A phase II study to evaluate the efficacy of dexmedetomidine for sedation in the medical intensive care unit

Use of dexmedetomidine in patients with sepsis: a systematic review and meta-analysis of randomized-controlled trials

Background

Dexmedetomidine is widely used in patients with sepsis. However, its effect on septic patients remains controversial. The objective of this study was to summarize all randomized controlled trials (RCTs) examining dexmedetomidine use in sepsis patients.

Methods

This systematic review and meta-analysis included RCTs comparing dexmedetomidine with other sedatives in adult sepsis patients. We generated pooled relative risks (RRs) and standardized mean differences and performed trial sequential analysis and a cumulative meta-analysis. The primary outcome was mortality, and the secondary outcomes were the length of the intensive care unit stay, duration of mechanical ventilation, number of ventilation-free days, incidence of total adverse event, incidence of delirium, and levels of interleukin 6, tumor necrosis factor alpha, and alanine aminotransferase.

Results

We included 19 RCTs that enrolled 1929 patients. Compared with other sedatives, dexmedetomidine decreased the all-cause mortality (RR 0.83; 95% confidence interval [CI] [0.69, 0.99]) and inflammatory response (interleukin 6 and tumor necrosis factor alpha levels at 24 h: standardized mean difference (SMD) − 2.15; 95% CI [− 3.25, − 1.05] and SMD − 1.07, 95% CI [− 1.92, − 0.22], respectively). Trial sequential analysis showed that it is not up to required information size. The overall risk adverse events was similar between dexmedetomidine and the other sedatives (RR 1.27, 95% CI [0.69, 2.36]), but dexmedetomidine increased the risk of arrhythmias (RR 1.43, 95% CI [0.59, 3.51]). Length of intensive care unit stay (SMD − 0.22; 95% CI [− 0.85, − 0.41]), duration of mechanical ventilation (SMD 0.12; 95% CI [− 1.10, 1.35]), incidence of delirium (RR 0.98; 95% CI [0.72, 1.33]), and levels of alanine aminotransferase and creatinine at 24 h were not significantly reduced.

Conclusions

Dexmedetomidine in sepsis patients could significantly reduce mortality compared with benzodiazepines but not with propofol. In addition, dexmedetomidine can significantly decrease inflammatory response in patients with sepsis compared with other sedatives. Dexmedetomidine might lead to an increased incidence of arrhythmias, but its safety profile did not show significant differences in the incidence of total adverse events. Future RCTs are needed to determine the sepsis patient population that would benefit most from dexmedetomidine and its optimal dosing regimen.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01052-2.

Anesthetic Stability of Propofol, Dexmedetomidine, and Isoflurane by Measuring Bispectral Index (BIS) and Hemodynamic Indices: A Comparative Study

Background

Hemodynamic changes and anesthetic awareness occurring during surgery under general anesthesia is a great concern for both surgeon and anesthesiologist. Maintenance of the adequate depth of anesthesia throughout the intraoperative period is important in maintaining hemodynamic stability, preventing intraoperative awareness, and avoiding postoperative recall.

Aim

This study aims to predict the anesthetic stability of propofol, dexmedetomidine, and isoflurane by measuring bispectral index (BIS) and hemodynamic indices.

Materials and methods

This is a prospective comparative study. Sixty patients of either sex, aged 18-60 years, with American Society of Anesthesiologist (ASA) physical status classification I and II, undergoing elective surgical procedures requiring general anesthesia were allocated into three groups of 20 each. Patients in each group were administered standard general anesthesia with routine hemodynamic monitoring along with BIS, and values were recorded at baseline and thereafter at every five-minute interval for the duration of surgery. Anesthesia was maintained in Group P using a bolus dose of propofol 1 milligram.kg^-1 for 10 minutes followed by propofol infusion 50-75 microgram.kg^-1.minute^-1, Group D with a bolus dose of dexmedetomidine 1 microgram.kg^-1 for 10 minutes followed by infusion 0.2-0.7 microgram.kg^-1.hour^-1, and Group I with isoflurane at 1 minimum alveolar concentration (MAC) for 10 minutes and then maintained between 0.5 MAC and 1.5 MAC until the duration of surgery. To maintain the surgical plane of anesthesia, the BIS score was monitored between 40 and 65. The quantitative variables were expressed as mean±SD and compared between groups using Student’s unpaired t-test. Data analysis was done using SPSS Statistics for Windows version 20.0 (IBM Corp., Armonk, NY, USA). A p-value of <0.05 was considered statistically significant.

Results

During intergroup comparison among study drugs, the mean BIS values were statistically significant among the groups (p<0.05). Hemodynamic indices were significantly better maintained in the dexmedetomidine group as compared to the isoflurane and propofol groups throughout the intraoperative period (p<0.05).

Conclusion

Dexmedetomidine is better than propofol and isoflurane in maintaining the BIS score and hemodynamic parameters during the intraoperative period.

Sequential use of midazolam and dexmedetomidine for long-term sedation may reduce weaning time in selected critically ill, mechanically ventilated patients: a randomized controlled study

Background

Current sedatives have different side effects in long-term sedation. The sequential use of midazolam and dexmedetomidine for prolonged sedation may have distinct advantages. We aimed to evaluate the efficacy and safety of the sequential use of midazolam and either dexmedetomidine or propofol, and the use of midazolam alone in selected critically ill, mechanically ventilated patients.

Methods

This single-center, randomized controlled study was conducted in medical and surgical ICUs in a tertiary, academic medical center. Patients enrolled in this study were critically ill, mechanically ventilated adult patients receiving midazolam, with anticipated mechanical ventilation for ≥ 72 h. They passed the spontaneous breathing trial (SBT) safety screen, underwent a 30-min-SBT without indication for extubation and continued to require sedation. Patients were randomized into group M-D (midazolam was switched to dexmedetomidine), group M-P (midazolam was switched to propofol), and group M (sedation with midazolam alone), and sedatives were titrated to achieve the targeted sedation range (RASS − 2 to 0).

Results

Total 252 patients were enrolled. Patients in group M-D had an earlier recovery, faster extubation, and more percentage of time at the target sedation level than those in group M-P and group M (all P < 0.001). They also experienced less weaning time (25.0 h vs. 49.0 h; HR1.47, 95% CI 1.05 to 2.06; P = 0.025), and a lower incidence of delirium (19.5% vs. 43.8%, P = 0.002) than patients in group M. Recovery (P < 0.001), extubation (P < 0.001), and weaning time (P = 0.048) in group M-P were shorter than in group M, while the acquisition cost of sedative drug was more expensive than other groups (both P < 0.001). There was no significant difference in adverse events among these groups (all P > 0.05).

Conclusions

The sequential use of midazolam and dexmedetomidine was an effective and safe sedation strategy for long-term sedation and could provide clinically relevant benefits for selected critically ill, mechanically ventilated patients.

Trial registration

NCT02528513. Registered August 19, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03967-5.

Dexmedetomidine Preconditioning Reduces Myocardial Ischemia-Reperfusion Injury in Rats by Inhibiting the PERK Pathway

BACKGROUND

Ischemic heart disease has attracted much attention due to its high mortality rates, treatment costs and the increasing morbidity in the young population. Strategies for reperfusion have reduced mortality. However, reperfusion can lead to cardiomyocyte death and subsequent irreversible myocardial damage. At present, the timely and targeted treatment of ischemia-reperfusion (I/R) injury is often lacking.

OBJECTIVES

To evaluate if dexmedetomidine (DEX) has a protective effect in myocardiual I/R and explore the possible mechanism behind it.

