Dexmedetomidine-Induced Decreases in Accumbal Dopamine in the Rat Are Partly Mediated via the Locus Coeruleus

Electrical stimulation of the ventral tegmental area restores consciousness from sevoflurane-, dexmedetomidine-, and fentanyl-induced unconsciousness in rats

BACKGROUND

Dopaminergic neurons in the ventral tegmental area (VTA) are crucially involved in regulating arousal, making them a potential target for reversing general anesthesia. Electrical deep brain stimulation (DBS) of the VTA restores consciousness in animals anesthetized with drugs that primarily enhance GABAA receptors. However, it is unknown if VTA DBS restores consciousness in animals anesthetized with drugs that target other receptors.

OBJECTIVE

To evaluate the efficacy of VTA DBS in restoring consciousness after exposure to four anesthetics with distinct receptor targets.

METHODS

Sixteen adult Sprague-Dawley rats (8 female, 8 male) with bipolar electrodes implanted in the VTA were exposed to dexmedetomidine, fentanyl, ketamine, or sevoflurane to produce loss of righting, a proxy for unconsciousness. After receiving the dopamine D1 receptor antagonist, SCH-23390, or saline (vehicle), DBS was initiated at 30 μA and increased by 10 μA until reaching a maximum of 100 μA. The current that evoked behavioral arousal and restored righting was recorded for each anesthetic and compared across drug (saline/SCH-23390) condition. Electroencephalogram, heart rate and pulse oximetry were recorded continuously.

RESULTS

VTA DBS restored righting after sevoflurane, dexmedetomidine, and fentanyl-induced unconsciousness, but not ketamine-induced unconsciousness. D1 receptor antagonism diminished the efficacy of VTA stimulation following sevoflurane and fentanyl, but not dexmedetomidine.

CONCLUSIONS

Electrical DBS of the VTA restores consciousness in animals anesthetized with mechanistically distinct drugs, excluding ketamine. The involvement of the D1 receptor in mediating this effect is anesthetic-specific.

The effect of intranasal dexmedetomidine administration on emergence agitation or delirium in pediatric patients after general anesthesia: A meta-analysis of randomized controlled trials

BACKGROUND

Emergence agitation or delirium can occur in pediatric patients after anesthesia. Dexmedetomidine is known to reduce the impairment of postoperative cognitive function.

AIMS

This study aimed to identify the role of intranasal administration of dexmedetomidine in lowering the development of emergence agitation or emergence delirium in pediatric patients after general anesthesia.

METHODS

Electronic databases, including PubMed, EMBASE, CENTRAL, Scopus, and Web of Science, were searched to identify studies. The primary outcome was the proportion of patients who underwent emergence agitation or emergence delirium after the surgery. Secondary outcomes included emergence time and incidence of postoperative nausea and/or vomiting. We estimated the odds ratio and mean difference with 95% confidence intervals for the determination of effect size using a random-effects model.

RESULTS

In total, 2103 pediatric patients from 20 randomized controlled trials were included in the final analysis. The incidence of emergence agitation or emergence delirium was 13.6% in the dexmedetomidine group and 33.2% in the control group. The pooled effect size revealed that intranasal dexmedetomidine administration significantly reduced the incidence of postoperative emergence agitation or emergence delirium in pediatric patients undergoing surgery under general anesthesia (odds ratio 0.25, 95% confidence interval 0.18-0.34; p = .0000; I²  = 37.74%). Additionally, significant difference was observed in emergence time between the two groups (mean difference 2.42, 95% confidence interval 0.37-4.46; p = .021; I²  = 98.40%). Children in the dexmedetomidine group had a significantly lower incidence of postoperative nausea and/or vomiting than those in the control group (odds ratio 0.39, 95% confidence interval 0.24-0.64; p = .0002; I²  = 0.00%).

CONCLUSIONS

Intranasal dexmedetomidine reduced the incidence of emergence agitation or emergence delirium in pediatric patients after general anesthesia.

A comparison of efficacy of parenteral and perineural dexmedetomidine with 0.25% ropivacaine for post-thyroidectomy analgesia using bilateral superficial cervical plexus block

Background and Aims

Opioids are conventionally used for post-thyroidectomy pain, regional anesthesia is becoming popular due to its feasibility and efficacy in minimizing use of opioids and hence its side effects. This study compared analgesic efficacy of bilateral superficial cervical plexus block (BSCPB) using perineural and parenteral dexmedetomidine with 0.25% ropivacaine in thyroidectomy patients.

Material and Methods

In this double-blind study, 60 American Society of Anesthesiologists (ASA) physical status I and II thyroidectomy patients, aged 18-65 years were randomized into two groups. Group A (n = 30) received BSCPB with 0.25% ropivacaine, 10 mL on each side with dexmedetomidine 0.5 μg/kg IV infusion. Group B (n = 30) received 0.25% ropivacaine plus dexmedetomidine 0.5 μg/kg, ten mL on each side. Duration of analgesia by measuring pain visual analog scores (VAS), total dose of analgesic requirement, Haemodynamics parameters and adverse events were recorded for 24 h. Categorical variables were analyzed using Chi-square test and continuous variables were computed as mean with standard deviation and analyzed using independent sample t-test. Mann-Whitney U test was used for analysis of ordinal variables.

