The analgesic effect of intrathecal dexmedetomidine or clonidine, with bupivacaine, in trauma patients undergoing lower limb surgery: a randomised, double-blind study

Dexmedetomidine Versus Clonidine as Additives for Spinal Anesthesia: A Comparative Study

Background

Postoperative pain management is vital to improve patient care. Successful postoperative pain relief is currently achieved only through NSAIDs and narcotics.

Objectives

We compared dexmedetomidine and clonidine as additives to hyperbaric levobupivicaine 0.5% for the sub-arachnoid block (spinal anesthesia) concerning the onset time, duration of the block, hemodynamic changes, level of sedation intraoperatively and postoperatively and time taken for the first postoperative analgesic request and frequency.

Methods

This prospective, double-blind study enrolled 60 patients who underwent lower abdominal surgeries and were eligible for a sub-arachnoid block. They were allocated randomly to one of the two groups. Group D received intrathecal dexmedetomidine 5 µg and 0.5% hyperbaric levobupivicaine 15 mg. Group C received intrathecal clonidine 50 µg and 0.5% hyperbaric levobupivicaine 15 mg.

Results

Patients who received dexmedetomidine had a longer duration of the block (2-segment regression: 135 ± 15 min vs. 130 ± 20 min, S1 segment regression: 305 ± 50.4 min vs. 290 ± 47.2 min, Bromage 0: 285 ± 60 min vs. 280 ± 45 min), delayed first rescue analgesia request (700 ± 160 min vs. 506 ± 112 min), reduced frequency of rescue analgesics (1 vs. 2), and desired level of sedation (1.3 ± 0.46 vs. 0.4 ± 0.01) when compared to those receiving clonidine. There were insignificant differences between the groups in intraoperative hemodynamic parameters, such as minimal bradycardia and minimal hypotension. Though dexmedetomidine had an early onset, there was no statistically significant difference compared to clonidine.

Conclusions

Comparing dexmedetomidine and clonidine as additives in the sub-arachnoid block, the group who received dexmedetomidine had similar onset, prolonged duration of blockade, delayed first rescue analgesia demand, reduced frequency of analgesics, and desired sedation with similar minimal hemodynamic changes such as bradycardia and hypotension.

A Systematic Review and Meta-analysis of Efficacy and Safety of Dexmedetomidine Combined With Intrathecal Bupivacaine Compared to Placebo

BACKGROUND

 Dexmedetomidine has been approved as a sedative agent in critical patients. It is also frequently used as an adjuvant with local anesthetic in spinal anesthesia. However, its use as an adjuvant has not been approved due to the paucity of data. The present systematic review and meta-analysis were undertaken to synthesize evidence for efficacy and safety when dexmedetomidine is combined with bupivacaine in spinal anesthesia.

METHODS

A literature search was done using PubMed, Google Scholar, Embase, and Cochrane Library. Search results were screened and eligible studies were included to perform a systematic review and meta-analysis using the software 'Review Manager (RevMan) version 5.4.1' using a random effect model. Cochrane's' Risk of Bias tool (RoB2)' was used for quality assessment. Mean and standard deviation was used to calculate the standardized mean difference and its forest plot for efficacy measures. For the adverse event, a number of events were used to determine the risk ratio and its forest plot using RevMan software. Publication bias is visualized using a funnel plot.

RESULTS

 A total of 21 randomized control trials evaluating the efficacy and safety of intrathecal dexmedetomidine were included in the meta-analysis. A total of 1382 participants was included in this meta-analysis. The effect estimates for efficacy parameters, i.e. duration of the sensory block having SMD 2.33; CI, 1.83-2.83, motor block with SMD 1.83, CI 1.21, 2.46, and analgesia SMD 2.81; CI, 2.11-3.51. The risk ratio for adverse effects, i.e. nausea/vomiting, bradycardia, hypotension was not significant whereas it was significant for the incidence of shivering with RR 0.38; CI 0.23-0.97. The overall risk of bias among included studies was either of 'some concern' or 'high risk.'

CONCLUSIONS

 Intrathecal dexmedetomidine when combined with bupivacaine was found to significantly increase the three efficacy parameters, i.e. duration of sensory block, motor block, and analgesia. It also appears to be safe with no increased risk of bradycardia or hypotension. It is also associated with decreased postoperative shivering.

Comparative Study of the Adverse Events Associated With Adjuvant Use of Dexmedetomidine and Clonidine in Local Anesthesia

Background: Although clonidine and dexmedetomidine are used as alpha-2 agonists to improve the quality and duration of blockade induced by local anesthetics, no study has been reported to compare their associated adverse events in local anesthesia. The aim of this study is to compare the adverse events associated with the adjuvant use of dexmedetomidine and clonidine in local anesthesia.

Methods: A comprehensive search was performed to retrieve any reported adverse event associated with adjuvant use of dexmedetomidine and clonidine in local anesthesia from published literature up to 1 July 2020. Assessment of the quality of included studies was performed by the Jadad score. A comparison of any reported adverse event was made between interventions by pooling data from studies using a direct meta-analysis technique. Dichotomous outcomes were summarized as risk ratios. The review was performed according to PRISMA guideline.