METHODS

Rat hearts were perfused with a Langendorff perfusion system, and randomly assigned to five groups: control group, perfused with Krebs-Henseleit (K-H) solution for 205 minutes without ischemia; and four test groups that underwent 40 minutes of global ischemia and 120 min of reperfusion. The DEX group, the yohimbine (YOH) group and the DEX + YOH group were perfused with DEX (10 nM), YOH (1 μM) or the combination of DEX and YOH prior to reperfusion, respectively. Cardiac hemodynamics, myocardial infarct size, and myocardial histology were evaluated. The expression of glucose-related protein 78 (GRP78), protein kinase R-like ER kinase (PERK), phosphorylated PERK, eukaryotic initiation factor 2α (eIF2α), phosphorylated eIF2α, activating transcription factor 4 (ATF4), and CCAAT/enhancer-binding protein homologous protein (CHOP) were assessed. P<0.05 was considered to indicate a statistically significant difference.

RESULTS

DEX preconditioning improved the cardiac function of I/R hearts, reduced myocardial infarction, myocardial apoptosis, and the expression of GRP78, p-PERK, eIF2α, p-eIF2α, ATF4 and CHOP.

CONCLUSIONS

DEX pretreatment reduced myocardial I/R injury by suppressing apoptosis, which was induced by the PERK pathway.

Is the Sympathetic System Detrimental in the Setting of Septic Shock, with Antihypertensive Agents as a Counterintuitive Approach? A Clinical Proposition

Mortality in the setting of septic shock varies between 20% and 100%. Refractory septic shock leads to early circulatory failure and carries the worst prognosis. The pathophysiology is poorly understood despite studies of the microcirculatory defects and the immuno-paralysis. The acute circulatory distress is treated with volume expansion, administration of vasopressors (usually noradrenaline: NA), and inotropes. Ventilation and anti-infectious strategy shall not be discussed here. When circulation is considered, the literature is segregated between interventions directed to the systemic circulation vs. interventions directed to the micro-circulation. Our thesis is that, after stabilization of the acute cardioventilatory distress, the prolonged sympathetic hyperactivity is detrimental in the setting of septic shock. Our hypothesis is that the sympathetic hyperactivity observed in septic shock being normalized towards baseline activity will improve the microcirculation by recoupling the capillaries and the systemic circulation. Therefore, counterintuitively, antihypertensive agents such as beta-blockers or alpha-2 adrenergic agonists (clonidine, dexmedetomidine) are useful. They would reduce the noradrenaline requirements. Adjuncts (vitamins, steroids, NO donors/inhibitors, etc.) proposed to normalize the sepsis-evoked vasodilation are not reviewed. This itemized approach (systemic vs. microcirculation) requires physiological and epidemiological studies to look for reduced mortality.

Dexmedetomidine as an adjunctive treatment for acute asthma

Objective

This study aimed to compare the efficacy of using dexmedetomidine with salbutamol and salbutamol nebulization alone in patients with acute exacerbation of asthma presenting to the emergency department.

Methods

This clinical trial included 60 patients, in the age range of 18 to 55 years, with signs of bronchospasm presenting to the emergency department. In the intervention group, dexmedetomidine 0.5 µg/kg was injected intravenously and three doses of salbutamol nebulization were administered over 60 minutes. In the control group, salbutamol nebulization was administered for 60 minutes three times. The patient’s clinical status, based on clinical symptoms, consciousness, speech, breathing rate, heart rate, and blood pressure were recorded before the intervention, and peak expiratory flow rate and forced expiratory volume in 1 second were measured at 20, 40, and 60 minutes after intervention. Patients who did not respond to the intervention were excluded from the study within 60 minutes.

Results

The increased mean forced expiratory volume in 1 second and mean peak expiratory flow rate were found to be similar in both groups during the treatment (P=0.304). The mean systolic and diastolic blood pressure recorded at 40 and 60 minutes were significantly lower in the intervention group. During this study, no patient was excluded before 60 minutes.

Conclusion

Administration of dexmedetomidine in addition to standard salbutamol treatment has no beneficial effect in patients with acute asthma attacks and merely causes hypotension in patients.

Clonidine as a strategy for discontinuing dexmedetomidine sedation in critically ill patients: A narrative review

PURPOSE

To review the efficacy and safety of transitioning from dexmedetomidine to clonidine to facilitate weaning of patients from sedation with dexmedetomidine. There is a paucity of data describing dexmedetomidine withdrawal syndrome (DWS) as well as clonidine's place in therapy for DWS. This review will describe and analyze current literature to provide clinical recommendations.

SUMMARY

A MEDLINE literature search was performed to identify original research articles describing DWS and/or transitioning from dexmedetomidine to clonidine for the purpose of weaning patients from sedation with dexmedetomidine. Four case reports describing DWS, 3 case reports describing the use of clonidine to treat DWS, and 3 observational studies describing the use of clonidine to facilitate dexmedetomidine weaning were identified. The incidence of and risk factors for DWS are unknown; factors including patient age and dexmedetomidine infusion rate, loading dose, and discontinuation strategy have inconsistent associations with DWS. All cases of DWS have been associated with infusion durations greater than 72 hours. While there are limited data describing clonidine use for the treatment of dexmedetomidine withdrawal, clonidine appears to be beneficial for dexmedetomidine weaning and its use for that purpose has been well described. Clonidine dosages that have been assessed for discontinuing dexmedetomidine vary from 0.1 to 0.3 mg orally or enterally every 6 to 8 hours; one study assessed use of transdermal clonidine (100 µg/24 h patch). Patients with extensive cardiac comorbidities may be more susceptible to adverse effects of clonidine, which may limit the drug's use for DWS intervention.

CONCLUSION

Despite limited supportive data, clonidine provides a promising option for sedation management in adult ICU patients, with successful transitions from dexmedetomidine reported within 24 hours after clonidine initiation.

Clinical Practice: Should we Radically Alter our Sedation of Critical Care Patients, Especially Given the COVID-19 Pandemics?

The high number of patients infected with the SARS-CoV-2 virus requiring care for ARDS puts sedation in the critical care unit (CCU) to the edge. Depth of sedation has evolved over the last 40 years (no-sedation, deep sedation, daily emergence, minimal sedation, etc.). Most guidelines now recommend determining the depth of sedation and minimizing the use of benzodiazepines and opioids. The broader use of alpha-2 adrenergic agonists ('alpha-2 agonists') led to sedation regimens beginning at admission to the CCU that contrast with hypnotics+opioids ("conventional" sedation), with major consequences for cognition, ventilation and circulatory performance. The same doses of alpha-2 agonists used for 'cooperative' sedation (ataraxia, analgognosia) elicit no respiratory depression but modify the autonomic nervous system (cardiac parasympathetic activation, attenuation of excessive cardiac and vasomotor sympathetic activity). Alpha-2 agonists should be selected only in patients who benefit from their effects ('personalized' indications, as opposed to a 'one size fits all' approach). Then, titration to effect is required, especially in the setting of systemic hypotension and/or hypovolemia. Since no general guidelines exist for the use of alpha-2 agonists for CCU sedation, our clinical experience is summarized for the benefit of physicians in clinical situations in which a recommendation might never exist (refractory delirium tremens; unstable, hypovolemic, hypotensive patients, etc.). Because the physiology of alpha-2 receptors and the pharmacology of alpha-2 agonists lead to personalized indications, some details are offered. Since interactions between conventional sedatives and alpha-2 agonists have received little attention, these interactions are addressed. Within the existing guidelines for CCU sedation, this article could facilitate the use of alpha-2 agonists as effective and safe sedation while awaiting large, multicentre trials and more evidence-based medicine.

Dexmedetomidine-Associated Hyperpyrexia in Three Critically Ill Patients With Coronavirus Disease 2019

Objectives:

To present three patients with severe coronavirus disease 2019 infection who developed life-threatening hyperpyrexia while being treated with dexmedetomidine for sedation.

Data Sources:

Clinical records.

Study Selection:

Case report.

Data Extraction:

Relevant clinical information.

Data Synthesis:

We describe three patients, a 60-year-old female, 43-year-old female, and 46-year-old male, who were hospitalized in surge ICUs during the coronavirus disease 2019 pandemic in the early spring of 2020. All developed hyperpyrexia, defined as a temperature above 41.1°C, following an increase in dexmedetomidine dosing to above 1.5 µg/kg/hr. Fevers resolved following discontinuation of dexmedetomidine.

