The beta-agonist lung injury trial (BALTI): a randomized placebo-controlled clinical trial

Inhaled procaterol for the treatment of transient tachypnea of the newborn

BACKGROUND

Transient tachypnea of the newborn (TTN) is a respiratory disorder that results from inadequate or delayed clearance of fetal lung fluid following delivery. At present, supportive care is generally practiced for the treatment of TTN. In this study, we focused on inhaled beta-agonists for the treatment of TTN, and the aim was to verify the efficacy and the safety of inhaled procaterol for the treatment of TTN.

METHODS

Inhaled procaterol or normal saline solution was administered to infants. Respiratory rate and mixed venous carbon dioxide (PvCO₂ ) were evaluated as the primary outcomes. The duration of hospitalization, duration of oxygen therapy, and changes in respiratory support were evaluated as secondary outcomes.

RESULTS

Thirty-seven neonates diagnosed with TTN were randomly assigned to the procaterol group (n = 18) or the placebo group (n = 19). There were no differences in PvCO₂ or respiratory rate between the two groups before and after intervention. Median duration of oxygen therapy (3 days; IQR, 3-6.5 days vs 2 days, IQR, 2-4.75 days; P = 0.13) and of hospitalization (15 days; IQR, 11.25-20 days vs 11 days, IQR, 8-15.5 days; P = 0.14) were not significantly different.

CONCLUSIONS

Inhaled procaterol was not effective for the treatment of TTN.

Specialized Pro-resolving Mediators Regulate Alveolar Fluid Clearance during Acute Respiratory Distress Syndrome

Objective

Acute respiratory distress syndrome (ARDS) is an acute and lethal clinical syndrome that is characterized by the injury of alveolar epithelium, which impairs active fluid transport in the lung, and impedes the reabsorption of edema fluid from the alveolar space. This review aimed to discuss the role of pro-resolving mediators on the regulation of alveolar fluid clearance (AFC) in ARDS.

Data Sources

Articles published up to September 2017 were selected from the PubMed, with the keywords of "alveolar fluid clearance" or "lung edema" or "acute lung injury" or "acute respiratory distress syndrome", and "specialized pro-resolving mediators" or "lipoxin" or "resolvin" or "protectin" or "maresin" or "alveolar epithelial cells" or "aspirin-triggered lipid mediators" or "carbon monoxide and heme oxygenase" or "annexin A1".

Study Selection

We included all relevant articles published up to September 2017, with no limitation of study design.

Results

Specialized pro-resolving mediators (SPMs), as the proinflammatory mediators, not only upregulated epithelial sodium channel, Na,K-ATPase, cystic fibrosis transmembrane conductance regulator (CFTR), and aquaporins levels, but also improved Na,K-ATPase activity to promote AFC in ARDS. In addition to the direct effects on ion channels and pumps of the alveolar epithelium, the SPMs also inhibited the inflammatory cytokine expression and improved the alveolar epithelial cell repair to enhance the AFC in ARDS.

Conclusions

The present review discusses a novel mechanism for pulmonary edema fluid reabsorption. SPMs might provide new opportunities to design "reabsorption-targeted" therapies with high degrees of precision in controlling ALI/ARDS.

Alveolar liquid clearance in lung injury: Evaluation of the impairment of the β2-adrenergic agonist response in an ischemia-reperfusion lung injury model

While alveolar liquid clearance (ALC) mediated by the β₂-adrenergic receptor (β₂-AR) plays an important role in lung edema resolution in certain models of lung injury, in more severe lung injury models, this response might disappear. Indeed, we have shown that in an ischemia-reperfusion-induced lung injury model, β₂-agonists do not enhance ALC. The objective of this study was to determine if downregulation of the β₂-AR could explain the lack of response to β₂-agonists in this lung injury model. In an in vivo canine model of lung transplantation, we observed no change in β₂-AR concentration or affinity in the injured transplanted lungs compared to the native lungs. Furthermore, we could not enhance ALC in transplanted lungs with dcAMP + aminophylline, a treatment that bypasses the β₂-adrenergic receptor and is known to stimulate ALC in normal lungs. However, transplantation decreased αENaC expression in the lungs by 50%. We conclude that the lack of response to β₂-agonists in ischemia-reperfusion-induced lung injury is not associated with significant downregulation of the β₂-adrenergic receptors but is attributable to decreased expression of the ENaC channel, which is essential for sodium transport and alveolar liquid clearance in the lung.

Bumetanide attenuates acute lung injury by suppressing macrophage activation

Bumetanide is a potent loop diuretic that acts as an inhibitor of sodium-potassium-chloride cotransporter 2 (NKCC2) and its isoform NKCC1. Although the expression of NKCC2 is limited to the kidney, NKCC1 is widely expressed in various cells, where it participates in a variety of physiological functions including ion transport, alveolar fluid secretion, and cell volume regulation. We investigated the role of NKCC1 in modulation of host immunity. Lipopolysaccharide (LPS) stimulated the expression and phosphorylation of NKCC1 in RAW264.7 cells in vitro and activated these cells to produce inflammatory cytokines. Enlarging the cell volume in a low-osmotic microenvironment amplified the LPS-induced inflammatory responses and phagocytosis activity of RAW264.7 cells. Pretreatment with the NKCC1 inhibitor bumetanide attenuated LPS-induced activation of inflammatory cells and cell volume-related function. Mice treated with an intratracheal bumetanide spray showed greater resistance to LPS-induced tissue inflammation and acute lung injury in vivo. Our studies suggest that NKCC1 plays a unique role as an amplifier of LPS-induced macrophage functions and that NKCC1 might be a novel target for treating sepsis-related acute respiratory distress syndrome.

Complications and Pharmacologic Interventions of Invasive Positive Pressure Ventilation During Critical Illness

Objective: To review the fundamentals of invasive positive pressure ventilation (IPPV) and the common complications and associated pharmacotherapeutic management in order to provide opportunities for pharmacists to improve patient outcomes. Data Sources: A MEDLINE literature search (1950-December 2017) was performed using the key search terms invasive positive pressure ventilation, mechanical ventilation, pharmacist, respiratory failure, ventilator associated organ dysfunction, ventilator associated pneumonia, ventilator bundles, and ventilator liberation. Additional references were identified from a review of literature citations. Study Selection and Data Extraction: All English-language original research and review reports were evaluated. Data Synthesis: IPPV is a common supportive care measure for critically ill patients. While lifesaving, IPPV is associated with significant complications including ventilator-associated pneumonia, sinusitis, organ dysfunction, and hemodynamic alterations. Optimization of pain and sedation management provides an opportunity for pharmacists to directly affect IPPV exposure. A number of pharmacotherapeutic interventions are related directly to prophylaxis against IPPV-associated adverse events or aimed at reduction of duration of IPPV. Conclusions: Enhanced knowledge of the common complications, associated pharmacotherapy, and monitoring strategies facilitate the pharmacist's ability to provide increased pharmacotherapeutic insight in a multidisciplinary intensive care unit setting.

Acute Respiratory Distress Syndrome: An Update and Review

Acute respiratory distress syndrome (ARDS) is a life threatening condition characterized by severe hypoxemia due to pulmonary gas exchange failure and was first recognized in 1960s.Since its first description, it has undergone intensive research in the past few decades to understand its pathogenesis and therapies. Despite this, the recommended therapies to decrease mortality in ARDS remain limited and include low-tidal volume mechanical ventilation, prone ventilation and recently, the ECMO rescue therapy in extreme cases. This review article will summarize the key features of ARDS with a brief overview of the therapeutic options in the management of ARDS.

