Dexmedetomidine: a review of clinical applications

Surgical conditions during FESS; comparison of dexmedetomidine and remifentanil

To compare dexmedetomidine with remifentanil in functional endoscopic sinus surgery (FESS) in regards to intra-operative bleeding, anesthetic consumption and post-operative recovery. Randomized, double blind study. Tertiary care medical center. Fifty patients with nasal polyposis who had been scheduled for FESS were randomly divided into two groups. In group D (n = 25), dexmedetomidine 1 µg/kg infused intravenous (IV) over 10 min before anesthesia induction, followed by a continuous of 0.7 µg/kg/h infusion during operation. In group R (n = 25), 1 µg/kg remifentanil IV bolus, was administered with induction of anesthesia and continued 0.25-0.50 µg/kg/min during operation. Heart rates, mean arterial pressure, end tidal CO₂, end tidal sevoflurane were recorded. The amount of bleeding, surgical field condition for bleeding and the time to reach Aldrete recovery score 9-10 were recorded. Postoperative nausea, vomiting, pain, shivering, sedation were followed up over 24 h. There was no significant difference between groups according to the amount of bleeding during surgery, assessment of surgical field condition, consumption of sevoflurane, scores of postoperative VAS, rates of nausea and vomiting, shivering, demands of additional analgesic medication (P > 0.05). The time to reach Aldrete recovery score 9-10, sedation scores at the postoperative first hour were significantly higher in group D (P = 0.001). We concluded that in comparison to remifentanil, dexmedetomidine during FESS for controlled hypotension is of limited value as it has no additional benefits in terms of control of hypotension and amount of bleeding in the surgical field and it is associated with higher recovery time and first-hour postoperative sedation scores.

The efficacy and safety of epidural dexmedetomidine and clonidine with bupivacaine in patients undergoing lower limb orthopedic surgeries

BACKGROUND AND AIMS

Alpha (α-2) adrenergic agonists have both analgesic and sedative properties when used as an adjuvant in regional anesthesia. A prospective randomized double-blind study was carried out to evaluate the efficacy of epidural route and to compare the efficacy and clinical profile of dexmedetomidine and clonidine as an adjuvant to bupivacaine with special emphasis on their quality of analgesia, sedation and the ability to provide the smooth intra-operative and postoperative course.

MATERIAL AND METHODS

The study was conducted in prospective, randomized and double-blind manner. It included 60 American Society of Anesthesiologists Class I and II patients undergoing lower limb surgery under epidural anesthesia. Patients were randomly divided into Group A receiving 0.5% isobaric bupivacaine 15 ml with dexmedetomidine 1 μg/kg and Group B receiving 0.5% isobaric bupivacaine 15 ml with clonidine 2 μg/kg epidurally. Onset and duration of sensory and motor blocks, duration of analgesia, sedation, and adverse effects were assessed.

RESULTS

Demographic data, surgical characteristics cardio-respiratory parameters, side-effect profile were comparable and statistically not significant in both the groups. However, sedation scores with dexmedetomidine were better than clonidine and turned out to be statistically significant. The onset times for sensory and motor blocks were significantly shorter in Group A as compared to Group B. The duration of analgesia and motor block was significantly longer in A Group as compared to Group B.

CONCLUSION

Dexmedetomidine is a superior neuraxial adjuvant to bupivacaine when compared to clonidine for early onset of analgesia, superior intra-operative analgesia, stable cardio-respiratory parameters, prolonged postoperative analgesia and providing patient comfort.

Management of Acute Exacerbation of Asthma and Chronic Obstructive Pulmonary Disease in the Emergency Department

Acute asthma and chronic obstructive pulmonary disease (COPD) exacerbations are the most common respiratory diseases requiring emergent medical evaluation and treatment. Asthma and COPD are chronic, debilitating disease processes that have been differentiated traditionally by the presence or absence of reversible airflow obstruction. Asthma and COPD exacerbations impose an enormous economic burden on the US health care budget. In daily clinical practice, it is difficult to differentiate these 2 obstructive processes based on their symptoms, and on their nearly identical acute treatment strategies; major differences are important when discussing anatomic sites involved, long-term prognosis, and the nature of inflammatory markers.

Feasibility of deep sedation with a combination of propofol and dexmedetomidine hydrochloride for esophageal endoscopic submucosal dissection

BACKGROUND AND AIM

The aim of the present study was to evaluate the efficacy and safety of sedation with a combination of propofol (PF) and dexmedetomidine (DEX) compared with sedation with benzodiazepines in esophageal endoscopic submucosal dissection (ESD).

METHODS

We retrospectively reviewed clinical data for 40 consecutive patients who had undergone esophageal ESD at the Yokohama City University Hospital between July 2012 and August 2014. Of these patients, 20 were sedated with benzodiazepines (conventional group) and another 20 patients were sedated with a combination of PF and DEX (combination group). Parameters for efficacy and safety of sedation were evaluated by comparisons between the two groups.

RESULTS

Median procedural times in the combination group were shorter than those in the conventional group (61 min vs. 89 min, P = 0.03), and the percentage of patients who showed restlessness in the combination group was significantly lower than that in the conventional group (25% vs. 65%, P = 0.025). Incidences of hypotension and bradycardia in the combination group were higher than those in the conventional group (60% vs. 15%, P = 0.008, and 60% vs. 15%, P = 0.008, respectively).

CONCLUSION

This retrospective study suggests that a combination of PF and DEX may provide stable deep sedation with less body movement than benzodiazepines during esophageal ESD.

[Protective effect of dexmedetomidine against glutamate-induced cytotoxicity in PC12 cells and its mechanism]

OBJECTIVE

To investigate the protective effects of dexmedetomidine (Dex) against glutamate-induced cytotoxicity in PC12 cells and its mechanism.

METHODS

PC12 cells were treated with varying concentrations of dexmedetomidine 1 h before exposure to a high concentration of glutamate. The cell viability was measured by MTT assay, and LDH release, MDA content and SOD activity were measured. The level of ROS was tested by DCFH-DA staining and flow cytometry. The level of intracellular Ca²⁺ was detected by Fluo-8 staining and flow cytometry, and the mitochondrial membrane potential (MMP) was determined with JC-1 staining and flow cytometry.

RESULTS

Within the concentration range of 0.01 to 100 µmol/L, Dex dose-dependently protected PC12 cells against glutamate-induced cytotoxicity. Treatment with 100 µmol/L Dex significantly increased the cell viability to (86.6∓2.2)% of that of the control cells (P<0.01) and decreased LDH release to 1.4∓0.1 folds of the control level (P<0.01). In PC12 cells exposed to glutamate, Dex pretreatment significantly reduced MDA content (P<0.01), enhanced SOD activity (P<0.01), inhibited ROS overproduction (P<0.01), reduced intracellular Ca²⁺ level (P<0.01) and maintained a stable MMP (P<0.01).

CONCLUSION

Dexmedetomidine can protect PC12 cells against glutamate-induced injury possibly in relation with its anti-oxidative activity, inhibitory effect on intracellular calcium overload and protective effect of the mitochondria.