Results: From 121 articles retrieved from the search finally 14 articles including 1,120 patients had eligibility criteria for including in the meta-analysis. No significant difference was observed between bradycardia/hypotension (OR = 1.17; 95 % CI = 0.66–2.10; P = 0.580; I² = 53.78 %, P = 0.027), nausea/vomiting (OR = 0.91; 95% CI = 0.59-1.42; P = 0.706; I² = 0.0 %, P = 0.940) dizziness/headache (OR = 1.10; 95% CI = 0.44–2.75; P = 0.831; I² = 0.0 %, P = 0.882) shivering (OR = 0.95 % CI = 0.50–1.66; P = 0.831; I² = 0.0 %, P = 0.920) and dry mouth (OR = 1.00; 95 % CI = 0.50–1.96; P = 0.996; I² = 0.0%, P = 0.900). No significant difference was observed in subgroup comparison of adverse events in the intravenous or local adjuvant use of the study drugs (p > 0.05).

Conclusion: There is no difference in adverse events associated with the intravenous or local adjuvant use of dexmedetomidine and clonidine in local anesthesia.

Comparative analgesic efficacy of intravenous vs intrathecal dexmedetomidine as an adjuvant to hyperbaric bupivacaine in subarachnoid block for below knee orthopaedic surgery

Background and Aim:

Intrathecal and intravenous dexmedetomidine has been used as adjuvant in subarachnoid block [SAB]. The aim of this study was to compare the analgesic efficacy of intravenous vs intrathecal dexmedetomidine as adjuvant to intrathecal bupivacaine.

Methods:

Ninety patients, aged 20–60 years belonging to American Society of Anaesthesiologists (ASA) physical status I and II, scheduled for below knee orthopaedic surgeries under SAB were enrolled. In group I (n = 45) patients received intravenous dexmedetomidine 0.5 μg/kg in 100 mL 0.9% normal saline [NS] intravenous over a period of 15 minutes given 20 minutes before SAB. Subarachnoid block was given with intrathecal (IT) 0.5% bupivacaine (H) 12.5 mg (2.5 mL) with 0.3 mL of NS. Patients in group II (n = 45) received 100 mL of 0.9% NS over a period of 15 minutes given 20 minutes before subarachnoid block. SAB was given with intrathecal 0.5% heavy bupivacaine 12.5 mg with 3 μg of dexmedetomidine (0.3 mL). The primary outcome was duration of analgesia and rescue analgesic requirement, whereas secondary outcome included pain scores.

Results:

The duration of analgesia was prolonged in group II (median [IQR]: 5 (6–7.5) h than in group I (median[IQR]: 4[2–4.5] h, P = 0.000). Median dose of rescue analgesics over period of 24 hours was less in group II as compared to group I (median [IQR]:150 (75–150) mg vs 195 (150–225) mg, P = 0.000). VAS score was lower in group II till 12 h in the postoperative period (P = 0.00).

Conclusion:

Intrathecal dexmedetomidine is more efficacious as compared to intravenous dexmedetomidine, due to favourable outcomes in terms of increased duration of postoperative analgesia and reduced rescue analgesic requirement.

Addition of dexmedetomidine, tramadol and neostigmine to lidocaine 1.5% increasing the duration of postoperative analgesia in the lower abdominal pain surgery among children: A double-blinded randomized clinical study

Pain is a common complication after surgery. Insufficient control of postoperative pain has adverse effects on the physiological, metabolic and psychological state of the child. The use of local analgesics and anesthetics alone cannot produce complete anesthesia and intraoperative comfort. The addition of adjuvant drugs is commonly used to improve the quality of the block. Therefore, adding new supplements may increase the duration of analgesia. The aim of this study was to compare the addition of dexmedetomidine, tramadol and neostigmine to lidocaine 1.5% in increasing the duration of postoperative analgesia in the lower abdominal pain surgery in children aged 2–8 years. This double-blind randomized clinical trial was conducted on children candidate for lower abdominal surgery. The 96 patients were randomly divided into 3 groups including dexmedetomidine, neostigmine, and tramadol. For all children, 3 mg of midazolam was administered orally before entering the operating room. The patients underwent general anesthesia with 2 μg/kg fentanyl, 0.03 mg/kg midazolam, 0.5 mg/kg atracurium and 5–6 mg/kg thiopental. After determining the hiatus membrane, 2 mL syringes containing air and distilled water (each of which 1 mL) slowly entered the space. After eliminating caudal resistance, 1.5% lidocaine was injected at dose of 0.5 mL/kg. A total of 96 patients were enrolled in this study. The results revealed that pain scores in the dexmedetomidine group in recovery, 2, 6 and 12 hours after surgery were less than the other two groups. Furthermore, the tramadol group showed a lower score in comparison with the neostigmine group and the duration of analgesia in the dexmedetomidine group was more than the other two groups. In addition, the mean of analgesic at 24 hours after operation in the dexmedetomidine group was lower as compared to the other two groups, indicating the effect of dexmedetomidine as an adjuvant in increasing the duration of analgesia and reducing postoperative pain in patients along with lidocaine 1.5%. All three drugs (neostigmine, tramadol and dexmedetomidine drugs), along with other local anesthetic, increased the duration of analgesia and decreased postoperative pain in children. The effect of dexmedetomidine was greater than the other two drugs. The study was approved by the Ethics Committee of Arak University of Medical Sciences, Iran (approved No. IR.ARAKMU.REC.1396.112) on October 28, 2017, and registered at Iranian Registry of Clinical Trials (registration No. IRCT20141209020258N83) on August 29, 2018.

