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

Dexmedetomidine on the interplay of IL-6 and STAT3 pathways in adrenal gland damage-induced scalding burns in rats

Scalding burns are a common form of thermal injury that often leads to systemic complications. Pro-inflammatory cytokines like interleukin-6 (IL-6) and the activation of signal transducer and activator of transcription 3 (STAT3) pathways have been linked to the pathophysiology of organ damage caused by burns. This study aimed to investigate the potential therapeutic effects of dexmedetomidine, an α2-adrenergic receptor agonist with anti-inflammatory properties, on the interplay of IL-6 and STAT3 pathways in adrenal gland damage following scalding burns in rats. Twenty-eight rats were divided randomly into four groups. Rats in group 1 (n=7, control) were given only 0.9% intraperitoneal (i.p.) NaCl. Rats in group 2 (n=7, DEX) were exposed to 25°C water for 17 s on day 1 and received 100 mcg/kg/day dexmedetomidine i.p. for 3 days; for rats in group 3 (n=7, Burn), boiling water of 94°C was applied inside for 17 s. Rats in group 4 (n=7, Burn+DEX) were exposed to 94°C water for 17 s and received 100 mcg/kg/day dexmedetomidine i.p. for 3 days. Adrenal gland tissues were histopathological examined, and STAT3, IL-6, and TUNEL staining were performed using immunohistochemically. Our results revealed that scalding burns increased IL-6 and STAT3 expression in the adrenal glands of rats. Histological analysis demonstrated that dexmedetomidine administration ameliorated adrenal gland damage and reduced inflammatory cell infiltration. Our findings suggest that dexmedetomidine protects the adrenal glands in scalding burns. This protection appears to be mediated, at least in part, by its modulation of IL-6 and STAT3 pathways.

Sedation strategies in children with pediatric acute respiratory distress syndrome (PARDS)

In this review, we discuss the changing landscape of sedation in mechanically ventilated children with pediatric acute respiratory distress syndrome (PARDS). While previous approaches advocated for early and deep sedation with benzodiazepines, emerging literature has highlighted the benefits of light sedation and use of non-benzodiazepine sedating agents, such as dexmedetomidine. Recent studies have emphasized the importance of monitoring multiple factors including, but not limited to, sedation depth, analgesia efficacy, opiate withdrawal, and development of delirium. Through this approach, we hope to improve PARDS outcomes. Overall, more research is needed to further our understanding of the best sedation strategies in children with PARDS.

Considerations for pediatric burn sedation and analgesia

Burn patients experience anxiety and pain in the course of their injury, treatment, and recovery. Hence, treatment of anxiety and pain is paramount after burn injury. Children, in particular, pose challenges in anxiety and pain management due to their unique physiologic, psychologic, and anatomic status. Burn injuries further complicate pain management and sedation as such injuries can have effects on medication response and elimination. Burn injuries further complicate pain management and sedation as such injuries can have effects on medication response and elimination. The purpose of this review is to describe the challenges associated with management of anxiety, pain, and sedation in burned children and to describe the different options for treatment of anxiety and pain in burned children.

Sedative-hypnotic Binding to 11β-hydroxylase

BACKGROUND

Etomidate potently suppresses adrenocortical steroid synthesis with potentially deleterious consequences by binding to 11β-hydroxylase and inhibiting its function. The authors hypothesized that other sedative-hypnotics currently in clinical use or under development (or their metabolites) might bind to the same site at clinically relevant concentrations. The authors tested this hypothesis by defining etomidate's affinity for this site and the potencies with which other sedative-hypnotics (and their metabolites) inhibit etomidate binding.

METHODS

H-etomidate's binding to adrenal membranes from Sprague-Dawley rats was characterized with a filtration assay, and its dissociation constant was defined using saturation and homologous ligand competition approaches. Half-inhibitory concentrations of sedative-hypnotics and metabolites were determined from the reduction in specific H-etomidate binding measured in the presence of ranging sedative-hypnotic and metabolite concentrations.

RESULTS

Saturation and homologous competition studies yielded H-etomidate dissociation constants of 40 and 21 nM, respectively. Half-inhibitory concentrations of etomidate and cyclopropyl methoxycarbonyl metomidate (CPMM) differed significantly (26 vs. 143 nM, respectively; P < 0.001), and those of the carboxylic acid (CA) metabolites etomidate-CA and CPMM-CA were greater than or equal to 1,000× higher than their respective parent hypnotics. The half-inhibitory concentration of dexmedetomidine was 2.2 µM, whereas those of carboetomidate, ketamine, and propofol were greater than or equal to 50 µM.

CONCLUSION

Etomidate's in vitro dissociation constant for 11β-hydroxylase closely approximates its in vivo adrenocortical half-inhibitory concentration. CPMM produces less adrenocortical suppression than etomidate not only because it is metabolized faster but also because it binds to 11β-hydroxylase with lower affinity. Other sedative-hypnotics and metabolites bind to 11β-hydroxylase and inhibit etomidate binding only at suprahypnotic concentrations.

Combined Use of Etomidate and Dexmedetomidine Produces an Additive Effect in Inhibiting the Secretion of Human Adrenocortical Hormones

Background

The direct effects of etomidate were investigated on the secretion of cortisol and its precursors by dispersed cells from the adrenal cortex of human of animals. Dexmedetomidine (DEX) is an anesthetic agent that may interfere with cortisol secretion via an unknown mechanism, such as involving inhibition of 11β-hydroxylase and the cholesterol side-chain cleavage enzyme system. The aim of this study was to determine whether dexmedetomidine (DEX) has a similar inhibitory effect on adrenocortical function, and whether combined use of etomidate (ETO) and DEX could produce a synergistic action in inhibiting the secretion of human adrenocortical hormones.

