Safety and efficacy of dexmedetomidine in children with heart failure

Dexmedetomidine Improves Lung Function by Promoting Inflammation Resolution in Patients Undergoing Totally Thoracoscopic Cardiac Surgery

Objective

Totally thoracoscopic cardiac surgery under cardiopulmonary bypass combined with one-lung ventilation has been identified as the trend in cardiac surgery. The aim of this study was to examine the effects of the selective α ₂ adrenergic receptor agonist dexmedetomidine on the pulmonary function of patients who underwent mitral valve surgery using the totally thoracoscopic technique.

Methods

Fifty-seven patients who underwent thoracoscopic mitral valve surgery between July 2019 and December 2019 were selected. The patients were randomly divided into the control (Con) group (n = 28) and the dexmedetomidine (DEX) group (n = 29) using the random number table method. Arterial blood gas analyses were performed, and the oxygenation (PaO₂/FiO₂) and respiratory indexes (P(A-a)O/PaO₂) were calculated 5 min after tracheal intubation (T1), 2 h after operation (T2), 6 h after operation (T3), and 24 h after operation (T4). Moreover, the serum cytokines interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and intercellular adhesion molecule-1 (ICAM-1) were detected using the enzyme-linked immunosorbent method at all time points. Chest radiography was performed 24 h after surgery. Peripheral blood samples were collected before and after the operation for a complete hemogram. Additionally, the procalcitonin concentration was measured and recorded when the patients were transported to the intensive care unit (ICU). The postoperative extubation time, length of ICU stay, and pulmonary infection rate were also recorded.

Results

Inflammatory reaction after surgery was evident. However, the inflammatory cytokines IL-6, TNF-α, and ICAM-1 in the DEX group were lower than those in the Con group after surgery (T2 to T4; P < 0.05). Neutrophil counts and procalcitonin concentration were higher in the Con group than in the DEX group (P < 0.05). In addition, in the DEX group, pulmonary exudation on chest radiography was lower, and pulmonary function, as shown by an increase in oxidation index and decrease in the respiratory index, improved after surgery (P < 0.05). Moreover, the duration of mechanical ventilation in the Con group was 3.4 h longer than that in the DEX group.

Conclusion

Dexmedetomidine has a protective effect on pulmonary function in patients undergoing mitral valve surgery using a totally video-assisted thoracoscopic technique, which may be related to a reduction in the concentration of inflammatory cytokines in the early perioperative period.

Dexmedetomidine for Prolonged Sedation in the PICU: A Systematic Review and Meta-Analysis

OBJECTIVES

We aimed to systematically describe the use of dexmedetomidine as a treatment regimen for prolonged sedation in children and perform a meta-analysis of its safety profile.

DATA SOURCES

PubMed, EMBASE, Cochrane Library, Scopus, Web of Science, ClinicalTrials.gov, and CINAHL were searched from inception to November 30, 2018.

STUDY SELECTION

We included studies involving hospitalized critically ill patients less than or equal to 18 years old receiving dexmedetomidine for prolonged infusion (≥ 24 hr).

DATA EXTRACTION

Data extraction included study characteristics, patient demographics, modality of dexmedetomidine use, associated analgesia and sedation details, comfort and withdrawal evaluation scales, withdrawal symptoms, and side effects.

DATA SYNTHESIS

Literature search identified 32 studies, including a total of 3,267 patients. Most of the studies were monocentric (91%) and retrospective (88%); one was a randomized trial. Minimum and maximum infusion dosages varied from 0.1-0.5 µg/kg/hr to 0.3-2.5 µg/kg/hr, respectively. The mean/median duration range was 25-540 hours. The use of a loading bolus was reported in eight studies (25%) (range, 0.5-1 µg/kg), the mode of weaning in 11 (34%), and the weaning time in six of 11 (55%; range, 9-96 hr). The pooled prevalence of bradycardia was 2.6% (n = 10 studies; 14/387 patients; 95% CI, 0.3-7.3; I = 75%), the pooled prevalence incidence of bradycardia was 2.6% (n = 10 studies; 14/387 patients; 95% CI, 0.3-7.3; I = 75%), the pooled incidence of hypotension was 6.1% (n = 8 studies; 19/304 patients; 95% CI, 0.8-15.9; I = 84%). Three studies (9%) reported side effects' onset time which in all cases was within 12 hours of the infusion starting.