Results

Time to rescue analgesia was longer in Group B (18.6 ± 3.27 h) as compared to Group A (10.2 ± 2.11 h) (P < 0.001). Total analgesic dose required was also found to be lesser in Group B (50.83 ± 20.37 mg) as compared to Group A (73.33 ± 18.27 mg) (P < 0.001). No significant hemodynamic changes or side effects were observed in both groups; (P > 0.05).

Conclusion

Perineural dexmedetomidine with ropivacaine in BSCPB significantly prolonged the duration of analgesia with reduced rescue analgesic requirement.

Dexmedetomidine Ameliorated Cognitive Dysfunction Induced by Intestinal Ischemia Reperfusion in Mice with Possible Relation to the Anti-inflammatory Effect Through the Locus Coeruleus Norepinephrine System

Cognitive impairment is a common central nervous system complication that occurs following surgery or organs damage outside the nervous system. Neuroinflammation plays a key role in the molecular mechanisms of cognitive impairment. Dexmedetomidine alleviates neuroinflammation and reduces cognitive dysfunction incidence; however, the mechanism by which dexmedetomidine alleviates cognitive dysfunction remains unclear. This study evaluated the effect of dexmedetomidine on attenuation of early cognitive impairment induced by intestinal ischemia–reperfusion in mice and examined whether the locus coeruleus norepinephrine (LCNE) system participates in the anti-inflammatory effect of dexmedetomidine. The superior mesenteric artery was clamped for 45 min to induce intestinal ischemia reperfusion injury. Dexmedetomidine alone or combined with DSP-4, a selective locus coeruleus noradrenergic neurotoxin, was used for pretreatment. Postoperative cognition was assessed using the Morris water maze. Serum and hippocampal levels of IL-1β, TNF-α, norepinephrine (NE), and malondialdehyde (MDA) were assessed by enzyme-linked immunosorbent assay. Immunofluorescence, immunohistochemistry, and hematoxylin and eosin staining were used to evaluate the expression of tyrosine hydroxylase (TH) in the locus coeruleus, hippocampal microglia, and intestinal injury. Pretreatment with dexmedetomidine alleviated intestinal injury and decreased the serum and hippocampal levels of NE, IL-1β, TNF-α, and MDA at 24 h after intestinal ischemia reperfusion, decreased TH-positive neurons in the locus coeruleus, and ameliorated cognitive impairment. Similarly, DSP-4 pre-treatment alleviated neuroinflammation and improved cognitive function. Furthermore, α2-adrenergic receptor antagonist atipamezole or yohimbine administration diminished the neuroprotective effects and improved cognitive function with dexmedetomidine. Therefore, dexmedetomidine attenuated early cognitive dysfunction induced by intestinal ischemia–reperfusion injury in mice, which may be related to its anti-inflammatory effects through the LCNE system.

Postoperative Nausea and Vomiting in Female Patients Undergoing Breast and Gynecological Surgery: A Narrative Review of Risk Factors and Prophylaxis

Postoperative nausea and vomiting (PONV) have been widely studied as a multifactorial entity, being of female gender the strongest risk factor. Reported PONV incidence in female surgical populations is extremely variable among randomized clinical trials. In this narrative review, we intend to summarize the incidence, independent predictors, pharmacological and non-pharmacological interventions for PONV reported in recently published clinical trials carried out in female patients undergoing breast and gynecologic surgery, as well as the implications of the anesthetic agents on the incidence of PONV. A literature search of manuscripts describing PONV management in female surgical populations (breast surgery and gynecologic surgery) was carried out in PubMed, MEDLINE, and Embase databases. Postoperative nausea and vomiting incidence were highly variable in patients receiving placebo or no prophylaxis among RCTs whereas consistent results were observed in patients receiving 1 or 2 prophylactic interventions for PONV. Despite efforts made, a considerable number of female patients still experienced significant PONV. It is critical for the anesthesia provider to be aware that the coexistence of independent risk factors such as the level of sex hormones (pre- and postmenopausal), preoperative anxiety or depression, pharmacogenomic pleomorphisms, and ethnicity further enhances the probability of experiencing PONV in female patients. Future RCTs should closely assess the overall risk of PONV in female patients considering patient- and surgery-related factors, and the level of compliance with current guidelines for prevention and management of PONV.

The Optimal Dose of Intraoperative Dexmedetomidine for Antiemetic Effects of Post-operative Nausea and Vomiting in Patients Undergoing Elective Thoracic Surgery: A Retrospective Cohort Study

Background

Dexmedetomidine (DEX) administration decreases post-operative nausea and vomiting (PONV), but it is a lack of large-scale retrospective cohort study and is unclear whether there is a dose-relationship and optimal dose for antiemetic effects between DEX and PONV. We performed a large-scale retrospective cohort study to explore the optimal dose of intraoperative DEX for antiemetic effects of PONV.