Intrathecal dexmedetomidine and postoperative pain: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

A systematic review and meta-analysis of randomized controlled trials (RCTs) was undertaken to evaluate the effect of intrathecal dexmedetomidine (DEX) on the duration of postoperative analgesia, postoperative pain scores and incidences of adverse effects.

DATABASES AND DATA TREATMENT

Database search was performed from inception until January 2019. All RCTs analysing acute postoperative pain characteristics after intrathecal DEX administration in adults undergoing spinal anaesthesia for elective surgery were included. The primary outcome was postoperative analgesic duration, defined as the time to first analgesic request. The secondary outcomes included pain scores at 6, 12 and 24 postoperative hours and rates of hypotension, bradycardia, shivering and postoperative nausea and vomiting.

RESULTS

Twenty-four studies comprising a total of 1,460 patients were included. Postoperative analgesic duration was prolonged with intrathecal DEX compared to placebo, with a pooled mean difference (MD) of 191.3 min (95% CI 168.8-213.8). Patients who received intrathecal DEX reported lower Visual Analogue Scale scores at 24 postoperative hours compared with those patients receiving placebo, with a MD (95% CI) of -1.05 (-1.89 to -0.20, p = 0.02). There were no differences in the incidence of adverse effects, except for a lower rate of postoperative shivering in the intrathecal DEX group (pooled relative risk 0.58, 95% CI 0.34-0.98, p = 0.04).

CONCLUSIONS

Compared to placebo, intrathecal DEX prolonged postoperative analgesic duration, reduced 24-hr pain intensity and reduced the incidence of shivering without an increase in other adverse effects.

SIGNIFICANCE

The analgesic role of intrathecal DEX is promising due to its ability to significantly increase postoperative analgesic duration when compared with placebo. Its usage can be considered for patients undergoing surgeries with significant postoperative pain, particularly those intolerant of systemic analgesia. However, the optimal dose for various surgeries as well as its long-term neurological effects warrants further studies.

Effect of 5-μg Dose of Dexmedetomidine in Combination With Intrathecal Bupivacaine on Spinal Anesthesia: A Systematic Review and Meta-analysis

PURPOSE

Intrathecal dexmedetomidine (DEX) has been used to improve the quality and duration of spinal anesthesia. The aim of this meta-analysis is to evaluate whether intrathecal DEX could prolong the duration of sensory and motor block during spinal anesthesia.

METHODS

We searched PubMed, EMBASE, Web of Science, and the Cochrane Library for randomized controlled trials that investigated the facilitatory effects of intrathecal administration of DEX compared with those of a placebo on spinal anesthesia from inception to April 2019. Sensory and motor block durations, sensory and motor block onset times, time to first analgesic request, and DEX-related adverse effects were evaluated. Results were combined using fixed-effects or random effects modeling when appropriate.

FINDINGS

A total of 1478 patients from 25 clinical studies were included in the analysis. Compared with placebo, intrathecal DEX significantly prolonged the durations of both sensory block (weighted mean difference [WMD] = 134.42 min; 95% CI, 109.71-159.13 min; P < 0.001) and motor block (WMD = 114.27 min; 95% CI, 93.18-135.35 min; P < 0.001). It also hastened the onset of sensory block (WMD = -0.80 min; 95% CI, -1.21 to -0.40; P < 0.001) and motor block (WMD = -1.03 min; 95% CI, -1.51 to -0.56 min; P < 0.001). Furthermore, it delayed the time to first analgesic request (WMD = 216.90 min; 95% CI, 178.90-254.90 min; P < 0.001) and reduced the incidence of shivering (risk ratio [RR] = 0.39; 95% CI, 0.27-0.55; P < 0.001). DEX was associated with increased risk of transient bradycardia (RR = 1.59; 95% CI, 1.07-2.37; P = 0.022) and hypotension (RR = 1.40; 95% CI, 1.04-1.89; P = 0.026) but did not increase the incidence of postoperative nausea and vomiting (RR = 0.87; 95% CI, 0.62-1.24; P = 0.45).

IMPLICATIONS

Intrathecal DEX can prolong the duration of sensory block, the duration of motor block, and the time to first analgesic request associated with spinal anesthesia.

Efficacy of Dexmedetomidine as an Adjuvant to Local Anesthetic Agent in Scalp Block and Scalp Infiltration to Control Postcraniotomy Pain: A Double-Blind Randomized Trial

Context

Scalp infiltration and scalp block are being used to manage postcraniotomy pain. Dexmedetomidine has been successfully used as an adjuvant in regional anesthesia. The study was intended to compare whether addition of dexmedetomidine prolonged the duration of analgesia as well as to compare the two techniques.

Aims

The primary objective was to assess whether addition of dexmedetomidine to bupivacaine prolonged the duration of analgesia. The secondary objective was to compare between scalp nerve block and scalp infiltration as techniques for pain relief.

Settings and Design

The randomized control study was conducted in a tertiary care center from November 2013 to October 2014.