Adjunctive therapies during veno-venous extracorporeal membrane oxygenation

Veno-venous extracorporeal membrane oxygenation (VV ECMO) restores gas exchanges in severely hypoxemic patients. The need for adjunctive therapies usually originates either from refractory hypoxemia during ECMO (defined as the persistence of low blood oxygen levels despite extracorporeal support) or from the attempt to give a specific therapy for acute respiratory distress syndrome (ARDS). In this review, therapeutic strategies to treat refractory and persistent hypoxemia during ECMO are evaluated. In the second part, therapies that can be added on top of VV ECMO to address inflammation and altered vascular permeability in ARDS are examined. The therapies currently available often allow for an effective treatment of hypoxemia during ECMO. ARDS is still lacking a specific therapy, with low-grade evidence sustaining the majority of currently used drugs.

Protectin DX increases alveolar fluid clearance in rats with lipopolysaccharide-induced acute lung injury

Acute respiratory distress syndrome is a life-threatening critical syndrome resulting largely from the accumulation of and the inability to clear pulmonary edema. Protectin DX, an endogenously produced lipid mediator, is believed to exert anti-inflammatory and pro-resolution effects. Protectin DX (5 µg/kg) was injected i.v. 8 h after LPS (14 mg/kg) administration, and alveolar fluid clearance was measured in live rats (n = 8). In primary rat ATII epithelial cells, protectin DX (3.605 × 10⁻³ mg/l) was added to the culture medium with LPS for 6 h. Protectin DX improved alveolar fluid clearance (9.65 ± 1.60 vs. 15.85 ± 1.49, p < 0.0001) and decreased pulmonary edema and lung injury in LPS-induced lung injury in rats. Protectin DX markedly regulated alveolar fluid clearance by upregulating sodium channel and Na, K-ATPase protein expression levels in vivo and in vitro. Protectin DX also increased the activity of Na, K-ATPase and upregulated P-Akt via inhibiting Nedd4–2 in vivo. In addition, protectin DX enhanced the subcellular distribution of sodium channels and Na, K-ATPase, which were specifically localized to the apical and basal membranes of primary rat ATII cells. Furthermore, BOC-2, Rp-cAMP, and LY294002 blocked the increased alveolar fluid clearance in response to protectin DX. Protectin DX stimulates alveolar fluid clearance through a mechanism partly dependent on alveolar epithelial sodium channel and Na, K-ATPase activation via the ALX/PI3K/Nedd4–2 signaling pathway.

Treatment that involves boosting levels of a signaling molecule could help reduce fluid on the lungs in acute respiratory distress syndrome (ARDS). This condition usually affects critically ill patients with illnesses such as pneumonia or sepsis, and leads to severe inflammation and flooding of the lungs with fluid. This prevents microscopic air sacs called aveoli from processing oxygen and carbon dioxide effectively. At present there is no effective management for the condition. Now, Sheng-Wei Jin at Wenzhou Medical University, China, and co-workers have shown that boosting levels of a signaling molecule called protectin DX can help with aveolar fluid clearance in rats. They found that protectin DX activates sodium channels within the aveoli, helping clear fluid, and also acts as an anti-inflammatory and pro-resolving mediator to protect lung tissues from further injury.

Assessing the validity of surrogate endpoints in the context of a controversy about the measurement of effectiveness of hepatitis C virus treatment

Surrogate endpoints are often used in clinical trials, as they allow for indirect measures of outcomes (eg, shorter trials with less participants). Improvements in surrogate endpoints (eg, reduction in low density lipoprotein cholesterol, normalisation of glycated haemoglobin) achieved with an intervention are, however, not always associated with improvements in patient-important outcomes. The common tendency in evidence-based medicine is to view results based on surrogate endpoints as less certain than results based on long term, final patient-important outcomes and rate them as 'lower quality evidence'. However, careful appraisal of the validity of a surrogate endpoint as a measure of the final, patient-important outcome is more useful than an automatic judgement. In this guide, we use a contemporary and currently highly debated example of the surrogate endpoint 'sustained viral response' (ie, viral eradication considered to represent successful treatment) in patients treated for chronic hepatitis C virus. We demonstrate how the validity of a surrogate endpoint can be critically appraised to assess the quality of the evidence (ie, the certainty in estimates) and the implications for decision-making.

Acute Respiratory Distress Syndrome: Advances in Diagnosis and Treatment

IMPORTANCE

Acute respiratory distress syndrome (ARDS) is a life-threatening form of respiratory failure that affects approximately 200 000 patients each year in the United States, resulting in nearly 75 000 deaths annually. Globally, ARDS accounts for 10% of intensive care unit admissions, representing more than 3 million patients with ARDS annually.

OBJECTIVE

To review advances in diagnosis and treatment of ARDS over the last 5 years.

EVIDENCE REVIEW

We searched MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews from 2012 to 2017 focusing on randomized clinical trials, meta-analyses, systematic reviews, and clinical practice guidelines. Articles were identified for full text review with manual review of bibliographies generating additional references.

FINDINGS

After screening 1662 citations, 31 articles detailing major advances in the diagnosis or treatment of ARDS were selected. The Berlin definition proposed 3 categories of ARDS based on the severity of hypoxemia: mild (200 mm Hg<Pao2/Fio2≤300 mm Hg), moderate (100 mm Hg<Pao2/Fio2≤200 mm Hg), and severe (Pao2/Fio2 ≤100 mm Hg), along with explicit criteria related to timing of the syndrome's onset, origin of edema, and the chest radiograph findings. The Berlin definition has significantly greater predictive validity for mortality than the prior American-European Consensus Conference definition. Clinician interpretation of the origin of edema and chest radiograph criteria may be less reliable in making a diagnosis of ARDS. The cornerstone of management remains mechanical ventilation, with a goal to minimize ventilator-induced lung injury (VILI). Aspirin was not effective in preventing ARDS in patients at high-risk for the syndrome. Adjunctive interventions to further minimize VILI, such as prone positioning in patients with a Pao2/Fio2 ratio less than 150 mm Hg, were associated with a significant mortality benefit whereas others (eg, extracorporeal carbon dioxide removal) remain experimental. Pharmacologic therapies such as β2 agonists, statins, and keratinocyte growth factor, which targeted pathophysiologic alterations in ARDS, were not beneficial and demonstrated possible harm. Recent guidelines on mechanical ventilation in ARDS provide evidence-based recommendations related to 6 interventions, including low tidal volume and inspiratory pressure ventilation, prone positioning, high-frequency oscillatory ventilation, higher vs lower positive end-expiratory pressure, lung recruitment maneuvers, and extracorporeal membrane oxygenation.

CONCLUSIONS AND RELEVANCE

The Berlin definition of acute respiratory distress syndrome addressed limitations of the American-European Consensus Conference definition, but poor reliability of some criteria may contribute to underrecognition by clinicians. No pharmacologic treatments aimed at the underlying pathology have been shown to be effective, and management remains supportive with lung-protective mechanical ventilation. Guidelines on mechanical ventilation in patients with acute respiratory distress syndrome can assist clinicians in delivering evidence-based interventions that may lead to improved outcomes.