Methods

A total of 5,310 patients aged ≥18 who underwent elective thoracic surgery from January 2016 to March 2020 under total intravenous anesthesia (TIVA) or combined intravenous and inhalation anesthesia in Henan Provincial People's Hospital. Patients were divided into two groups, those who received DEX intraoperatively and those who did not receive DEX. Patients who received DEX after surgery were excluded. Our primary outcomes were the association, the dose-response relationship, and the optimal dose for antiemetic effects between intraoperative DEX and PONV.

Results

Among the 3,878 patients enrolled, 2,553 patients received DEX and 1,325 patients did not receive DEX. The incidence of PONV in patients who received DEX was 21.3%, and the incidence of PONV in patients who did not receive DEX was 46.5% (P = 0.001). After the matched-pairs cohort consisted of 1,325 patients, the incidence of PONV in patients who received DEX was 23.6%, and the incidence of PONV in patients who did not receive DEX was 46.5% (P = 0.001). We analyzed three different models after propensity matching to validate the stability of the prediction model between intraoperative DEX and PONV. A dose-response relationship between intraoperative DEX and PONV was observed. The optimal dose range of intraoperative DEX for antiemetic effects of PONV is 50–100 μg in elective thoracic surgery.

Conclusions

Intraoperative DEX was associated with a decreased incidence of PONV in the large-scale retrospective cohort study. A dose-response relationship between intraoperative DEX and PONV was observed. The optimal dose range of intraoperative DEX for antiemetic effects of PONV is 50–100 μg in elective thoracic surgery.

The Effect of Dexmedetomidine on Postoperative Nausea and Vomiting in Patients Undergoing Thoracic Surgery-A Meta-Analysis of a Randomized Controlled Trial

Background

Dexmedetomidine reduces the occurrence of postoperative nausea and vomiting (PONV); however, the effect of dexmedetomidine on PONV in patients undergoing thoracic surgery remains inconclusive. In addition, the effect of different dexmedetomidine application methods, anesthetics, and surgical procedures on the effects of dexmedetomidine on PONV remains unclear. Therefore, the purpose of this meta-analysis was to study the effect of dexmedetomidine on PONV in patients undergoing thoracic surgery.

Methods

Electronic databases were searched to identify randomized controlled trials studying the effects of dexmedetomidine on nausea and vomiting after thoracic surgery. In total, 12 articles that met the inclusion criteria were obtained. The primary outcome of this comprehensive analysis was the incidence of PONV; secondary outcomes included the incidence of postoperative nausea, the incidence of postoperative vomiting, postoperative visual analog score (VAS), the amount of intraoperative sufentanil, and the number of times postoperative salvage analgesia was administered.

Results

Twelve trials involving 905 participants undergoing thoracic surgery were included. Compared with placebo, dexmedetomidine reduced the incidence of nausea and vomiting after thoracic surgery [12 trials; 905 participants; risk ratio (RR) = 0.32; 95% CI (0.23, 0.44); P < 0.00001, I2 = 0%]. The subgroup analysis revealed that dexmedetomidine reduces the occurrence of PONV in both thoracotomy and thoracoscopic surgery. In addition, both intravenous and local infusion of dexmedetomidine can reduce the occurrence of PONV, and intravenous or inhaled anesthetics do not affect the effect of dexmedetomidine on reducing PONV. Dexmedetomidine can reduce the postoperative resting VAS of patients, and no statistically significant differences in the amount of intraoperative sufentanil and the number of salvage analgesia procedures after surgery were noted.

Conclusion

Compared with placebo, dexmedetomidine can reduce the occurrence of PONV in patients undergoing thoracic surgery, and this effect is not affected by the method of dexmedetomidine administration, use of minimally invasive surgery, and use of a combination of intravenous or inhalation anesthetics.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/#myprospero, PROSPERO, identifier: CRD42021269358.

Effects of dexmedetomidine sedation for magnetic resonance imaging in children: a systematic review and meta-analysis

PURPOSE

Pediatric sedation is commonly required to obtain high-quality images in magnetic resonance imaging (MRI). We performed a systematic review and meta-analysis to assess the effects of dexmedetomidine sedation for MRI in children.

METHODS

A systematic review was conducted to find all randomized controlled trials concerning dexmedetomidine sedation for MRI in children. We searched databases using the Ovid platform in the Cochrane Controlled Trials Register, MEDLINE, and EMBASE. This study was registered in the PROSPERO database: CRD42020198368.

RESULTS

Seven studies and 753 participants were included. Dexmedetomidine sedation showed a significantly delayed onset time [weighted mean differences (WMD) = 8.13 min, 95% confidence interval (CI) 4.64 to 11.63, I² = 98%] and recovery time (WMD = 5.22 min, 95% CI 0.35 to 10.09, I² = 92%) compared to propofol, ketamine, and midazolam sedation. There was no difference in quality of sedation [risk ratio (RR) = 1.25, 95% CI 0.92 to 1.69, I² = 89%], or incidence of sedation failure (RR = 1.39, 95% CI 0.53 to 3.66, I² = 83%) between groups. Although a significantly decreased heart rate (WMD = - 17.34 beats/minute, 95% CI - 22.42 to - 12.26, I² = 96%) was observed, bradycardia that required treatment was not increased (RR = 8.00, 95% CI 1.02 to 62.64, I² = 0%). Dexmedetomidine sedation had a lower incidence of desaturation events (RR = 0.42, 95% CI 0.20 to 0.86, I² = 4%). However, there was no difference in incidence of postoperative vomiting (RR = 0.42, 95% CI 0.15 to 1.17, I² = 17%) between groups.