Materials and Methods

A total of 150 American Society of Anesthesiologists Physical Status I-II patients, aged 18-70 years undergoing elective craniotomy were included. Patients were randomized into three groups of 50 patients, i.e., Group BI (bupivacaine infiltration), Group BDI (bupivacaine and dexmedetomidine infiltration), and Group BDNB (bupivacaine and dexmedetomidine scalp nerve block). Patient's pain score, pain-free interval, rescue analgesic requirement, and hemodynamic and respiratory parameters were noted for 48 h. Patients were followed up at 1 and 3 months to assess postcraniotomy pain.

Results

Pain-free period was significantly longer in Group BDNB than Groups BDI and BI (P < 0.0001) and pain control was better in dexmedetomidine containing groups than in bupivacaine group (BI) (P < 0.0001). The rescue analgesic requirement was significantly lower in Group BDNB and Group BDI compared to Group BI.

Conclusion

The addition of dexmedetomidine (1 μg/kg) to bupivacaine prolonged the pain-free period. Scalp nerve block is a superior technique than scalp infiltration.

Comparison of Continuous Epidural Analgesia and Intravenous Patient-Controlled Analgesia with Opioids in Terms of Postoperative Pain and Their Complications in Mega-Prosthesis Total Knee Arthroplasty for Bone Cancers

Total knee arthroplasty with mega-prosthesis in oncologic patients is a painful surgery and may be associated with nerve injury. Epidural analgesia (EA) with local anaesthetics (LA) is routinely used for pain relief in these patients. At our institute, we came across a high incidence of motor weakness in these patients compelling to shift to patient-controlled analgesia (PCA) with intravenous opioids. We retrospectively analysed our data to find the incidence and reasons for motor weakness and also to compare the efficacy of EA and PCA as analgesics. Over a period of 15 months, 68 patients were operated; out of these, 41 were in EA and 27 in PCA. Demographic details, level of epidural placement, drug used, pain scores, degree of motor weakness, measures taken to relieve the motor weakness and the improvement in symptoms after treatment were recorded. In the IV PCA group, details of drug used, dose of bolus, pain and sedation scores were analysed. Groups were comparable demographically. Motor weaknesses were present in 9 (22%) and 0 patients in EA and IV PCA groups respectively (p = 0.009). Average and maximum pain scores were significantly higher on day 1 in the IV PCA group (p of 0.00 and 0.001 respectively). Maximum pain scores were also significantly higher in the IV PCA group on day 2 (p = 0.010). Two patients out of 27 in IV PCA were found drowsy. Motor weakness is known with EA but can be managed effectively using a lower concentration of LA or by stopping the infusion of LA.

Spinal α2 -adrenoceptors and neuropathic pain modulation; therapeutic target

Neuropathic pain can arise from disease or damage to the nervous system. The most common symptoms of neuropathic pain include spontaneous pain, allodynia, and hyperalgesia. There is still limited knowledge about the factors that initiate and maintain neuropathic pain. However, ample evidence has proved the antinociceptive role of spinal α-adrenoceptors following nerve injury. It is well-documented that noradrenergic descending pathways from supraspinal loci exert an inhibitory influence on the spinal cord nociceptive neurons, mostly through the activation of spinal α₂ -adrenoceptors. This, in turn, suppresses transmission of pain input and the hyperexcitability of spinal dorsal horn neurons. There is considerable evidence demonstrating that spinal application of α₂ -adrenoceptor agonists leads to analgesic effects in animal models of neuropathic pain. Today, despite the recent rapid development of neuroscience and drug discovery, effective drugs with clear basic mechanisms have remained a mystery. Here, we give an overview of the cellular mechanisms through which brainstem adrenergic descending inhibitory processing can alter spinal pain transmission to the higher centres, and how these pathways change in neuropathic pain conditions focusing on the role of spinal α₂ -adrenoceptors in the spinal dorsal horn. We then suggest that α₂ -adrenoceptor agonist may be useful to treat neuropathic pain. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.

CONSORT-epidural dexmedetomidine improves gastrointestinal motility after laparoscopic colonic resection compared with morphine

BACKGROUND

We have previously shown that epidural dexmedetomidine, when used as an adjunct to levobupivacaine for control of postoperative pain after open colonic resection, improves recovery of gastrointestinal motility compared with morphine.

METHODS

Sixty patients undergoing laparoscopic colonic resection were enrolled and allocated randomly to treatment with dexmedetomidine (group D) or morphine (group M). Group D received an epidural loading dose of dexmedetomidine (5 mL, 0.5 μg/kg), followed by continuous epidural administration of dexmedetomidine (80 μg) in 0.125% levobupivacaine (240 mL) at a rate of 5 mL/h for 2 days. Group M received an epidural loading dose of morphine (5 mL, 0.03 mg/kg) followed by continuous epidural administration of morphine (4.5 mg) in 0.125% levobupivacaine (240 mL) at a rate of 5 mL/h for 2 days. Verbal rating score (VRS) of pain, postoperative analgesic requirements, side effects related to analgesia, and time to postoperative first flatus (FFL) and first feces (FFE) were recorded.

RESULTS

VRS and postoperative analgesic requirements were not significantly different between the treatment groups. In contrast, FFL and FFE were significant delayed in group M compared with group D (P < .05). Patients in group M also had a significantly higher incidence of nausea, vomiting, and pruritus (P < .05). No neurological deficits were observed in either group.

CONCLUSIONS

Compared with morphine, epidural dexmedetomidine is a better adjunct to levobupivacaine for control of postoperative pain after laparoscopic colonic resection.

