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

Erythrocytic metabolism of ATLX-0199: An agent that increases minute ventilation

Both L- and D-isomers of S-nitrosocysteine (CSNO) can bind to the intracellular domain of voltage-gated potassium channels in vitro. CSNO binding inhibits these channels in the carotid body, leading to increased minute ventilation in vivo. However, only the l-isomer is active in vivo because it requires the l-amino acid transporter (LAT) for transmembrane transport. In rodents and dogs, the esterified D-CSNO precursor-d-cystine dimethyl ester (ATLX-0199)-overcomes opioid- and benzodiazepine-induced respiratory depression while maintaining analgesia. Although ATLX-0199 can enter cells independently of LAT because it is an ester, its stability in plasma is limited by the presence of esterases. Here, we hypothesized that the drug could be sequestered in erythrocytes to avoid de-esterification in circulation. We developed a liquid chromatography-mass spectrometry method for detecting ATLX-0199 and characterized a new metabolite, S-nitroso-d-cysteine monomethyl ester (DNOCE), which is also a D-CSNO precursor. We found that both ATLX-0199 and DNOCE readily enter erythrocytes and neurons and remain stable over 20 min; thus ATLX-0199 can enter cells where the ester is stable, but the thiol is reduced. Depending on hemoglobin conformation, the reduced ester can be S-nitrosylated and enter carotid body neurons, where it then increases minute ventilation. These data may help explain the paradox that ATLX-0199, a dimethyl ester, can avoid de-esterification in plasma and exert its effects at the level of the carotid body.

Dexmedetomidine alleviates acute lung injury by promoting Tregs differentiation via activation of AMPK/SIRT1 pathway

OBJECTIVES

To explore the anti-inflammatory effect and the potential mechanism of dexmedetomidine in ARDS/ALI.

MATERIALS AND METHODS

C57BL/6 mice and EL-4 cells were used in this research. The ALI model was established by CLP. The level of inflammatory cytokines in the lung and blood, the severity of lung injury, the expression of Foxp3, and the proportion of Tregs were detected before and after dexmedetomidine treatment. The expression of the AMPK/SIRT1 after dexmedetomidine treatment was detected in vivo and in vitro. After blocking the AMPK/SIRT1 pathway or depleting Tregs in vivo, the level of the inflammatory response, tissue injury, and Tregs differentiation were detected again to clarify the effect of dexmedetomidine.

RESULTS

Dexmedetomidine significantly reduced systemic inflammation and lung injury in CLP mice. Dexmedetomidine enhanced the Foxp3 expression in the lungs and the frequency of Tregs in the spleen. Dexmedetomidine up-regulated the protein expression of p-AMPK and SIRT1 in lungs and EL-4 cells and facilitated the differentiation of naïve CD4⁺ T cells into Tregs in vitro. Meanwhile, DEX also increased the expression of Helios in Treg cells.

CONCLUSIONS

DEX could improve ARDS/ALI by facilitating the differentiation of Tregs from naïve CD4⁺ T cells via activating the AMPK/SIRT1 pathway.

Current State of Analgesia and Sedation in the Pediatric Intensive Care Unit

Critically ill pediatric patients often require complex medical procedures as well as invasive testing and monitoring which tend to be painful and anxiety-provoking, necessitating the provision of analgesia and sedation to reduce stress response. Achieving the optimal combination of adequate analgesia and appropriate sedation can be quite challenging in a patient population with a wide spectrum of ages, sizes, and developmental stages. The added complexities of critical illness in the pediatric population such as evolving pathophysiology, impaired organ function, as well as altered pharmacodynamics and pharmacokinetics must be considered. Undersedation leaves patients at risk of physical and psychological stress which may have significant long term consequences. Oversedation, on the other hand, leaves the patient at risk of needing prolonged respiratory, specifically mechanical ventilator, support, prolonged ICU stay and hospital admission, and higher risk of untoward effects of analgosedative agents. Both undersedation and oversedation put critically ill pediatric patients at high risk of developing PICU-acquired complications (PACs) like delirium, withdrawal syndrome, neuromuscular atrophy and weakness, post-traumatic stress disorder, and poor rehabilitation. Optimal analgesia and sedation is dependent on continuous patient assessment with appropriately validated tools that help guide the titration of analgosedative agents to effect. Bundled interventions that emphasize minimizing benzodiazepines, screening for delirium frequently, avoiding physical and chemical restraints thereby allowing for greater mobility, and promoting adequate and proper sleep will disrupt the PICU culture of immobility and reduce the incidence of PACs.

Extubation Readiness Practices and Barriers to Extubation in Pediatric Subjects

BACKGROUND

Invasive mechanical ventilation is a lifesaving intervention that is associated with short- and long-term morbidities. Extubation readiness protocols aim to decrease extubation failure rates and simultaneously shorten the duration of invasive ventilation. This study sought to analyze extubation readiness practices at one institution and identify barriers to extubation in pediatric patients who have passed an extubation readiness test (ERT).

METHODS

We performed a retrospective chart review of all pediatric subjects admitted between April 2017 and March 2018, and who were on mechanical ventilation. Exclusion criteria were cardiac ICU admission, tracheostomy, chronic ventilator support, limited resuscitation status, and death before extubation attempt. Data with regard to the method of ERT and reasons for delaying extubation were collected.

RESULTS

There were 427 subjects included in the analysis with 69% having had an ERT before extubation. Of those, 39% were extubated per our daily spontaneous breathing trial (SBT) protocol, and the daily SBT failed in 30% but they had passed a subsequent pressure support and CPAP trial on the same day. The most common reasons for failing the daily SBT were a lack of spontaneous breathing (30% [75/252]), being intubated < 24 h (24% [60/252]), breathing frequency outside the target range (22% [55/252]), and not meeting tidal volume goal (14% [34/252]). The most common documented reasons for delaying extubation despite passing daily SBT were planned procedure (29% [26/90]), neurologic status (23% [21/90]), and no leak around the endotracheal tube (18% [16/90]). The median time between passing ERT and extubation was 7 h (interquartile range, 5-10).

CONCLUSIONS

In our institution, there was variation in extubation readiness practices that could lead to a significant delay in liberation from invasive ventilation. Adjustment of our daily SBT to tolerate a higher work of breathing, such as higher breathing frequencies and lower tidal volumes, and incorporating sedation scoring into the protocol could be made without significantly affecting extubation failure rates.