX is a potential anesthetic adjuvant that can facilitate better anesthesia and analgesia when administered in BPB. However, it also increased the risk of bradycardia, hypotension, and somnolence. Further research should focus on the efficacy and safety of the preneural administration of DEX.

The newer aspect of dexmedetomidine use in dentistry: As an additive to local anesthesia, initial experience, and review of literature

INTRODUCTION

Despite the availability of a wide variety of pharmacological agents in the field of anesthesia, there has always been a continuous search for newer local anesthetic agents with improved efficacy, potency, and better handling properties. Dexmedetomidine, a selective alpha-2 adrenergic receptor agonist, is an emerging agent for provision of additive local anesthetic effect if used with conventional local anesthetics, which can be implicated in dentistry for performing many minor oral surgical procedures. The present paper reports a pilot study comparing clinical efficacy and potency of this newer emerging drug in combination with lignocaine.

MATERIALS AND METHODS

Ten patients undergoing orthodontic extraction for correction of malocclusion and other dentofacial deformities requiring orthodontic treatment were locally infiltrated with 2% lignocaine plus dexmedetomidine 1μ/ml and 2% lignocaine plus adrenaline in 1:200,000 dilution at two different appointments. The onset of action, duration of action, and pain threshold were assessed.

RESULTS

Onset of action was found to be faster with longer duration of action with the newer drug dexmedetomidine and lignocaine combination when compared with combination of lignocaine and adrenaline.

CONCLUSION

The study demonstrated that the combination of dexmedetomidine with lignocaine enhances the local anesthetic potency of lignocaine without significant systemic effects when locally injected into oral mucosa.

Dexmedetomidine augments the effect of lidocaine: power spectrum and nerve conduction velocity distribution study

Background

In this study, the individual and combined inhibitory effects of dexmedetomidine and lidocaine on the conduction group of isolated nerve were investigated by determining conduction velocity distribution (CVD) and power spectrum.

Methods

Electrophysiological compound action potential (CAP) recordings were conducted on isolated rat sciatic nerve before (Con) and 20 minutes after exposure to 1 mM lidocaine (Lido), 21pM dexmedetomidine (Dex) and their combination (Lido + Dex). Then for CVD, mathematical model and for power spectrum Fast Fourier analysis were conducted.

Results

Dexmedetomidine alone made no significant difference in shape and duration of CAPs as compared to Con, on the other hand lidocaine depresses amplitude and prolongs the duration of CAPs, but not more than combination of dexmedetomidine and lidocaine can do.

Lidocaine caused a shift in the CVD histogram to relatively slower conducting group significantly while dexmedetomidine did not cause any significant change as compared to Control. Lidocaine, when combined with dexmedetomidine revealed a remarkable effect on the whole CVD histogram by causing almost complete blockage of fast conducting nerve fibers. The relative number of fibers in CVD is conserved for separate applications of anesthetics, but not for their combination.

As in CVD, power spectrum shifted from higher to lower frequency region by lidocaine and significantly for lidocaine combined with dexmedetomidine application. Shifts for dexmedetomidine applied group were seen beggarly.

Conclusions

We have concluded that dexmedetomidine alone did not influence nerve conduction, but when it is used with lidocaine it augments neural conduction blockage effect, especially on fast conducting nerve fibers.