Alpha-2 adrenergic agonists for the prevention of cardiac complications among adults undergoing surgery

BACKGROUND

The surgical stress response plays an important role on the pathogenesis of perioperative cardiac complications. Alpha-2 adrenergic agonists attenuate this response and may help prevent postoperative cardiac complications.

OBJECTIVES

To determine the efficacy and safety of α-2 adrenergic agonists for reducing mortality and cardiac complications in adults undergoing cardiac surgery and non-cardiac surgery.

SEARCH METHODS

We searched CENTRAL (2017, Issue 4), MEDLINE (1950 to April Week 4, 2017), Embase (1980 to May 2017), the Science Citation Index, clinical trial registries, and reference lists of included articles.

SELECTION CRITERIA

We included randomized controlled trials that compared α-2 adrenergic agonists (i.e. clonidine, dexmedetomidine or mivazerol) against placebo or non-α-2 adrenergic agonists. Included trials had to evaluate the efficacy and safety of α-2 adrenergic agonists for preventing perioperative mortality or cardiac complications (or both), or measure one or more relevant outcomes (i.e. death, myocardial infarction, heart failure, acute stroke, supraventricular tachyarrhythmia and myocardial ischaemia).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality, extracted data and independently performed computer entry of abstracted data. We contacted study authors for additional information. Adverse event data were gathered from the trials. We evaluated included studies using the Cochrane 'Risk of bias' tool, and the quality of the evidence underlying pooled treatment effects using GRADE methodology. Given the clinical heterogeneity between cardiac and non-cardiac surgery, we analysed these subgroups separately. We expressed treatment effects as pooled risk ratios (RR) with 95% confidence intervals (CI).

MAIN RESULTS

We included 47 trials with 17,039 participants. Of these studies, 24 trials only included participants undergoing cardiac surgery, 23 only included participants undergoing non-cardiac surgery and eight only included participants undergoing vascular surgery. The α-2 adrenergic agonist studied was clonidine in 21 trials, dexmedetomidine in 24 trials and mivazerol in two trials.In non-cardiac surgery, there was high quality evidence that α-2 adrenergic agonists led to a similar risk of all-cause mortality compared with control groups (1.3% with α-2 adrenergic agonists versus 1.7% with control; RR 0.80, 95% CI 0.61 to 1.04; participants = 14,081; studies = 16). Additionally, the risk of cardiac mortality was similar between treatment groups (0.8% with α-2 adrenergic agonists versus 1.0% with control; RR 0.86, 95% CI 0.60 to 1.23; participants = 12,525; studies = 5, high quality evidence). The risk of myocardial infarction was probably similar between treatment groups (RR 0.94, 95% CI 0.69 to 1.27; participants = 13,907; studies = 12, moderate quality evidence). There was no associated effect on the risk of stroke (RR 0.93, 95% CI 0.55 to 1.56; participants = 11,542; studies = 7; high quality evidence). Conversely, α-2 adrenergic agonists probably increase the risks of clinically significant bradycardia (RR 1.59, 95% CI 1.18 to 2.13; participants = 14,035; studies = 16) and hypotension (RR 1.24, 95% CI 1.03 to 1.48; participants = 13,738; studies = 15), based on moderate quality evidence.There was insufficient evidence to determine the effect of α-2 adrenergic agonists on all-cause mortality in cardiac surgery (RR 0.52, 95% CI 0.26 to 1.04; participants = 1947; studies = 16) and myocardial infarction (RR 1.01, 95% CI 0.43 to 2.40; participants = 782; studies = 8), based on moderate quality evidence. There was one cardiac death in the clonidine arm of a study of 22 participants. Based on very limited data, α-2 adrenergic agonists may have reduced the risk of stroke (RR 0.37, 95% CI 0.15 to 0.93; participants = 1175; studies = 7; outcome events = 18; low quality evidence). Conversely, α-2 adrenergic agonists increased the risk of bradycardia from 6.4% to 12.0% (RR 1.88, 95% CI 1.35 to 2.62; participants = 1477; studies = 10; moderate quality evidence), but their effect on hypotension was uncertain (RR 1.19, 95% CI 0.87 to 1.64; participants = 1413; studies = 9; low quality evidence).These results were qualitatively unchanged in subgroup analyses and sensitivity analyses.

AUTHORS' CONCLUSIONS

Our review concludes that prophylactic α-2 adrenergic agonists generally do not prevent perioperative death or major cardiac complications. For non-cardiac surgery, there is moderate-to-high quality evidence that these agents do not prevent death, myocardial infarction or stroke. Conversely, there is moderate quality evidence that these agents have important adverse effects, namely increased risks of hypotension and bradycardia. For cardiac surgery, there is moderate quality evidence that α-2 adrenergic agonists have no effect on the risk of mortality or myocardial infarction, and that they increase the risk of bradycardia. The quality of evidence was inadequate to draw conclusions regarding the effects of alpha-2 agonists on stroke or hypotension during cardiac surgery.