ResolvinD1 stimulates epithelial wound repair and inhibits TGF-β-induced EMT whilst reducing fibroproliferation and collagen production

Acute and chronic inflammatory lung diseases are often associated with epithelial cell injury/loss and fibroproliferative responses. ResolvinD₁ (RvD1) is biosynthesized during the resolution phase of inflammatory response and exerts potent anti-inflammatory and promotes resolution of inflammatory lung diseases. The aim of this study was to investigate whether RvD1 exerts protective effects on alveolar epithelial cell function/differentiation and protects against fibroproliferative stimuli. Primary human alveolar type II cells were used to model the effects of RvD1 in vitro upon wound repair, proliferation, apoptosis, transdifferentiation, and epithelial-mesenchymal transition (EMT). Effects of RvD1 upon primary human lung fibroblast proliferation, collagen production, and myofibroblast differentiation were also examined. RvD1 promoted alveolar type II (ATII) cell wound repair and proliferation. RvD1 protected ATII cells against sFas-ligand/TNF-α-induced apoptosis and inhibition on cell proliferation and viability. RvD1 promoted ATII cells transdifferentiation. Moreover, we demonstrate that RvD1 inhibited EMT in response to TGF-β. Furthermore RvD1 inhibited human lung fibroblast proliferation, collagen production, and myofibroblast differentiation induced by both TGF-β and bronchoalveolar lavage fluid from acute respiratory distress syndrome (ARDS) patients. The effects of RvD1 were PI3-kinase dependent and mediated via the resolvin receptor. RvD1 seems to promote alveolar epithelial repair by stimulating ATII cells wound repair, proliferation, reducing apoptosis, and inhibiting TGF-β-induced EMT. While RvD1 reduced fibroproliferation, collagen production, and myofibroblast differentiation. Together, these results suggest a potential new therapeutic strategy for preventing and treating chronic diseases (such as idiopathic pulmonary fibrosis) as well as the fibroproliferative phase of ARDS by targeting RvD1 actions that emphasizes natural resolution signaling pathways.

Cystic Fibrosis Transmembrane Conductance Regulator Potentiation as a Therapeutic Strategy for Pulmonary Edema: A Proof-of-Concept Study in Pigs

OBJECTIVES

To determine the feasibility of using a cystic fibrosis transmembrane conductance regulator potentiator, ivacaftor (VX-770/Kalydeco, Vertex Pharmaceuticals, Boston, MA), as a therapeutic strategy for treating pulmonary edema.

DESIGN

Prospective laboratory animal investigation.

SETTING

Animal research laboratory.

SUBJECTS

Newborn and 3 days to 1 week old pigs.

INTERVENTIONS

Hydrostatic pulmonary edema was induced in pigs by acute volume overload. Ivacaftor was nebulized into the lung immediately after volume overload. Grams of water per grams of dry lung tissue were determined in the lungs harvested 1 hour after volume overload.

MEASUREMENTS AND MAIN RESULTS

Ivacaftor significantly improved alveolar liquid clearance in isolated pig lung lobes ex vivo and reduced edema in a volume overload in vivo pig model of hydrostatic pulmonary edema. To model hydrostatic pressure-induced edema in vitro, we developed a method of applied pressure to the basolateral surface of alveolar epithelia. Elevated hydrostatic pressure resulted in decreased cystic fibrosis transmembrane conductance regulator activity and liquid absorption, an effect which was partially reversed by cystic fibrosis transmembrane conductance regulator potentiation with ivacaftor.

CONCLUSIONS

Cystic fibrosis transmembrane conductance regulator potentiation by ivacaftor is a novel therapeutic approach for pulmonary edema.

Treatments for Pulmonary Ricin Intoxication: Current Aspects and Future Prospects

Ricin, a plant-derived toxin originating from the seeds of Ricinus communis (castor beans), is one of the most lethal toxins known, particularly if inhaled. Ricin is considered a potential biological threat agent due to its high availability and ease of production. The clinical manifestation of pulmonary ricin intoxication in animal models is closely related to acute respiratory distress syndrome (ARDS), which involves pulmonary proinflammatory cytokine upregulation, massive neutrophil infiltration and severe edema. Currently, the only post-exposure measure that is effective against pulmonary ricinosis at clinically relevant time-points following intoxication in pre-clinical studies is passive immunization with anti-ricin neutralizing antibodies. The efficacy of this antitoxin treatment depends on antibody affinity and the time of treatment initiation within a limited therapeutic time window. Small-molecule compounds that interfere directly with the toxin or inhibit its intracellular trafficking may also be beneficial against ricinosis. Another approach relies on the co-administration of antitoxin antibodies with immunomodulatory drugs, thereby neutralizing the toxin while attenuating lung injury. Immunomodulators and other pharmacological-based treatment options should be tailored according to the particular pathogenesis pathways of pulmonary ricinosis. This review focuses on the current treatment options for pulmonary ricin intoxication using anti-ricin antibodies, disease-modifying countermeasures, anti-ricin small molecules and their various combinations.

A journey between high altitude hypoxia and critical patient hypoxia: What can it teach us about compression and the management of critical disease?

High altitude sickness (hypobaric hypoxia) is a form of cellular hypoxia similar to that suffered by critically ill patients. The study of mountaineers exposed to extreme hypoxia offers the advantage of involving a relatively homogeneous and healthy population compared to those typically found in Intensive Care Units (ICUs), which are heterogeneous and generally less healthy. Knowledge of altitude physiology and pathology allows us to understanding how hypoxia affects critical patients. Comparable changes in mitochondrial biogenesis between both groups may reflect similar adaptive responses and suggest therapeutic interventions based on the protection or stimulation of such mitochondrial biogenesis. Predominance of the homozygous insertion (II) allele of the angiotensin-converting enzyme gene is present in both individuals who perform successful ascensions without oxygen above 8000 m and in critical patients who overcome certain disease conditions.

The clinical practice guideline for the management of ARDS in Japan

BACKGROUND

The Japanese Society of Respiratory Care Medicine and the Japanese Society of Intensive Care Medicine provide here a clinical practice guideline for the management of adult patients with ARDS in the ICU.

METHOD

The guideline was developed applying the GRADE system for performing robust systematic reviews with plausible recommendations. The guideline consists of 13 clinical questions mainly regarding ventilator settings and drug therapies (the last question includes 11 medications that are not approved for clinical use in Japan).

RESULTS

The recommendations for adult patients with ARDS include: we suggest against early tracheostomy (GRADE 2C), we suggest using NPPV for early respiratory management (GRADE 2C), we recommend the use of low tidal volumes at 6-8 mL/kg (GRADE 1B), we suggest setting the plateau pressure at 30cmH20 or less (GRADE2B), we suggest using PEEP within the range of plateau pressures less than or equal to 30cmH2O, without compromising hemodynamics (Grade 2B), and using higher PEEP levels in patients with moderate to severe ARDS (Grade 2B), we suggest using protocolized methods for liberation from mechanical ventilation (Grade 2D), we suggest prone positioning especially in patients with moderate to severe respiratory dysfunction (GRADE 2C), we suggest against the use of high frequency oscillation (GRADE 2C), we suggest the use of neuromuscular blocking agents in patients requiring mechanical ventilation under certain circumstances (GRADE 2B), we suggest fluid restriction in the management of ARDS (GRADE 2A), we do not suggest the use of neutrophil elastase inhibitors (GRADE 2D), we suggest the administration of steroids, equivalent to methylprednisolone 1-2mg/kg/ day (GRADE 2A), and we do not recommend other medications for the treatment of adult patients with ARDS (GRADE1B; inhaled/intravenous β2 stimulants, prostaglandin E1, activated protein C, ketoconazole, and lisofylline, GRADE 1C; inhaled nitric oxide, GRADE 1D; surfactant, GRADE 2B; granulocyte macrophage colony-stimulating factor, N-acetylcysteine, GRADE 2C; Statin.).

CONCLUSIONS

This article was translated from the Japanese version originally published as the ARDS clinical practice guidelines 2016 by the committee of ARDS clinical practice guideline (Tokyo, 2016, 293p, available from http://www.jsicm.org/ARDSGL/ARDSGL2016.pdf). The original article, written for Japanese healthcare providers, provides points of view that are different from those in other countries.

Fifty Years of Research in ARDS. Is Acute Respiratory Distress Syndrome a Preventable Disease?