CONCLUSIONS

Dexmedetomidine sedation provided a similar sedation quality with a reduced incidence of desaturation events. However, the delayed onset and recovery times were drawbacks. The clinical significance of bradycardia is considered to be low. GRADE assessment revealed the quality of the evidence in this meta-analysis ranged from very low to moderate.

Clinical Effect of Different Drugs and Infusion Techniques for Patient-Controlled Analgesia After Spinal Tumor Surgery: A Prospective, Randomized, Controlled Clinical Trial

PURPOSE

To evaluate the outcomes of the different drug combination and infusion techniques for patient-controlled analgesia (PCA).

METHODS

Ninety-seven patients who had undergone spinal tumor surgery were randomized to 4 groups with different PCA drugs and infusion techniques: subcutaneous sufentanil (SS) group; (n=25), subcutaneous sufentanil and dexmedetomidine (SDS) group (n=24), intravenous sufentanil (SI) group (n=23), and intravenous sufentanil and dexmedetomidine (SDI) group (n=25). The primary outcome measured the cumulative amount of sufentanil delivered to the patients through PCA 24 and 48 hours after the surgery. Secondary outcomes measured the visual analog scale pain scores 24 and 48 hours after the surgery, Pittsburgh Sleep Quality Index before and 1 month after surgery, Athens Insomnia Score before and the first 2 nights after surgery, and the rate of adverse events within 48 hours after surgery.

FINDINGS

At 24 and 48 hours after surgery, the cumulative amount of sufentanil in the SDS group (mean [SD], 76.44 [10.75] at 24 hours and 151.96 [20.92] at 48 hours) and the SDI group (mean [SD], 75.08 [9.00] at 24 hours and 149.56 [18.22] at 48 hours) were significantly lower than in SS group (mean [SD] 95.52 [12.40] at 24 hours and 183.23 [23.06] at 48 hours) and the SI group (mean [SD], 97.25 [10.80] at 24 hours and 186.67 [20.14] at 48 hours; P < 0.001). The visual analog scale pain scores and Athens Insomnia Scale scores were also lower in the SDS and SDI groups than in the SS and SI groups 24 and 48 hours after surgery (P < 0.05). The Pittsburgh Sleep Quality Index was lower in the SDS and SDI groups 1 month after surgery. Lastly, the rate of nausea and vomiting was higher in the SI group than in the SS, SDS, and SDI groups (P = 0.018).

IMPLICATIONS

Dexmedetomidine in PCA could decrease sufentanil intake and improve analgesic effect and sleep quality. Subcutaneous PCA can provide the same benefit with a lower rate of nausea and vomiting. ClinicalTrials.gov identifier: NCT04111328. (Clin Ther. 2021;XX:XXX-XXX) © 2021 Elsevier HS Journals, Inc.

The effect of dexmedetomidine and remifentanil on the postoperative sore throat after thyroidectomy

BACKGROUND

Postoperative sore throat (POST) is an important concern in surgical patients undergoing endotracheal intubation. Its prevalence after thyroidectomy is up to 80%. The current study aimed to assess the effect of dexmedetomidine and remifentanil on postoperative sore throat.

METHODS

Seventy-four patients who underwent thyroidectomy were randomized to receive either dexmedetomidine (group D) or remifentanil (group R). At anesthesia induction, group D received dexmedetomidine 1 μg/kg over 10 minutes, followed by continuous dexmedetomidine infusion at 0.3 to 0.6 μg/kg/hour during surgery. Group R received remifentanil of 3 to 4 ng/ml during induction, followed by 1.5 to 2.5 ng/ml remifentanil infusion during surgery. POST at rest and swallowing was assessed during the first 24 hours in serial time periods (0-1, 1-6, and 6-24 hours). Hoarseness and postoperative pain score were also assessed.

RESULTS

POST incidence at rest (0-1, 1-6, and 6-24 hours) and swallowing (1-6 and 6-24 hours) was lower in group D than in group R. POST severity was significantly lower in group D than in group R during each time period. The incidence of postoperative hoarseness was also lower in group D than in group R at 1 to 6 and 6 to 24 hours. The postoperative pain score was lower in group D than in group R during each time period.

CONCLUSION

Intraoperative dexmedetomidine infusion reduced the incidence and severity of POST for 24 hours after thyroidectomy.

Dexmedetomidine Activation of Dopamine Neurons in the Ventral Tegmental Area Attenuates the Depth of Sedation in Mice

Background

Dexmedetomidine induces a sedative response that is associated with rapid arousal. To elucidate the underlying mechanisms, the authors hypothesized that dexmedetomidine increases the activity of dopaminergic neurons in the ventral tegmental area, and that this action contributes to the unique sedative properties of dexmedetomidine.