Conclusions:

While the exact mechanism of hyperpyrexia remains unclear, findings in this study suggest that high doses of dexmedetomidine infusion are associated with hyperpyrexia in a seemingly dose-dependent fashion in critically ill patients with coronavirus disease 2019. Coronavirus disease 2019 infection causes a hyperinflammatory state characterized by pro-inflammatory cytokine dysregulation. Dexmedetomidine, a centrally acting alpha-2 agonist, may alter hypothalamic temperature regulation through disturbances in neurotransmitter expression and metabolism. We postulate that the use of high-dose dexmedetomidine in a hyperinflammatory state may increase the risk of developing hyperpyrexia in this severe disease state.

Identification of risk factors for hypertension and tachycardia upon dexmedetomidine discontinuation

PURPOSE

Dexmedetomidine may cause hypertension and tachycardia upon discontinuation. Risk factors are poorly described but may include prolonged infusion, higher doses, a history of hypertension, and abrupt cessation. This study aims to identify risk factors for hypertension and tachycardia upon dexmedetomidine discontinuation.

MATERIALS/METHODS

In this single-center, case-control study, critically ill patients requiring dexmedetomidine for 6 h or more were screened for hypertension or tachycardia within 24 h of discontinuation. We compared baseline and dexmedetomidine-specific data between patients who developed hypertension or tachycardia (cases) and those who did not (controls) and used logistic regression to identify independent risk factors.

RESULTS

Of 110 patients, 35 (31.8%) experienced hypertension or tachycardia. When comparing cases to controls, the maximum dexmedetomidine dose was 0.7 and 0.75 μg/kg/h (p = .54), cumulative dose was 1174.5 and 1063.5 μg/kg/h (p = .43), and duration was 31and 23.25 h (p = .22), respectively. Only a past medical history of hypertension was an independent predictor of hypertension or tachycardia upon dexmedetomidine discontinuation.

CONCLUSIONS

Approximately one third of patients experienced hypertension or tachycardia upon dexmedetomidine discontinuation. A past medical history of hypertension was the only independent risk factor identified in this study based on the clinical data collected.

Dexmedetomidine Infusion without Loading Dose in Surgical Patients Requiring Mechanical Ventilation: Haemodynamic Effects and Efficacy

We investigated the haemodynamic effects and the efficacy of a continuous infusion of dexmedetomidine without a loading dose in 50 patients having had cardiac surgery (n=33), complex major surgery (n=9) and multiple trauma (n=8). The mean age was 60 (±16) years, and the mean APACHE II score was 13 (±5). Dexmedetomidine was commenced at an initial rate of 0.2 to 0.4 μg/kg/h (depending on whether anaesthetic or sedative agents had already been used) and rescue analgesia and sedation was administered with morphine and midazolam respectively. Propofol was used if additional sedation was needed. Sedation was targeted to a modified Motor Activity Assessment Score. Eighty percent of patients required no or “minimal” rescue therapy (<10 mg midazolam /day and/or <10 mg morphine/day and/or <100 mg propofol/day). The cardiac surgery group needed the least rescue therapy. A statistically significant but clinically unimportant reduction in mean heart rate and mean systolic blood pressure was observed over the first six hours (P<0.0001, and P=0.009 respectively). The baseline heart rate of 85 (±17) beats per minute (bpm), fell to a low of 78 (±13) bpm at four hours and then remained stable throughout the infusion period. The systolic blood pressure fell from 125 (±22) mmHg to a low of 112 (±20) mmHg at 1.5 hours with minimal change afterwards.

Dexmedetomidine was an effective sedative and analgesic in this group of complex surgical and trauma patients with pronounced benefit in the cardiac surgery group. Omitting the loading dose avoided undesirable haemodynamic effects without compromising sedation and analgesia.

Effects of dexmedetomidine infusion during spinal anesthesia on hemodynamics and sedation

Background: We evaluated the effects of intravenous dexmedetomidine during spinal anesthesia on hemodynamics, respiratory rate, oxygen saturation, sedpain, and compared them with those of saline infusion. Sixty American Society of Anesthesiologists physical status I and II cases were randomly divided into two groups. Patients were connected to the monitor after premedication, and spinal anesthesia was administered. Sensory and motor blockades were assessed using pinprick test and Bromage scale, respectively. Group I received dexmedetomidine infusion and Group II received saline infusion. Throughout the infusion process, hemodynamic data, respiratory rate, oxygen saturation, sedation, pain, Bromage score, amnesia, bispectral index, and side effects were recorded. Postoperative hemodynamic measurements, oxygen saturation, sedation, pain scores were obtained. Sedation and pain were evaluated using the Ramsay and visual analog scales, respectively. Analgesics were administered in cases with high scores on the visual analog scale. Postoperative analgesic consumption, side effects, treatments were recorded. No significant differences were found between the groups with respect to oxygen saturation, respiratory rate, pain, and side effects in the intraoperative period. Time to onset of sensorial block, maximum sensorial block, onset of motor block, and maximum motor block; bispectral index values; and apex heartbeat until 80 min of infusion, systolic arterial blood pressure until 90 min, and diastolic arterial blood pressure until 50 min were lower, whereas amnesia and sedation levels were higher in dexmedetomidine group. Postoperative pain and analgesic requirement were not different. Apex heartbeat at 15 min and systolic arterial blood pressure at 30 min were lower and sedation scores were higher in the dexmedetomidine infusion group. We demonstrated dexmedetomidine infusion had a hemodynamic depressant effect intraoperatively whereas it had no significant effect on peripheral oxygen saturation, respiratory rate, visual analog scale scores, and side effects. Dexmedetomidine infusion enhanced motor and sensory blockade quality and induced amnesia and sedation.

Building on the Shoulders of Giants: Is the use of Early Spontaneous Ventilation in the Setting of Severe Diffuse Acute Respiratory Distress Syndrome Actually Heretical?

Acute respiratory distress syndrome (ARDS) is not a failure of the neurological command of the ventilatory muscles or of the ventilatory muscles; it is an oxygenation defect. As positive pressure ventilation impedes the cardiac function, paralysis under general anaesthesia and controlled mandatory ventilation should be restricted to the interval needed to control the acute cardio-ventilatory distress observed upon admission into the critical care unit (CCU; "salvage therapy" during "shock state"). Current management of early severe diffuse ARDS rests on a prolonged interval of controlled mechanical ventilation with low driving pressure, paralysis (48 h, too often overextended), early proning and positive end-expiratory pressure (PEEP). Therefore, the time interval between arrival to the CCU and switching to spontaneous ventilation (SV) is not focused on normalizing the different factors involved in the pathophysiology of ARDS: fever, low cardiac output, systemic acidosis, peripheral shutdown (local acidosis), supine position, hypocapnia (generated by hyperpnea and tachypnea), sympathetic activation, inflammation and agitation. Then, the extended period of controlled mechanical ventilation with paralysis under general anaesthesia leads to CCU-acquired pathology, including low cardiac output, myoneuropathy, emergence delirium and nosocomial infection. The stabilization of the acute cardio-ventilatory distress should primarily itemize the pathophysiological conditions: fever control, improved micro-circulation and normalized local acidosis, 'upright' position, minimized hypercapnia, sympathetic de-activation (normalized sympathetic activity toward baseline levels resulting in improved micro-circulation with alpha-2 agonists administered immediately following optimized circulation and endotracheal intubation), lowered inflammation and 'cooperative' sedation without respiratory depression evoked by alpha-2 agonists. Normalised metabolic, circulatory and ventilatory demands will allow one to single out the oxygenation defect managed with high PEEP (diffuse recruitable ARDS) under early spontaneous ventilation (airway pressure release ventilation+SV or low-pressure support). Assuming an improved overall status, PaO₂/FiO₂≥150-200 allows for extubation and continuous non-invasive ventilation. Such fast-tracking may avoid most of the CCU-acquired pathologies. Evidence-based demonstration is required.