Despite significant advances in our understanding and management of patients with acute respiratory distress syndrome (ARDS), the morbidity and mortality from ARDS remains high. Given the limited number of effective treatments for established ARDS, the strategic focus of ARDS research has shifted toward identifying patients with or at high risk of ARDS early in the course of the underlying illness, when strategies to reduce the development and progression of ARDS and associated organ failures can be systematically evaluated. In this review, we summarize the rationale, current evidence, and future directions in ARDS prevention.

Alveolar recruitment maneuver attenuates extravascular lung water in acute respiratory distress syndrome

BACKGROUND

The alveolar recruitment maneuver (RM) has been reported to improve oxygenation in acute respiratory distress syndrome (ARDS) and may be related to reduced extravascular lung water (EVLW) in animals. This study was designed to investigate the effects of RM on EVLW in patients with ARDS.

METHODS

An open label, prospective, randomized controlled trial including patients with ARDS was conducted in hospitals in North Taiwan between 2010 and 2016. The patients were divided into 2 groups (with and without RM). The primary endpoint was the comparison of the EVLW index between the 2 groups.

RESULTS

Twenty-four patients with ARDS on mechanical ventilator support were randomized to receive ventilator treatment with RM (RM group, n = 12) or without RM (non-RM group, n = 12). Baseline demographic characteristics were similar between the 2 groups. After recruitment, the day 3 extravascular lung water index (EVLWI) (25.3 ± 9.3 vs 15.5 ± 7.3 mL/kg, P = .008) and the arterial oxygen tension/fractional inspired oxygen ratio (PaO2/FiO2) (132.3 ± 43.5 vs 185.6 ± 38.8 mL/kg, P = .003) both improved over that of day 1. However, both EVLWI and PaO2/FiO2 did not significantly change from day 1 to 3 in the non-RM group.

CONCLUSION

RM is a feasible method for improving oxygenation and the EVLW index in patients with ARDS, as well as for decreasing ventilator days and intensive care unit stay duration.

Inhalation therapies in acute respiratory distress syndrome

The defining features of acute respiratory distress syndrome (ARDS) are an excessive inflammatory respiratory response associated with high morbidity and mortality. Treatment consists mainly of measures to avoid worsening lung injury and cannot reverse the underlying pathophysiological process. New pharmacological agents have shown promising results in preclinical studies; however, they have not been successfully translated to patients with ARDS. The lack of effective therapeutic interventions has resulted in a recent interest in strategies to prevent ARDS with treatments delivering medications directly to the lungs by inhalation and nebulization, hopefully minimizing systemic adverse events. We analyzed the effect of different aerosolized drugs such as bronchodilators, corticosteroids, pulmonary vasodilators, anticoagulants, mucolytics and surfactant. New therapeutic strategies and ongoing trials using carbon monoxide (CO) and AP301 peptide are also briefly reviewed.

Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016

OBJECTIVE

To provide an update to "Surviving Sepsis Campaign Guidelines for Management of Sepsis and Septic Shock: 2012."

DESIGN

A consensus committee of 55 international experts representing 25 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. A stand-alone meeting was held for all panel members in December 2015. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development.

METHODS

The panel consisted of five sections: hemodynamics, infection, adjunctive therapies, metabolic, and ventilation. Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. Each subgroup generated a list of questions, searched for best available evidence, and then followed the principles of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system to assess the quality of evidence from high to very low, and to formulate recommendations as strong or weak, or best practice statement when applicable.

RESULTS

The Surviving Sepsis Guideline panel provided 93 statements on early management and resuscitation of patients with sepsis or septic shock. Overall, 32 were strong recommendations, 39 were weak recommendations, and 18 were best-practice statements. No recommendation was provided for four questions.

CONCLUSIONS

Substantial agreement exists among a large cohort of international experts regarding many strong recommendations for the best care of patients with sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for these critically ill patients with high mortality.

Higher mini-BAL total protein concentration in early ARDS predicts faster resolution of lung injury measured by more ventilator-free days

The protein concentration of alveolar edema fluid in acute respiratory distress syndrome (ARDS) is dynamic. It reflects alveolar flooding during acute injury, as well as fluid and protein clearance over time. We hypothesized that among ARDS patients treated with low tidal volume ventilation, higher concentrations of protein in mini-bronchoalveolar lavage (mBAL) samples would predict slower resolution of lung injury and worse clinical outcomes. Total protein and IgM concentrations in day 0 mBAL samples from 79 subjects enrolled in the aerosolized albuterol (ALTA) ARDS Network Albuterol Trial were measured by colorimetric assay and ELISA, respectively. Linear regression models were used to test the association of mBAL proteins with clinical outcomes and measures of length of illness, including ventilator-free days (VFDs). Median mBAL total protein concentration was 1,740 μg/ml [interquartile range (IQR): 890-3,170]. Each 500 μg/ml increase in day 0 mBAL total protein was associated with an additional 0.8 VFDs [95% confidence interval (CI): 0.05-1.6, P value = 0.038]. Median mBAL IgM concentration was 410 ng/ml (IQR: 340-500). Each 50 ng/ml increase in mBAL IgM was associated with an additional 1.1 VFDs (95% CI 0.2-2.1, P value = 0.022). These associations remained significant and were not attenuated in multivariate models adjusted for age, serum protein concentration, and vasopressor use in the 24 h before enrollment. Thus, higher mBAL total protein and IgM concentrations at day 0 are associated with more VFDs in patients with ARDS and may identify patients with preserved alveolar epithelial mechanisms for net alveolar fluid clearance.

Maresin1 stimulates alveolar fluid clearance through the alveolar epithelial sodium channel Na,K-ATPase via the ALX/PI3K/Nedd4-2 pathway

Maresin1 (MaR1) is a new docosahexaenoic acid-derived pro-resolving agent that promotes the resolution of inflammation. In this study, we sought to investigate the effect and underlining mechanisms of MaR1 in modulating alveolar fluid clearance (AFC) on LPS-induced acute lung injury. MaR1 was injected intravenously or administered by instillation (200 ng/kg) 8 h after LPS (14 mg/kg) administration and AFC was measured in live rats. In primary rat alveolar type II epithelial cells, MaR1 (100 nM) was added to the culture medium with lipopolysaccharide for 6 h. MaR1 markedly stimulated AFC in LPS-induced lung injury, with the outcome of decreased pulmonary edema and lung injury. In addition, rat lung tissue protein was isolated after intervention, and we found MaR1 improved epithelial sodium channel (ENaC), Na,K-adenosine triphosphatase (ATPase) protein expression and Na,K-ATPase activity. MaR1 down-regulated Nedd4-2 protein expression though PI3k/Akt but not though PI3k/SGK1 pathway in vivo. In primary rat alveolar type II epithelial cells stimulated with LPS, MaR1-upregulated ENaC and Na,K-ATPase protein abundance in the plasma membrane. Finally, the lipoxin A4 Receptor inhibitor (BOC-2) and PI3K inhibitor (LY294002) not only blocked MaR1's effects on cAMP/cGMP, the expression of phosphorylated Akt and Nedd4-2, but also inhibited the effect of MaR1 on AFC in vivo. In conclusion, MaR1 stimulates AFC through a mechanism partly dependent on alveolar epithelial ENaC and Na,K-ATPase activation via the ALX/PI3K/Nedd4-2 signaling pathway. Our findings reveal a novel mechanism for pulmonary edema fluid reabsorption and MaR1 may provide a new therapy for the resolution of ALI/ARDS.