Methods

Only male mice were used. The activity of ventral tegmental area dopamine neurons was measured by a genetically encoded Ca2+ indicator and patch-clamp recording. Dopamine neurotransmitter dynamics in the medial prefrontal cortex and nucleus accumbens were measured by a genetically encoded dopamine sensor. Ventral tegmental area dopamine neurons were inhibited or activated by a chemogenetic approach, and the depth of sedation was estimated by electroencephalography.

Results

Ca2+ signals in dopamine neurons in the ventral tegmental area increased after intraperitoneal injection of dexmedetomidine (40 μg/kg; dexmedetomidine, 16.917 [14.882; 21.748], median [25%; 75%], vs. saline, –0.745 [–1.547; 0.359], normalized data, P = 0.001; n = 6 mice). Dopamine transmission increased in the medial prefrontal cortex after intraperitoneal injection of dexmedetomidine (40 μg/kg; dexmedetomidine, 10.812 [9.713; 15.104], median [25%; 75%], vs. saline, –0.498 [–0.664; –0.355], normalized data, P = 0.001; n = 6 mice) and in the nucleus accumbens (dexmedetomidine, 8.543 [7.135; 11.828], median [25%; 75%], vs. saline, –0.329 [–1.220; –0.047], normalized data, P = 0.001; n = 6 mice). Chemogenetic inhibition or activation of ventral tegmental area dopamine neurons increased or decreased slow waves, respectively, after intraperitoneal injection of dexmedetomidine (40 μg/kg; delta wave: two-way repeated measures ANOVA, F[2, 33] = 8.016, P = 0.002; n = 12 mice; theta wave: two-way repeated measures ANOVA, F[2, 33] = 22.800, P &lt; 0.0001; n = 12 mice).

Conclusions

Dexmedetomidine activates dopamine neurons in the ventral tegmental area and increases dopamine concentrations in the related forebrain projection areas. This mechanism may explain rapid arousability upon dexmedetomidine sedation.

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Effect of dexmedetomidine on prevention of postoperative nausea and vomiting in pediatric strabismus surgery: a randomized controlled study

BACKGROUND

Postoperative nausea and vomiting (PONV) are common side-effects following strabismus surgery. The present study aimed to compare the effects of different doses of dexmedetomidine (DEX) on PONV incidence in pediatric patients undergoing strabismus surgery.

METHODS

In this prospective randomized double-blinded study, 126 pediatric patients undergoing strabismus surgery were randomized into one of three groups: Placebo group, normal saline; DEX1 group, 0.3 μg/kg dexmedetomidine, and DEX2 group, 0.5 μg/kg dexmedetomidine. Oculocardiac reflex (OCR) events were recorded during surgery. PONV or postoperative vomiting (POV) was recorded for 24 h in the ward. Pediatric anesthesia emergence delirium (PAED) scale and emergence agitation (EA) scale were recorded in the recovery room.

RESULTS

Intraoperative OCR was significantly reduced in DEX2 group (42%) as compared to that of Placebo group (68%) (p = 0.0146). During the first 24 h post-op, the overall incidence of PONV was significantly lower in DEX2 group (10%) than that of Placebo group (32%) (p = 0.0142). There was no significant difference in POV among the three groups. PAED or EA scores among the three groups were similar during recovery time.

CONCLUSION

Dexmedetomidine (0.5 μg/kg) reduced OCR and PONV without lengthening extubation time or recovery time in pediatric patients undergoing strabismus surgery.

TRIAL REGISTRATION

The trial was prospectively registered before patient enrollment at Chinese Clinical Trial Registry (Clinical Trial Number: ChiCTR1800020176, Date: 12/19/2018).

The Effect of Dexmedetomidine Added to Preemptive Ropivacaine Infiltration on Postoperative Pain After Lumbar Fusion Surgery: A Randomized Controlled Trial

STUDY DESIGN

A prospective and controlled study of dexmedetomidine added to preemptive ropivacaine infiltration in lumbar fusion surgery.

OBJECTIVE

Assessment of dexmedetomidine added to preemptive ropivacaine infiltration for the relief of postoperative pain after lumbar fusion surgery.

SUMMARY OF BACKGROUND DATA

Single local anesthetic preemptive wound infiltration for the relief of postoperative pain does not translate into major or consistent clinical benefits after lumbar fusion surgery. Dexmedetomidine added to local anesthetics prolonged the duration of blockade and enhanced the analgesic in peripheral nerve block. The effect of dexmedetomidine added to preemptive ropivacaine infiltration in lumbar fusion surgery for the relief of postoperative pain has yet not been studied.

METHODS

Fifty-seven patients with elective posterior lumbar fusion were randomly divided into two groups. Five minutes before incision, the skin and subcutaneous tissues were injected with 20 mL 0.5% ropivacaine in group R (n = 28) and 20 mL 0.5% ropivacaine and 1 ug/kg of dexmedetomidine in group RD (n = 29) in two divided doses (i.e., 10 mL per side of the incision line). After the operation, all patients received intravenous morphine for analgesia. The total morphine consumption, the time of first analgesic demand, numbers of PCA analgesia, Visual Analog Scale, and postoperative adverse effects were collected.