Outcomes When Using Adjunct Dexmedetomidine with Propofol Sedation in Mechanically Ventilated Surgical Intensive Care Patients

Objective: Compare the duration of mechanical ventilation between patients receiving sedation with continuous infusions of propofol alone or combination with the use of dexmedetomidine and propofol. Design: Retrospective, propensity matched (1:1) cohort study, employing eight variables chosen a priori for matching. Timing of exposure to dexmedetomidine initiation was incorporated into a matching algorithm. Setting: Level 1, university-based, 32-bed, adult, mixed trauma and surgical intensive care unit (SICU). Continuous sedation was delivered according to a protocol methodology with daily sedation vacation and spontaneous breathing trials. Choice of sedation agent was physician directed. Patients: Between 2010 and 2014, 149 SICU patients receiving mechanical ventilation for >24 h received dexmedetomidine with propofol. Propensity matching resulted in 143 pair cohorts. Interventions: Dexmedetomidine with propofol or propofol alone. Measurements and Main Results: There was no statistical difference in SICU length of stay (LOS), with a median absolute difference of 5.3 h for propofol alone group (p = 0.43). The SICU mortality was not statistically different (RR = 1.002, p = 0.88). Examining a 14-day period post-treatment with dexmedetomidine, on any given day (excluding days 1 and 14), dexmedetomidine with propofol-treated patients had a 0.5% to 22.5% greater likelihood of being delirious (CAM-ICU positive). In addition, dexmedetomidine with propofol-treated patients had a 4.5% to 18.8% higher likelihood of being above the target sedation score (more agitated) compared to propofol-alone patients. Conclusions: In this propensity matched cohort study, adjunct use of dexmedetomidine to propofol did not show a statistically significant reduction with respect to mechanical ventilation (MV) duration, SICU LOS, or SICU mortality, despite a trend toward receiving fewer hours of propofol. There was no evidence that dexmedetomidine with propofol improved sedation scores or reduced delirium.

Outcomes When Using Adjunct Dexmedetomidine with Propofol Sedation in Mechanically Ventilated Surgical Intensive Care Patients

Objective: Compare the duration of mechanical ventilation between patients receiving sedation with continuous infusions of propofol alone or combination with the use of dexmedetomidine and propofol. Design: Retrospective, propensity matched (1:1) cohort study, employing eight variables chosen a priori for matching. Timing of exposure to dexmedetomidine initiation was incorporated into a matching algorithm. Setting: Level 1, university-based, 32-bed, adult, mixed trauma and surgical intensive care unit (SICU). Continuous sedation was delivered according to a protocol methodology with daily sedation vacation and spontaneous breathing trials. Choice of sedation agent was physician directed. Patients: Between 2010 and 2014, 149 SICU patients receiving mechanical ventilation for >24 h received dexmedetomidine with propofol. Propensity matching resulted in 143 pair cohorts. Interventions: Dexmedetomidine with propofol or propofol alone. Measurements and Main Results: There was no statistical difference in SICU length of stay (LOS), with a median absolute difference of 5.3 h for propofol alone group (p = 0.43). The SICU mortality was not statistically different (RR = 1.002, p = 0.88). Examining a 14-day period post-treatment with dexmedetomidine, on any given day (excluding days 1 and 14), dexmedetomidine with propofol-treated patients had a 0.5% to 22.5% greater likelihood of being delirious (CAM-ICU positive). In addition, dexmedetomidine with propofol-treated patients had a 4.5% to 18.8% higher likelihood of being above the target sedation score (more agitated) compared to propofol-alone patients. Conclusions: In this propensity matched cohort study, adjunct use of dexmedetomidine to propofol did not show a statistically significant reduction with respect to mechanical ventilation (MV) duration, SICU LOS, or SICU mortality, despite a trend toward receiving fewer hours of propofol. There was no evidence that dexmedetomidine with propofol improved sedation scores or reduced delirium.

Effectivness of Clonidine in Treating Dexmedetomidine Withdrawal in a Patient with Co-Existing Psychiatric Illness: A Case Report

Patient: Female, 40

Final Diagnosis: Dexmedetomidine withdrawal

Symptoms: Severe agitation • sweating • tachycardia

Medication: —

Clinical Procedure: None

Specialty: Critical Care Medicine

Hypothesis: Fever control, a niche for alpha-2 agonists in the setting of septic shock and severe acute respiratory distress syndrome?

During severe septic shock and/or severe acute respiratory distress syndrome (ARDS) patients present with a limited cardio-ventilatory reserve (low cardiac output and blood pressure, low mixed venous saturation, increased lactate, low PaO2/FiO2 ratio, etc.), especially when elderly patients or co-morbidities are considered. Rescue therapies (low dose steroids, adding vasopressin to noradrenaline, proning, almitrine, NO, extracorporeal membrane oxygenation, etc.) are complex. Fever, above 38.5-39.5°C, increases both the ventilatory (high respiratory drive: large tidal volume, high respiratory rate) and the metabolic (increased O2 consumption) demands, further limiting the cardio-ventilatory reserve. Some data (case reports, uncontrolled trial, small randomized prospective trials) suggest that control of elevated body temperature ("fever control") leading to normothermia (35.5-37°C) will lower both the ventilatory and metabolic demands: fever control should simplify critical care management when limited cardio-ventilatory reserve is at stake. Usually fever control is generated by a combination of general anesthesia ("analgo-sedation", light total intravenous anesthesia), antipyretics and cooling. However general anesthesia suppresses spontaneous ventilation, making the management more complex. At variance, alpha-2 agonists (clonidine, dexmedetomidine) administered immediately following tracheal intubation and controlled mandatory ventilation, with prior optimization of volemia and atrio-ventricular conduction, will reduce metabolic demand and facilitate normothermia. Furthermore, after a rigorous control of systemic acidosis, alpha-2 agonists will allow for accelerated emergence without delirium, early spontaneous ventilation, improved cardiac output and micro-circulation, lowered vasopressor requirements and inflammation. Rigorous prospective randomized trials are needed in subsets of patients with a high fever and spiraling toward refractory septic shock and/or presenting with severe ARDS.

Dose-related effects of dexmedetomidine on immunomodulation and mortality to septic shock in rats

BACKGROUND

Dexmedetomidine has already been used in septic patients as a new sedative agent, few studies have examined its effects on immunomodulation. Therefore, the authors have designed a controlled experimental study to characterize the immunomodulation effects of dexmedetomidine in the cecal ligation and puncture (CLP) model in rats.

METHODS

After CLP, 48 Wistar rats were randomly allocated into four groups: (1) CLP group; (2) small-dose treatment group (2.5 μg·kg^-1·h^-1); (3) medium-dose treatment group (5.0 μg·kg^-1· h^-1); and (4) large-dose treatment group (10.0 μg·kg^-1·h^-1). HLA-DR and plasma cytokine (IL-4, IL-6, IL-10 and TNF-α) levels were measured, and the mean arterial blood pressure (MAP), heart rate (HR), arterial blood gases, lactate concentrations and mortality were also documented.

RESULTS

The HLA-DR level, inflammatory mediator levels, MAP and HR had no obvious changes among Dexmedetomidine treatment groups (DEX groups). Compared with the CLP group, the DEX groups exhibited decreased HLA-DR levels (P_group=0.0202) and increased IL-6 production, which was increased at 3 h (P= 0.0113) and was then attenuated at 5 h; additionally, the DEX groups exhibited decreased HR (P<0.001) while maintaining MAP (P_group=0.1238), and remarkably improving lactate (P<0.0001). All of these factors led to a significant decrease in the mortality, with observed rates of 91.7%, 66.7%, 25% and 18% for the CLP, DEX2.5, DEX5.0, DEX10.0 groups, respectively.

CONCLUSION

Dexmedetomidine treatment in the setting of a CLP sepsis rat model has partially induced immunomodulation that was initiated within 5 h, causing a decreased HR while maintaining MAP, remarkably improving metabolic acidosis and improving mortality dose-dependently.