CONCLUSIONS

High-quality data on dexmedetomidine use for prolonged sedation and a consensus on correct dosing and weaning protocols in children are currently missing. Infusion of dexmedetomidine can be considered relatively safe in pediatrics even when longer than 24 hours.

Survey of Palliative Sedation at End of Life in Terminally Ill Heart Failure Patients - A Single-Center Experience of 5-Year Follow-up

BACKGROUND

Little is known about palliative sedation in terminally ill heart failure (HF) patients.Methods and Results:We retrospectively reviewed terminally ill HF patients who received palliative sedation from September 2013 to August 2018. Among 95 terminally ill HF patients, 25 were prescribed dexmedetomidine and 12 were prescribed midazolam at the end of life. Richmond Agitation-Sedation Scale was significantly reduced (P<0.01), but blood pressure and heart rate were unaltered after treatment in both the dexmedetomidine and midazolam groups.

CONCLUSIONS

Prescription of dexmedetomidine and/or midazolam might be feasible in selected terminally ill HF patients.

Prolonged sedation in critically ill children: is dexmedetomidine a safe option for younger age? An off-label experience

BACKGROUND

Dexmedetomidine (DEX) is an alpha-2-adrenergic agonist, recently approved by Italian-Medicines-Agency for difficult sedation in pediatrics, but few data exist regarding prolonged infusions in critically-ill children, especially in younger ages. Aim of our study was to evaluate DEX use and safety for prolonged sedation in Pediatric Intensive Care Units (PICUs).

METHODS

Patients receiving DEX for ≥24 hours were retrospectively evaluated to analyze DEX indications, dosages, use of analgesics or sedatives, adverse events (AEs), withdrawal syndrome or delirium.

RESULTS

Forty-seven patients (median 0.7years) from nine PICUs were enrolled. Main indications were adjuvant for drugs sparing (59.6%) and for analgosedation weaning (36.2%). Median infusion duration was 82.0 hours (IQR 62.2-126.0), with dosages between 0.4 (IQR 0.2-0.5) and 0.8 mcg/kg/h (IQR 0.6-1.2). Fifty-nine-percent of patients received other sedatives, 83% other analgesics. Twenty-one-percent presented withdrawal syndrome, 4.2% delirium, none of them DEX-related. Forty-six-percent experienced a potentially-DEX-related AE. AEs were all hemodynamic, 14.9% requiring intervention but none DEX interruption. The median minimum and maximum dosages were significantly higher in patients with AEs (0.5 vs. 0.3,P=0.001; 1.0 vs. 0.7,P<0.001), without correlations with the infusion duration. AEs rate was higher in patients receiving benzodiazepines (P=0.020) or more than one analgesic (P=0.003) and in those presenting withdrawal syndrome (P<0.001).

CONCLUSIONS

DEX was confirmed as useful and relatively safe drug for prolonged sedation in critically-ill children, particularly in younger ages. Main AEs were cardiovascular, reversible, related with higher doses, with the concomitant use of benzodiazepines or multiple sedation drugs and with the presence of withdrawal syndrome.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

The Perioperative Use of Dexmedetomidine in Pediatric Patients with Congenital Heart Disease: An Analysis from the Congenital Cardiac Anesthesia Society-Society of Thoracic Surgeons Congenital Heart Disease Database

BACKGROUND

Dexmedetomidine is a selective α-2 receptor agonist with a sedative and cardiopulmonary profile that makes it an attractive anesthetic for pediatric patients with congenital heart disease (CHD). Although several smaller, single-center studies suggest that dexmedetomidine use is gaining traction in the perioperative setting in children with CHD, there are limited multicenter data, with little understanding of the variation in use across age ranges, procedural complexity, and centers. The aim of this study was to use the Congenital Cardiac Anesthesia Society-Society of Thoracic Surgeons (CCAS-STS) registry to describe patient- and center-level variability in the use of dexmedetomidine in the perioperative setting in children with heart disease.

METHODS

To describe the use of dexmedetomidine in patients for CHD surgery, we analyzed all index cardiopulmonary bypass operations entered in the CCAS-STS database from 2010 to 2013. Patient and operative characteristics were compared between those who received intraoperative dexmedetomidine and those who did not. Selective outcomes associated with dexmedetomidine use were also described.