RESULTS

In group RD, cumulative morphine dose and numbers of PCA analgesia in group RD were significantly reduced, the time of first analgesic demand was significantly delayed compared to the group R. Visual Analog Scale in group RD showed a marked reduction at 8 hours, 12 hours, 16 hours after operation and less patients in group RD experienced postoperative nausea or vomiting compared to the group R.

CONCLUSION

The addition of dexmedetomidine to preemptive ropivacaine wound infiltration provided a superior analgesic effect, reduced postoperative morphine consumption, and prolonged the time of the first analgesic demand with no serious side effects.

LEVEL OF EVIDENCE

2.

Antiemetic efficacy of dexmedetomidine versus dexmedetomidine-dexamethasone combination in patients undergoing breast surgery

Objective

To compare the antiemetic efficacy of dexmedetomidine alone versus combined dexmedetomidine–dexamethasone on incidence of postoperative nausea and vomiting (PONV) in patients undergoing breast surgery.

Methods

A total of 149 patients (aged 20–65 years) were assigned to receive normal saline (control group, n = 50), dexmedetomidine 0.5 μg/kg (DEX group, n = 49), or a combination of dexmedetomidine 0.5 μg/kg and dexamethasone 5 mg (dual group, n = 50) at 30 minutes prior to the end of surgery. The primary outcome measure was the incidence of PONV in the post-anesthesia care unit (PACU).

Results

During the first 24 hours after surgery, the incidence of PONV was significantly higher in the control group than in the DEX and dual groups (70% vs. 20% and 12%, respectively), with no intergroup difference observed between the DEX and dual groups. In the PACU, the incidence of PONV differed significantly among the control, DEX, and dual groups (12%, 4%, and 3%, respectively).

Conclusion

Dexmedetomidine alone and in combination with dexamethasone significantly reduced PONV with similar antiemetic efficacies in female patients during the first 24 hours after breast surgery.

Clinical trial registration: ClinicalTrials.gov (NCT 02550795).

Dexmedetomidine Ameliorates Sleep Deprivation-Induced Depressive Behaviors in Mice

PURPOSE

Sleep deprivation induces depressive symptoms. Dexmedetomidine is a α2-adrenoreceptor agonist and this drug possesses sedative, anxiolytic, analgesic, and anesthetic-sparing effect. In this study, the action of dexmedetomidine on sleep deprivation-induced depressive behaviors was investigated using mice.

METHODS

For the inducing of sleep deprivation, the mice were placed inside a water cage containing 15 platforms and filled with water up to 1 cm below the platform surface for 7 days. One day after sleep deprivation, dexmedetomidine at the respective dosage (0.5, 1, and 2 μg/kg) was intraperitoneally treated into the mice, one time per a day during 6 days. Then, forced swimming test and tail suspension test were conducted. Immunohistochemistry for tyrosine hydroxylase (TH), 5-hydroxytryptamine (5-HT; serotonin), tryptophan hydroxylase (TPH) and western blot for D1 dopamine receptor were also performed.

RESULTS

Sleep deprivation increased the immobility latency in the forced swimming test and tail suspension test. The expressions of TPH, 5-HT, and D1 dopamine receptor were decreased, whereas, TH expression was increased by sleep deprivation. Dexmedetomidine decreased the immobility latency and increased the expressions of TPH, 5-HT, and D1 dopamine receptor, whereas, HT expression was decreased by dexmedetomidine treatment.

CONCLUSION

In our results, dexmedetomidine alleviated sleep deprivation-induced depressive behaviors by increasing 5-HT synthesis and by decreasing dopamine production with up-regulation of D1 dopamine receptor.

Effects of dexmedetomidine versus midazolam for premedication in paediatric anaesthesia with sevoflurane: A meta-analysis

Background Dexmedetomidine (DEX), an α₂-adrenergic receptor agonist, produces ideal sedation and early postoperative recovery for premedication in paediatric surgery, reducing preoperative anxiety and facilitating smooth induction of anaesthesia. We performed a meta-analysis to compare the effects of DEX and midazolam (MDZ) in paediatric anaesthesia with sevoflurane. Methods PubMed, Ovid, Web of Science, and Public Health Management Corporation were searched through December 2016 for randomized controlled trials (RCTs) that compared DEX and MDZ in children undergoing sevoflurane anaesthesia. The risk ratio (RR) with 95% incidence interval (95%CI) was used for dichotomous variables. Results Twelve RCTs involving 422 patients in the DEX group and 448 patients in the MDZ group were included. Patients in the DEX group had a significantly lower incidence of unsatisfactory sedation (RR [95%CI] = 0.71 [0.57-0.89]), unsatisfactory parental separation (RR [95%CI] = 0.56 [0.35-0.87]), and rescue analgesia (RR [95%CI] = 0.52 [0.35-0.77]) than patients in the MDZ group. However, both groups had a similar incidence of unsatisfactory mask acceptance, emergence agitation, and postoperative nausea and vomiting. Conclusion Compared with MDZ, DEX is beneficial in paediatric anaesthesia with sevoflurane because of its lower incidence of unsatisfactory sedation, parental separation, and rescue analgesia.