Dexmedetomidine enhances human lung fluid clearance through improving alveolar sodium transport

Accumulating evidence shows that dexmedetomidine can attenuate lung edema with acute lung injury in experimental mouse and rat models, but the mechanisms of dexmedetomidine on human alveolar fluid transport are still unknown. We measured the effects of dexmedetomidine on alveolar fluid clearance in human lung lobes ex vivo. Moreover, we measured the regulation of transepithelial Na⁺ transport by dexmedetomidine in H441 cells by electrophysiological technique and Western blot method. Our results showed that intratracheal instillation of dexmedetomidine markedly increased the reabsorption of 5% bovine serum albumin instillate (19.8 ± 1.4%, P < 0.01 vs. Control, n = 5). Further studies suggested that dexmedetomidine increased amiloride-sensitive short-circuit currents in permeabilized H441 monolayers and whole cell amiloride-sensitive Na⁺ currents in a dose-dependent fashion. Real-time PCR and Western blot results showed that dexmedetomidine could enhance the mRNA and protein expression of α-ENaC subunit, while inhibiting the phosphorylation of ERK_1/2 . These data demonstrate that dexmedetomidine could improve human lung fluid clearance and lung epithelial Na⁺ channel activity, and these effects may be mediated through the enhancement of α-ENaC expression and inhibition of ERK_1/2 pathway.

Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016

OBJECTIVE

To provide an update to "Surviving Sepsis Campaign Guidelines for Management of Sepsis and Septic Shock: 2012".

DESIGN

A consensus committee of 55 international experts representing 25 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. A stand-alone meeting was held for all panel members in December 2015. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development.

METHODS

The panel consisted of five sections: hemodynamics, infection, adjunctive therapies, metabolic, and ventilation. Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. Each subgroup generated a list of questions, searched for best available evidence, and then followed the principles of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system to assess the quality of evidence from high to very low, and to formulate recommendations as strong or weak, or best practice statement when applicable.

RESULTS

The Surviving Sepsis Guideline panel provided 93 statements on early management and resuscitation of patients with sepsis or septic shock. Overall, 32 were strong recommendations, 39 were weak recommendations, and 18 were best-practice statements. No recommendation was provided for four questions.

CONCLUSIONS

Substantial agreement exists among a large cohort of international experts regarding many strong recommendations for the best care of patients with sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for these critically ill patients with high mortality.

δβγ-ENaC is inhibited by CFTR but stimulated by cAMP in Xenopus laevis oocytes

The epithelial sodium channel (ENaC) and the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel critically regulate airway surface liquid by driving fluid absorption and secretion, respectively. Their functional interplay is complex and incompletely understood. ENaC is a heteromeric channel with three well-characterized subunits (α, β, and γ). In humans, an additional δ-ENaC subunit exists in lung and several other tissues, where it may replace the α-subunit to form δβγ-ENaC. Little is known about the physiological role of δβγ-ENaC and its possible interaction with CFTR. The aim of the present study was to investigate the effect of human CFTR on human δβγ-ENaC heterologously expressed in Xenopus laevis oocytes. In oocytes coexpressing δβγ-ENaC and CFTR the ENaC-mediated amiloride-sensitive whole cell current (ΔI_ami) was reduced by ~50% compared with that measured in oocytes expressing δβγ-ENaC alone. Moreover, basal level of proteolytic ENaC activation was reduced in the presence of CFTR. The inhibitory effect of CFTR on δβγ-ENaC was due to a combination of decreased average open probability (P_o) and reduced channel expression at the cell surface. Interestingly, in oocytes expressing δβγ-ENaC, increasing intracellular [cAMP] by IBMX and forskolin increased ΔI_ami by ~50%. This stimulatory effect was not observed for human and rat αβγ-ENaC and was independent of CFTR coexpression and coactivation. Experiments with a mutant channel (δβ_S520Cγ-ENaC) which can be converted to a channel with a P_o of nearly 1 suggested that cAMP activates δβγ-ENaC by increasing P_o In conclusion, our results demonstrate that δβγ-ENaC is inhibited by CFTR but activated by cAMP.

Albuterol Improves Alveolar-Capillary Membrane Conductance in Healthy Humans

BACKGROUND

Beta-2 adrenergic receptors (β₂ARs) are located throughout the body including airway and alveolar cells. The β₂ARs regulate lung fluid clearance through a variety of mechanisms including ion transport on alveolar cells and relaxation of the pulmonary lymphatics. We examined the effect of an inhaled β₂-agonist (albuterol) on alveolar-capillary membrane conductance (DM) and pulmonary capillary blood volume (V_C) in healthy humans.

METHODS

We assessed the diffusing capacity of the lungs for carbon monoxide (DLCO) and nitric oxide (DLNO) at baseline, 30 minutes, and 60 minutes following nebulized albuterol (2.5 mg, diluted in 3 mL normal saline) in 45 healthy subjects. Seventeen subjects repeated these measures following nebulized normal saline (age = 27 ± 9 years, height = 165 ± 21 cm, weight = 68 ± 12 kg, BMI = 26 ± 9 kg/m²). Cardiac output (Q), heart rate, systemic vascular resistance (SVR), blood pressure, oxygen saturation, forced expiratory volume at one-second (FEV₁), and forced expiratory flow at 50% of forced vital capacity (FEF₅₀) were assessed at baseline, 30 minutes, and 60 minutes following the administration of albuterol or saline.

RESULTS

Albuterol resulted in a decrease in SVR, and an increase in Q, FEV₁, and FEF₅₀ compared to saline controls. Albuterol also resulted in a decrease in V_C at 60 minutes post albuterol. Both albuterol and normal saline resulted in no change in DLCO or DM when assessed alone, but a significant increase was observed in DM when accounting for changes in V_C.

CONCLUSION

These data suggest that nebulized albuterol improves pulmonary function in healthy humans, while nebulization of both albuterol and saline results in an increase in DM/V_C.

Lipoxin A4 promotes lung epithelial repair whilst inhibiting fibroblast proliferation

Therapy that promotes epithelial repair whilst protecting against fibroproliferation is critical for restoring lung function in acute and chronic respiratory diseases.

Primary human alveolar type II cells were used to model the effects of lipoxin A₄in vitro upon wound repair, proliferation, apoptosis and transdifferention. Effects of lipoxin A₄ upon primary human lung fibroblast proliferation, collagen production, and myofibroblast differentiation were also assessed.

Lipoxin A₄ promoted type II cell wound repair and proliferation, blocked the negative effects of soluble Fas ligand/tumour necrosis factor α upon cell proliferation, viability and apoptosis, and augmented the epithelial cell proliferative response to bronchoaveolar lavage fluid (BALF) from acute respiratory distress syndrome (ARDS). In contrast, Lipoxin A₄ reduced fibroblast proliferation, collagen production and myofibroblast differentiation induced by transforming growth factor β and BALF from ARDS. The effects of Lipoxin A₄ were phosphatidylinositol 3′-kinase dependent and mediated via the lipoxin A₄ receptor.

Lipoxin A₄ appears to promote alveolar epithelial repair by stimulating epitheial cell wound repair, proliferation, reducing apoptosis and promoting trans-differentiation of alveolar type II cells into type I cells. Lipoxin A₄ reduces fibroblast proliferation, collagen production and myofibroblast differentiation. These data suggest that targeting lipoxin actions may be a therapeutic strategy for treating the resolution phase of ARDS.

Lipoxin A4 promotes epithelial repair while inhibiting fibroproliferation in vitro in human alveolar epithelial cellshttp://ow.ly/SxMu301cBRP

Scandinavian clinical practice guideline on fluid and drug therapy in adults with acute respiratory distress syndrome

BACKGROUND

The objective of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI) task force on fluid and drug therapy in adults with acute respiratory distress syndrome (ARDS) was to provide clinically relevant, evidence-based treatment recommendations according to standards for trustworthy guidelines.

METHODS

The guideline was developed according to standards for trustworthy guidelines, including a systematic review of the literature and use of the GRADE methodology for assessment of the quality of evidence and for moving from evidence to recommendations.