Effects of dexmedetomidine on sleep quality of patients after surgery without mechanical ventilation in ICU

Sleep quality of patients in intensive care unit (ICU) has been recently recognized as an important aspect of the intensive care. Dexmedetomidine is one of the most recently introduced for sedation in the ICU. This study was designed to evaluate the effect of dexmedetomidine on sleep quality of patients without mechanical ventilation in ICU.The patients who were included in this study were divided into two groups. In the sedation group, dexmedetomidine was given by a continuous infusion targeting a sedation level -1 to -2 on the score of RASS (Richmond Agitation-Sedation Scale). In the no sedation group, the patients slept by themselves. No other sedatives were given. Bispectral Index (BIS) was performed on these hemodynamically stable critically ill patients for 12 consecutive hours. Sleep time and sleep depth were recorded.Twenty patients were studied. Compared to no sedation group, sleep efficiency and sleep time of patients in the sedation group was significantly higher during the night. Moreover, there was no significantly difference between the changes of blood pressure, heart rate, and respiratory rate.Dexmedetomidine is a clinically effective and safe sedative for the highly selected critically ill patients without endotracheal tube and mechanical ventilation in the ICU to increases total sleep time and improve sleep efficiency.

Efficacy of Prophylactic Dexmedetomidine in Preventing Postoperative Junctional Ectopic Tachycardia After Pediatric Cardiac Surgery

BACKGROUND

Postoperative junctional ectopic tachycardia is one of the most serious arrhythmias that occur after pediatric cardiac surgery, difficult to treat and better to be prevented. Our aim was to assess the efficacy of prophylactic dexmedetomidine in preventing junctional ectopic tachycardia after pediatric cardiac surgery.

METHODS AND RESULTS

A prospective controlled study was carried out on 90 children who underwent elective cardiac surgery for congenital heart diseases. Patients were randomized into 2 groups. Group I (dexmedetomidine group): 60 patients received dexmedetomidine; Group II (Placebo group): 30 patients received the same amount of normal saline intravenously. The primary outcome was the incidence of postoperative junctional ectopic tachycardia. Secondary outcomes included bradycardia, hypotension, vasoactive inotropic score, ventilation time, pediatric cardiac care unit stay, length of hospital stay, and perioperative mortality. The incidence of junctional ectopic tachycardia was significantly reduced in the dexmedetomidine group (3.3%) compared with the placebo group (16.7%) with P<0.005. Heart rate while coming off cardiopulmonary bypass was significantly lower in the dexmedetomidine group (130.6±9) than the placebo group (144±7.1) with P<0.001. Mean ventilation time, and mean duration of intensive care unit and hospital stay (days) were significantly shorter in the dexmedetomidine group than the placebo group (P<0.001). However, there was no significant difference between the 2 groups as regards mortality, bradycardia, or hypotension (P>0.005).

CONCLUSION

Prophylactic use of dexmedetomidine is associated with significantly decreased incidence of postoperative junctional ectopic tachycardia in children after congenital heart surgery without significant side effects.

Neurocritical Care of Acute Subdural Hemorrhage

Although urgent surgical hematoma evacuation is necessary for most patients with subdural hematoma (SDH), well-orchestrated, evidenced-based, multidisciplinary, postoperative critical care is essential to achieve the best possible outcome. Acute SDH complicates approximately 11% of mild to moderate traumatic brain injuries (TBIs) that require hospitalization, and approximately 20% of severe TBIs. Acute SDH usually is related to a clear traumatic event, but in some cases can occur spontaneously. Management of SDH in the setting of TBI typically conforms to the Advanced Trauma Life Support protocol with airway taking priority, and management breathing and circulation occurring in parallel rather than sequence.

Analgesia in the surgical intensive care unit

Critically ill patients are a heterogeneous group with diverse comorbidities and physiological derangements. The management of pain in the critically ill population is emerging as a standard of care in the intensive care unit (ICU). Pain control of critically ill patients in the ICU presents numerous challenges to intensivists. Inconsistencies in pain assessment, analgesic prescription and variation in monitoring sedation and analgesia result in suboptimal pain management. Inadequate pain control can have deleterious effects on several organ systems in critically ill patients. Therefore, it becomes incumbent on physicians and nurses caring for these patients to carefully evaluate their practice on pain management and adopt an optimal pain management strategy that includes a reduction in noxious stimuli, adequate analgesia and promoting education regarding sedation and analgesia to the ICU staff. Mechanistic approaches and multimodal analgesic techniques have been clearly demonstrated to be the most effective pain management strategy to improve outcomes. For example, recent evidence suggests that the use of short acting analgesics and analgesic adjuncts for sedation is superior to hypnotic based sedation in intubated patients. This review will address analgesia in the ICU, including opioid therapy, adjuncts, regional anaesthesia and non-pharmacological options that can provide a multimodal approach to treating pain.

The efficacy of pre-emptive dexmedetomidine versus amiodarone in preventing postoperative junctional ectopic tachycardia in pediatric cardiac surgery

OBJECTIVE

The objective of this study was to assess the effectiveness of pre-emptive dexmedetomidine versus amiodarone in preventing junctional ectopic tachycardia (JET) in pediatric cardiac surgery.

DESIGN

This is a prospective, controlled study.

SETTING

This study was carried out at a single university hospital.

SUBJECTS AND METHODS

Ninety patients of both sexes, American Society of Anesthesiologists Physical Status II and III, age range from 2 to 18 years, and scheduled for elective cardiac surgery for congenital and acquired heart diseases were selected as the study participants.

INTERVENTIONS

Patients were randomized into three groups (30 each). Group I received dexmedetomidine 1 mcg/kg diluted in 100 ml of normal saline intravenously (IV) over a period of 20 min, and the infusion was completed 10 min before the induction followed by a 0.5 mcg/kg/h infusion for 72 h postoperative, Group II received amiodarone 5 mg/kg diluted in 100 ml of normal saline IV over a period of 20 min, and the infusion was completed 10 min before the induction followed by a 10-15 mcg/kg/h infusion for 72 h postoperative, and Group III received 100 ml of normal saline IV. Primary outcome was the incidence of postoperative JET. Secondary outcomes included vasoactive-inotropic score, ventilation time (VT), pediatric cardiac care unit stay, hospital length of stay, and perioperative mortality.

MEASUREMENTS AND MAIN RESULTS

The incidence of JET was significantly reduced in Group I and Group II (P = 0.004) compared to Group III. Heart rate while coming off from cardiopulmonary bypass (CPB) was significantly low in Group I compared to Group II and Group III (P = 0.000). Mean VT, mean duration of Intensive Care Unit stay, and length of hospital stay (day) were significantly short (P = 0.000) in Group I and Group II compared to Group III (P = 0.000).

CONCLUSION

Perioperative use of dexmedetomidine and amiodarone is associated with significantly decreased incidence of JET as compared to placebo without significant side effects.

Pharmacokinetics and pharmacodynamics of dexmedetomidine

Dexmedetomidine is an alpha-2 adrenoceptor agonist and has been used as a general anesthetic, sedative and analgesic for about 30 years. The aim of this paper is to review the pharmacokinetics and pharmacodynamics of dexmedetomidine, evaluate physiological factors that may affect the pharmacokinetics of dexmedetomidine, and summarize the pharmacodynamics of dexmedetomidine at different plasma levels. The pharmacokinetic parameters reported in previous studies according to noncompartmental analyses or population modeling results are compared. We concluded that the pharmacokinetic profile can be adequately described by a two-compartment model in population pharmacokinetic modeling. Body weight, height, albumin level, cardiac output, disease condition and other factors were considered to have significant influence on the clearance and/or distribution volume in different population pharmacokinetic models. The pharmacological effects of dexmedetomidine, such as sedation, heart rate reduction and biphasic change of blood pressure, vary at different plasma levels. These findings provide a reference for individualizing the dose of dexmedetomidine and achieving the desired pharmacological effects in clinical applications.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effect of dexmeditomidine on postoperative junctional ectopic tachycardia after complete surgical repair of tetralogy of Fallot: A prospective randomized controlled study

Introduction:

Incidence of junctional ectopic tachycardia (JET) after repair of tetralogy of Fallot (TOF) is 5.6–14%. Dexmeditomidine is a α-2 adrenoceptor agonist modulates the release of catecholamine, resulting in bradycardia and hypotension. These effects are being explored as a therapeutic option for the prevention of perioperative tachyarrhythmia. We undertook this study to examine possible preventive effects of dexmedetomidine on postoperative JET and its impact on the duration of ventilation time and length of Intensive Care Unit stay.

