[Dexmedetomidine and clonidine: a review of their pharmacodynamy to define their role for sedation in intensive care patients]

Procedural Sedation With Dexmedetomidine in Combination With Ketamine in the Emergency Department

BACKGROUND

Dexmedetomidine is an alternative agent for procedural sedation in the emergency department thanks to its ability to maintain hemodynamic and respiratory stability. Dexmedetomidine must, however, be combined with a powerful analgesic.

OBJECTIVE

Our aim was to evaluate the quality and safety of procedural sedation using the combination of dexmedetomidine and ketamine for patients undergoing painful procedures in the emergency department.

METHODS

This prospective interventional single-center study was conducted in an academic emergency department of an urban hospital in Brussels, Belgium. Patients received a bolus injection of 1 µg/kg dexmedetomidine over 10 min and then a continuous infusion of 0.6 µg/kg/h followed by a bolus of 1 mg/kg ketamine. The painful procedure was carried out 1 min later. The level of pain was evaluated with a numerical rating scale from 0 (no pain) to 10 (maximal pain). The level of patient comfort for the procedure was measured using a comfort scale.

RESULTS

Thirty patients were included. Overall, 90% of patients felt little or no pain (n = 29 of 30) or discomfort (n = 28 of 30) during the procedure. One patient experienced apnea with desaturation, which was resolved by a jaw-thrust maneuver. Although 23% of patients had significant arterial hypertension, none required drug treatment.

CONCLUSIONS

The combination of dexmedetomidine and ketamine provides conscious sedation, bringing comfort and pain relief to patients in optimal conditions for respiratory and hemodynamic safety. However, sedation and recovery times are longer than with conventional drug combinations. The dexmedetomidine-ketamine combination should therefore be recommended for nonurgent procedures and fragile patients.

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.

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.

Mechanisms of Dexmedetomidine in Neuropathic Pain

Dexmedetomidin is a new-generation, highly selective α2 adrenergic receptor agonist with a large number of advantages, including its sedative and analgesic properties, its ability to inhibit sympathetic nerves, its reduced anesthetic dosage, its hemodynamic stability, its mild respiratory depression abilities, and its ability to improve postoperative recognition. Its safety and effectiveness, as well as its ability to provide a certain degree of comfort to patients, make it a useful anesthetic adjuvant for a wide range of clinical applications. For example, dexmedetomidine is commonly used in patients undergoing general anesthesia, and it also exerts sedative effects during tracheal intubation or mechanical ventilation in intensive care unit patients. In recent years, with the deepening of clinical research on dexmedetomidine, the drug is still applied in the treatment of spastic pain, myofascial pain, neuropathic pain, complex pain syndrome, and chronic headache, as well as for multimodal analgesia. However, we must note that the appropriateness of patient and dose selection should be given attention when using this drug; furthermore, patients should be observed for adverse reactions such as hypotension and bradycardia. Therefore, the safety and effectiveness of this drug for long-term use remain to be studied. In addition, basic experimental studies have also found that dexmedetomidine can protect important organs, such as the brain, heart, kidney, liver, and lung, through various mechanisms, such as antisympathetic effects, the inhibition of apoptosis and oxidative stress, and a reduction in the inflammatory response. Moreover, the neuroprotective properties of dexmedetomidine have received the most attention from scholars. Hence, in this review, we mainly focus on the characteristics and clinical applications of dexmedetomidine, especially the role of dexmedetomidine in the nervous system and the use of dexmedetomidine in the relief of neuropathic pain.

Effects of dexmedetomidine on delirium duration of non-intubated ICU patients (4D trial): study protocol for a randomized trial

Background

Delirium during intensive care unit (ICU) stay is frequent and associated with significant morbidity, mortality and healthcare-related costs. International guidelines suggest its prevention. However, curative treatment remains unclearly established. Despite contradictory and ambiguous academic literature, international guidelines suggest the use of second-generation (atypical) antipsychotics over haloperidol. However, haloperidol remains the most widely used neuroleptic worldwide as a first-line treatment of agitation and/or delirium. Dexmedetomidine, an alpha2-adrenergic receptors agonist, has shown its efficiency in the treatment of delirium in intubated patients but also in its prevention. Dexmedetomidine represents a widely used alternative to haloperidol. Only few studies have compared the efficacy of dexmedetomidine in non-intubated ICU patients as a first-line curative treatment of delirium. The main objective of the 4D trial is to demonstrate that dexmedetomidine decreases delirium duration compared to placebo.