Epidural Dexmedetomidine Reduces the Requirement of Propofol during Total Intravenous Anaesthesia and Improves Analgesia after Surgery in Patients undergoing Open Thoracic Surgery

The aim of this study was to assess the systemic and analgesic effects of epidural dexmedetomidine in thoracic epidural anaesthesia (TEA) combined with total intravenous anaesthesia during thoracic surgery. Seventy-one patients undergoing open thoracotomy were included in this study and randomly divided into three groups: Control group (Group C): patients received TEA with levobupivacaine alone and were intravenously infused with saline; Epidural group (Group E): patients received TEA with levobupivacaine and dexmedetomidine, and were intravenously infused with saline; Intravenous group (group V): patients received TEA with levobupivacaine alone and were intravenously infused with dexmedetomidine. The doses of propofol used in the induction and maintenance of general anaesthesia, cardiovascular response, dose and first time of postoperative analgesia and verbal rating scale were recorded. The induction and maintenance were significantly lower in the Groups E and V. Verbal rating scale and postoperative analgesic requirements were significantly lower in Group E than in Groups C and V. Patients in Group C had more severe cardiovascular responses, as compared with Groups E and V. Epidural administration of dexmedetomidine reduced the induction and maintenance of propofol, and inhibited the cardiovascular response after intubation and extubation. Moreover, epidural dexmedetomidine provided better analgesia after open thoracotomy.

Comparison of Intranasal Dexmedetomidine with Intranasal Clonidine as a Premedication in Surgery

OBJECTIVES

To compare effectiveness of intranasal dexmedetomidine and clonidine as anxiolytics and sedatives in pediatric patients undergoing various surgeries.

METHODS

This double blind randomized placebo controlled study was conducted on 105 surgical patients of American Society of Anesthesiologist (ASA) physical status І-ІІ, aged between 2 and 9 y in a tertiary-care hospital (February 2014 to September 2015). Participants were randomly allocated to three groups to receive either intranasal dexmedetomidine 2 μg/kg (Group І) or intranasal clonidine 3 μg/kg (Group ІІ) or intranasal saline 0.5 ml (Group ІІІ). The primary outcome measure was proportion of patients with satisfactory anxiolysis and sedation at 30 min after drug administration. Secondary outcome measures included time taken to achieve Aldrete score of 9 and number of doses of rescue analgesia required in 12 h after surgery.

RESULTS

Satisfactory anxiolysis was achieved by 88.5% in Group І vs. 60% in Group ІІ (p = 0.001) and satisfactory sedation by 57.1% in Group І vs. 25.7% in Group ІІ (p = 0.001) 30 min after premedication. Rescue analgesia requirement was significantly less in Group І as compared to Group ІІ (p = 0.001) while time taken to achieve Aldrete score was comparable between the study groups (p = 0.185).

CONCLUSIONS

Intranasal dexmedetomidine is a better anxiolytic and sedative as compared to clonidine. Postoperative analgesic requirement was also significantly decreased after intranasal dexmedetomidine. Thus, it can be preferred as compared to clonidine for premedication in pediatric surgical patients.

Epidural Co-Administration of Dexmedetomidine and Levobupivacaine Improves the Gastrointestinal Motility Function after Colonic Resection in Comparison to Co-Administration of Morphine and Levobupivacaine

Gastrointestinal motility may be impaired after intestinal surgery. Epidural morphine is effective in controlling postoperative pain, but can further reduce gastrointestinal motility. Here, we aimed to investigate the effects of epidural dexmedetomidine on gastrointestinal motility in patients undergoing colonic resection. Seventy-four patients undergoing colonic resection were enrolled in this clinical trial and allocated randomly to treatment with dexmedetomidine (D group) or morphine (M group). The D group received a loading dose epidural administration of 3 ml dexmedetomidine (0.5 μg kg(-1)) and then a continuous epidural administration of 80 μg dexmedetomidine in 150 ml levobupivacaine (0.125%) at 3 ml h(-1) for two days. The M group received a loading dose epidural administration of 3 ml morphine (0.03 mg kg(-1)) and then a continuous epidural administration of 4.5 mg morphine in 150 ml levobupivacaine at 3 ml h(-1) for two days. Verbal rating score (VRS), postoperative analgesic requirements, side effects related to analgesia, the time to postoperative first flatus (FFL) and first feces (FFE) were recorded. VRS and postoperative analgesic requirements were not significantly different between treatment groups. In contrast, the time to FFL and time to FFE were significant longer in M group in comparison to D group (P < 0.05). Moreover, patients in M group had a significantly higher incidence of nausea, vomiting, and pruritus (P < 0.05). No patients showed neurologic deficits in either group. In comparison to morphine, epidural dexmedetomidine is safe and beneficial for the recovery of gastrointestinal motility after colonic resection when used as an adjunct with levobupivacaine for postoperative pain control.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR-TRC-14004644.

Comparison of Dexmedetomidine and Clonidine as Adjuvants to Local Anesthetics for Intrathecal Anesthesia: A Meta-Analysis of Randomized Controlled Trials

The authors performed a meta-analysis to compare the characteristics of clonidine and dexmedetomidine as adjuvants to local anesthetic in intravertebral anesthesia. Four investigators independently searched electronic databases for randomized trials comparing the characteristics of clonidine vs dexmedetomidine as adjuvants to local anesthetic on adults. The endpoints were onset of analgesia, sensory and motor block, and duration of analgesia. A random-effects model was used to perform quantitative analysis. Seven studies comprising 354 subjects were included in this meta-analysis. The onset of sensory block was significantly 40 seconds shorter when dexmedetomidine was added as an adjuvant in the intrathecal injection. The duration of stable sensory block, duration of overall sensory block, and the time before the need for analgesic requirements were significantly extended, 10.8 minutes, 22.3 minutes, and 38.6 minutes, respectively, when dexmedetomidine was used as an adjuvant to local anesthetics (bupivacaine or ropivacaine). No significant differences were detected in the motor block characteristics and the time to achieve peak sensory level between dexmedetomidine and clonidine as adjuvants to local anesthetics. Compared to clonidine, the addition of dexmedetomidine as an adjuvant to local anesthetics is associated with earlier, prolonged sensory block characteristics and later need for analgesic requirements.