RESULTS

Of the 12,142 operations studied, 3600 (29.6%) received perioperative dexmedetomidine (DEX) and 8542 did not receive the drug (NoDEX). Patient characteristics were different between the 2 groups with the DEX group generally exhibiting both lower patient and procedural risk factors. Patients who received dexmedetomidine were more likely to have a lower level of Society of Thoracic Surgeons mortality complexity than patient who did not receive it. Consistent with their overall lower risk profile, children in the DEX group also demonstrated improved outcomes compared with patients who did not receive dexmedetomidine.

CONCLUSIONS

We described the growing use of dexmedetomidine in children anesthetized for surgical repair of CHD. Dexmedetomidine appears to be preferentially given to older and larger children who are undergoing less complex CHD surgery. We believe that the data provided in this study are the largest investigating the use of an anesthetic drug in CHD patients. It is also the first analysis of the anesthesia data in the CCAS-STS Congenital Heart Disease database.

Utility and Clinical Profile of Dexmedetomidine in Pediatric Cardiac Catheterization Procedures: A Matched Controlled Analysis

Background. Dexmedetomidine is increasingly used in children undergoing cardiac catheterization procedures. We compared the percentage of surgical time with hemodynamic instability and the incidence of postoperative agitation between pediatric cardiac catheterization patients who received dexmedetomidine infusion and those who did not and the incidence of postoperative agitation. Materials and methods. We matched 653 pediatric patients scheduled for cardiac catheterization. Two separate multivariable linear mixed models were used to assess the association between dexmedetomidine use and intraoperative blood pressure and heart rate instability. A multivariate logistic regression was used for relationship between dexmedetomidine and postoperative agitation. Results. No difference between the study groups was found in the duration of MAP ( P = .867) or heart rate (HR) instabilities ( P = .224). The relationship between dexmedetomidine use and the duration of negative hemodynamic effects does not depend on any of the considered CHD types (all P > .001) or intervention ( P = .453 for MAP and P = .023 for HR). No difference in postoperative agitation was found between the study groups ( P = .590). Conclusion. Our study demonstrated no benefit in using dexmedetomidine infusion compared with other general anesthesia techniques to maintain hemodynamic stability or decrease agitation in pediatric patients undergoing cardiac catheterization procedures.

Safety and efficacy of chloral hydrate for conscious sedation of infants in the pediatric cardiovascular intensive care unit

This study evaluates the safety and efficacy of chloral hydrate administration for the conscious sedation of infants in the pediatric cardiovascular intensive care unit (PCICU).We conducted a retrospective review of the charts of 165 infants with congenital heart disease who received chloral hydrate in our PCICU between January 2014 and December 2014. Chloral hydrate was administered orally or rectally to infants using doses of 50 mg/kg. We collected and analyzed relevant clinical parameters.The overall length of time to achieve sedation was ranged from 5 to 35 min (10.8 ± 6.2 min); the overall mean duration of sedation was ranged from 15 to 60 min (33.5 ± 11.3 min); and the overall mean length of time to return to normal activity was 10 min to 6 h (34.3 ± 16.2 min). The length of the PCICU stay was ranged from 3 to 30 days (8.2 ± 7.1 days). Physiologically, there were no clinically significant changes in heart rate, mean arterial pressure, respiratory rate, or peripheral oxygen saturation before, during, or after use of the chloral hydrate. There were no significant differences regarding sedative effects in the subgroups (cyanotic vs acyanotic group, with pulmonary infection vs without pulmonary infection group, and with pulmonary hypertension vs without pulmonary hypertension group).Our experience suggests that chloral hydrate is a safe and efficacious agent for conscious sedation of infants in the PCICU.

Importance of the use of protocols for the management of analgesia and sedation in pediatric intensive care unit