Evaluation of the impact of a prescribing guideline on the use of intraoperative dexmedetomidine at a tertiary academic medical center

Objective: To evaluate usage patterns of dexmedetomidine in the operating room after implementation of a prescribing guideline. Methods: We conducted a retrospective analysis to evaluate the impact of a prescribing guideline on usage patterns of dexmedetomidine in the operating room at a tertiary, academic medical center during one-month period pre- (July 2010) and post-guideline (July 2011 and July 2012) implementation. Results: A total of 267 patients received intraoperative dexmedetomidine during the study period. Dexmedetomidine use in surgical procedures decreased post-guideline implementation [5.7% (pre) vs. 1.9% and 3.3% (post)]. The most common guideline-based indication for intraoperative dexmedetomidine was for anesthesia during bariatric surgery (41% and 38% in 2011 and 2012, respectively). We estimated a cost-avoidance of $308,856 over the two-year period after guideline implementation. Conclusion: Our results suggest that implementation of a prescribing guideline for the use of dexmedetomidine in the operating room is feasible and associated with improved utilization patterns.

Dexmedetomidine as an adjuvant to levobupivacaine in supraclavicular brachial plexus block: A novel anesthetic approach

Aims and Objectives:

Supplementation of dexmedetomidine produces a dose-dependent sedation, anxiolysis and analgesia without respiratory depression. This study was conducted to evaluate the possible effect of dexmedetomidine as an adjuvant to levobupivacaine for supraclavicular brachial plexus block in upper limb surgery.

Settings and Design:

Tertiary care institute, Department of Anaesthesiology and Intensive Care, a placebo-controlled study.

Materials and Methods:

After obtaining Ethical Committee approval, a randomized, double-blind, placebo-controlled study was conducted on sixty American Society of Anesthesiologists physical status I and II patients in the age group of 18–60 years, divided randomly into two groups, Group I received 30 ml of 0.5% levobupivacaine with 1 ml of isotonic sodium chloride solution and Group II received 30 ml of 0.5% levobupivacaine and 1 ml (100 mcg) of dexmedetomidine for supraclavicular brachial plexus block. The onset and duration of sensory and motor blockade, duration of analgesia (DOA) and any adverse effects were noted. At the end of the study, data were compiled and analyzed using appropriate statistical tests. The value of P < 0.05 was considered significant.

Results:

Demographic profile was comparable in both the groups. The time to onset of sensory and motor block was 10.54 ± 2.333 min and 12.21 ± 2.529 min in Group I while it was 3.24 ± 0.951 min and 2.83 ± 1.197 min in Group II, respectively. The duration of sensory and motor block was 7.79 ± 2.007 h and 9.18 ± 1.701 h in Group I, and it was 16.31 ± 2.606 h and 17.52 ± 2.098 h in Group II, respectively. The DOA was 678.68 ± 20.492 min in Group I and 1273.79 ± 83.139 min in Group II. On statistical comparison, these values were highly significant (P < 0.001). Side effects such as nausea, vomiting, hypoxemia, pruritis, or urinary retention were not observed in either of the groups.

Conclusion:

Dexmedetomidine shortens the onset time for sensory and motor block significantly and prolongs DOA as well when used with levobupivacaine for supraclavicular brachial plexus block, without increasing the incidence of any adverse effects.

A comparative study of dexmedetomidine and fentanyl as adjuvants to levobupivacaine for caudal analgesia in children undergoing lower limb orthopedic surgery

Background:

Levobupivacaine is an effective local anesthetic agent with less systemic toxicity than racemic bupivacaine, but it has short postoperative analgesic duration. Dexmedetomidine and fentanyl are promising adjuncts to provide excellent and prolonged postoperative caudal analgesia. This study compared the effects of caudal levobupivacaine plus dexmedetomidine and levobupivacaine plus fentanyl for postoperative analgesia and sedation in children undergoing lower limb orthopedic surgery.

Patients and Methods:

Ninety children, whose age ranged from 1 to 7 years, American Society of Anesthesiologists I-II, undergoing orthopedic lower limb surgery under general anesthesia received caudal block for postoperative analgesia. The children were randomly allocated into three groups: Group L (control) received 0.75 ml/kg levobupivacaine 0.25% diluted in saline; Group LD received 0.75 ml/kg levobupivacaine 0.25% with dexmedetomidine 1 μg/kg; and Group LF received 0.75 ml/kg levobupivacaine 0.25% with fentanyl 1 μg/kg. Following the administration of the drugs; hemodynamic variables, the total anesthesia time, sedation score, Face, Legs, Activity, Cry, Consolability score, duration of analgesia, and side effects were recorded.

Results:

Demographically, all the groups were comparable, both the baseline and the intraoperative hemodynamic profile were similar in all groups. The mean duration of analgesia and the mean sedation score in the Group LD were significantly greater as compared to both the other groups.

Conclusion:

Dexmedetomidine may be a better additive to levobupivacaine than fentanyl for caudal postoperative analgesia, arousable sedation with comparable hemodynamic and side effect profile in children.

The role of spleen in the treatment of experimental lipopolysaccharide-induced sepsis with dexmedetomidine

Dexmedetomidine (Dex), a highly selective α2-adrenergic receptor agonist, has been shown to attenuate systemic inflammatory response induced by lipopolysaccharide (LPS). The protective effects of Dex may reportedly be due to the activation of the α7 nicotinic acetylcholine receptor (α7nAChR)-dependent cholinergic anti-inflammatory pathway. Spleen has been shown to play a pivotal role in the neural cholinergic anti-inflammatory pathway. However, little is known about the specific function of spleen in the protective effects of Dex against sepsis. To investigate the role of spleen in the treatment of Dex against sepsis, we studied the effects of preemptive administration of Dex to septic mice on the NF-κB p65 activation and downstream pro-inflammatory cytokine expression in the spleen. Our results provided evidence that Dex treatment attenuated LPS-activated NF-κB p65 activation, as well as the production of tumor necrosis factor-α, interleukin-6, and interleukin-1β at the level of both mRNA and protein in spleen. Consequently, serum concentrations of these cytokines decreased. Conversely, preemptive injection of α-bungarotoxin, a selective α7nAChR antagonist, reversed these effects of Dex. Our findings indicated that spleen played a critical role in the protective effects of Dex against sepsis and provided further insight into the anti-inflammatory mechanisms of Dex.

Neuroprotective effects of dexmedetomidine conditioning strategies: Evidences from an in vitro model of cerebral ischemia

AIMS

Dexmedetomidine is a selective agonist of α2-adrenergic receptors with clinical anesthetic and analgesic properties that has also shown neuroprotective effects on several models of brain injury. Because perioperative stroke and brain damage are frequent causes of death in critical care units, we aimed to investigate neuroprotective properties of dexmedetomidine using an in vitro model of cerebral ischemia.

MAIN METHODS

Primary mixed rat brain cortical cultures were subjected to oxygen and glucose deprivation and treated with different doses of dexmedetomidine in order to analyze three conditioning strategies: preconditioning, intraconditioning and postconditioning.

KEY FINDINGS

All dexmedetomidine pre-, intra- and postconditioning treatments showed neuroprotective effects reducing brain cell necrosis, although only preconditioning showed antiapoptotic effects. Dexmedetomidine treatments also reduced IL-6 and TNF-α levels, especially in the preconditioning groups. Oxidative stress was attenuated with all dexmedetomidine preconditioning treatments, but only with the higher dose in the intraconditioning group, and no effects were observed in the postconditioning. All conditioning strategies increased BDNF levels.

SIGNIFICANCE

Dexmedetomidine-mediated neuroprotective effects in an in vitro model of cerebral ischemia involve the attenuation of inflammation and oxidative stress and the increment of BDNF expression.

