Effect of intraoperative Dexmedetomidine infusion on Sevoflurane requirement and blood glucose levels during entropy-guided general anesthesia

A Comparative Study of Fixed-Dose Dexmedetomidine and Propofol Infusions on Intraoperative Desflurane Consumption During Bispectral Index-Guided Laparoscopic Surgeries: A Randomized Controlled Study

Background Desflurane is an excellent but expensive volatile anesthetic agent. Dexmedetomidine and propofol may decrease intraoperative desflurane consumption. This study aimed to compare the desflurane-sparing effect of dexmedetomidine and propofol in patients undergoing laparoscopic surgeries under bispectral index (BIS)-guided general anesthesia (GA). Methods Sixty-two adult patients, ASA (American Society of Anesthesiologists) physical status I or II, of either sex, aged between 18 and 60 years, were randomly allocated into group D or group P. Only group D patients received an intravenous (IV) bolus of dexmedetomidine (1 mcg/kg) over 15 minutes before induction. In both groups, GA was induced following the standard protocol with propofol infusion (0.5 mg/kg/min) until the BIS value dropped below 60. For maintenance, group D and group P patients received IV dexmedetomidine infusion (0.5 mcg/kg/h) and propofol infusion (50 mcg/kg/min), respectively. In both groups, desflurane dial concentration was adjusted between 3 and 8% to maintain the BIS within the range of 45-55. An hourly bolus of IV fentanyl (0.5 mcg/kg) and a half-hourly bolus of IV vecuronium (0.02 mg/kg) were administered. The total amount of desflurane consumed, duration of pneumoperitoneum, extra aliquots of propofol used during maintenance, number of boluses of IV atropine, fentanyl, and esmolol, time to attain Ramsay Sedation Score of 2 after extubation, time to first postoperative analgesic request at Numerical Rating Scale (NRS) score ≥ 4, time to reach a Modified Aldrete Score of ≥9, and incidence of any side effects were recorded. All the data were analyzed and compared using appropriate statistical tests, and a p-value of <0.05 was considered significant. Results The final data analysis was performed on 60 patients. The mean desflurane consumption was clinically higher in group P patients than in group D, but the difference was statistically insignificant (p-value > 0.05). The mean induction dose of propofol was significantly less in group D than in group P (p-value < 0.05). After extubation, the difference in time to the first analgesic request (NRS ≥ 4) between the groups was statistically significant (p-value < 0.05). Group D patients had a residual intraoperative analgesic effect. Conclusion The effects of dexmedetomidine and propofol infusions on desflurane consumption in laparoscopic surgeries are comparable, with minimal effects on intraoperative hemodynamics and postoperative recovery profiles.

Add dexmedetomidine to levobupivacaine for transversus abdominis plane block in elderly patients undergoing inguinal hernia repair: Could it make a difference? A randomised trial

BACKGROUND

Transversus abdominis plane block is becoming more common as part of multimodal analgesia for post-abdominal operation pain relief. This study compared the analgesic effects of adding dexmedetomidine to levobupivacaine (transversus abdominis plane) block in elderly patients undergoing inguinal hernia surgery to adding fentanyl.

METHODS

Overall, 90 elderly patients with a simple inguinal hernia repair were randomly assigned to one of three groups. After spinal anaesthesia, an ultrasound-guided transversus abdominis plane block was performed. Transversus abdominis plane block was accomplished with 0.25% levobupivacaine + 0.9% normal saline in Group L (n = 30) (20mL). Transversus abdominis plane block was accomplished with 0.25% levobupivacaine + 1 µg/kg dexmedetomidine in Group D (n = 30) (20mL). Transversus abdominis plane block was obtained with 0.25% levobupivacaine + 1 µg/kg fentanyl in Group F (n = 30) (20mL). The primary outcome was the first analgesic request, and the secondary outcomes were the visual analog scale, postoperative analgesic requirements, sedation, hemodynamic stability, and related complications 24 hours postoperatively. 1gm paracetamol intravenously was provided as rescue analgesia.

RESULTS

The time to first analgesic request in the dexmedetomidine group was substantially more prolonged than in the fentanyl and control groups (516.5±27.8, 451.2±11.1, and 403.9±10.5min, respectively; p < 0.05). Postoperative analgesic requirements were significantly decreased in dexmedetomidine 1(1-2) than control 2(1-3) and fentanyl 1.5(1-2) respectively (P<0.01). VAS was significantly lower in Group D and Group F than in Group L postoperatively. No significant difference in side effects was noted between the groups.