Summary Introduction: Analgesia and sedation are essential elements in patient care in the intensive care unit (ICU), in order to promote the control of pain, anxiety and agitation, prevent the loss of devices, accidental extubation, and improve the synchrony of the patient with mechanical ventilation. However, excess of these medications leads to rise in morbidity and mortality. The ideal management will depend on the adoption of clinical and pharmacological measures, guided by scales and protocols. Objective: Literature review on the main aspects of analgesia and sedation, abstinence syndrome, and delirium in the pediatric intensive care unit, in order to show the importance of the use of protocols on the management of critically ill patients. Method: Articles published in the past 16 years on PubMed, Lilacs, and the Cochrane Library, with the terms analgesia, sedation, abstinence syndrome, mild sedation, daily interruption, and intensive care unit. Results: Seventy-six articles considered relevant were selected to describe the importance of using a protocol of sedation and analgesia. They recommended mild sedation and the use of assessment scales, daily interruptions, and spontaneous breathing test. These measures shorten the time of mechanical ventilation, as well as length of hospital stay, and help to control abstinence and delirium, without increasing the risk of morbidity and morbidity. Conclusion: Despite the lack of controlled and randomized clinical trials in the pediatric setting, the use of protocols, optimizing mild sedation, leads to decreased morbidity.

Drugs That May Cause or Exacerbate Heart Failure: A Scientific Statement From the American Heart Association

Heart failure is a common, costly, and debilitating syndrome that is associated with a highly complex drug regimen, a large number of comorbidities, and a large and often disparate number of healthcare providers. All of these factors conspire to increase the risk of heart failure exacerbation by direct myocardial toxicity, drug-drug interactions, or both. This scientific statement is designed to serve as a comprehensive and accessible source of drugs that may cause or exacerbate heart failure to assist healthcare providers in improving the quality of care for these patients.

Clonidine as a First-Line Sedative Agent After Neonatal Cardiac Surgery: Retrospective Cohort Study

OBJECTIVES

To determine the cardiovascular tolerance of clonidine used as a first-line sedative after cardiac surgery in small infants.

DESIGN

Retrospective chart review.

SETTING

A tertiary and quaternary referral cardiac PICU.

PATIENTS

All infants younger than 2 months who received a clonidine infusion for sedation after cardiac surgery from October 2011 to July 2013.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Heart rate, blood pressure, central venous and left atrial pressure, vasoactive inotropic score, volume of fluid bolus, and lactate and central mixed venous saturation were assessed. Preinfusion values were compared with postinfusion values. Of 224 potentially eligible patients, only 23 infants met inclusion criteria, as most patients only received high doses of morphine and some received midazolam instead of clonidine. Clonidine administration was started at a median of 12 hours after surgery (Q1-Q3, 5-23), and infusion rate was 0.5-2 μg/kg/hr for a median duration of 30 hours (Q1-Q3, 12-54). Heart rate decreased (maximal mean decrease: 12% [149 beats/min (SD, 17) to 131 beats/min (SD, 17)]; p < 0.0001). Apart from a transient and limited drop in diastolic blood pressure of 13% (maximal mean decrease: from 42.8 mm Hg [SD, 5.9] to 37.1 mm Hg [SD, 4.0]; p = 0.018), all other cardiovascular variables were stable or improved. A contemporaneous cohort of patients who received midazolam, did so sooner after surgery, stayed longer in the PICU and showed less favorable hemodynamics.

CONCLUSIONS

IV clonidine as sedative added to morphine in selected patients seems hemodynamically safe. The observed decrease in heart rate and diastolic blood pressure seems of minimal clinical importance as all other hemodynamic variables remained stable or improved. The safety of clonidine given early after cardiac surgery as alternative to midazolam merits further study.

Efficacy of α2-Agonists for Sedation in Pediatric Critical Care: A Systematic Review

OBJECTIVE

Children in PICUs normally require analgesics and sedatives to maintain comfort, safety, and cooperation with interventions. α2-agonists (clonidine and dexmedetomidine) have been described as adjunctive (or alternative) sedative agents alongside opioids and benzodiazepines. This systematic review aimed to determine whether α2-agonists were effective in maintaining patients at a target sedation score over time compared with a comparator group. We also aimed to determine whether concurrent use of α2-agonists provided opioid-sparing effects.

DATA SOURCES

A systematic search was performed using the Cochrane Central Register of Controlled Trials, PubMed, EMBASE, CINAHL, and LILACS.

STUDY SELECTION

We included randomized controlled trials of children in PICU treated with clonidine or dexmedetomidine for the indication of sedation.

DATA EXTRACTION

Two authors independently screened articles for inclusion.

DATA SYNTHESIS

Six randomized controlled trials with sufficient data were identified and critically appraised. Three clonidine trials (two vs placebo and one vs midazolam) and three dexmedetomidine trials (two vs fentanyl, one vs midazolam) were included. Due to study heterogeneity it was not possible to pool studies. A narrative synthesis is provided.