Effective dose of dexmedetomidine to induce adequate sedation in elderly patients under spinal anesthesia

Background

During sedation with dexmedetomidine, a dose adjustment may be needed based on the invasiveness of the procedure, the patient's general condition, and their age. We aim here to determine the effective dose (ED) of dexmedetomidine to induce an adequate depth of sedation in elderly patients undergoing spinal anesthesia.

Methods

In this study, 47 patients aged 65 years or older, American Society of Anesthesiologists physical status I or II, undergoing spinal anesthesia were included. Patients were randomly allocated into group I, II, III, IV or V according to the dexmedetomidine loading dose of 0.1, 0.3, 0.5, 0.7 and 1.0 µg/kg, respectively. After spinal anesthesia, the assigned loading dose of dexmedetomidine was infused intravenously for 10 minutes, after which infusion was maintained at a rate of 0.3 µg/kg/h for the next 10 minutes in all groups. We assessed the depth of sedation with the Ramsay sedation scale every five minutes and measured vital signs and the oxygen saturation. The ED₅₀ and ED₉₅ of dexmedetomidine to obtain adequate sedation (Ramsay sedation score ≥ 3) upon the completion of the loading dose were calculated with logistic regression.

Results

The ED₅₀ and ED₉₅ of dexmedetomidine for adequate sedation were 0.29 µg/kg (95% confidence intervals [CI] 0.14-0.44) and 0.86 µg/kg (95% CI 0.52-1.20), respectively. Hypotension was frequent in groups IV, V compared to groups I, II, III (31.6 vs. 3.6%, P = 0.013).

Conclusions

ED₉₅ of dexmedetomidine loading dose for adequate sedation is 0.86 µg/kg. However, dose higher than 0.5 µg/kg can lead to hemodynamic instability.

The effect of dexmedetomidine sedation on patient and surgeon satisfaction during retinal surgery under sub-tenon's anesthesia: a randomized controlled trial

Background

The purpose of this study was to evaluate the effect of intraoperative dexmedetomidine sedation on patient's and surgeon's satisfaction during retinal surgery under sub-tenon's anesthesia.

Methods

Forty-four patients scheduled for elective retinal surgery under sub-tenon's anesthesia were enrolled in this randomized controlled trial. The patients were divided into Dexmedetomidine (n = 22) and Control (n = 22) groups. Intravenous dexmedetomidine or 0.9% saline via infusion pump were administered continuously to the dexmedetomidine or control group, respectively. Ramsay sedation scale with a target level of 3-4 was used to assess adequacy of sedation. Perioperative pain, hemodynamic and respiratory data were collected, while satisfaction from patients and surgeon were assessed post-surgery using a 5-point satisfaction scale.

Results

Patient and surgeon satisfaction was higher in the dexmedetomidine group (P < 0.001, P = 0.002, respectively). The pain associated with sub-tenon's anesthesia and peripheral vitrectomy was lesser in the dexmedetomidine group than in the control group (P = 0.020). There was significant reduction of heart rate in the dexmedetomidine group (P = 0.001), but only one patient needed treatment with atropine. There was no respiratory effect on both groups.

Conclusions

Dexmedetomidine sedation during retinal surgery improved satisfaction from both patient and surgeon without respiratory complication. It is a safe and preferable choice of sedation for retinal surgery.

Comparison of Effects of Different Doses Dexmedetomidine on Inhibiting Tracheal Intubation-Evoked Haemodynamic Response in the Elderly Patients

BACKGROUND

Dexmedetomidine (DEX) is a selective α2-adrenergic receptor agonist with anxiolytic and analgesic properties. In the present study, we aimed primarily to assess the effects of DEX on sedation, cognitive function and cardiovascular reflex responses before, during and after the tracheal intubation in the elderly patients.

MATERIALS AND METHODS

Eighty patients undergoing elective abdominal surgery were randomly assigned to four Groups: Group A(saline, n=20), Group B (0.25μg/kg DEX, n=20), Group C (0.50μg/kg DEX, n=20) and Group D (1.00μg/kg DEX, n=20). With the constant speed infusion of saline and a loading different doses of DEX (diluted with saline to 50ml) for 10min respectively before induction of anaesthesia, the values of arterial pressure {systolic blood pressure (SBP), diastolic blood pressure (DBP)}, heart rate (HR) and bispectral index (BIS) at the time point of before pump DEX (T0), at the end of infusing DEX (T1), before tracheal intubation (T2), at the moment of tracheal intubation (T3) and 5min after trachea intubation (T4) were observed, oxygen saturation (SPO2) and the Modified Observers Assessment of Alertness/Sedation Scale (OAA/S) score were observed at the time of T1 and T0.

RESULTS

Comparison among Groups, compared with Group A, SBP and DBP values in Group C at T2 showed significant differences (p<0.05), SBP and DBP values in Group D at T1, T2 and T4 indicated significant differences (p<0.05), HR values in Group D at T1, T2, T3 and T4 showed significant differences (p<0.05); Compared with Group A, BIS values in Group C at T2 and T3 indicated significant differences (p<0.05), BIS values in Group D at T1, T2, T3 and T4 showed significant differences (p<0.05); Comparison between T3 andT2, means of SBP, DBP and HR in Group A and in Group B showed significant differences (p<0.05); Group D showed significant differences in SPO2 and (OAA/S) betweenT1 and T0 (p<0.05).

CONCLUSION

Comparison within Groups and between Groups in different doses DEX, the present result showed that 0.5μg/kg DEX had an effective inhibition, without respiratory depression, on tracheal intubation evoked cardiovascular response in the elderly patients.

Dexmedetomidine versus propofol in dilatation and curettage: An open-label pilot randomized controlled trial

Background:

Traditionally propofol has been used for providing sedation in dilatation and curettage (D and C). Recently, dexmedetomidine has been tried, but very little evidence exists to support its use.

Aims:

The aim was to compare hemodynamic and recovery profile of both the drugs along with a degree of comfort experienced by patients and the usefulness of the drug to surgeons.

Settings and Design:

Tertiary care center and open-label randomized controlled trial.

Materials and Methods:

Patients posted for D and C were enrolled in two groups (25 each). Both groups received fentanyl 1 μg/kg intravenous (IV) at the beginning of the procedure. Group P received IV propofol in dose of 1.5 mg/kg over 10-15 min and Group D received dexmedetomidine at a loading dose of 1 μg/kg over 10 min, followed by 0.5 μg/kg/h infusion until Ramsay sedation score reached 3-4. Hemodynamic vitals were compared during and after the procedure. In the recovery room time to reach modified Aldrete score (MAS) of 9-10 and patient's and surgeon's satisfaction scores were also recorded and compared.

Results:

In Group D, patients had statistically significant lower heart rate at 2, 5, 10 and 15 min as compared to Group P. Hypotension was present in 52% in Group P and 4% in Group D (P < 0.05). MAS of 9-10 was achieved in 4.4 min in subjects in Group D in contrast to 16.2 min in Group P (P < 0.05). Group D showed higher patient and surgeon satisfaction scores (P < 0.05).

Conclusion:

Dexmedetomidine provide better hemodynamic and recovery profile than propofol. It can be a superior alternative for short surgical day care procedures.

Dexmedetomidine Reduces Shivering during Mild Hypothermia in Waking Subjects

Background and Purpose

Reducing body temperature can prolong tolerance to ischemic injury such as stroke or myocardial infarction, but is difficult and uncomfortable in awake patients because of shivering. We tested the efficacy and safety of the alpha-2-adrenergic agonist dexmedetomidine for suppressing shivering induced by a rapid infusion of cold intravenous fluids.