CONCLUSION

The transversus abdominis plane block is the best multimodal analgesia choice for inguinal hernia repair in older patients. Combining dexmedetomidine with levobupivacaine in the transversus abdominis plane block can improve the quality of postoperative analgesia while avoiding significant side effects.

Suppression of perioperative stress response in elective abdominal surgery: A randomized comparison between dexmedetomidine and epidural block

Background and Aims

Stress response after surgery induces local and systemic inflammation which may be detrimental if it goes unchecked. Blockade of afferent neurons or inhibition of hypothalamic function may mitigate the stress response.

Material and Methods

A total of 50 consenting adult ASA I/II patients undergoing elective abdominal surgery were randomized to receive either dexmedetomidine (Group D) or epidural bupivacaine (Group E) in addition to balanced general anesthesia. Laparoscopic surgery, contraindications to epidural administration, history of psychiatric disorders, obesity (BMI >30 kg/m2), on beta blockers or continuous steroid therapy for >5 days over last 1 year, and known case of endocrine abnormalities or malignancy were excluded. Serum cortisol, blood glucose, and blood urea were estimated. Hemodynamic parameters, total dose of dexmedetomidine, bupivacaine, emergence characteristics, and analgesic consumption over 24 h postoperatively were recorded. Statistical comparisons were done using Student's t-test, repeated measure analysis of variance followed by Dunnett's test, generalized linear model and Chi-square/Fisher's exact test. A P value <0.05 was considered significant.

Results

Serum cortisol levels were significantly lower in group E than group D 24 h after surgery (P = 0.029). Intraoperative and postoperative glucose level was lower in group E compared with group D. Time to request of first rescue analgesic was longer in group E than group D (P = 0.040). There was no significant difference between the number of doses of paracetamol required in the postoperative period (P = 0.198).

Conclusion

Epidural bupivacaine was more effective than intravenous dexmedetomidine for suppression of neuroendocrine and metabolic response to surgery. Dexmedetomidine provided better hemodynamic stability at the time of noxious stimuli and postoperatively.

Electroencephalogram Mechanism of Dexmedetomidine Deepening Sevoflurane Anesthesia

Dexmedetomidine, as an α2-adrenoceptor agonist, plays anti-sympathetic, sedative and analgesic roles in perioperative period. Also, dexmedetomidine can reduce the minimal alveolar concentration (MAC) of sevoflurane and the risk of postoperative cognitive dysfunction (POCD) induced by sevoflurane anesthesia. But so far, the electroencephalogram (EEG) mechanism of dexmedetomidine deepening sevoflurane anesthesia is not clear. In this study, by analyzing the changes of the power spectrum and bicoherence spectrum of EEG before and after dexmedetomidine infusion, the EEG mechanism of dexmedetomidine deepening sevoflurane anesthesia was studied. We analyzed dexmedetomidine-induced changes in power spectrum and bicoherence spectrum in 23 patients under sevoflurane anesthesia. After anesthesia induction, the sevoflurane concentration was maintained at 0.8 MAC for 15 min, and then dexmedetomidine was administered at a loading dose of 0.8 μg/kg in 10 min, followed by a maintenance rate of 0.5 μg⋅kg^–1⋅h^–1. Frontal EEG data from 5 min before and 10 min after dexmedetomidine infusion were compared. After dexmedetomidine infusion, the mean α power peak decreased from 6.09 to 5.43 dB and shifted to a lower frequency, the mean θ bicoherence peak increased from 29.57 to 41.25% and shifted to a lower frequency, and the median α bicoherence peak increased from 41.49 to 46.36% and shifted to a lower frequency. These results demonstrate that dexmedetomidine deepens sevoflurane anesthesia, and enhances α and θ bicoherences while shifting peak values of these bands to lower frequencies through regulating thalamo-cortical reverberation networks probably.

The effect of dexmedetomidine on intraoperative blood glucose homeostasis: secondary analysis of a randomized controlled trial

Purpose

To investigate the effect of dexmedetomidine on intraoperative blood glucose hemostasis in elderly patients undergoing non-cardiac major surgery.