RESULTS

A total of seven ARDS interventions were assessed. We suggest fluid restriction in patients with ARDS (weak recommendation, moderate quality evidence). Also, we suggest early use of neuromuscular blocking agents (NMBAs) in patients with severe ARDS (weak recommendation, moderate quality evidence). We recommend against the routine use of other drugs, including corticosteroids, beta2 agonists, statins, and inhaled nitric oxide (iNO) or prostanoids in adults with ARDS (strong recommendations: low- to high-quality evidence). These recommendations do not preclude the use of any drug or combination of drugs targeting underlying or co-existing disorders.

CONCLUSION

This guideline emphasizes the paucity of evidence of benefit - and potential for harm - of common interventions in adults with ARDS and highlights the need for prudence when considering use of non-licensed interventions in this patient population.

Epinephrine for transient tachypnea of the newborn

BACKGROUND

Transient tachypnea of the newborn is characterized by tachypnea and signs of respiratory distress. Transient tachypnea typically appears within the first two hours of life in term and late preterm newborns. Although transient tachypnea of the newborn is usually a self limited condition, it is associated with wheezing syndromes in late childhood. The rationale for the use of epinephrine (adrenaline) for transient tachypnea of the newborn is based on studies showing that β-agonists can accelerate the rate of alveolar fluid clearance.

OBJECTIVES

To assess whether epinephrine compared to placebo, no treatment or any other drugs (excluding salbutamol) is effective and safe in the treatment of transient tachypnea of the newborn in infants born at 34 weeks' gestational age or more.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2016, Issue 3), MEDLINE (1996 to March 2016), EMBASE (1980 to March 2016) and CINAHL (1982 to March 2016). We applied no language restrictions. We searched the abstracts of the major congresses in the field (Perinatal Society of Australia and New Zealand and Pediatric Academic Societies) from 2000 to 2015.

SELECTION CRITERIA

Randomized controlled trials, quasi-randomized controlled trials and cluster trials comparing epinephrine versus placebo or no treatment or any other drugs administered to infants born at 34 weeks' gestational age or more and less than three days of age with transient tachypnea of the newborn.

DATA COLLECTION AND ANALYSIS

For the included trial, two review authors independently extracted data (e.g. number of participants, birth weight, gestational age, duration of oxygen therapy (hours), need for continuous positive airway pressure and need for mechanical ventilation, duration of mechanical ventilation, etc.) and assessed the risk of bias (e.g. adequacy of randomization, blinding, completeness of follow-up). The primary outcomes considered in this review were duration of oxygen therapy (hours), need for continuous positive airway pressure and need for mechanical ventilation.

MAIN RESULTS

One trial, which included 20 infants, met the inclusion criteria of this review. Study authors administered three doses of nebulized 2.25% racemic epinephrine or placebo. We found no differences between the two group in the duration of supplemental oxygen therapy (mean difference (MD) -6.60, 95% confidence interval (CI) -54.80 to 41.60 hours) and need for mechanical ventilation (risk ratio (RR) 0.67, 95% CI 0.08 to 5.88; risk difference (RD) -0.07, 95% CI -0.46 to 0.32). Among secondary outcomes, we found no differences in terms of initiation of oral feeding. The quality of the evidence was limited due to the imprecision of the estimates.

AUTHORS' CONCLUSIONS

At present there is insufficient evidence to determine the efficacy and safety of epinephrine in the management of transient tachypnea of the newborn.

Salbutamol for transient tachypnea of the newborn

BACKGROUND

Transient tachypnea of the newborn is characterized by tachypnea and signs of respiratory distress. Transient tachypnea typically appears within the first two hours of life in term and late preterm newborns. Although transient tachypnea of the newborn is usually a self limited condition, it is associated with wheezing syndromes in late childhood. The rationale for the use of salbutamol (albuterol) for transient tachypnea of the newborn is based on studies showing that β-agonists can accelerate the rate of alveolar fluid clearance.

OBJECTIVES

To assess whether salbutamol compared to placebo, no treatment or any other drugs administered to treat transient tachypnea of the newborn, is effective and safe in the treatment of transient tachypnea of the newborn in infants born at 34 weeks' gestational age or more.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2016, Issue 3), MEDLINE (1996 to March 2016), EMBASE (1980 to March 2016) and CINAHL (1982 to March 2016). We applied no language restrictions. We searched the abstracts of the major congresses in the field (Perinatal Society of Australia New Zealand and Pediatric Academic Societies) from 2000 to 2015 and clinical trial registries.

SELECTION CRITERIA

Randomized controlled trials, quasi-randomized controlled trials and cluster trials comparing salbutamol versus placebo or no treatment or any other drugs administered to infants born at 34 weeks' gestational age or more and less than three days of age with transient tachypnea of the newborn.

DATA COLLECTION AND ANALYSIS

For each of the included trials, two review authors independently extracted data (e.g. number of participants, birth weight, gestational age, duration of oxygen therapy, need for continuous positive airway pressure and need for mechanical ventilation, duration of mechanical ventilation, etc.) and assessed the risk of bias (e.g. adequacy of randomization, blinding, completeness of follow-up). The primary outcomes considered in this review were duration of oxygen therapy, need for continuous positive airway pressure and need for mechanical ventilation.

MAIN RESULTS

Three trials, which included 140 infants, met the inclusion criteria. All three trials compared a nebulized dose of salbutamol with placebo; in one of the three trials newborns were assigned to two different doses of the intervention. We found differences in the duration of oxygen therapy (mean difference (MD) -43.10 hours, 95% confidence interval (CI) -81.60 to -4.60). There were no differences in the need for continuous positive airway pressure (risk ratio (RR) 0.73, 95% CI 0.38 to 1.39; risk difference (RD) -0.15, 95% CI -0.45 to 0.16; 1 study, 46 infants) or the need for mechanical ventilation (RR 1.50, 95% CI 0.06 to 34.79; RD 0.03, 95% CI -0.08 to 0.14; 1 study, 46 infants). Tests for heterogeneity were not applicable for any of the analyses as only one study was included. Among secondary outcomes, we found no differences in terms of duration of hospital stay and tachypnea. The quality of the evidence was very low due to the imprecision of the estimates. One trial is ongoing.

AUTHORS' CONCLUSIONS

At present there is insufficient evidence to determine the efficacy and safety of salbutamol in the management of transient tachypnea of the newborn. The quality of evidence was low due to paucity of included trials, small sample sizes and overall poor methodologic quality.

Review of the British Thoracic Society Winter Meeting 2015, 2-4 December, London, UK

The British Thoracic Society Winter Meeting 2015 is reviewed in this article. Over 3 days in December, this annual scientific meeting attracted over 2300 delegates and up-to-date respiratory research was presented by leading UK and international speakers. This article reviews a number of symposia and selected abstract presentations from the meeting.

Influenza leaves a TRAIL to pulmonary edema

Influenza infection can cause acute respiratory distress syndrome (ARDS), leading to poor disease outcome with high mortality. One of the driving features in the pathogenesis of ARDS is the accumulation of fluid in the alveoli, which causes severe pulmonary edema and impaired oxygen uptake. In this issue of the JCI, Peteranderl and colleagues define a paracrine communication between macrophages and type II alveolar epithelial cells during influenza infection where IFNα induces macrophage secretion of TRAIL that causes endocytosis of Na,K-ATPase by the alveolar epithelium. This reduction of Na,K-ATPase expression decreases alveolar fluid clearance, which in turn leads to pulmonary edema. Inhibition of the TRAIL signaling pathway has been shown to improve lung injury after influenza infection, and future studies will be needed to determine if blocking this pathway is a viable option in the treatment of ARDS.