Methods

Ten subjects received a rapid intravenous infusion of two liters of cold (4°C) isotonic saline on two separate test days, and we measured their core body temperature, shivering, hemodynamics and sedation for two hours. On one test day, fluid infusion was preceded by placebo infusion. On the other test day, fluid infusion was preceded by 1.0 μg/kg bolus of dexmedetomidine over 10 minutes.

Results

All ten subjects experienced shivering on placebo days, with shivering beginning at a mean (SD) temperature of 36.6 (0.3)°C. The mean lowest temperature after placebo was 36.0 (0.3)°C (range 35.7-36.5°C). Only 3/10 subjects shivered on dexmedetomidine days, and the mean lowest temperature was 35.7 (0.4)°C (range 35.0-36.3°C). Temperature remained below 36°C for the full two hours in 6/10 subjects. After dexmedetomidine, subjects had moderate sedation and a mean 26 (13) mmHg reduction in blood pressure that resolved within 90 minutes. Heart rate declined a mean 23 (11) bpm after both placebo and dexmedetomidine. Dexmedetomidine produced no respiratory depression.

Conclusion

Dexmedetomidine decreases shivering in normal volunteers. This effect is associated with decreased systolic blood pressure and sedation, but no respiratory depression.

Alpha-2 adrenergic receptor agonists: a review of current clinical applications

The α-2 adrenergic receptor agonists have been used for decades to treat common medical conditions such as hypertension; attention-deficit/hyperactivity disorder; various pain and panic disorders; symptoms of opioid, benzodiazepine, and alcohol withdrawal; and cigarette craving. (1) However, in more recent years, these drugs have been used as adjuncts for sedation and to reduce anesthetic requirements. This review will provide an historical perspective of this drug class, an understanding of pharmacological mechanisms, and an insight into current applications in clinical anesthesiology.

Dexmedetomidine improves the quality of the operative field for functional endoscopic sinus surgery: systematic review

BACKGROUND

Intra-operative bleeding diminishes visualisation during functional endoscopic sinus surgery and can cause unfavourable outcomes. Dexmedetomidine is a potent alpha-2 agonist, with sympatholytic effects. This systematic review aimed to assess whether dexmedetomidine decreases intra-operative bleeding and improves operative field quality.

METHODS

All randomised, controlled trials that assessed the ability of dexmedetomidine to provide good operative fields for functional endoscopic sinus surgery were identified from Medline and Embase. The outcomes of interest were: operative field quality, intra-operative bleeding, operative time and adverse events.

RESULTS

Five studies (254 patients) met the inclusion criteria. When compared to saline, dexmedetomidine improved the quality of the operative field. The operative time was similar between groups. When compared to other drugs, dexmedetomidine was as effective as esmolol and remifentanil. There were no adverse incidents.

CONCLUSION

Dexmedetomidine is beneficial in providing good visibility during functional endoscopic sinus surgery. Controlled hypotensive anaesthesia with this medicine decreases intra-operative bleeding and enhances surgical field quality.

Dexmedetomidine, ketamine, and midazolam for oral rehabilitation: a case report

Intravenous sedation is frequently provided by anesthesiologists for phobic patients undergoing elective dental treatment in outpatient settings. Propofol is one of the most commonly used anesthetic agents that can result in apnea and respiratory depression, thereby posing potential difficulties with perioperative airway management. Dexmedetomidine has been utilized successfully in intravenous sedation for a wide variety of procedures and holds potential as an alternative to propofol in outpatient dental settings. However, as a single agent, it may not provide adequate depth of sedation and analgesia for oral rehabilitation. In this case report we demonstrate an effective alternative intravenous deep-sedation technique for an adult phobic patient undergoing oral rehabilitation utilizing 3 agents in combination: dexmedetomidine, ketamine, and midazolam. This combination of agents may be especially useful for those patients with a history of substance abuse, where administration of opioids may be undesirable or contraindicated.

Rethinking critical care: decreasing sedation, increasing delirium monitoring, and increasing patient mobility

BACKGROUND

Sedation management, delirium monitoring, and mobility programs have been addressed in evidence-based critical care guidelines and care bundles, yet implementation in the ICU remains variable. As critically ill patients occupy higher percentages of hospital beds in the United States and beyond, it is increasingly important to determine mechanisms to deliver better care. The Institute for Healthcare Improvement's Rethinking Critical Care (IHI-RCC) program was established to reduce harm of critically ill patients by decreasing sedation, increasing monitoring and management of delirium, and increasing patient mobility. Case studies of a convenience sample of five participating hospitals/health systems chosen in advance of the determination of their clinical outcomes are presented in terms of how they got started and process improvements in sedation management, delirium management, and mobility.

METHODS

The IHI-RCC program involved one live case study and five iterations of an in-person seminar in a 33-month period (March 2011-November 2013) that emphasized interdisciplinary teamwork and culture change.

RESULTS

Qualitative descriptions of the changes tested at each of the five case study sites demonstrate improvements in teamwork, processes, and reliability of daily work. Improvement in ICU length of stay and length of stay on the ventilator between the pre- and postimplementation periods varied from slight to substantial.

CONCLUSION

Changing critical care practices requires an interdisciplinary approach addressing cultural, psychological, and practical issues. The key lessons of the IHI-RCC program are as follows: the importance of testing changes on a small scale, feeding back data regularly and providing sufficient education, and building will through seeing the work in action.

Effects of low dose dexmedetomidine infusion on haemodynamic stress response, sedation and post-operative analgesia requirement in patients undergoing laparoscopic cholecystectomy

Background and Aim:

Dexmedetomidine is a α2 agonist with sedative, sympatholytic and analgesic properties and hence, it can be a very useful adjuvant in anaesthesia as stress response buster, sedative and analgesic. We aimed primarily to evaluate the effects of low dose dexmedetomidine infusion on haemodynamic response to critical incidences such as laryngoscopy, endotracheal intubation, creation of pneumoperitoneum and extubation in patients undergoing laparoscopic cholecystectomy. The secondary aims were to observe the effects on extubation time, sedation levels, post-operative analgesia requirements and occurrence of adverse effects.

Methods:

Sixty patients of American Society of Anaesthesiologists(ASA) physical grades I and II undergoing laparoscopic cholecystectomy were randomly allocated into three groups of 20 patients each. Group NS patients received normal saline, Group Dex 0.2 and Group Dex 0.4 patients received dexmedetomidine infusion at 0.2 mcg/kg/h and 0.4 mcg/kg/h respectively, starting 15 min before induction and continued till end of surgery. Parameters noted were pulse rate, mean arterial pressure, oxygen saturation, post-operative sedation and analgesia requirements. SPSS 15.0 version software was used for statistical analysis. ANOVA test for continuous variables, post-hoc test for intergroup comparison, and Chi-square test for discrete values were applied.

Results:

In Group NS significant haemodynamic stress response was seen following laryngoscopy, tracheal intubation, creation of pneumoperitoneum and extubation. In dexmedetomidine groups, the haemodynamic response was significantly attenuated. The results, however, were statistically better in Dex 0.4 group compared with Dex 0.2 group. Post-operative 24 hour analgesic requirements were much less in dexmedetomidine groups. No significant side effects were noted.