Methods

This was secondary analysis of a randomized controlled trial. Patients in dexmedetomidine group received a loading dose dexmedetomidine (0.6 μg/kg in 10 min before anaesthesia induction) followed by a continuous infusion (0.5 μg/kg/hr) till 1 h before the end of surgery. Patients in control group received volume-matched normal saline at the same time interval. Primary outcome was the incidence of intraoperative hyperglycemia (blood glucose higher than 10 mmol/L).

Results

303 patients in dexmedetomidine group and 306 patients in control group were analysed. The incidence of intraoperative hyperglycemia showed no statistical significance between dexmedetomidine group and control group (27.4% vs. 22.5%, RR = 1.22, 95%CI 0.92–1.60, P = 0.167). Median value of glycemic variation in dexmedetomidine group (2.5, IQR 1.4–3.7, mmol) was slightly lower than that in control group (2.6, IQR 1.5–4.0, mmol), P = 0.034. In multivariable logistic analysis, history of diabetes (OR 3.007, 95%CI 1.826–4.950, P < 0.001), higher baseline blood glucose (OR 1.353, 95%CI 1.174–1.560, P < 0.001) and prolonged surgery time (OR 1.197, 95%CI 1.083–1.324, P < 0.001) were independent risk factors of hyperglycaemia.

Conclusions

Dexmedetomidine presented no effect on intraoperative hyperglycemia in elderly patients undergoing major non-cardiac surgery.

Trial registration

Present study was registered at Chinese Clinical Trial Registry on December 1, 2015 (www.chictr.org.cn, registration number ChiCTR-IPR-15007654).

Effects of continuous endotracheal-laryngopharynx topical anesthesia on the general anesthetic requirements during surgery

The purpose of this study was to investigate the general anesthetic requirements in patients with continuous endotracheal-laryngopharynx topical anesthesia using medicine injecting endotracheal tube during surgery. A total of 78 patients with American Society of Anesthesiologists (ASA) physical status I-II were randomly divided into test group and control group. After anesthesia, patients were injected by 1.5 mL of 1% Tetracaine for topical anesthesia, and later injected similarly at hourly intervals during surgery while patients in control group were non-injected. There was no statistical significance in values of SBP, DBP, MAP, HR and plasma concentrations of E, NE and Cor at same time point between the two groups during operation (P>0.05). There was no statistical significance in value of BIS at T0-T5 between the two groups (P>0.05). However, value of BIS at T6 in test group was significantly higher than that in control group (69.7±2.1 vs. 58.6±2.3, P<0.01). Doses of sevoflurane, propofol sufentanil and cisatracurium used up in test group decreased by 12.3% (P<0.01); 12.7% (P<0.01); 14.5% (P<0.01) and 4.9% (P>0.05) than those in control group, respectively. Continuous endotracheal-laryngopharynx topical anesthesia using 1% Tetracaine via medicine-injecting endotracheal tube can significantly decrease general anesthetic requirements of surgery.

Intraoperative dexmedetomidine attenuates norepinephrine levels in patients undergoing transsphenoidal surgery: a randomized, placebo-controlled trial

Background

Dexmedetomidine has sympatholytic effects. We investigated whether dexmedetomidine could attenuate stress responses in patients undergoing endoscopic transnasal transseptal transsphenoidal surgery.

Methods

Forty-six patients were randomized to receive a continuous infusion of 0.9% saline (n = 23) or dexmedetomidine (n = 23). Immediately after general anesthesia induction, the dexmedetomidine group received a loading dose of 1 mcg/kg dexmedetomidine over 10 min, followed by a maintenance dose of 0.2–0.7 mcg/kg/h and the control group received 0.9% saline at the same volume until 30 min before the end of surgery. Serum levels of epinephrine, norepinephrine, and glucose were assessed before surgery (T1) and the end of drug infusion (T2). The primary outcome was the change in norepinephrine levels between the two time points.

Results

Changes (T2-T1 values) in perioperative serum norepinephrine levels were significantly greater in the dexmedetomidine group than in the control group (median difference, 56.9 pg/dL; 95% confidence interval, 20.7 to 83.8 pg/dL; P = 0.002). However, epinephrine level changes did not show significant intergroup differences (P = 0.208). Significantly fewer patients in the dexmedetomidine group than in the control group required rescue analgesics at the recovery area (4.3% vs. 30.4%, P = 0.047).

Conclusions

Intraoperative dexmedetomidine administration reduced norepinephrine release and rescue analgesic requirement. Dexmedetomidine might be used as an anesthetic adjuvant in patients undergoing transnasal transseptal transsphenoidal surgery.