Methods:

After obtaining approval from the hospitals ethics committee and written informed consent from parents, this quasi-randomized trial was initiated. Of 94 patients, 47 patients received dexmedetomidine (dexmedetomidine group) and 47 patients did not receive the drug (control group).

Results:

Dexmedetomidine group had more number of complex variants like TOF with an absent pulmonary valve or pulmonary atresia (P = 0.041). Hematocrit on cardiopulmonary bypass (CPB), heart rate while coming off from CPB and inotrope score was significantly low in the dexmedetomidine group compared to control group. The incidence of JET was significantly low in dexmedetomidine group (P = 0.040) compared to control group.

Conclusions:

Dexmedetomidine may have a potential benefit of preventing perioperative JET.

Dexmedetomidine as an adjunct in postoperative analgesia following cardiac surgery: A randomized, double-blind study

Objectives:

The purpose of this study was to determine analgesic efficacy of dexmedetomidine used as a continuous infusion without loading dose in postcardiac surgery patients.

Settings and Design:

A prospective, randomized, double-blind clinical study in a single tertiary care hospital on patients posted for elective cardiac surgery under cardiopulmonary bypass.

Interventions:

Sixty-four patients who underwent elective cardiac surgery under general anesthesia were shifted to intensive care unit (ICU) and randomly divided into two groups. Group A (n = 32) received a 12 h infusion of normal saline and group B (n = 32) received a 12 h infusion of dexmedetomidine 0.4 μg/kg/h. Postoperative pain was managed with bolus intravenous fentanyl. Total fentanyl consumption, hemodynamic monitoring, Visual Analogue Scale (VAS) pain ratings, Ramsay Sedation Scale were charted every 6^th hourly for 24 h postoperatively and followed-up till recovery from ICU. Student's t-test, Chi-square/Fisher's exact test has been used to find the significance of study parameters between the groups.

Results:

Dexmedetomidine treated patients had significantly less VAS score at each level (P < 0.001). Total fentanyl consumption in dexmedetomidine group was 128.13 ± 35.78 μg versus 201.56 ± 36.99 μg in saline group (P < 0.001). A statistically significant but clinically unimportant sedation was noted at 6 and 12 h (P < 0.001, and P = 0.046 respectively). Incidence of delirium was less in dexmedetomidine group (P = 0.086+). Hemodynamic parameters were statistically insignificant.

Conclusions:

Dexmedetomidine infusion even without loading dose provides safe, effective adjunct analgesia, reduces narcotic consumption, and showed a reduced trend of delirium incidence without undesirable hemodynamic effects in the cardiac surgery patients.

A new approach to the prevention and treatment of delirium in elderly patients in the intensive care unit

The pronounced prevalence of delirium in geriatric patients admitted to the intensive care unit (ICU) and its increased morbidity and mortality is a well-established phenomenon. The purpose of this review is to explore the potential use of dexmedetomidine in preventing or managing ICU delirium in older patients. Articles used were identified and selected through multiple search engines, including Google Scholar, PubMed, and MEDLINE. Keywords such as dexmedetomidine, delirium, geriatric, ICU delirium, delirium in elderly, and palliative were used to obtain the specific articles used for this paper and restricted to articles published in 1990 or later. Articles specifically looking at the use of dexmedetomidine as compared to a study drug and its potential for use in ICU patients, as opposed to overall reviews of dexmedetomidine, were compared. When compared to benzodiazepines for the prevention or treatment of ICU delirium in the elderly, dexmedetomidine was associated with a reduction in delirium, as well as decreased morbidity and mortality. Dexmedetomidine has also been shown to be effective in limiting risk factors associated with ICU delirium such as length and depth of sedation. As opposed to benzodiazepines or opiates, dexmedetomidine provides effective analgesia, sympatholysis, and anxiolysis without causing respiratory depression and allows a patient to more effectively interact with practitioners. The review of these nine articles indicates that these favorable attributes and overall decreased duration and incidence of delirium make dexmedetomidine a viable option in preventing or reducing ICU delirium in high-risk geriatric patients and as a palliative adjunct to help control symptoms and stressors.

Different effects of propofol and dexmedetomidine on preload dependency in endotoxemic shock with norepinephrine infusion

BACKGROUND

To clarify whether propofol (PROP) and dexmedetomidine (DEX) differentially affect preload dependency in an endotoxemic model based on evaluations of the systemic vascular system and cardiac function.

METHODS

Animals were prepared under PiCCO monitoring (BL), and endotoxemic shock was induced using an intravenous bolus of lipopolysaccharide (055:B5) in 16 New Zealand ketamine-anesthetized rabbits. After fluid resuscitation and norepinephrine infusion (SD0), the animals were randomized to PROP (n = 8) or DEX (n = 8) sedation at two incremental doses (SD1 and SD2). The mean arterial pressure and the central venous pressure were monitored. Pulse pressure variation (PPV) was assessed to evaluate preload dependency. Global end-diastolic volume, vascular resistance, mean systemic filling pressure, and cardiac function index were assessed at each time point.

RESULTS

PPV progressively and significantly increased with increasing infusion rates of PROP (SD1 versus SD0, P < 0.01; SD2 versus SD0, P < 0.001; and SD2 versus SD1, P = 0.024) but not DEX. PPV was higher at SD1 and SD2 in the PROP group than in the DEX group (P < 0.001). PROP increased the heart rate without affecting cardiac contractility or vascular resistance. In contrast, DEX decreased heart contractility and increased vascular resistance at the highest dose. However, neither drug affected mean arterial pressure, central venous pressure, mean systemic filling pressure, global end-diastolic volume, or venous return.

CONCLUSIONS

PROP more effectively increased PPV than DEX in an endotoxemic shock model after fluid resuscitation during norepinephrine infusion. DEX, but not PROP, at the highest dose influenced vascular resistance and heart contractility.

Dexmedetomidine attenuates the microcirculatory derangements evoked by experimental sepsis

BACKGROUND

Dexmedetomidine, an α-2 adrenergic receptor agonist, has already been used in septic patients although few studies have examined its effects on microcirculatory dysfunction, which may play an important role in perpetuating sepsis syndrome. Therefore, the authors have designed a controlled experimental study to characterize the microcirculatory effects of dexmedetomidine in an endotoxemia rodent model that allows in vivo studies of microcirculation.

METHODS

After skinfold chamber implantation, 49 golden Syrian hamsters were randomly allocated in five groups: (1) control animals; (2) nonendotoxemic animals treated with saline; (3) nonendotoxemic animals treated with dexmedetomidine (5.0 μg kg h); (4) endotoxemic (lipopolysaccharide 1.0 mg/kg) animals treated with saline; and (5) endotoxemic animals treated with dexmedetomidine. Intravital microscopy of skinfold chamber preparations allowed quantitative analysis of microvascular variables and venular leukocyte rolling and adhesion. Mean arterial blood pressure, heart rate, arterial blood gases, and lactate concentrations were also documented.

RESULTS

Lipopolysaccharide administration increased leukocyte rolling and adhesion and decreased capillary perfusion. Dexmedetomidine significantly attenuated these responses: compared with endotoxemic animals treated with saline, those treated with dexmedetomidine had less leukocyte rolling (11.8 ± 7.2% vs. 24.3 ± 15.0%; P < 0.05) and adhesion (237 ± 185 vs. 510 ± 363; P < 0.05) and greater functional capillary density (57.4 ± 11.2% of baseline values vs. 45.9 ± 11.2%; P < 0.05) and erythrocyte velocity (68.7 ± 17.6% of baseline values vs. 54.4 ± 14.8%; P < 0.05) at the end of the experiment.