Dexmedetomidine pretreatment alleviates propofol injection pain

OBJECTIVE

The incidence of propofol injection pain during induction of general anesthesia varies from 28% to 90%. This prospective, randomized, double-blind, placebo-controlled study evaluated the effect of dexmedetomidine (DEX) for reducing the incidence and severity of propofol injection pain.

METHODS

Patients undergoing elective surgical procedures were randomly allocated into seven groups of 30 patients each. Experimental treatments were intravenously administered over 10 min (total volume 10 mL) prior to intravenous propofol injection, as follows: group I, the control group, was given isotonic saline. Patients in groups II, III, and IV received DEX 0.25 µg/kg, 0.5 µg/kg, or 1.0 µg/kg, respectively, mixed with isotonic saline immediately before propofol injection. Patients in groups V, VI, and VII received DEX as above, but 5 minutes before propofol injection. Propofol consisted of 1% long-chain triglyceride propofol (2.5 mg/kg) injected at 1 mL/s.

RESULTS

Median propofol injection pain score was 0.00 (IQR 0.00-3.00) in patients who received 1.0 µg/kg DEX 5 min before the propofol injection (group VII), and only 1 patient (of 30) in this group received a pain score >2. The median pain score and number of patients with pain scores >2 in group VII were both significantly less than in the control (group I; p = 0.000, both). There were no differences in either mean arterial pressure or heart rate at any time point after DEX injection among the groups.

CONCLUSIONS

Pretreatment with intravenous DEX 1 µg/kg 5 min prior to injection of long-chain triglyceride propofol is effective and safe in reducing the incidence and severity of pain due to propofol injection.

Preoperative dexmedetomidine attenuates hemodynamic responses to hydrodissection in patients undergoing robotic thyroidectomy

PURPOSE

Percutaneous tunneling (hydrodissection) in the neck and anterior chest in patients undergoing robotic thyroidectomy leads to significant hemodynamic responses such as increases in blood pressure and heart rate. We evaluated whether a single preoperative dexmedetomidine injection attenuated hemodynamic responses to hydrodissection by reducing the half-maximal effective concentration (EC50) of remifentanil needed to maintain hemodynamic stability during hydrodissection.

METHODS

Forty-one patients undergoing robot-assisted endoscopic thyroidectomy were randomly allocated to one of the two groups-group D (n = 22) and group C (n = 19) patients received dexmedetomidine 1 µg/kg and normal saline for 10 min before anesthetic induction, respectively. The EC50 of remifentanil for hemodynamic stability during hydrodissection was determined using Dixon's up-and-down method with initial dose (4 and 5 ng/mL in groups D and C, respectively). The concentration of remifentanil for consecutive patients in each group was determined by the response of the previous patient, using increments or decrements of 0.5 ng/mL. Hemodynamic stability during hydrodissection was defined as increased systolic blood pressure <20 % of baseline.

RESULTS

The EC50 of remifentanil for maintaining hemodynamic stability during hydrodissection was 0.8 ng/mL in group D and 7.3 ng/mL in group C (p = 0.002).

CONCLUSIONS

A single preoperative dexmedetomidine injection attenuated hydrodissection-induced hemodynamic responses in patients undergoing robotic thyroidectomy.

Low-dose epidural dexmedetomidine improves thoracic epidural anaesthesia for nephrectomy

Thoracic epidural anaesthesia alone is an applied technique of anaesthesia for nephrectomy which has both advantages and limitations. Dexmedetomidine is a highly selective alpha2-adrenoreceptor agonist which has both central and peripheral analgesic properties. Forty patients undergoing nephrectomy were enrolled in this clinical trial and allocated randomly to two groups, a control group (C group) and a dexmedetomidine group (D group). The C group received epidural 0.75% levobupivacaine 12 ml with 1 ml of isotonic sodium chloride solution, while the D group received epidural 0.75% levobupivacaine 12 ml with 1 ml (0.5 µg/kg) of dexmedetomidine. Haemodynamic changes, onset time and duration of sensory and motor block, muscle relaxation score, verbal rating score for pain, sedation score and the total postoperative analgesic consumption were evaluated. Sensory blockade duration was longer in the D group than in the C group (P=0.01). The incidence of motor block and the muscle relaxation score were significantly higher in the D group compared with the C group (P=0.01). Compared with the C group, pain scores were significantly lower in the first four postoperative hours in the D group (two hours rest P=0.038; two hours activity P=0.009; four hours rest P=0.044; four hours activity P=0.003). The total amount of flurbiprofen analgesic was significantly lower in the D group compared with the C group (P=0.03). Epidural dexmedetomidine 0.5 µg/kg appears to intensify thoracic epidural anaesthesia with levobupivacaine.