Trial registration

Clinical Trial Registry of Korea, identifier: KCT0003366; registration date: 21/11/2018; presenting author: Ji Seon Jeong.

Effects of Dexmedetomidine on Blood Glucose and Serum Potassium Levels in Children Undergoing General Anesthesia: A Secondary Analysis of Safety Endpoints During a Randomized Controlled Trial

BACKGROUND

Dexmedetomidine is a highly selective α2-adrenergic agonist, which is increasingly used in pediatric anesthesia and intensive care. Potential adverse effects that have not been rigorously evaluated in children include its effects on blood glucose and serum potassium concentrations, which are relevant due to the associations of derangements of both parameters with undesired outcomes. We investigated the effects of 3 different doses of dexmedetomidine on these outcomes in a randomized controlled trial in children undergoing elective surgery.

METHODS

Sixty-four American Society of Anesthesiologists I-II children were randomized to receive either dexmedetomidine 0.25 µg/kg, dexmedetomidine 0.5 µg/kg, dexmedetomidine 0.75 µg/kg, or 0 µg/kg (control), as a bolus administered over 60 seconds after induction of anesthesia. Changes in plasma glucose and serum potassium concentrations were measured in venous blood sampled before and at 15 and 30 minutes after study drug administration. Data were plotted within and between groups and analyzed using a constrained longitudinal data approach.

RESULTS

Forty-nine children completed the study. Mean glucose levels at 15 and 30 minutes were elevated with estimated changes from baseline of 0.37 mmol/L (95% CI, 0.29-0.45 mmol/L) and 0.05 mmol/L (95% CI, 0.00-0.10 mmol/L), respectively. At 15 minutes, there was a linear dose-response relationship (1.07 mmol/L/μg/kg [95% CI, 0.57-1.58 mmol/L/μg/kg]), but there was no appreciable effect of dexmedetomidine at 30 minutes (0.15 mmol/L/μg/kg [95% CI, -0.40 to 0.70 mmol/L/μg/kg]). Potassium levels were depressed relative to baseline, with a mean difference at 15 minutes of -0.20 mEq/L (95% CI, -0.28 to -0.12 mEq/L) and at 30 minutes of -0.12 mEq/L (95% CI, -0.15 to -0.08 mEq/L), but there was no appreciable effect of dexmedetomidine at either time.

CONCLUSIONS

Small elevations in glucose and decreases in potassium were observed after induction of anesthesia in children. The elevation in glucose at 15 minutes depended on the dose of dexmedetomidine administered. These preliminary data warrant further investigation.

Effect of Intravenous Dexmedetomidine During General Anesthesia on Acute Postoperative Pain in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Dexmedetomidine has been shown to have an analgesic effect. However, no consensus was reached in previous studies.

METHODS

Electronic databases such as PubMed, Embase, and Cochrane Central were searched for relevant randomized controlled trials. The relative risk and weighted mean difference (WMD) were used to analyze the outcomes. Random-effects model was used for meta-analysis.

RESULTS

Compared with the normal saline group, patients using DEX showed a significantly decreased pain intensity within 6 hours [WMD=-0.93; 95% confidence interval (CI), -1.34 to -0.53) and at 24 hours after surgery (WMD=-0.47; 95% CI, -0.83 to -0.11). DEX usage significantly reduced the cumulative opioids consumption at 24 hours after surgery (WMD=-6.76; 95% CI, -10.16 to -3.35), decreased the rescue opioids consumption in postanesthesia care unit (WMD=-3.11; 95% CI, -5.20 to -1.03), reduced the risk of rescue analgesics (relative risk=0.49; 95% CI, 0.33-0.71), and the interval to first rescue analgesia was prolonged (WMD=34.93; 95% CI, 20.27-49.59).

CONCLUSIONS

Intravenous DEX effectively relieved the pain intensity, extended the pain-free period, and decreased the consumption of opioids during postoperative recovery of adults in general anesthesia.

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).

Comparison of dexmedetomidine vs. remifentanil combined with sevoflurane during radiofrequency ablation of hepatocellular carcinoma: a randomized controlled trial

BACKGROUND

Remifentanil is widely used for ultrasound-guided percutaneous radiofrequency ablation (RFA) of small hepatocellular carcinoma (HCC). We determined whether dexmedetomidine could be an alternative to remifentanil for RFA of HCC under general anesthesia with sevoflurane.