CONCLUSIONS

Dexmedetomidine decreased lipopolysaccharide-induced leukocyte-endothelial interactions in the hamster skinfold chamber microcirculation. This was accompanied by a significant attenuation of capillary perfusion deficits, suggesting that dexmedetomidine yields beneficial effects on endotoxemic animals' microcirculation.

Effects of Clonidine on Withdrawal From Long-term Dexmedetomidine in the Pediatric Patient

OBJECTIVE

To compare withdrawal symptoms among pediatric intensive care patients receiving clonidine to those not receiving clonidine while being weaned from long-term dexmedetomidine.

METHODS

This retrospective analysis evaluated Withdrawal Assessment Tool-1 (WAT-1) scores and hemodynamic parameters in pediatric patients on dexmedetomidine for 5 days or longer between January 1, 2009, and December 31, 2012. The primary objective was to compare withdrawal symptoms based on the number of elevated WAT-1 scores among patients on clonidine to those not on clonidine, while being weaned from long-term dexmedetomidine. The secondary objective was to describe withdrawal symptoms associated with long-term dexmedetomidine use.

RESULTS

Nineteen patients (median age, 1.5 years; interquartile range [IQR], 0.67-3.3) received 20 treatment courses of dexmedetomidine for at least 5 days. Clonidine was received by patients during 12 of the treatment courses. The patients in the clonidine group had an average of 0.8 (range, 0-6) elevated WAT-1 scores 24 hours post wean compared to an average of 3.2 (0-8) elevated WAT-1 scores in the no clonidine group (p = 0.49). There were no significant difierences between prewean and postwean systolic or diastolic blood pressures among the 2 groups. The average heart rate during the postwean period was 112 beats per minute (bpm) (range, 88.5-151.5) in the clonidine group compared to 138.4 bpm (range, 117.8-168.3) in the no clonidine group (p = 0.003). In the clonidine group, the mean change in heart rate postwean compared to prewean was an increase of 3.6 bpm (range, -39.6 to 47.5), compared to a mean increase of 29.9 bpm (range, 5.5-74.7) in the no clonidine group (p = 0.042).

CONCLUSIONS

There was no difierence in WAT-1 scores between groups, with the clonidine group displaying a trend towards fewer elevated WAT-1 scores during the 24 hours post dexmedetomidine wean. Patients who received clonidine had significantly lower heart rates than the no clonidine group.

Comparison of clonidine and dexmedetomidine for short-term sedation of intensive care unit patients

BACKGROUND AND OBJECTIVES

Patients on mechanical ventilation in intensive care unit (ICU) are often uncomfortable because of anxiety, pain, and endotracheal intubation; therefore, require sedation. Alpha-2 agonists are known to produce sedation. We compared clonidine and dexmedetomidine as sole agents for sedation.

STUDY DESIGN

Prospective, randomized, controlled open-label study.

MATERIALS AND METHODS

A total of 70 patients requiring a minimum of 12 h of mechanical ventilation with concomitant sedation, were randomly allocated into two groups. Group C (n = 35) received intravenous (IV) clonidine (1 μg/kg/h titrated up to 2 μg/kg/h to attain target sedation), and Group D (n = 35) received IV dexmedetomidine for sedation (loading 0.7 μg/kg and maintenance 0.2 μg/kg/h titrated up to 0.7 μg/kg/h to achieve target sedation). A Ramsay Sedation Score of 3-4 was considered as target sedation. Additional sedation with diazepam was given when required to achieve target sedation. The quality of sedation, hemodynamic changes and adverse effects were noted and compared between the two groups.

RESULTS

Target sedation was achieved in 86% observations in Group D and 62% in Group C (P = 0.04). Additional sedation was needed by more patients in Group C compared with Group D (14 and 8 in Groups C and D, respectively, P = 0.034), mainly due to concomitant hypotension on increasing the dose of clonidine. Hypotension was the most common side-effect in Group C, occurring in 11/35 patients of Group C and 3/35 patients of Group D (P = 0.02). Rebound hypertension was seen in four patients receiving clonidine, but none in receiving dexmedetomidine.

CONCLUSION

Both clonidine and dexmedetomidine produced effective sedation; however, the hemodynamic stability provided by dexmedetomidine gives it an edge over clonidine for short-term sedation of ICU patients.

The effects of preemptive tramadol and dexmedetomidine on shivering during arthroscopy

Background:

Shivering, the rate of which in regional anesthesia is 39% is an undesired complication seen postoperatively.

Aims:

This study aims to compare the ability of preventing the shivering of preemptive tramadol and dexmedetomidine during the spinal anesthesia (SA).

Methods:

A total of 90 patients with American Society of Anesthesiologists physical status I-II, aged 18-60 years and undergoing elective arthroscopic surgery with SA were divided into three groups randomly. After spinal block, 100 mg tramadol in 100 ml saline was applied in group T- (n = 30) and 0.5 μg/kg dexmedetomidine in 100 ml saline was applied in group D- (n = 30) and 100 ml saline was administered in group P- (n = 30) in 10 min. The hemodynamics, oxygen saturation, tympanic temperature, shivering and sedation scores were evaluated and recorded intraoperatively and 45 min after a postoperative period.

Results:

In group T and D, shivering scores were significantly lower when compared with group P in the intraoperative 20^th min (P = 0.01). Sedation scores in group D were significantly higher than the baseline values (P = 0.03) and values in group T and P (P = 0.04).

Conclusions:

Preemptive tramadol and dexmedetomidine are effective in preventing the shivering under SA. In addition, dexmedetomidine was superior in increasing the level of sedation which is sufficient to prevent the anxiety without any adverse effects.

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 as an adjunct to epidural analgesia after abdominal surgery in elderly intensive care patients: A prospective, double-blind, clinical trial

BACKGROUND

The ideal postoperative analgesia management of elderly surgical patients in intensive care units (ICUs) is continually being investigated.

OBJECTIVE

The purpose of this study was to assess the effectiveness and tolerability of IV administration of dexmedetomidine as an adjunct to a low-dose epidural bupivacaine infusion for postoperative analgesia after abdominal surgery in elderly patients in the ICU.

METHODS

ICU patients aged >70 years undergoing abdominal surgery were eligible for the study. A lumbar epidural catheter was inserted at the beginning of the surgery with no medication. On arrival at the ICU, the catheter was loaded with 0.25% bupivacaine 25 mg at the T8 to T10 sensory level, and a continuous infusion of 0.125% bupivacaine was started at 4 to 6 mL/h in combination with patient-controlled epidural analgesia (PCEA) of fentanyl (4 μg/bolus) for pain treatment. Patients in the treatment group received dexmedetomidine as an IV loading dose of 0.6 pg/kg for 30 minutes followed by continuous infusion at 0.2 μg/kg · h(-1). Patients in the control group were not administered dexmedetomidine. The effectiveness of the pain relief was determined using a visual analog scale (VAS) (0 = no pain to 10 = worst pain imaginable) at rest. VAS score, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure, and arterial blood gases were monitored periodically for 24 hours after surgery. If required, tenoxicam (20-mg IV bolus) was used to ensure a VAS score of ≤3. The number of times PCEA and tenoxicam were administered and the occurrence of adverse events (AEs) were also recorded.