Postoperative nausea and vomiting after thyroidectomy: a comparison between dexmedetomidine and remifentanil as part of balanced anesthesia

BACKGROUND

Postoperative nausea and vomiting (PONV) is the major complication related to general anesthesia, occurring in 60-80% of patients after thyroidectomy. The objective of this study was to compare the effects of an intraoperative dexmedetomidine infusion with remifentanil, as anesthetic adjuvants of balanced anesthesia, on PONV in patients undergoing thyroidectomy.

METHODS

Eighty patients scheduled for thyroidectomy were randomized into the following two groups: 1) The dexmedetomidine group (Group D), who received an initial loading dose of dexmedetomidine (1 µg/kg over 10 min) during the induction of anesthesia, followed by a continuous infusion at a rate of 0.3-0.5 µg/kg/h; 2) the remifentanil group (group R), who received remifentanil at an initial target effect site concentration of 4 ng/ml during the induction of anesthesia, followed by a target effect site concentration of 2-3 ng/ml. PONV was assessed during the first 24 hours in 2 time periods (0-2 h and 2-24 h). The pain intensity, sedation score, extubation time, and hemodynamics were also assessed.

RESULTS

During the 2 time periods, the incidence and severity of PONV in group D were significantly lower than in group R. In addition, the need for rescue antiemetics was significantly lower in group D than in group R. The effect of dexmedetomidine on postoperative pain relief (2-24 h) was superior to that of remifentanil. The hemodynamics were similar in both groups, whereas eye opening and extubation time were delayed in group D.

CONCLUSIONS

Adjuvant use of intraoperative dexmedetomidine infusion may be effective for the prevention of PONV.

The Effectiveness of Intravenous Dexmedetomidine on Perioperative Hemodynamics, Analgesic Requirement, and Side Effects Profile in Patients Undergoing Laparoscopic Surgery Under General Anesthesia

Background:

There is an upward surge in the use of laparoscopic surgeries due to various advantages when compared to open surgeries. Major advantages are, due to small incisions which are cosmetically acceptable and most of them are now daycare procedures. Problem of economic burden and hospital bed occupancy has been overcome with laparoscopic surgeries. All these advantages are not free from disadvantages, as hemodynamic changes such as hypertension; tachycardia and other surgical-related complications are commonly observed intraoperatively. Dexmedetomidine is one of the α₂ agonist drugs which acts at both supraspinal and spinal level and modulate the transmission of nociceptive signals in the central nervous system. The basic effect of dexmedetomidine on the cardiovascular system is to decrease the heart rate and systemic vascular resistance with additional feature of opioid sparing effect. This drug has become an ideal adjuvant during general anesthesia, especially when stress is expected. Hence, the drug was studied in laparoscopic surgeries.

Aims and Objectives:

(a) To study the effect of dexmedetomidine on hemodynamic parameters during perioperative period in patients undergoing laparoscopic surgery. (b) To study the postoperative sedation score and analgesic requirement. (c) To study the side effect profile of dexmedetomidine.

Settings and Design:

Randomized double blind controlled trial.

Subjects and Methods:

After obtaining the Institutional Ethical Clearance, the study was conducted. Forty patients of American Society of Anesthesiologists Class I and II were enrolled in this randomized study. The patients were randomly divided into two groups; group normal saline (NS) and group dexmedetomidine. Patient received either NS or dexmedetomidine in group NS and group dexmedetomidine, respectively, depending upon the allocation. The infusion rate was adjusted according to; loading dose (1 μg/kg) over 10 min and maintenance dose (0.5 μg/kg/h) and perioperative hemodynamics was recorded. Routine general anesthesia was administered in all the patients with conventional technique without deviating from institutional protocols. Postoperatively, Rasmsay sedation score, time taken for request of first analgesic dose, and side effects if any were recorded.

Statistical Analysis Used:

The categorical factors are represented by the number and frequency (%) of cases. The continuous variables are represented by measures of central frequency and standard deviation. The statistical analysis was done by using unpaired t-test and Chi-square. P < 0.05 was considered statistically significant.

Results:

Significant hemodynamic changes are observed in NS group during laryngoscopy, intubation, during pneumoperitoneum formation, and during extubation. Hemodynamic stress response in dexmedetomidine group was significantly attenuated. Analgesic requirement during postoperative 24 h were much less in dexmedetomidine group when compared to NS group. No significant side effects were noted except for bradycardia; which was observed in two cases of dexmedetomidine group.

Conclusion:

Dexmedetomidine infusion in the dose of 1 μg/kg body weight as bolus over 10 min and 0.5 μg/kg/h intraoperatively as maintenance dose controlled the hemodynamic stress response in patients undergoing laparoscopic surgery. Use of dexmedetomidine extends the pain free period postoperatively and thereby reducing total analgesic requirement. Thus, dexmedetomidine can be utilized as an ideal anesthetic adjuvant during laparoscopic surgeries.

Potential risk factors for dexmedetomidine withdrawal seizures in infants after surgery for congenital heart disease

PURPOSE

Few studies are available on withdrawal seizures about dexmedetomidine (DEX). Thus, we retrospectively evaluated the incidence of withdrawal seizures after discontinuation of DEX and examined potential risk factors in infants after cardiovascular surgery.