Conclusion:

Low dose dexmedetomidine infusion in the dose of 0.4 mcg/kg/h effectively attenuates haemodynamic stress response during laparoscopic surgery with reduction in post-operative analgesic requirements.

A comparison of midazolam and dexmedetomidine for the recovery of serotonin syndrome in rats

Serotonin syndrome is a drug-related toxicity caused by excess serotonin within the central nervous system. We recently encountered a case of serotonin syndrome that developed in the early postoperative period that was successfully treated with intravenous dexmedetomidine. Although the prescriptive literature has commonly recommended sedation with benzodiazepines for controlling agitation in serotonin syndrome, the effectiveness of dexmedetomidine has also been reported in several clinical conditions. In the present study, we conducted a reverse translational experiment to compare the efficacy of dexmedetomidine and midazolam, at equi-sedative doses, on serotonergic toxicity-like responses in rats. Animals were subcutaneously injected with 0.75 mg/kg 8-OH-DPAT, a full 5-HT1A agonist. 8-OH-DPAT-treated rats showed serotonin syndrome-like behaviors (low body posture, forepaw treading), hyperlocomotion, and decreased body temperature, which were completely inhibited by pretreatment with WAY 100635, a selective 5-HT1A antagonist (n = 8). Intramuscular injection of midazolam (1.0 mg/kg) or dexmedetomidine (0.01 mg/kg), which comparably induced observable signs of sedation, was tested in the present study. Concomitant treatment with midazolam significantly attenuated the hyperlocomotion, but failed to affect traditional serotonin syndrome behaviors and body temperature in 8-OH-DPAT-treated rats (n = 8). On the other hand, concomitant treatment with dexmedetomidine significantly attenuated all of these parameters (n = 8). The present case and related reverse translational experiment demonstrate that dexmedetomidine may be more beneficial for the treatment of serotonin syndrome compared to the current recommended treatment with benzodiazepines.

Special considerations in infants and children

Head injury in children is one of the most common causes of death and disability in the US and, increasingly, worldwide. This chapter reviews the causes, patterns, pathophysiology, and treatment of head injury in children across the age spectrum, and compares pediatric head injury to that in adults. Classification of head injury in children can be organized according to severity, pathoanatomic type, or mechanism. Response to injury and repair mechanisms appear to vary at different ages, and these may influence optimal treatment; however, much work is still needed before investigation leads to clearly effective clinical interventions. This is true both for the more severe injuries as well as those at the milder end of the injury spectrum, the latter of which have received increasing attention. In this chapter, neuroassessment tools for each age, newer imaging modalities including magnetic resonance imaging (MRI), and specific pediatric management issues, including intracranial pressure (ICP) monitoring and seizure prophylaxis, are reviewed. Finally, specific head injury patterns and functional outcomes relevant to pediatric patients are discussed. While head injury is common, the number of head-injured children is significantly smaller than the corresponding adult head-injured population. When divided further by specific ages, injury types, and other sources of heterogeneity, properly powered clinical research is likely to require large data sets that will allow for stratification across variables, including age. While much has been learned in the past several decades, further study will be required to determine the best management practices for optimizing recovery in individual pediatric patients. This approach is likely to depend on collaborative international head injury databases that will allow researchers to better understand the nuanced evolution of different types of head injury in patients at each age, and the pathophysiologic, treatment-related, and genetic factors that influence recovery.

The dose-related effects of dexmedetomidine on renal functions and serum neutrophil gelatinase-associated lipocalin values after coronary artery bypass grafting: a randomized, triple-blind, placebo-controlled study

OBJECTIVES

Acute kidney failure after coronary artery bypass grafting (CABG) is a serious complication that increases morbidity and mortality rates. Early detection and prevention of this complication are very important. A novel biomarker named neutrophil gelatinase-associated lipocalin (NGAL) can play an important role in early diagnosis of acute kidney injury. Recent studies on the favourable effects of Dexmedetomidine on cardiac surgery have been published. The aim of this study is to investigate whether there is a dose-dependent positive effect of Dexmedetomidine on neutrophil gelatinase-associated lipocalin levels and renal functions when used after CABG.

METHODS

Our randomized, triple-blinded, placebo-controlled study was conducted among 295 patients scheduled for CABG surgery between August 2009 and March 2011 in a tertiary cardiac and vascular surgery clinic. A total of 90 consecutive patients who met inclusion criteria were randomized and divided into three groups. The first group received a placebo. The second and the third groups received 4 and 8 µg/cc concentration of the Dexmedetomidine infusion, respectively. Infusion rates were regulated to obtain sedation with a Ramsey sedation score of 2 or 3. Patients were regrouped according to the total Dexmedetomidine dose. Statistical analyses of variables including serum neutrophil gelatinase-associated lipocalin values and conventional renal function tests were made for all six possibilities before the blind was broken.

RESULTS

Results of conventional renal function tests were not significantly different. However, neutrophil gelatinase-associated lipocalin levels for the first postoperative day for placebo, low-dose and high-dose Dexmedetomidine groups were 176.8 ± 145.9, 97.7 ± 63.4 and 67.3 ± 10.9 ng/ml, respectively. These values were significantly different among the groups (P <0.001).

CONCLUSIONS

In our study, we found that Dexmedetomidine infusion for sedation after CABG under cardiopulmonary bypass can be useful in the prevention of kidney injury. Conventional renal function tests, including blood urea nitrogen, serum creatinine, urine output and creatinine clearance rate measurements typically may not detect the development of acute kidney dysfunction in the first 48-h postoperative period. Differences were detected in renal function in the early postoperative period and the development of acute kidney injury, as determined by measurements of blood NGAL levels, was significant and dose-dependent.

Effects of dexmedetomidine on insulin secretion from rat pancreatic β cells

PURPOSE

Dexmedetomidine acts as a selective α2-adrenergic receptor agonist and an imidazoline receptor agonist, both of which are known to affect insulin secretion. Here, we investigated the effects of clinically relevant concentrations of dexmedetomidine on insulin secretion under in vivo conditions. Furthermore, its underlying mechanisms were examined using isolated islets in vitro.

METHODS

For the in vivo oral glucose tolerance test (OGTT), male Sprague-Dawley rats were randomly allocated to one of three groups (n = 7 in each group): two groups infused with dexmedetomidine at a low (group L) or a high (group H) dose, and one control group infused with the same amount of saline (group C). For the in vitro perifusion study, insulin released from isolated islets was measured during stepwise changes in glucose. Dexmedetomidine (0.1-100 µM) was added to the chamber.

RESULTS

During the OGTT test, the insulin levels in group H were significantly lower than those in group C at 30, 60, and 90 min after glucose load. On the other hand, insulin levels in group L were comparable to those of group C at all time points. In the perfusion study, dexmedetomidine inhibited glucose-stimulated insulin secretion in a concentration-dependent manner. When co-treated with yohimbine, an α2-adrenoceptor blocker, dexmedetomidine adversely increased glucose-induced insulin secretion. However, co-treatment with idazoxan, an antagonist for α2-adrenergic and imidazoline receptors, completely abolished the action of dexmedetomidine.

CONCLUSIONS

Dexmedetomidine had no effect on insulin secretion at sedative dose, whereas it significantly inhibited insulin secretion at supraclinical high concentrations mainly via the α2-adrenoceptor.