METHODS

We prospectively randomized patients scheduled to undergo RFA for HCC to a dexmedetomidine (DEX) group or remifentanil (REMI) group (47 patients each). In the DEX group, a bolus infusion (0.4 μg kg^- 1) was started 15 min before anesthesia induction and continued at 0.2 μg kg^- 1 h^- 1 until 10 min before the end of surgery. In the REMI group, 3 μg kg^- 1 h^- 1 of remifentanil was administered from 15 min before anesthesia induction to the end of the surgery. The primary endpoint was postoperative pain intensity. Secondary endpoints included analgesic requirement, postoperative liver function, patient comfort, and hemodynamic changes. Group allocation was concealed from patients and data analysts but not from anesthesiologists.

RESULTS

Postoperative pain intensity, analgesic consumption, comfort, liver function, and time to emergence and extubation did not differ between the two groups. Heart rate, but not mean arterial pressure, was significantly lower in the DEX group than in the REMI group, at 1 min after intubation and from 30 min after the start of the surgery until anesthesia recovery. Sevoflurane concentration and dosage were significantly lower in the DEX group than in the REMI group.

CONCLUSION

During RFA for HCC, low-dose dexmedetomidine reduced the heart rate and need for inhalational anesthetics, without exacerbating postoperative discomfort or liver dysfunction. Although it did not exhibit outstanding advantages over remifentanil in terms of pain management, dexmedetomidine could be a safe alternative adjuvant for RFA under sevoflurane anesthesia.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-OPC-15006613 . Registered on 16 June 2015.

Effects of dexmedetomidine as an adjunct in transversus abdominis plane block during gynecological laparoscopy

Ultrasound-guided transversus abdominis plane (TAP) block for abdominal surgery has been widely studied in clinical settings. However, dexmedetomidine as an adjunctive analgesic combined with TAP block has been rarely reported. The present study evaluated the efficacy of TAP block combined with dexmedetomidine adjunct for gynecological laparoscopy. In brief, 90 patients were randomly divided into three groups: Group I, which received post-operative intravenous analgesia only after general anesthesia; Group II, which received a TAP block with 20 ml 0.375% ropivacaine; and Group III, which received a TAP block with 20 ml of 0.375% ropivacaine and 1 µg/kg dexmedetomidine after induction. In all groups, propofol was used for general anesthesia. The dosage of propofol, duration of the operation, and the time of awakening, spontaneous breathing and extubation were recorded. In addition, the Steward and visual analogue scale (VAS) scores were determined at 2, 4, 8, 12 and 24 h post-surgery. The occurrence of nausea and vomiting and/or respiratory depression was also recorded. Compared with those in Group I, the dosage of propofol, as well as the time of awakening, spontaneous breathing and extubation were significantly decreased in Group III (P<0.01 and P<0.05, respectively). In addition, the VAS score at 2 and 4 h in Group II (both P<0.05) and 2, 4 (both P<0.01) and 8 h (P<0.05) in Group III after the surgery were significantly lower compared with those in Group I. Furthermore, in Groups II and III, a lower number of cases experienced nausea and vomiting (P<0.05). In conclusion, the ultrasound-guided TAP block combined with dexmedetomidine adjunct may improve recovery from anesthesia and reduce post-operative pain (trial registration no. ChiCTR-IPR-15007398).

Is It Time for an Expanded Role of Dexmedetomidine in Contemporary Anesthesia Practice? - A Clinician's Perspective

Since its approval by US Food and Drug Administration in 1999 the clinical use of dexmedetomidine has been gaining in popularity. The indications and clinical applications of this drug have been expanded significantly. In this paper we reviewed its pharmacokinetics, pharmacodynamics, mechanisms of action and mainly focused on its clinical uses and outcomes. Common clinical uses of dexmedetomidine include pre-operative anxiolysis, heart rate control during intubation, treatment of bronchospasm, prevention of laryngospasm and avoiding opioid-induced post-operative respiratory depression and nausea and vomiting. Avoiding opioid induced respiratory depression has been especially beneficial in patients with sleep apnea syndrome. Other problems that can be prevented with dexmedetomidine are tachydysrhythmias, myocardial ischemia, delirium and acute kidney injury. Dexmedetomidine is an excellent sedative drug for intubated patients and it greatly facilitates neurological evaluation. It has been used successfully as a patient-controlled anesthesia drug and to prevent shivering. It is also used as an adjuvant to local anesthetics. It has been suggested that dexmedetomidine is a drug that has many beneficial effects and should be used more frequently by anesthesia care providers to prevent common problems in the peri-operative period. With judicious titration to effect during the intravenous administration of this drug the occurrence of side effects can be minimized. It is very likely that this drug will ascend to take a much more prominent role in future anesthesia practice.