1,25-Dihydroxyvitamin D Enhances Alveolar Fluid Clearance by Upregulating the Expression of Epithelial Sodium Channels

Vitamin D is implicated in the pathogenesis of asthma, acute lung injury, and other respiratory diseases. 1,25-Dihydroxyvitamin D (1,25(OH)2D3), the hormonal form of vitamin D, has been shown to reduce vascular permeability and ameliorate lung edema. Therefore, we speculate that 1,25(OH)2D3 may regulate alveolar Na(+) transport via targeting epithelial Na(+) channels (ENaC), a crucial pathway for alveolar fluid clearance. In vivo total alveolar fluid clearance was 39.4 ± 3.8% in 1,25(OH)2D3-treated mice, significantly greater than vehicle-treated controls (24.7 ± 1.9 %, n = 10, p < 0.05). 1,25(OH)2D3 increased amiloride-sensitive short-circuit currents in H441 monolayers, and whole-cell patch-clamp data confirmed that ENaC currents in single H441 cell were enhanced in 1,25(OH)2D3-treated cells. Western blot showed that the expression of α-ENaC was significantly elevated in 1,25(OH)2D3-treated mouse lungs and 1,25(OH)2D3-treated H441 cells. These observations suggest that vitamin D augments transalveolar fluid clearance, and vitamin D therapy may potentially be used to ameliorate pulmonary edema.

Chronic Hypoxemia in Children With Congenital Heart Defect Impairs Airway Epithelial Sodium Transport

OBJECTIVE

Ambient hypoxia impairs the airway epithelial Na transport, which is crucial in lung edema reabsorption. Whether chronic systemic hypoxemia affects airway Na transport has remained largely unknown. We have therefore investigated whether chronic systemic hypoxemia in children with congenital heart defect affects airway epithelial Na transport, Na transporter-gene expression, and short-term lung edema accumulation.

DESIGN

Prospective, observational study.

SETTING

Tertiary care medical center responsible for nationwide pediatric cardiac surgery.

PATIENTS

Ninety-nine children with congenital heart defect or acquired heart disease (age range, 6 d to 14.8 yr) were divided into three groups based on their level of preoperative systemic hypoxemia: 1) normoxemic patients (SpO2% ≥ 95%; n = 44), 2) patients with cyanotic congenital heart defect and moderate hypoxemia (SpO2 86-94%; n = 16), and 3) patients with cyanotic congenital heart defect and profound systemic hypoxemia (SpO2 ≤ 85%; n = 39).

MEASUREMENTS AND MAIN RESULTS

Nasal transepithelial potential difference served as a surrogate measure for epithelial Na transport of the respiratory tract. Profoundly hypoxemic patients had 29% lower basal nasal transepithelial potential difference (p = 0.02) and 55% lower amiloride-sensitive nasal transepithelial potential difference (p = 0.0003) than normoxemic patients. In profoundly hypoxemic patients, nasal epithelial messenger RNA expressions of two airway Na transporters (amiloride-sensitive epithelial Na channel and β1- Na-K-ATPase) were not attenuated, but instead α1-Na-K-ATPase messenger RNA levels were higher (p = 0.03) than in the normoxemic patients, indicating that posttranscriptional factors may impair airway Na transport. The chest radiograph lung edema score increased after congenital cardiac surgery in profoundly hypoxemic patients (p = 0.0004) but not in patients with normoxemia or moderate hypoxemia.

CONCLUSIONS

The impaired airway epithelial amiloride-sensitive Na transport activity in profoundly hypoxemic children with cyanotic congenital heart defect may hinder defense against lung edema after cardiac surgery.

With-No-Lysine Kinase 4 Mediates Alveolar Fluid Regulation in Hyperoxia-Induced Lung Injury

OBJECTIVES

To investigate mechanisms involved in the regulation of epithelial ion channels and alveolar fluid clearance in hyperoxia-induced lung injury.

DESIGN

Laboratory animal experiments.

SETTING

Animal care facility procedure room in a medical center.

SUBJECTS

Wild-type, STE20/SPS1-related proline/alanine-rich kinase knockout (SPAK(-/-)), and with-no-lysine kinase 4 knockin (WNK4(D561A/+)) mice.

INTERVENTIONS

Mice were exposed to room air or 95% hyperoxia for 60 hours.

MEASUREMENTS AND MAIN RESULTS

Exposure to hyperoxia for 60 hours increased the lung expression of with-no-lysine kinase 4 and led to STE20/SPS1-related proline/alanine-rich kinase and sodium-potassium-chloride cotransporter phosphorylation, which resulted in the suppression of alveolar fluid clearance and increase of lung edema. WNK4(D561A/+) mice at the baseline presented an abundance of epithelium sodium channel and high levels of STE20/SPS1-related proline/alanine-rich kinase and sodium-potassium-chloride cotransporter phosphorylation. Compared with the wild-type group, hyperoxia caused greater epithelium sodium channel expression in WNK4(D561A/+) mice, but no significant difference in STE20/SPS1-related proline/alanine-rich kinase and sodium-potassium-chloride cotransporter phosphorylation. The functional inactivation of sodium-potassium-chloride cotransporter by gene knockout in SPAK(-/-) mice yielded a lower severity of lung injury and longer animal survival, whereas constitutive expression of with-no-lysine kinase 4 exacerbated the hyperoxia-induced lung injury. Pharmacologic inhibition of sodium-potassium-chloride cotransporter by inhaled furosemide improved animal survival in WNK4(D561A/+) mice. By contrast, inhibition of epithelium sodium channel exacerbated the hyperoxia-induced lung injury and animal death.

CONCLUSIONS

With-no-lysine kinase 4 plays a crucial role in the regulation of epithelial ion channels and alveolar fluid clearance, mainly via phosphorylation and activation of STE20/SPS1-related proline/alanine-rich kinase and sodium-potassium-chloride cotransporter.

Lipoxin A4 activates alveolar epithelial sodium channel gamma via the microRNA-21/PTEN/AKT pathway in lipopolysaccharide-induced inflammatory lung injury

Lipoxin A4 (LXA4), as an endogenously produced lipid mediator, promotes the resolution of inflammation. Previously, we demonstrated that LXA4 stimulated alveolar fluid clearance through alveolar epithelial sodium channel gamma (ENaC-γ). In this study, we sought to investigate the mechanisms of LXA4 in modulation of ENaC-γ in lipopolysaccharide (LPS)-induced inflammatory lung injury. miR-21 was upregulated during an LPS challenge and downregulated by LXA4 administration in vivo and in vitro. Serum miR-21 concentration was also elevated in acute respiratory distress syndrome patients as compared with healthy volunteers. LPS increased miR-21 expression by activation of activator protein 1 (AP-1). In A549 cells, miR-21 upregulated phosphorylation of AKT activation via inhibition of phosphatase and tensin homolog (PTEN), and therefore reduced the expression of ENaC-γ. In contrast, LXA4 reversed LPS-inhibited ENaC-γ expression through inhibition of AP-1 and activation of PTEN. In addition, an miR-21 inhibitor mimicked the effects of LXA4; overexpression of miR-21 abolished the protective effects of LXA4. Finally, both AKT and ERK inhibitors (LY294002 and UO126) blocked effects of LPS on the depression of ENaC-γ. However, LXA4 only inhibited LPS-induced phosphorylation of AKT. In summary, LXA4 activates ENaC-γ in part via the miR-21/PTEN/AKT signaling pathway.