The dexmedetomidine concentration required after remifentanil anesthesia is three-fold higher than that after fentanyl anesthesia or that for general sedation in the ICU

Purpose

The general dexmedetomidine (DEX) concentration required for sedation of intensive care unit patients is considered to be approximately 0.7 ng/mL. However, higher DEX concentrations are considered to be required for sedation and/or pain management after major surgery using remifentanil. We determined the DEX concentration required after major surgery by using a target-controlled infusion (TCI) system for DEX.

Methods

Fourteen patients undergoing surgery for abdominal aortic aneurysms (AAA) were randomly, double-blindly assigned to two groups and underwent fentanyl- or remifentanil-based anesthetic management. DEX TCI was started at the time of closing the peritoneum and continued for 12 hours after stopping propofol administration (M0); DEX TCI was adjusted according to the sedation score and complaints of pain. The doses and concentrations of all anesthetics and postoperative conditions were investigated.

Results

Throughout the observation period, the predicted plasma concentration of DEX in the fentanyl group was stable at approximately 0.7 ng/mL. In contrast, the predicted plasma concentration of DEX in the remifentanil group rapidly increased and stabilized at approximately 2 ng/mL. The actual DEX concentration at 540 minutes after M0 showed a similar trend (0.54±0.14 [fentanyl] versus 1.57±0.39 ng/mL [remifentanil]). In the remifentanil group, the dopamine dose required and the duration of intubation decreased, and urine output increased; however, no other outcomes improved.

Conclusion

The DEX concentration required after AAA surgery with remifentanil was three-fold higher than that required after AAA surgery with fentanyl or the conventional DEX concentration for sedation. High DEX concentration after remifentanil affords some benefits in anesthetic management.

Safe Sedation and Hypnosis using Dexmedetomidine for Minimally Invasive Spine Surgery in a Prone Position

Dexmedetomidine, an imidazoline compound, is a highly selective α2-adrenoceptor agonist with sympatholytic, sedative, amnestic, and analgesic properties. In order to minimize the patients' pain and anxiety during minimally invasive spine surgery (MISS) when compared to conventional surgery under general anesthesia, an adequate conscious sedation (CS) or monitored anesthetic care (MAC) should be provided. Commonly used intravenous sedatives and hypnotics, such as midazolam and propofol, are not suitable for operations in a prone position due to undesired respiratory depression. Dexmedetomidine converges on an endogenous non-rapid eye movement (NREM) sleep-promoting pathway to exert its sedative effects. The great merit of dexmedetomidine for CS or MAC is the ability of the operator to recognize nerve damage during percutaneous endoscopic lumbar discectomy, a representative MISS. However, there are 2 shortcomings for dexmedetomidine in MISS: hypotension/bradycardia and delayed emergence. Its hypotension/bradycardiac effects can be prevented by ketamine intraoperatively. Using atipamezole (an α2-adrenoceptor antagonist) might allow doctors to control the rate of recovery from procedural sedation in the future. MAC, with other analgesics such as ketorolac and opioids, creates ideal conditions for MISS. In conclusion, dexmedetomidine provides a favorable surgical condition in patients receiving MISS in a prone position due to its unique properties of conscious sedation followed by unconscious hypnosis with analgesia. However, no respiratory depression occurs based on the dexmedetomidine-related endogenous sleep pathways involves the inhibition of the locus coeruleus in the pons, which facilitates VLPO firing in the anterior hypothalamus.

Avian reflex and electroencephalogram responses in different states of consciousness

Defining states of clinical consciousness in animals is important in veterinary anaesthesia and in studies of euthanasia and welfare assessment at slaughter. The aim of this study was to validate readily observable reflex responses in relation to different conscious states, as confirmed by EEG analysis, in two species of birds under laboratory conditions (35-week-old layer hens (n=12) and 11-week-old turkeys (n=10)). We evaluated clinical reflexes and characterised electroencephalograph (EEG) activity (as a measure of brain function) using spectral analyses in four different clinical states of consciousness: conscious (fully awake), semi-conscious (sedated), unconscious-optimal (general anaesthesia), unconscious-sub optimal (deep hypnotic state), as well as assessment immediately following euthanasia. Jaw or neck muscle tone was the most reliable reflex measure distinguishing between conscious and unconscious states. Pupillary reflex was consistently observed until respiratory arrest. Nictitating membrane reflex persisted for a short time (<1 min) after respiratory arrest and brain death (isoelectric EEG). The results confirm that the nictitating membrane reflex is a conservative measure of death in poultry. Using spectral analyses of the EEG waveforms it was possible to readily distinguish between the different states of clinical consciousness. In all cases, when birds progressed from a conscious to unconscious state; total spectral power (PTOT) significantly increased, whereas median (F50) and spectral edge (F95) frequencies significantly decreased. This study demonstrates that EEG analysis can differentiate between clinical states (and loss of brain function at death) in birds and provides a unique integration of reflex responses and EEG activity.

Dexmedetomidine increases the activity of excitatory amino acid transporter type 3 expressed in Xenopus oocytes: the involvement of protein kinase C and phosphatidylinositol 3-kinase

Dexmedetomidine, an α2 adrenergic agonist, has neuroprotective and anticonvulsant properties in addition to its sedative and anxiolytic effects. We hypothesized that dexmedetomidine would increase the activity of excitatory amino acid transporter type 3 (EAAT3) and that this effect would involve protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K), two protein kinases known to regulate EAAT3 activity. EAAT3 was expressed in Xenopus oocytes by injecting its mRNA. Two-electrode voltage clamping was used to record membrane currents before, during, and after application of 30 μM l-glutamate in the presence of 0.1-30 nM dexmedetomidine. Dexmedetomidine-treated oocytes were also exposed to a PKC activator (phorbol-12-myristate-13-acetate [PMA]), PKC inhibitors (chelerythrine, staurosporine, and calphostin C), and PI3K inhibitors (wortmannin and LY294002) before current measurement. Dexmedetomidine application resulted in a concentration-dependent increase in the EAAT3 activity in response to l-glutamate. The kinetic study showed that dexmedetomidine significantly increased the Vmax without changing Km. Treatment of oocytes with PMA significantly increased transporter currents compared with controls, but treatment with dexmedetomidine plus PMA did not further increase the response compared with PMA or dexmedetomidine alone. In addition, pre-treatment of oocytes with PKC inhibitors and PI3K inhibitors significantly abolished the dexmedetomidine-enhanced EAAT3 activity. These results suggest that dexmedetomidine increases the activity of EAAT3 expressed in Xenopus oocytes. PKC and PI3K seem to mediate this effect. These findings may explain the neuroprotective and anticonvulsant effects of dexmedetomidine.

A comparative study of the effect of caudal dexmedetomidine versus morphine added to bupivacaine in pediatric infra-umbilical surgery

BACKGROUND

One of the most commonly used regional anesthetic techniques in pediatric surgeries is the caudal epidural block. Its main disadvantage remains the short duration of action. Hence, different additives have been used. Dexmedetomidine is a potent as well as highly selective α2 adrenergic receptor agonist. The aim of this randomized, double-blinded, study was to compare the duration of postoperative analgesia of caudal dexmedetomidine versus morphine in combination with bupivacaine in pediatric patients undergoing lower abdominal or perineal surgery.