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.

Effect of Two Different Doses of Dexmedetomidine on Stress Response in Laparoscopic Pyeloplasty: A Randomized Prospective Controlled Study

Background

Clonidine, opioids, β-blockers, and dexmedetomidine have been tried to attenuate stress responses during laparoscopic surgery. We evaluated the efficacy of dexmedetomidine in two different doses in attenuating stress responses on patients undergoing laparoscopic pyeloplasty.

Subjects and Methods

Ninety patients were assigned to one of the three groups: Group A, Group B, and Group C. Group B received dexmedetomidine 1 mcg/kg as loading dose, followed by 0.7 mcg/kg/h for maintenance; Group C received dexmedetomidine 0.7 mcg/kg as a loading dose, followed by 0.5 mcg/kg/h for maintenance. Group A received normal saline. Stress responses were assessed by the variations in heart rate (HR), mean arterial pressure (MAP), blood glucose levels, and serum cortisol levels. One-way analysis of variance test was applied. Multiple comparisons between groups were done with post hoc Bonferroni test.

Results

The HR and MAP were found to be higher in Group A. The difference was statistically significant (P < 0.05) during intubation, carbon dioxide insufflation, and extubation when compared with Groups B and C. Blood glucose levels at postintubation and at extubation were higher in Group A and statistically significant (P < 0.05) when compared with Groups B and C. Serum cortisol levels at postintubation, during midsurgery, and 2 h after extubation were higher in Group A and statistically significant (P < 0.05) when compared with Groups B and C. However, HR, MAP, blood glucose levels, and serum cortisol levels were similar in dexmedetomidine groups.

Conclusions

Dexmedetomidine decreases stress response and provides good condition for maintenance of anesthesia. Dexmedetomidine when used in lower dose in Group C decreases stress response comparable to higher dose in Group B.

The Effects of Dexmedetomidine Administration on Postoperative Blood Glucose Levels in Diabetes Mellitus Patients Undergoing Spinal Anesthesia: A Pilot Study

Background

Dexmedetomidine (DEX) is an α2-adrenergic receptor agonist with sedative and sympatholytic effects. It inhibits the stress response and insulin secretion. Therefore, postoperative changes to blood glucose levels were investigated when DEX was intraoperatively infused for sedation purposes in diabetic patients under spinal anesthesia.

Methods

Twenty diabetic patients were randomly allocated to two groups (n = 10). Group A patients were infused with DEX at a dose of 0.4 - 0.8 μg/kg/hour and group B (control) patients were infused with the same volume of normal saline. The blood glucose levels were measured preoperatively and at 1, 3, 6, 12, and 24 hours postoperatively.

Results

There was no statistically significant difference between the blood glucose levels in groups A and B up to 24 hours postoperatively (P = 0.088). A statistically significant difference in the blood glucose level was not demonstrated 24 hours after surgery in comparison with the baseline level in Group A. The blood glucose level significantly decreased at three hours in group B in comparison with the level at baseline (P = 0.007) and increased at 24 hours (P = 0.037).

Conclusions

An intraoperative DEX infusion maintains blood glucose levels at a constant level relative to baseline in diabetic patients within 24 hours postoperatively. The frequency of hyperglycemia was low in group A in the perioperative period compared with that in the control group (group B).

Effect of Continuous Paravertebral Dexmedetomidine Administration on Intraoperative Anesthetic Drug Requirement and Post-Thoracotomy Pain Syndrome After Thoracotomy: A Randomized Controlled Trial

OBJECTIVES

To assess the effect of paravertebral administration of dexmedetomidine as an adjuvant to local anesthetic on the intraoperative anesthetic drug requirement and incidence of post-thoracotomy pain syndrome.

DESIGN

Prospective, randomized, controlled, double-blind trial.

SETTING

Single university hospital.

PARTICIPANTS

The study comprised 30 patients who underwent elective thoracotomy and were assigned randomly to either the Ropin or Dexem group (n = 15 each).