METHODS

The medical records of 142 infants who had undergone cardiovascular surgery between April 2010 and November 2013 were examined. Clinical characteristics and usage of DEX were analyzed. DEX withdrawal seizures were evaluated using Withdrawal Assessment Tool - version 1 (WAT-1). All the patients and controls were categorized according to DEX discontinuation strategy, which was either gradual or abrupt.

RESULTS

Nine patients (6.3%) developed generalized clonic or generalized tonic-clonic seizures accompanied by preceding fever of >38°C approximately four to eight hours following the discontinuation of DEX, and were clinically diagnosed as DEX withdrawal seizures with a median WAT-1 score of 3. Clinical characteristics and operative data were similar, but median cumulative dose and maximum temperature after discontinuation of DEX were significantly higher in infants with withdrawal seizures than in those without (P=0.007 and P<0.001, respectively). Eight of the 9 patients with withdrawal seizures (88.9%) and 20 of the 133 patients (15.0%) with no withdrawal seizures had discontinued DEX abruptly (P<0.001). Cumulative dose and abrupt discontinuation of DEX were significantly associated with DEX withdrawal seizures in infants after cardiovascular surgery (R=0.619, P=0.004).

CONCLUSIONS

Physicians should be aware that infants who received DEX after cardiovascular surgery had potential to cause withdrawal seizures accompanied by preceding pyrexia after discontinuation of DEX. Higher cumulative dose and abrupt discontinuation of DEX appears to increase the risk for these withdrawal seizures.

Comparison of dexmedetomidine and dexamethasone for prevention of postoperative nausea and vomiting after laparoscopic cholecystectomy

Background

Postoperative nausea and vomiting (PONV) are common following laparoscopic cholecystectomy (LC). Dexamethasone has been reported to reduce PONV. However, there is insufficient evidence regarding the effect of dexmedetomidine in decreasing PONV. This study was designed to compare the effects of a single dose of dexmedetomidine to dexamethasone for reducing PONV after LC.

Methods

Eighty-six adult patients scheduled for LC were randomized to receive either single dose 1 µg/kg of dexmedetomidine (Dexmed group, N = 43) or 8 mg dexamethasone (Dexa group, N = 43) before skin incision. During the first 24 h postoperatively, the incidence and severity of PONV were assessed. Pain and sedation scores were assessed on arrival in the recovery room and early postoperatively. Analgesic and antiemetic consumption during the 24 h after surgery were calculated. Intra-operative and postoperative hemodynamics were recorded.

Results

Twenty-one percent of the patients in the Dexmed group developed PONV compared to 28% in the Dexa group (P = 0.6). Severity of PONV was similar between the two groups (P = 0.07). Early postoperatively, pain severity was significantly lower in the Dexmed group, but sedation scores were significantly higher. The first analgesic request was significantly delayed in the Dexmed group (P = 0.02). The total amounts of intraoperative fentanyl and postoperative tramadol administered were significantly lower in the Dexmed group. No difference in ondansetron was noted between the two groups. Mean arterial pressure and heart rate were significantly lower in the Dexmed group after administration of dexmedetomidine. No major side effects were reported.

Conclusions

Dexmedetomidine reduces the incidence and severity of PONV, similar to dexamethasone. It is superior to dexamethasone in reducing postoperative pain and total analgesic consumption during the first 24 h after LC.

New therapeutic uses for an alpha2 adrenergic receptor agonist--dexmedetomidine in pain management

Dexmedetomidine was initially approved for clinical use as a sedative. Its development in pain management has been limited. Dexmedetomidine has analgesic effects and analgesic-sparing properties, especially for patients with obstructed airways. Mixing dexmedetomidine with local anesthetics is a promising new avenue to enhance local anesthetics' effectiveness. Peripheral, spinal and supraspinal α(2A)-ARs are responsible for the analgesic function of dexmedetomidine. Animal studies have shown that antinociceptive synergism results from co-application of dexmedetomidine and opioids or local anesthetics. Dexmedetomidine has potential adverse effects such as hypotension and bradycardia. Therefore, dexmedetomidine is contraindicated for patients suffering from bradycardia or using β-adrenergic antagonists. Clinical trials of dexmedetomidine in chronic pain or hyperalgesia are lack.

Epileptic seizures induced by dexmedetomidine in a neonate

BACKGROUND

Dexmedetomidine hydrochloride, a highly selective 2-adrenoceptoragonist, is used in combination with local anesthetics for sedation and analgesia. It is known to be efficacious in adult patients and is enthusiastically expected to be successful for sedation in neonates.

PATIENT

The present case report details a term infant who was sedated by dexmedetomidine during artificial ventilation. He underwent electroencephalograms that confirmed epileptic seizures and non-epileptic abnormal movements. Twelve hours after the discontinuation of dexmedetomidine, both symptoms gradually disappeared without the use of any antiepileptic medication. After then, he had achieved normal development, with no obvious neurological abnormalities.

CONCLUSION

Dexmedetomidine acts throughout the central nervous system and leads to a reduction in the anticonvulsant activity of the locus coeruleus. This case suggests potential adverse effects of dexmedetomidine in terms of inducing both epileptic seizures and non-epileptic movements in neonates.