PATIENTS AND METHODS

A total of 50 pediatric patients 1-5 years old The American Society of Anesthesiologists status I, II scheduled for lower abdominal and perineal surgeries were included in the study. The patients were enrolled into 2 equal groups: Group A patients (n = 25) received dexmedetomidine with bupivacaine while Group B patients (n = 25) received morphine with bupivacaine. Patients were placed in a supine position then inhalational general anesthesia was induced, and laryngeal mask airway (LMA) was placed. Patients were then given caudal epidural analgesia. By the end of surgery reversal of muscle relaxation was done and the LMA was removed. Post-operatively, the sedation as well as pain score were observed and recorded.

RESULTS

The current study showed that minor complications were recorded in the post-anesthesia care unit; in addition, significantly longer periods of analgesia and sedation were detected in Group A. However, no significant differences in demographic data, as well as in the duration of surgery, and the time of emergence from anesthesia and patient condition during recovery were detected.

CONCLUSION

The present study suggested that use of dexmedetomidine, during single dose injection, as an additive to the local anesthetic bupivacaine in caudal epidural analgesia prolongs the duration of post-operative analgesia following lower abdominal as well as perineal surgery compared with caudal morphine with no side-effects on the vital signs. Postoperative side effects were seen with caudal morphine injection rather than with dexmedetomidine.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

Dexmedetomidine versus midazolam for conscious sedation in endoscopic retrograde cholangiopancreatography: An open-label randomised controlled trial

Background:

Traditionally, midazolam has been used for providing conscious sedation in endoscopic retrograde cholangiopancreatography (ERCP). Recently, dexmedetomidine has been tried, but very little evidence exists to support its use.

Objective:

The primary objective was to compare haemodynamic, respiratory and recovery profile of both drugs. Secondary objective was to compare the degree of comfort experienced by patients and the usefulness of the drug to endoscopist.

Study Design:

Open-label Randomised Controlled Trial.

Methods:

Subjects between 18 and 60 years of age with American Society of Anaesthesiologist Grade I-II requiring ERCP were enrolled in two groups (30 each). Both groups received fentanyl 1 μg/kg IV at the beginning of ERCP. Group M received IV midazolam (0.04 mg/kg) and additional 0.5 mg doses until Ramsay Sedation Scale (RSS) score reached 3-4. Group D received dexmedetomidine at loading dose of 1 μg/kg over 10 min followed by 0.5 μg/kg/h infusion until RSS reached 3-4. The vital parameters (heart rate (HR), blood pressure (BP), respiration rate, SpO₂), time to achieve RSS 3-4 and facial pain score (FPS) were compared during and after the procedure. In the recovery room, time to reach modified Aldrete score (MAS) 9-10 and patient and surgeon's satisfaction scores was also recorded and compared. Any complication during or after the procedure were also noted.

Results:

In Group D, patients had lower HR and FPS at 5, 10 and 15 min following the initiation of sedation (P<0.05). There was no statistically significant difference in BP and respiratory rate. The procedure elicited a gag response in 29 (97%) and 7 (23%) subjects in Group M and Group D respectively (P<0.05). MAS of 9-10 at 5 min during recovery was achieved in 27 (90%) subjects in Group D in contrast to 5 (17%) in Group M (P<0.05). Dexmedetomidine showed higher patient and surgeon satisfaction scores (P<0.05).

Conclusion:

Dexmedetomidine can be a superior alternative to midazolam for conscious sedation in ERCP.

Sedation during noninvasive mechanical ventilation with dexmedetomidine or midazolam: A randomized, double-blind, prospective study

BACKGROUND

Effective noninvasive mechanical ventilation (NIV) requires a patient to be comfortable and in synch with the ventilator, for which sedation is usually needed. Choice of the proper drug for sedation can lead to improved clinical outcomes.

OBJECTIVE

The aim of this study was to compare the effectiveness of dexmedetomidine and midazolam on sedation and their effects on hemodynamics and gas exchange.

METHODS

In this randomized, double-blind study, intensive care unit patients with acute respiratory failure due to acute exacerbations of chronic obstructive pulmonary disease undergoing NIV were equally randomized to receive a loading dose of 1 μg/kg IV dexmedetomidine or 0.05 μg/kg midazolam over 10 minutes followed by a maintenance infusion of 0.5 μg/kg/h dexmedetomidine (group D) or 0.1 mg/kg/h midazolam (group M). The following parameters were measured by a blinded clinician at baseline and 1, 2, 4, 6, 8, 12, and 24 hours after the loading dose was administered: Ramsay Sedation Score (RSS), Riker Sedation-Agitation Scale (RSAS), Bispectral Index (BIS), arterial blood gases, and vital signs. A second blinded investigator determined dosing changes according to the outcome of maintaining a target sedation level of RSS 2 to 3, RSAS 3 to 4, and BIS >85.

RESULTS

A total of 45 patients were assessed for enrollment in the study; 4 did not meet the inclusion criteria and 1 refused to participate (men/women 19/21; mean age 58/60; all patients were receiving bronchodilators, steroids, antibiotics, and mucolytics). In both groups (n = 20), RSS significantly increased and RSAS levels and BIS values significantly decreased after the loading dose, compared with baseline (P < 0.05). RSS levels were significantly lower beginning at 4 hours in group D compared with group M (P < 0.05). RSAS levels were not significantly different between the 2 groups in the first 8 hours. However, RSAS levels were significantly higher at 8 hours after the loading dose was administered in group D compared with group M (P < 0.01). BIS was significantly higher in group D throughout the study period (P < 0.05). Respiratory rates and gas exchange values were not significantly different between the Accepted for publication April 7, 2010. 2 groups. The number of times a change in infusion dose was needed was significantly lower in group D (2 patients with 1 change each) than in group M (3 patients with 1 change, 1 patient with 2 changes, and 3 patients with 3 changes each) (P < 0.01).

CONCLUSIONS

Dexmedetomidine and midazolam are both effective sedatives for patients with NIV. Dexmedetomidine required fewer adjustments in dosing compared with midazolam to maintain adequate sedation.

An evaluation of intranasal sufentanil and dexmedetomidine for pediatric dental sedation

Conscious or moderate sedation is routinely used to facilitate the dental care of the pre- or un-cooperative child. Dexmedetomidine (DEX) has little respiratory depressant effect, possibly making it a safer option when used as an adjunct to either opioids or benzodiazepines. Unlike intranasal (IN) midazolam, IN application of DEX and sufentanil (SUF) does not appear to cause much discomfort. Further, although DEX lacks respiratory depressive effects, it is an α2-agonist that can cause hypotension and bradycardia when given in high doses or during prolonged periods of administration. The aim of this feasibility study was to prospectively assess IN DEX/SUF as a potential sedation regimen for pediatric dental procedures. After IRB approval and informed consent, children (aged 3-7 years; n = 20) from our dental clinic were recruited. All patients received 2 μg/kg (max 40 μg) of IN DEX 45 min before the procedure, followed 30 min later by 1 μg/kg (max 20 μg) of IN SUF. An independent observer rated the effects of sedation using the Ohio State University Behavior Rating Scale (OSUBRS) and University of Michigan Sedation Scale (UMSS). The dentist and the parent also assessed the efficacy of sedation. Dental procedures were well tolerated and none were aborted. The mean OSUBRS procedure score was 2.1, the UMSS procedure score was 1.6, and all scores returned to baseline after the procedure. The average dentist rated quality of sedation was 7.6 across the 20 subjects. After discharge, parents reported one child with prolonged drowsiness and one child who vomited at home. The use of IN DEX supplemented with IN SUF provided both an effective and tolerable form of moderate sedation. Although onset and recovery are slower than with oral (PO) midazolam and transmucosal fentanyl, the quality of the sedation may be better with less risk of respiratory depression. Results from this preliminary study showed no major complications from IN delivery of these agents.