INTERVENTIONS

All patients received the study medications through paravertebral catheter. Patients in the Ropin group received a bolus of 15 mL of 0.75% ropivacaine over 3-to-5 minutes followed by an infusion of 0.2% ropivacaine at 0.1 mL/kg/hour. Patients in the Dexem group received 15 mL of 0.75% ropivacaine plus dexmedetomidine, 1 µg/kg bolus over 3-to-5 minutes followed by an infusion of 0.2% ropivacaine plus 0.2 µg/kg/hour of dexmedetomidine at 0.1 mL/kg/hour.

MEASUREMENTS AND MAIN RESULTS

The primary outcome of the study was intraoperative anesthetic drug requirement. The secondary outcome was the incidence of post-thoracotomy pain syndrome 2 months after surgery. The amount of propofol required for induction of anesthesia was significantly less in the Dexem group (Dexem 49.33±20.51 v 74.33±18.40 in the Ropin group, p = 0.002). End-tidal isoflurane needed to maintain target entropy was significantly less in the Dexem group at all time points. Intraoperative fentanyl requirement was lower in the Dexem group (Dexem 115.33±33.77 v 178.67±32.48 in the Ropin group, p = 0.002). Postoperative pain scores and morphine consumption were significantly less in the Dexem group (p<0.001). The incidence of post-thoracotomy pain syndrome was comparable between the 2 groups (69.23% v 50%, p = 0.496).

CONCLUSIONS

Paravertebral dexmedetomidine administration resulted in decreased intraoperative anesthetic drug requirement, less pain, and lower requirements of supplemental opioid in the postoperative period. However, it had no effect on the incidence of post-thoracotomy pain syndrome.

Perioperative dexmedetomidine for acute pain after abdominal surgery in adults

BACKGROUND

Acute postoperative pain is still an issue in patients undergoing abdominal surgery. Postoperative pain and side effects of analgesic treatment, in particular those of opioids, need to be minimized. Opioid-sparing analgesics, possibly including dexmedetomidine, seem a promising avenue by which to improve postoperative outcomes.

OBJECTIVES

Our primary aim was to determine the analgesic efficacy and opioid-sparing effect of perioperative dexmedetomidine for acute pain after abdominal surgery in adults.Secondary aims were to establish effects of dexmedetomidine on postoperative nausea and vomiting (PONV), gastrointestinal function and mobilization, together with the side effect profile of dexmedetomidine.

SEARCH METHODS

We searched the following databases: Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Institute for Scientific Information (ISI), Web of Science and Cumulative Index to Nursing and Allied Health Literature (CINAHL), and reference lists of articles to May 2014. We searched the Science Citation Index, ClinicalTrials.gov and Current Controlled Trials, and we contacted pharmaceutical companies to identify unpublished and ongoing studies. We applied no language restrictions. We reran the search in May 2015 and found nine studies of interest. We will deal with the studies of interest when we update the review.

SELECTION CRITERIA

We included randomized, controlled trials of perioperative dexmedetomidine versus placebo or other drug during abdominal surgery in adults. Trials included one of the following outcomes: amount of 'rescue' opioid, postoperative pain, time to 'rescue' analgesia, participants requiring 'rescue' analgesia, postoperative sedation, PONV, time to first passage of flatus and stool or time to first out-of-bed mobilization.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts for eligibility. We retrieved full trial reports if necessary, and we extracted relevant data from the included studies using a data collection form and assessed risk of bias. We resolved disagreements by discussion with the third review author. We sought additional information of relevance for risk of bias assessment or extraction of data by contacting study authors or, if necessary, co-authors from present or former studies.

MAIN RESULTS

Our systematic review included seven studies with a total of 492 participants. We included 422 participants in our analysis. Thirteen studies are awaiting classification. For the comparison dexmedetomidine versus placebo (six studies, 402 participants), most studies found a reduction in 'rescue' opioid consumption in the first 24 hours after surgery, together with in general no clinically important differences in postoperative pain (visual analogue scale (VAS) 0 to 100 mm, where 0 = no pain and 100 = worst imaginable pain) in the first 24 hours after surgery - except for one study (80 participants) with a reduction in VAS pain at two hours after surgery in favour of dexmedetomidine, with a mean difference of -30.00 mm (95% confidence interval (CI) -38.25 to -21.75). As the result of substantial heterogeneity, pooling of data in statistical meta-analyses was not appropriate. The quality of evidence was very low for our primary outcomes because of imprecision of results and risk of bias. Regarding our secondary aims, evidence was too scant in general to allow robust conclusions, or the estimates too imprecise or of poor methodological quality. Regarding adverse effects, low quality data (one study, 80 participants) suggest that the proportion of participants with hypotension requiring intervention was slightly higher in the high-dose dexmedetomidine group with a risk ratio of 2.50 (95% CI 0.94 to 6.66), but lower doses of dexmedetomidine led to no differences compared with control. Evidence for the comparison dexmedetomidine versus fentanyl was insufficient to permit robust conclusions (one study, 20 participants).