Material/Methods

Human adrenocortical cells were exposed to different concentrations of ETO and DEX. The dose-effect model between the ETO concentration and the mean secretion of cortisone (CORT) and aldosterone (ALDO) per hour was estimated.

Results

Hill’s equation well-described the dose-effect correlation between the ETO concentration and the amount of ALDO and CORT secretion. When the DEX concentration was introduced into the model by using E₀ (basal secretion) as the covariate, the goodness of fit of the ETO-CORT dose-effect model was improved significantly and the objective function value was reduced by 4.55 points (P<0.05). The parameters of the final ETO-ALDO pharmacodynamics model were EC₅₀=9.74, E_max=1.20, E₀=1.33, and γ=18.5; the parameters of the final ETO-CORT pharmacodynamics model were EC₅₀=9.49, E_max=8.16, E₀=8.57, and γ=37.0. In the presence of DEX, E₀ was 8.57–0.0247×(CDEX–4.6), and the other parameters remained unchanged. All parameters but γ were natural logarithm conversion values.

Conclusions

Combined use of DEX and ETO reduced ETO’s inhibitory E₀ (basal secretion) of CORT from human adrenocortical cells in a dose-dependent manner, suggesting that combined use of ETO and DEX produced an additive effect in inhibiting the secretion of human adrenocortical hormones.

Optimizing Sedation Management to Promote Early Mobilization for Critically Ill Children

Achieving successful early mobilization for the intubated, critically ill child is dependent on optimizing sedation and analgesia. Finding the fine balance between oversedation and undersedation can be challenging. The ideal is for a child to be lucid and interactive during the daytime and demonstrate normal circadian rhythm for sleep with rest at night. Being alert during the day facilitates active participation in therapy including potential ambulation, while decreasing the risk of delirium during mechanical ventilation. An active state during the day with frequent mobilization promotes restorative sleep at night, which brings with it multiple benefits for healing and recovery. Indeed, this ideal may not be physiologically feasible given a child's critical illness and trajectory, but defining it as the "gold standard" for early mobilization provides a consistent goal for the pediatric intensive care unit (PICU) hospitalization. As such, goal-directed, patient-specific sedation plans are integral to creating a culture of mobility in the PICU. We review currently available sedation strategies for mechanically ventilated children for successful implementation of early mobilization in the PICU, as well as pharmacologic considerations for specific classes of sedative-analgesics.

Dexmedetomidine for Sedation during Withdrawal of Support

Agents used to control end-of-life suffering are associated with troublesome side effects. The use of dexmedetomidine for sedation during withdrawal of support in pediatrics is not yet described. An adolescent female with progressive and irreversible pulmonary deterioration was admitted. Despite weeks of therapy, she did not tolerate weaning of supplemental oxygen or continuous bilevel positive airway pressure. Given her condition and the perception that she was suffering, the family requested withdrawal of support. Despite opioids and benzodiazepines, she appeared to be uncomfortable after support was withdrawn. Ketamine was initiated. Relief from ketamine was brief, and its use was associated with a "wide-eyed" look that was distressing to the family. Ketamine was discontinued and a dexmedetomidine infusion was initiated. The patient's level of comfort improved greatly. The child died peacefully 24 hours after initiating dexmedetomidine from her underlying disease rather than the effects of the sedative.

Sedation, sleep promotion, and delirium screening practices in the care of mechanically ventilated children: a wake-up call for the pediatric critical care community*

OBJECTIVES

To examine pediatric intensivist sedation management, sleep promotion, and delirium screening practices for intubated and mechanically ventilated children.

DESIGN

An international, online survey of questions regarding sedative and analgesic medication choices and availability, sedation protocols, sleep optimization, and delirium recognition and treatment.

SETTING

Member societies of the World Federation of Pediatric Intensive and Critical Care Societies were asked to send the survey to their mailing lists; responses were collected from July 2012 to January 2013.

SUBJECTS

Pediatric critical care providers.

INTERVENTIONS

Survey.

MEASUREMENTS AND MAIN RESULTS

The survey was completed by 341 respondents, the majority of whom were from North America (70%). Twenty-seven percent of respondents reported having written sedation protocols. Most respondents worked in PICUs with sedation scoring systems (70%), although only 42% of those with access to scoring systems reported routine daily use for goal-directed sedation management. The State Behavioral Scale was the most commonly used scoring system in North America (22%), with the COMFORT score more prevalent in all other countries (39%). The most commonly used sedation regimen for intubated children was a combination of opioid and benzodiazepine (72%). Most intensivists chose fentanyl as their first-line opioid (66%) and midazolam as their first-line benzodiazepine (86%) and prefer to administer these medications as continuous infusions. Propofol and dexmedetomidine were the most commonly restricted medications in PICUs internationally. Use of earplugs, eye masks, noise reduction, and lighting optimization for sleep promotion was uncommon. Delirium screening was not practiced in 71% of respondent's PICUs, and only 2% reported routine screening at least twice a day.

CONCLUSIONS

The results highlight the heterogeneity in sedation practices among intensivists who care for critically ill children as well as a paucity of sleep promotion and delirium screening in PICUs worldwide.