CONCLUSIONS

Reporting of study results using the outcome "time maintained at target sedation score' for clonidine or dexmedetomidine was poor. Only one trial compared clonidine with midazolam using a sedation score outcome. This study was underpowered to demonstrate equivalence to midazolam as a sedative. The adjunctive use of clonidine demonstrated significant decreases in opioid use in neonates but not in older groups. Clonidine dose was inconsistent between studies. Dexmedetomidine demonstrated an opioid-sparing effect in two small trials. Further studies, including dose-finding studies and studies with sedation score-based outcomes, are needed.

Cardiac Arrest in a Heart Transplant Patient Receiving Dexmedetomidine During Cardiac Catheterization

Dexmedetomidine is an α-2 agonist with a sedative and cardiopulmonary profile that makes it an attractive anesthetic in pediatric cardiac patients. Cardiac transplant patients may suffer from acute cellular rejection of the cardiac conduction system and, therefore, are at an increased risk of the electrophysiological effect of dexmedetomidine. We present such a patient who had a cardiac arrest while receiving dexmedetomidine during cardiac catheterization. Because acute cellular rejection of the cardiac conduction system is difficult to diagnose, dexmedetomidine should be used with caution in pediatric heart transplant patients.

Pain and Sedation Management in Mechanically Ventilated Children

Assessing and managing pain and agitation in critically ill children can be challenging. Multiple factors contribute to the challenges of management, including prior medication exposure, surgical and procedural interventions, pharmacokinetics, and age-related pharmacodynamics making the population heterogeneous. Therefore, individualizing treatment approaches embedded with frequent assessments is likely to improve the management of pain and agitation in critically ill children. Novel approaches to manage pain and agitation continue to evolve and will require ongoing evaluation prior to widespread adoption.

Efficacy and Safety of Postoperative Dexmedetomidine Administration in Infants and Children Undergoing Cardiac Surgery: A Retrospective Cohort Study

In this retrospective cohort study, we describe efficacy and safety of dexmedetomidine administration in the cardiac intensive care unit, in children undergoing cardiac surgery. This study consisted of pediatric patients 3 days to 17.5 years of age, undergoing cardiac surgery from April 2010 to April 2011. In addition to a scheduled opioid, usually fentanyl, 107 patients received dexmedetomidine postoperatively, including 19 (18%) patients diagnosed with trisomy 21 and 9 (8%) neonates/newborns. Median dexmedetomidine starting dose was 0.45 µg/kg/h and overall median dose higher than previously published, ranging from 0.8 µg/kg/h to 2.17 µg/kg/h. We compared infants (younger than 1 year) with older children (1-17 years of age). Median duration of administration was 1.6 days (0-23.9 days) and duration to extubation in infants was 46.5 hours, and in the older children it was 22.6 hours. Seven patients (6.5%) were discontinued dexmedetomidine due to adverse events, most commonly bradycardia. Neonates experienced more pronounced heart rate reduction (no bradycardia) and received lower maintenance doses than older infants (0.56 vs. 0.77 µg/kg/h). The face, leg, activity, cry, consolability pain scale and the state behavioral scale scores indicated adequate sedation and good analgesia. The most common adverse reaction postdiscontinuation was agitation, more frequent in the infant group (20 vs. 11.2%). Thirty patients (28.3%) received prolonged infusion (>72 hours). Patients with and without trisomy 21 did not differ with dose, safety, efficacy, or adverse events. Dexmedetomidine, as part of multimodal management, appears to be a safe, efficacious agent providing analgesia and sedation throughout all pediatric age groups following cardiac surgery. Overall, dexmedetomidine is well tolerated and safe with higher doses than previously noted, and is well tolerated by neonates, infants, and patients with trisomy 21. Withdrawal effects were noted in patients following prolonged infusion.

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.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Advances in pediatric pharmacology, therapeutics, and toxicology

In the United States, passage of the FDASIA legislation made BPCA and PREA permanent, no longer requiring reauthorization every 5 years. This landmark legislation also stressed the importance of performing clinical trials in neonates when appropriate. In Europe the Pediatric Regulation, which went into effect in early 2007, also provides a framework for expanding pediatric clinical research. Although much work remains, as a result of greater regulatory guidance more pediatric data are reaching product labels.