AUTHORS' CONCLUSIONS

Dexmedetomidine, when administered perioperatively for acute pain after abdominal surgery in adults, seemed to have some opioid-sparing effect together with in general no important differences in postoperative pain when compared with placebo. However the quality of the evidence was very low as the result of imprecision, methodological limitations and substantial heterogeneity among the seven included studies. The clinical importance for patients is uncertain, in as much as the influence of dexmedetomidine on patient-important outcomes such as gastrointestinal function, mobilization and adverse effects could not be satisfactorily determined. All included studies were relatively small, and publication bias could not be ruled out. Applicability of evidence was limited to middle-aged participants who were relatively free of co-morbidity and were undergoing elective abdominal surgery. A potential bias was a considerable quantity of unobtainable data from studies with mixed surgery. To detect and investigate patient-important outcomes, larger studies with longer periods of follow-up are needed.

Intravenous Dexmedetomidine Promotes Spinal Bupivacaine Anesthesia and Postoperative Analgesia in Lower Limb Surgery: A Double-Blind, Randomized Clinical CONSORT Study

Dexmedetomidine (DEX) has been reported to have synergistic action with local anesthetics. This prospective, randomized, double-blind clinical study was designed to observe the efficacy of intravenous DEX without loading dose on spinal blockade duration, postoperative sedation, patient-controlled analgesia and its morphine-sparing effect in lower limb surgeries.Seventy-five patients, scheduled for lower limb surgery under spinal anesthesia, were randomly allocated into 2 groups: group BS (received 15 mg of 0.5% of bupivacaine for subarachnoid anesthesia and continuous intravenous infusion of saline in Ringer solution) and BD group (received 15 mg of 0.5% of bupivacaine for subarachnoid anesthesia and continuous intravenous infusion of DEX in Ringer solution at a rate of 0.25 μg/kg/h). Intravenous infusion started 15 minutes before spinal anesthesia.The onset time of sensory and motor blockade was shorten, the duration of sensory and motor blockade was significantly prolonged in BD patients when compared to BS patients. The Ramsay sedation score measured immediately after surgery was greater in BD group than BS group. BD patients also shown increased time to the first request of postoperative morphine and decreased total morphine consumption as compared with BS patients.Collectively, intravenous administration of DEX without loading dose promoted the efficacy of spinal bupivacaine anesthesia and postoperative analgesia in patients undergoing lower limb surgery.

Intranasal Dexmedetomidine on Stress Hormones, Inflammatory Markers, and Postoperative Analgesia after Functional Endoscopic Sinus Surgery

Background. A strong ongoing intraoperative stress response can cause serious adverse reactions and affect the postoperative outcome. This study evaluated the effect of intranasally administered dexmedetomidine (DEX) in combination with local anesthesia (LA) on the relief of stress and the inflammatory response during functional endoscopic sinus surgery (FESS). Methods. Sixty patients undergoing FESS were randomly allocated to receive either intranasal DEX (DEX group) or intranasal saline (Placebo group) 1 h before surgery. Stress hormones, inflammatory markers, postoperative pain relief, hemodynamic variables, blood loss, surgical field quality, body movements, and satisfaction were assessed. Results. Plasma epinephrine, norepinephrine, and blood glucose levels were significantly lower in DEX group as were the plasma IL-6 and TNF-α levels (P < 0.05). The weighted areas under the curve (AUCw) of the VAS scores were also significantly lower in DEX group at 2–12 h after surgery (P < 0.001). Furthermore, hemodynamic variables, blood loss, body movements, discomfort with hemostatic stuffing, surgical field quality, and satisfaction scores of patients and surgeons were significantly better (P < 0.05) in DEX group. Conclusions. Patients receiving intranasal DEX with LA for FESS exhibited less perioperative stress and inflammatory response as well as better postoperative comfort with hemostatic stuffing and analgesia.