[Dexmedetomidine]

Dexmedetomidine is a highly selective α2-receptor agonist with sedative, analgetic and anxiolytic effects. It is chemically related to clonidine and has been an authorized drug in Europe since September 2011. Dexmedetomidine enables a level of sedation in which mechanically ventilated patients may be woken by verbal stimulation (Richmond agitation sedation scale RASS 0--3). In this respect dexmedetomidine achieves the same desired effect as propofol and midazolam; however, in direct comparison to a sedation regime with benzodiazepines, dexmedetomidine reduces the prevalence, duration and severity of delirium in intensive care. Patients sedated by dexmedetomidine can statistically be extubated earlier and an influence on duration of stay in the intensive care unit (ICU) has not been shown. Daily therapy costs are approximately 5 times higher than those of propofol but an objective standpoint in relation to clinical cost efficiency is unattainable.

Dexmedetomidine prolongs the effect of bupivacaine in supraclavicular brachial plexus block

BACKGROUND

We compared the effects of adding dexmedetomidine to a 30 ml solution of 0.325% bupivacaine in supraclavicular brachial plexus block. Onset and duration of sensory and motor block along with the duration of analgesia were the primary endpoints.

MATERIALS AND METHODS

Fifty patients posted for upper limb surgeries were enrolled for a prospective, randomized, double-blind, placebo-controlled trial. Patients were divided into two groups, the control group S and the study group SD. In group S (n = 25), 30 ml of 0.325% bupivacaine + 1 ml normal saline; and in group SD (n = 25), 30 ml of 0.325% bupivacaine + 1 ml (100 μg) dexmedetomidine were given for supraclavicular brachial plexus block using the peripheral nerve stimulator. Onset and duration of sensory and motor blocks were assessed along with the duration of analgesia, sedation, and adverse effects, if any. Hemodynamic parameters, like heart rate (HR), systolic arterial blood pressure (SBP), and diastolic arterial blood pressure (DBP) were also monitored.

RESULTS

Demographic data and surgical characteristics were comparable in both the groups. The onset times for sensory and motor blocks were significantly shorter in SD than S group (P < 0.001), while the duration of blocks was significantly longer (P < 0.001) in SD group. Except for the initial recordings (at 0, 5, 10, and 15 min), heart rate levels in group SD were significantly lower (P < 0.001). SBP and DBP levels in SD group at 15, 30, 45, 60, 90 and 120 min were significantly lower than in S group (P < 0.001). In fact, when the percentage changes in HR/SBP/DBP were compared from 0-5/0-10/0-15/0-30/0-45/0-60/0-90/0-120 min in SD with S group, they came out to be highly significant (P < 0.001) in group SD. The duration of analgesia (DOA) was significantly longer in SD group than S group (P < 0.001). Except that, bradycardia was observed in one patient in the group SD, no other adverse effects were observed in either of the groups.

CONCLUSION

Dexmedetomidine added as an adjuvant to bupivacaine for supraclavicular brachial plexus block significantly shortens the onset time and prolongs the duration of sensory and motor blocks and duration of analgesia. Patients in group SD were adequately sedated (modified Ramsay Sedation Score, RSS = 2/6 or 3/6) with no adverse effects except bradycardia in one patient of group SD.

Heart rate variability dynamics during controlled hypotension with nicardipine, remifentanil and dexmedetomidine

BACKGROUND

This study was done to investigate how nicardipine, remifentanil and dexmedetomidine affect the balance of the autonomic nervous system in patients receiving controlled hypotension under general anaesthesia by evaluating heart rate variability indices.

METHODS

Sixty-two patients were randomly allocated to either the nicardipine-sevoflurane (Group N, n = 21), remifentanil-sevoflurane (Group R, n = 21) or dexmedetomidine-sevoflurane (Group D, n = 20) group for controlled hypotension during orthognathic surgery. Electrocardiogram data acquisition was done after vital sign stabilization following anaesthesia induction (T1) and 30 min after controlled hypotension was induced (T2).

RESULTS

Total power and low frequency (LF) power was significantly decreased at T2 compared with T1 in all groups, while a decrease in high frequency (HF) power was only observed in Group N (P < 0.001). LF/HF ratios of Group R and D were significantly suppressed at T2 compared with T1 (P = 0.001 and P < 0.001, respectively), but was increased Group N (P = 0.009). The LF/HF ratio of Group N was significantly higher than Group R and D at T2 (P < 0.001 in both), with Group D showing a significantly lower LF/HF ratio compared with Group R (P < 0.001).

CONCLUSIONS

Remifentanil and dexmedetomidine did not have sympathetic nervous system-stimulating effects during controlled hypotension, while remifentanil seemed to be superior in preserving the overall balance in autonomic nervous system activity. Nicardipine was found to stimulate the sympathetic nervous system, which may be problematic in patients vulnerable to disturbances in the autonomic nervous system.

The effect of intravenous anesthetics on ischemia-reperfusion injury

The effects of intravenous anesthetics on ischemia-reperfusion injury (IRI) have been investigated in both animals and clinical studies. The protective effects and the dosages of the intravenous anesthetics on IRI were discussed in this paper. The prevention of the tissue injury after the IRI was demonstrated with intravenous anesthetics in some studies. In the future, the studies should be focused on the dosage of the anesthetics related to diminishing the tissue injuries. Further studies might be required in order to investigate the effects of the anesthetics on molecular levels.

Safety and effectiveness using dexmedetomidine versus propofol TCI sedation during oesophagus interventions: a randomized trial

Background

Endoscopic treatment of early neoplastic lesions in oesophagus has evolved as a valid and less invasive alternative to surgical resection. These endoscopic interventions are minimal invasive treatment options usually done with sedation on an outpatient basis. The aim of this trial is to determine the safety and effectiveness of dexmedetomidine sedation compared to the standard used propofol TCI sedation during endoscopic oesophageal interventions.

Methods

The study will be performed as a randomized controlled trial. The first 64 consenting patients will be randomized to either the propofol or the dexmedetomidine group. Following endoscopy patients and gastroenterologists have to fill in questionnaires (PSSI, CSSI) (see abbreviations) about their sedation experiences. Additionally, patients have to accomplish the Trieger test before and after the procedure. Patient monitoring includes time adapted HR, SO₂, ECG, NIBP, exCO_2, NICO, sweat conductance measurement, OAA/S, and the Aldrete score. Effectiveness of sedation, classified by satisfaction levels and pain and sedation score measured by questionnaires is the primary outcome parameter. Respiratory and hemodynamic complications are surrogate parameters for the secondary outcome parameter “safety”.

Discussion

The acceptance level among patients after propofol sedation is high. Dexmedetomidine is a relatively new representative for procedural sedation. Has this new form of conscious sedation the potential to be safer and more effective for patients and endoscopists than propofol during endoscopic oesophageal interventions?

Trial registration

This trial is registered in the ISRCTN Register (ISRCTN 68599804). It will be conducted in accordance with the protocol and in compliance with the moral, ethical, and scientific principles governing clinical research as set out in the Declaration of Helsinki (1989) and Good Clinical Practice (GCP). The Departments of Anesthesiology and Gastroenterology & Hepatology of the Academic Medical Center of Amsterdam are responsible for the design and conduct of the trial.