Methods/design

The 4D trial is an investigator-initiated, prospective, multicenter, randomized, double-blinded, two-arm trial, randomizing 300 non-intubated ICU patients with a diagnosis of agitated delirium to receive dexmedetomidine or placebo as a cure. In case of agitation (RASS≥ + 2), immediate haloperidol administration will be allowed, to protect patient and staff in charge, while waiting for study treatment action. The primary outcome measure is a composite of duration of agitation or delirium or the use of intubation with deep sedation and mechanical ventilation. Secondary outcomes include mortalities at 7 and 30 days, ICU length of stay and occurrence of adverse effects related to dexmedetomidine use (bradycardia or hypotension requesting any treatment; or haloperidol use (neuroleptic malignant syndrome, extrapyramidal syndrome, prolonged QTc). The sample size will allow the detection of a 50% decrease of agitation duration (120 min), of an absolute reduction of delirium duration (1 day) and of a 50% relative decrease of intubation and mechanical ventilation, with a type 1 error rate of 1.8% (error risk inflation due to components of composite) and power of 90%, assuming a 15% incidence of intubation and mechanical ventilation requirements, an agitation duration of 240 min and a delirium duration of 3 days. One hundred and ten patients by group will be needed. An intermediate analysis is scheduled and requires the inclusion of 150 patients.

Discussion

The 4D trial may provide important data on the safety of commonly used sedative dexmedetomidine and could have a significant impact on future treatment of non-intubated ICU patients presenting with agitated delirium.

Trial registration

ClinicalTrials.gov, ID: NCT 03317067. Registered on 23 October 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2656-x) contains supplementary material, which is available to authorized users.

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.

Postoperative Analgesia with Epidural Dexmedetomidine Compared with Clonidine following Total Abdominal Hysterectomies: A Prospective Double-blind Randomized Trial

Background and Aims:

Anesthesia for total abdominal hysterectomies is not only concerned with relieving pain during intraoperative period but also during the postoperative period. We compared clonidine and dexmedetomidine as an adjuvant to levobupivacaine for epidural analgesia with respect to onset and duration of sensory block, duration of analgesia, and adverse effects.

Materials and Methods:

A total of 80 individuals between the age of 45 and 65 years of American Society of Anesthesiologists (ASA) physical status Classes I and II who underwent total abdominal hysterectomies were randomly allocated into two groups, comprising 40 patients in each group. Group LC received 10 ml of 0.125% levobupivacaine and 2 μg/kg of clonidine while Group LD received 10 ml of 0.125% levobupivacaine and 1 μg/kg of dexmedetomidine through the epidural catheter. Onset of analgesia, time of peak effect, duration of analgesia, cardiorespiratory parameters, side effects, and need of rescue intravenous (IV) analgesics were observed. The data analysis was carried out with Z-test and Chi-square test.

Results:

The demographic profile and ASA physical classes were comparable between the groups. Group LD had early onset, early peak effect, prolonged duration, and stable cardiorespiratory parameters when compared with Group LC. Less number of patients (42.5%) in Group LD required IV rescue analgesics when compared to Group LC (70%) and was statistically significant. The side effects’ profile was also comparable.

Conclusion:

Dexmedetomidine is a better neuraxial adjuvant compared with clonidine for providing early onset and prolonged postoperative analgesia and stable cardiorespiratory parameters.

Prevention of acute kidney injury and protection of renal function in the intensive care unit: update 2017 : Expert opinion of the Working Group on Prevention, AKI section, European Society of Intensive Care Medicine

BACKGROUND

Acute kidney injury (AKI) in the intensive care unit is associated with significant mortality and morbidity.

OBJECTIVES

To determine and update previous recommendations for the prevention of AKI, specifically the role of fluids, diuretics, inotropes, vasopressors/vasodilators, hormonal and nutritional interventions, sedatives, statins, remote ischaemic preconditioning and care bundles.

METHOD

A systematic search of the literature was performed for studies published between 1966 and March 2017 using these potential protective strategies in adult patients at risk of AKI. The following clinical conditions were considered: major surgery, critical illness, sepsis, shock, exposure to potentially nephrotoxic drugs and radiocontrast. Clinical endpoints included incidence or grade of AKI, the need for renal replacement therapy and mortality. Studies were graded according to the international GRADE system.

RESULTS

We formulated 12 recommendations, 13 suggestions and seven best practice statements. The few strong recommendations with high-level evidence are mostly against the intervention in question (starches, low-dose dopamine, statins in cardiac surgery). Strong recommendations with lower-level evidence include controlled fluid resuscitation with crystalloids, avoiding fluid overload, titration of norepinephrine to a target MAP of 65-70 mmHg (unless chronic hypertension) and not using diuretics or levosimendan for kidney protection solely.

CONCLUSION

The results of recent randomised controlled trials have allowed the formulation of new recommendations and/or increase the strength of previous recommendations. On the other hand, in many domains the available evidence remains insufficient, resulting from the limited quality of the clinical trials and the poor reporting of kidney outcomes.