RESULTS

Sixty patients (34 men, 26 women; mean [SD] age, 75.96 [4.25] years; mean [SD] weight, 74.13 [10.62] kg) were included in the study. VAS scores were significantly lower in the dexmedetomidine group compared with the control group at hours 1, 2, and 12 (VAS [hour 1]: 2.8 [0.4], P < 0.001; VAS [hour 2]: 2.7 [0.5], P < 0.001; and VAS [hour 12]: 0.9 [0.7], P 0.044). The mean number of administrations of fentanyl via PCEA was significantly greater in the control group compared with the dexmedetomidine group (2.20 vs 6.63 times; P < 0.001). The mean number of administrations of tenoxicam was significantly lower in the treatment group than the control group (0.27 vs 1.07 times; P < 0.001). In the control group, the decreases in sedation at 0, 8, 12, 16, and 20 hours were significant compared with baseline (P = 0.024, P = 0.001, P = 0.020, P < 0.001, and P = 0.005, respectively). Mean HR, SBR and AEs (eg, bradycardia [HR <60 beats/min], respiratory depression [respiratory rate <8 breaths/min], hypotension \SBP <90 mm Hg], oversedation, hypoxia, and hypercapnia) decreased significantly in the dexmedetomidine group (all, P < 0.05). Significantly more patients in the dexmedetomidine group rated their satisfaction with postoperative pain control as excellent compared with the control group (12 vs 6 patients; P = 0.014).

CONCLUSION

Intravenous dexmedetomidine was effective and generally well tolerated as an analgesic adjunct to epidural low-dose bupivacaine infusion for pain treatment, with lower need for opioids after abdominal surgery in these elderly intensive care patients than in the control group.

Population pharmacokinetics of dexmedetomidine in critically ill patients

Background and Objectives

Although the pharmacokinetics of dexmedetomidine in healthy volunteers have been studied, there are limited data about the pharmacokinetics of long-term administration of dexmedetomidine in critically ill patients.

Methods

This population pharmacokinetic analysis was performed to quantify the pharmacokinetics of dexmedetomidine in critically ill patients following infusions up to 14 days in duration. The data consisted of three phase III studies (527 patients with sparse blood sampling, for a total of 2,144 samples). Covariates were included in a full random-effects covariate model and the most important covariate relationships were tested separately. The linearity of dexmedetomidine clearance was evaluated by observing steady-state plasma concentrations acquired at various infusion rates.

Results

The data were adequately described with a one-compartment model. The clearance of dexmedetomidine was 39 (95 % CI 37–41) L/h and volume of distribution 104 (95 % CI 93–115) L. Both clearance and volume of distribution were highly variable between patients (coefficients of variation of 62 and 57 %, respectively), which highlights the importance of dose titration by response. Covariate analysis showed a strong correlation between body weight and clearance of dexmedetomidine. The clearance of dexmedetomidine was constant in the dose range 0.2–1.4 μg/kg/h.

Conclusions

The pharmacokinetics of dexmedetomidine are dose-proportional in prolonged infusions when dosing rates of 0.2–1.4 μg/kg/h, recommended by the Dexdor^® summary of product characteristics, are used.

A case-based approach to the practical application of dexmedetomidine in critically ill adults

Dexmedetomidine is a selective α(2) -adrenoceptor agonist that offers unique sedation because patients are readily awakened while administration continues and the drug does not suppress the respiratory center. Limitations of use include higher acquisition cost, inability to produce deep sedation, and bradycardia and hypotension. Using a case-based approach, the purpose of this review was to qualitatively assess the role of dexmedetomidine in the care of the critically ill and in the management of alcohol withdrawal, and to formulate recommendations regarding its clinical application. Sixty-six studies were identified that investigated dexmedetomidine for the provision of sedation. These studies were heterogeneous in design and patient populations; most investigated patients did not require heavy sedation, and few used propofol as the comparator. In general, though, the aggregate results of all studies demonstrate that dexmedetomidine provides comfort, possibly shortens the duration of mechanical ventilation to facilitate extubation, reduces the occurrence of acute brain dysfunction, and facilitates communication, but the drug is associated with hemodynamic instability and requires the supplemental use of traditional sedative and analgesic agents. These outcomes need to be substantiated in additional studies that include assessments of cost-effectiveness. Dexmedetomidine should be considered when patients require mild to moderate levels of sedation of short to intermediate time frames, and they qualify for daily awakenings with traditional sedative therapies. The data for dexmedetomidine in relation to alcohol withdrawal are limited to 12 retrospective reports representing a total of 127 patients. Its role for this indication requires further study, but it may be considered as adjunctive therapy when clinicians are concerned about respiratory suppression associated with escalating doses of γ-aminobutyric acid agonists. Regardless of the indication for dexmedetomidine, the practitioner must closely monitor patient comfort and the occurrence of hemodynamic deviations with the realization that as-needed administration of traditional sedatives and analgesics will be required and some degree of bradycardia and hypotension expected but intervention rarely required.

Dexmedetomidine overdosage: An unusual presentation

We present a case of dexmedetomidine toxicity in a 3-year-old child. The case report describes the features and outlines the treatment strategy adopted. The child presented with bradypnoea, bradycardia, hypotension, deep hypnosis and miosis. He was successfully managed with oxygen, saline boluses and adrenaline infusion. He became haemodynamically stable with adrenaline infusion. He started responding to painful stimuli in 3 h and became oriented in 7 h. Dexmedetomidine, a selective α₂ adrenoceptor agonist, is claimed to have a wide safety margin. This case report highlights the fact that dexmedetomidine administered in a toxic dose may be life-threatening may present with miosis and adrenaline infusion may be a useful supportive treatment.

Dexmedetomidine infusion associated with transient adrenal insufficiency in a pediatric patient: a case report

Dexmedetomidine is a highly selective α₂-adrenoceptor agonist used for sedation due to its anxiolytic and analgesic properties without respiratory compromise. Due to its structural similarity to etomidate, there has been concern that dexmedetomidine may cause adrenal insufficiency. This concern was initially supported by animal studies, but subsequent human studies demonstrated mixed results. We describe the case of transient adrenal insufficiency in a 1-year-old male who presented with 24% total body surface 2nd degree burns. He required sedation with a prolonged, high-dose dexmedetomidine infusion with a peak infusion dose of 2.7 mcg/kg/hr and duration of 6.5 days. The patient developed lethargy and hypotension four days after discontinuation of his infusion. He had a random cortisol level which was low at 0.4 mcg/dL, and the concern for adrenal suppression was confirmed with an ACTH stimulation test with the baseline cortisol of 0.4 mcg/dL and inappropriate 60 minute post-ACTH stimulation cortisol of 7.8 mcg/dL. While further studies will be needed to clarify the risk of adrenal suppression secondary to dexmedetomidine, this case suggests that caution should be taken when administering dexmedetomidine to pediatric patients and highlights the need for future studies to look at appropriate dosing and duration of dexmedetomidine infusions.

Is there a place for pressure-support ventilation and high positive end-expiratory pressure combined to alpha-2 agonists early in severe diffuse acute respiratory distress syndrome?

Acute respiratory distress syndrome (ARDS) is associated with a high mortality linked primarily to co-morbidities (sepsis, cardiac failure, multiple organ failure, etc.). When the lung is the single failing organ, quick resolution of ARDS should skip some complications arising from a prolonged stay in the critical care unit. In severe ARDS (PaO2/FIO2=P/F<100 with positive end-expiratory pressure (PEEP) ≥ 5 cm H2O), current recommendations are to intubate the trachea of the patient and use mechanical ventilation, low tidal volume, high PEEP, prone positioning and possibly neuromuscular blockade in association with intravenous sedation. Another strategy is possible. Firstly, spontaneous ventilation (SV) coupled with pressure support (PS) ventilation and high PEEP is possible from tracheal intubation onwards, with the possible exception of the short period following immediately tracheal intubation. Secondly, using alpha-2 adrenergic agonists (e.g. clonidine, dexmedetomidine) can provide first-line sedation from the beginning of mechanical ventilation, as they preserve respiratory drive, lower oxygen consumption and pulmonary hypertension and increase diuresis. Alpha-2 agonists are to be supplemented, if appropriate, by drugs devoid of effect on respiratory drive (neuroleptics, etc.). The expected benefits would be to prevent acquired diaphragmatic weakness, accumulation of sedation, cognitive dysfunction, and presumably improved outcome. This hypothesis should be tested in a double blind randomized controlled trial.