Does dexmedetomidine as a neuraxial adjuvant facilitate better anesthesia and analgesia? A systematic review and meta-analysis

Background

Neuraxial application of dexmedetomidine (DEX) as adjuvant analgesic has been invetigated in some randomized controlled trials (RCTs) but not been approved because of the inconsistency of efficacy and safety in these RCTs. We performed this meta-analysis to access the efficacy and safety of neuraxial DEX as local anaesthetic (LA) adjuvant.

Methods

We searched PubMed, PsycINFO, Scopus, EMBASE, and CENTRAL databases from inception to June 2013 for RCTs that investigated the analgesia efficacy and safety for neuraxial application DEX as LA adjuvant. Effects were summarized using standardized mean differences (SMDs), weighed mean differences (WMDs) or odds ratio (OR) with suitable effect model. The primary outcomes were postoperative pain intensity and analgesic duration, bradycardia and hypotension.

Results

Sixteen RCTs involving 1092 participants were included. Neuraxial DEX significantly decreased postoperative pain intensity (SMD, −1.29; 95% confidence interval (CI), −1.70 to −0.89; P<0.00001), prolonged analgesic duration (WMD, 6.93 hours; 95% CI, 5.23 to 8.62; P<0.00001) and increased the risk of bradycardia (OR, 2.68; 95% CI, 1.18 to 6.10; P = 0.02). No evidence showed that neuraxial DEX increased the risk of other adverse events, such as hypotension (OR, 1.54; 95% CI, 0.83 to 2.85; P = 0.17). Additionally, neuraxial DEX was associated with beneficial alterations in postoperative sedation scores and number of analgesic requirements, sensory and motor block characteristics, and intro-operative hemodynamics.

Conclusion

Neuraxial DEX is a favorable LA adjuvant with better and longer analgesia. The greatest concern is bradycardia. Further large sample trials with strict design and focusing on long-term outcomes are needed.

Inhibiting spinal neuron-astrocytic activation correlates with synergistic analgesia of dexmedetomidine and ropivacaine

Background

This study aims to identify that intrathecal (i.t.) injection of dexmedetomidine (Dex) and ropivacaine (Ropi) induces synergistic analgesia on chronic inflammatory pain and is accompanied with corresponding “neuron-astrocytic” alterations.

Methods

Male, adult Sprague-Dawley rats were randomly divided into sham, control and i.t. medication groups. The analgesia profiles of i.t. Dex, Ropi, and their combination detected by Hargreaves heat test were investigated on the subcutaneous (s.c.) injection of complete Freund adjuvant (CFA) induced chronic pain in rat and their synergistic analgesia was confirmed by using isobolographic analysis. During consecutive daily administration, pain behavior was daily recorded, and immunohistochemical staining was applied to investigate the number of Fos-immunoreactive (Fos-ir) neurons on hour 2 and day 1, 3 and 7, and the expression of glial fibrillary acidic protein (GFAP) within the spinal dorsal horn (SDH) on day 1, 3, 5 and 7 after s.c. injection of CFA, respectively, and then Western blot to examine spinal GFAP and β-actin levels on day 3 and 7.

Results

i.t. Dex or Ropi displayed a short-term analgesia in a dose-dependent manner, and consecutive daily administrations of their combination showed synergistic analgesia and remarkably down-regulated neuronal and astrocytic activations indicated by decreases in the number of Fos-ir neurons and the GFAP expression within the SDH, respectively.

Conclusion

i.t. co-delivery of Dex and Ropi shows synergistic analgesia on the chronic inflammatory pain, in which spinal “neuron-astrocytic activation” mechanism may play an important role.

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.

Effects of intravenous and intrathecal dexmedetomidine in spinal anesthesia: a meta-analysis

PURPOSE

To assess the effects of dexmedetomidine on the duration of sensory and motor block, postoperative analgesia, hypotension, bradycardia, and side effects in patients undergoing spinal anesthesia.

METHODS

Two researchers searched MEDLINE, EMBASE, and the Cochrane controlled trial register independently for randomized controlled trials comparing dexmedetomidine with a placebo without any language restrictions.

RESULTS

A total of 412 patients from eight trials were included in this study. The results revealed that dexmedetomidine was statistically significant in prolonging the duration of sensory block (mean difference, MD = 73.55; 95% CI, [55.69, 91.40] P < 0.00001, I(2)  = 89%) and motor block (MD = 59.11; 95% CI, [29.58, 88.65] P < 0.00001, I(2)  = 91%) and the time to first request for postoperative analgesia (MD = 245.77, 95% CI, [143.53, 348.00] P < 0.00001, I(2)  = 98%). The occurrence of hypotension (OR = 0.60, 95% CI, [0.3-1.23], P = 0.40, I(2)  = 3%) and side effects (OR = 0.9, 95% CI, [0.36-2.22], P = 0.88, I(2)  = 0%) was not significantly different between dexmedetomidine and placebo. However, dexmedetomidine was associated with more frequent bradycardia requiring atropine (OR = 7.55; 95% CI, [2.76-20.63], P = 0.63, I(2)  = 0%).

CONCLUSIONS

This meta-analysis has shown that dexmedetomidine prolonged the duration of spinal anesthesia and improved postoperative analgesia and did not increase the incidence of hypotension and adverse events, but needs more atropine to reverse bradycardia.