[Management of cardiogenic shock: Results from a survey in France and Belgium]

PURPOSE

Physician survey on cardiogenic shock management; recommendations for the management of patients with cardiogenic shock are based mostly on experts' opinion.

METHODS

Overall 1585 emails were sent to "senior" intensive care physicians from France and Belgium from September 2014 to march 2015. Response rate was 10% (157 respondents). Agreement was assessed based on RAND/UCLA methodology.

RESULTS

Continuous monitoring of cardiac output, vascular filling, noninvasive ventilation were deemed appropriate. The use of systematic diuretics and dopamine seemed inappropriate. There was a strong agreement to use dobutamine as inotropic drug in first intention. The use of noradrenaline and adrenaline was considered appropriate. There was a strong agreement to use mechanical circulatory support, in particular extracorporeal life support, in refractory cardiogenic shock. Only 25% of responders felt that there are criteria of refractory cardiogenic shock. Concerning the objectives of systolic, diastolic and mean blood pressure, 95% of the responses were in the range between 70 to 100, 30 to 50, and 55 to 65mmHg, respectively. The target of SvO₂ was between 55% and 75%, and cardiac index between 1.5 and 3L/min/m² for 95% of responders. There was a strong agreement to maintain hemoglobin between 7 and 9.9g/dL.

CONCLUSION

Based on our physician survey, we found an agreement in vascular filling and early enteral nutrition. Dobutamine and noradrenaline should be the preferred drugs, but not dopamine. Mechanical circulatory support (preferably with extracorporeal support) should be restricted to refractory cardiogenic shock. Those responses differed slightly from experts' opinion, available in terms of recommendations.

Dexmedetomidine Dose-Dependently Attenuates Ropivacaine-Induced Seizures and Negative Emotions Via Inhibiting Phosphorylation of Amygdala Extracellular Signal-Regulated Kinase in Mice

Ropivacaine (Ropi), one of the newest and safest amino amide local anesthetics, is linked to toxicity, including the potential for seizures, changes in behavior, and even cardiovascular collapse. Dexmedetomidine (Dex), an α2-adrenergic receptor agonist, has been widely used in anesthesia and critical care practice. To date, the underlying mechanisms of the effects of Dex premedication on Ropi-induced toxicity have not been clearly identified. In the current study, we investigated the effects of increasing doses of Dex premedication on 50% convulsive dose (CD50) of Ropi. With increasing doses of intraperitoneal (i.p.) Dex 10 min prior to each i.p. RopiCD50, the latency and duration of seizure activity were recorded. Open-field (OF) and elevated plus maze (EPM) test were used to measure negative behavioral emotions such as depression and anxiety. Immunohistochemistry and Western blot were utilized to investigate phosphorylation-extracellular regulated protein kinases (p-ERK) expression in the basolateral amygdala (BLA) on 2 h and in the central amygdala (CeA) on 24 h after convulsion in mice. The results of our investigation demonstrated that Dex dose-dependently increased RopiCD50, prolonged the latency and shortened the duration of each RopiCD50-induced seizure, improved the negative emotions revealed by both OF and EPM test, and inhibited p-ERK expression in the BLA and the CeA.

A comparative study in the post-operative spine surgeries: Epidural ropivacaine with dexmedetomidine and ropivacaine with clonidine for post-operative analgesia

BACKGROUND

Anaesthesia for spine surgeries is not only concerned with relieving pain during surgeries but also during the post-operative period. A prospective randomised 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 ropivacaine, in epidural analgesia with special emphasis on their quality of analgesia and the ability to provide the smooth post-operative course.

METHODS

A total of 60 subjects, 33 were men and 27 were women between the age of 18 and 65 years of American Society of Anaesthesiologists (ASA) I/II class who underwent spine surgeries were randomly allocated into two groups, ropivacaine + dexmedetomidine (RD) and ropivacaine + clonidine (RC), comprising 30 patients each. Group RD received 20 ml of 0.2% ropivacaine and 1 μg/kg of dexmedetomidine while group RC received 20 ml of 0.2% ropivacaine and 2 μg/kg of clonidine through the epidural catheter. Onset of analgesia, time of peak effect, duration of analgesia, cardiorespiratory parameters, side-effects and need of rescue intravenous (IV) analgesics were observed.

RESULTS

The demographic profile and ASA class were comparable between the groups. None of the patients needed rescue analgesics in either group. Group RD had early onset, early peak effect, prolonged duration and stable cardiorespiratory parameters when compared with group RC. The side-effects profile was also comparable with a little higher incidence of nausea and dry mouth in both groups.

CONCLUSION

Epidural route provided acceptable analgesia in spine surgeries and avoided the need of IV analgesics in either group. Dexmedetomidine is a better neuraxial adjuvant compared with clonidine for providing early onset and prolonged post-operative analgesia and stable cardiorespiratory parameters.

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.