Dexmedetomidine: a review of applications for cardiac surgery during perioperative period

Cardiac surgery is associated with a high incidence of cardiovascular and other complications during the perioperative period that translate into increased mortality and prolonged hospital stays. Safe comprehensive perioperative management is required to eliminate these adverse events. Dexmedetomidine is a selective α2-adrenoreceptor agonist that has been described as an ideal medication in the perioperative period of cardiac surgery. The major clinical effects of dexmedetomidine in this perioperative period can be summarized as attenuating the hemodynamic response, cardioprotective effects, antiarrhythmic effects, sedation in the ICU setting, treatment of delirium, and procedural sedation. Although there are some side effects of dexmedetomidine, it is emerging as an effective therapeutic agent in the management of a wide range of clinical conditions with an efficacious, safe profile. The present review serves as an overview update in the diverse applications of dexmedetomidine for cardiac surgery during the perioperative period.

Dexmedetomidine: a review of applications for cardiac surgery during perioperative period

Cardiac surgery is associated with a high incidence of cardiovascular and other complications during the perioperative period that translate into increased mortality and prolonged hospital stays. Safe comprehensive perioperative management is required to eliminate these adverse events. Dexmedetomidine is a selective α2-adrenoreceptor agonist that has been described as an ideal medication in the perioperative period of cardiac surgery. The major clinical effects of dexmedetomidine in this perioperative period can be summarized as attenuating the hemodynamic response, cardioprotective effects, antiarrhythmic effects, sedation in the ICU setting, treatment of delirium, and procedural sedation. Although there are some side effects of dexmedetomidine, it is emerging as an effective therapeutic agent in the management of a wide range of clinical conditions with an efficacious, safe profile. The present review serves as an overview update in the diverse applications of dexmedetomidine for cardiac surgery during the perioperative period.

The Year in Review

Congenital cardiac anesthesiology is a young and rapidly growing subspecialty. It embraces a large spectrum of congenital and acquired heart diseases, which now affect the entire life span of patients from “cradle to grave.” One of the challenges faced by congenital cardiac anesthesiologists is reading the large amount of relevant literature from the fields of cardiology, cardiac surgery, intensive care medicine, and anesthesiology. This review highlights some of the current themes in the literature during the past year.

α2 Adrenergic receptor-mediated inhibition of thermogenesis

α2 adrenergic receptor (α2-AR) agonists have been used as antihypertensive agents, in the management of drug withdrawal, and as sedative analgesics. Since α2-AR agonists also influence the regulation of body temperature, we explored their potential as antipyretic agents. This study delineates the central neural substrate for the inhibition of rat brown adipose tissue (BAT) and shivering thermogenesis by α2-AR agonists. Nanoinjection of the α2-AR agonist clonidine (1.2 nmol) into the rostral raphe pallidus area (rRPa) inhibited BAT sympathetic nerve activity (SNA) and BAT thermogenesis. Subsequent nanoinjection of the α2-AR antagonist idazoxan (6 nmol) into the rRPa reversed the clonidine-evoked inhibition of BAT SNA and BAT thermogenesis. Systemic administration of the α2-AR agonists dexmedetomidine (25 μg/kg, i.v.) and clonidine (100 μg/kg, i.v.) inhibited shivering EMGs, BAT SNA, and BAT thermogenesis, effects that were reversed by nanoinjection of idazoxan (6 nmol) into the rRPa. Dexmedetomidine (100 μg/kg, i.p.) prevented and reversed lipopolysaccharide-evoked (10 μg/kg, i.p.) thermogenesis in free-behaving rats. Cholera toxin subunit b retrograde tracing from rRPa and pseudorabies virus transynaptic retrograde tracing from BAT combined with immunohistochemistry for catecholaminergic biosynthetic enzymes revealed the ventrolateral medulla as the source of catecholaminergic input to the rRPa and demonstrated that these catecholaminergic neurons are synaptically connected to BAT. Photostimulation of ventrolateral medulla neurons expressing the PRSx8-ChR2-mCherry lentiviral vector inhibited BAT SNA via activation of α2-ARs in the rRPa. These results indicate a potent inhibition of BAT and shivering thermogenesis by α2-AR activation in the rRPa, and suggest a therapeutic potential of α2-AR agonists for reducing potentially lethal elevations in body temperature during excessive fever.