The Immunomodulatory and Therapeutic Effects of Mesenchymal Stromal Cells for Acute Lung Injury and Sepsis

It is increasingly recognized that immunomodulation represents an important mechanism underlying the benefits of many stem cell therapies, rather than the classical paradigm of transdifferentiation and cell replacement. In the former paradigm, the beneficial effects of cell therapy result from paracrine mechanism(s) and/or cell-cell interaction as opposed to direct engraftment and repair of diseased tissue and/or dysfunctional organs. Depending on the cell type used, components of the secretome, including microRNA (miRNA) and extracellular vesicles, may be able to either activate or suppress the immune system even without direct immune cell contact. Mesenchymal stromal cells (MSCs), also referred to as mesenchymal stem cells, are found not only in the bone marrow, but also in a wide variety of organs and tissues. In addition to any direct stem cell activities, MSCs were the first stem cells recognized to modulate immune response, and therefore they will be the focus of this review. Specifically, MSCs appear to be able to effectively attenuate acute and protracted inflammation via interactions with components of both innate and adaptive immune systems. To date, this capacity has been exploited in a large number of preclinical studies and MSC immunomodulatory therapy has been attempted with various degrees of success in a relatively large number of clinical trials. Here, we will explore the various mechanism employed by MSCs to effect immunosuppression as well as review the current status of its use to treat excessive inflammation in the context of acute lung injury (ALI) and sepsis in both preclinical and clinical settings.

High-dose Oral Ambroxol for Early Treatment of Pulmonary Acute Respiratory Distress Syndrome: an Exploratory, Randomized, Controlled Pilot Trial

OBJECTIVE

To evaluate efficacy of high-dose oral ambroxol in acute respiratory distress syndrome (ARDS) with respect to ventilator-free days (VFD).

DESIGN

Prospective, randomized, placebo-controlled, blinded pilot trial.

PATIENTS

Sixty-six mechanically ventilated patients (1 month to 12 years) with ARDS who were hand-ventilated for <24 hr before pediatric intensive care unit admission.

INTERVENTIONS

Patients randomized to oral ambroxol (40 mg/kg/day, in four divided doses) (n = 32) or placebo (n = 34) until 10 days, extubation or death whichever is earlier.

MEASUREMENTS AND MAIN RESULTS

Majority (91%) had pneumonia and bronchiolitis. Two study groups were similar in baseline characteristics. Mean partial pressure of arterial oxygen/fraction of inspired oxygen and oxygenation index were >175 and <10, respectively, with no difference in the two study groups. VFD were similar in the two study groups. Overall mortality was 26%. No adverse events were noted with ambroxol.

CONCLUSIONS

Among ventilated pulmonary ARDS patients with oxygenation index of <10, mortality was 26%. Ambroxol did not improve VFD. Study with higher and more frequently administered doses of ambroxol in larger sample is suggested after having generated relevant pharmacokinetic data among critically ill children.

Albuterol in the treatment of acute respiratory distress syndrome: A meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis of randomized controlled trials aimed to systematically evaluate the value of albuterol in the treatment of patients with acute respiratory distress syndrome (ARDS).

DATA SOURCES

Randomized controlled trials on albuterol treatment of ARDS from its inception to October 2014 were searched systematically. The databases searched included: PubMed, Ovid EMBASE, Ovid Cochrane, CNKI, WANFANG and VIP. The trials were screened according to the pre-designed inclusion and exclusion criteria. We performed a systematic review and meta-analysis of the randomized controlled trials (RCTs) on albuterol treatment, attempting to improve outcomes, i.e. lowering the 28-day mortality and ventilator-free days.

RESULTS

Three RCTs involving 646 patients met the inclusion criteria. There was no significant decrease in the 28-day mortality (risk difference=0.09; P=0.07, P for heterogeneity=0.22, I (2)=33%). The ventilator-free days and organ failure-free days were significantly lower in the patients who received albuterol (mean difference=-2.20; P<0.001, P for heterogeneity=0.49, I (2)=0% and mean difference=-1.71, P<0.001, P for heterogeneity=0.60, I (2)=0%).

CONCLUSIONS

Current evidences indicate that treatment with albuterol in the early course of ARDS was not effective in increasing the survival, but significantly decreasing the ventilator-free days and organ failure-free days. Owing to the limited number of included trails, strong recommendations cannot be made.

Exchange protein directly activated by cyclic AMP (EPAC) activation reverses neutrophil dysfunction induced by β2-agonists, corticosteroids, and critical illness

BACKGROUND

Neutrophils play a role in the pathogenesis of asthma, chronic obstructive pulmonary disease, and pulmonary infection. Impaired neutrophil phagocytosis predicts hospital-acquired infection. Despite this, remarkably few neutrophil-specific treatments exist.

OBJECTIVES

We sought to identify novel pathways for the restoration of effective neutrophil phagocytosis and to activate such pathways effectively in neutrophils from patients with impaired neutrophil phagocytosis.

METHODS

Blood neutrophils were isolated from healthy volunteers and patients with impaired neutrophil function. In healthy neutrophils phagocytic impairment was induced experimentally by using β2-agonists. Inhibitors and activators of cyclic AMP (cAMP)-dependent pathways were used to assess the influence on neutrophil phagocytosis in vitro.

RESULTS

β2-Agonists and corticosteroids inhibited neutrophil phagocytosis. Impairment of neutrophil phagocytosis by β2-agonists was associated with significantly reduced RhoA activity. Inhibition of protein kinase A (PKA) restored phagocytosis and RhoA activity, suggesting that cAMP signals through PKA to drive phagocytic impairment. However, cAMP can signal through effectors other than PKA, such as exchange protein directly activated by cyclic AMP (EPAC). An EPAC-activating analog of cAMP (8CPT-2Me-cAMP) reversed neutrophil dysfunction induced by β2-agonists or corticosteroids but did not increase RhoA activity. 8CPT-2Me-cAMP reversed phagocytic impairment induced by Rho kinase inhibition but was ineffective in the presence of Rap-1 GTPase inhibitors. 8CPT-2Me-cAMP restored function to neutrophils from patients with known acquired impairment of neutrophil phagocytosis.

CONCLUSIONS

EPAC activation consistently reverses clinical and experimental impairment of neutrophil phagocytosis. EPAC signals through Rap-1 and bypasses RhoA. EPAC activation represents a novel potential means by which to reverse impaired neutrophil phagocytosis.

Inhaled β2-Agonist Therapy Increases Functional Residual Capacity in Mechanically Ventilated Children With Respiratory Failure

OBJECTIVES

To test the hypothesis that in mechanically ventilated children with respiratory failure, aerosolized albuterol modifies functional residual capacity, lung mechanics, oxygen consumption, and hemodynamics.

DESIGN

Prospective, self-control clinical trial.

SETTING

A 24-bed PICU in a quaternary care, academic children's hospital.

PATIENTS

25 children (age range, 1-18 yr) undergoing mechanical ventilation to treat respiratory failure. Entry criteria included previously prescribed inhaled β2 agonists. Physiologic measurements were performed prior to and 20 minutes after administration of aerosolized albuterol solution. Functional residual capacity was determined via nitrogen washout.

INTERVENTIONS

Functional residual capacity, oxygen consumption, respiratory mechanics, and vital signs were measured were measured prior to and 20 minutes after administration of aerosolized albuterol solution. Functional residual capacity was determined via nitrogen washout.

MEASUREMENT AND MAIN RESULTS

At baseline, functional residual capacity is only 53% of predicted. After aerosolized albuterol, functional residual capacity increased by 18.3% (p = 0.008). Overall, aerosolized albuterol had no effect on airway resistance. However, in patients with an endotracheal tube size of more than or equal to 4.0 mm, resistance decreased from 33 ± 3 to 25 ± 3 (p < 0.02). Inhaled albuterol administration had no effect on oxygen consumption despite an increase in heart rate from 116 ± 2 to 128 ± 2 beats/min (p < 0.0001).

CONCLUSIONS

In pediatric patients with respiratory failure, aerosolized albuterol increases functional residual capacity without a decrease in resistance. In infants and children, aerosolized albuterol might favorably enhance pulmonary mechanics and thereby represent a novel strategy for lung recruitment in children with respiratory failure.

Postperfusion lung syndrome: Respiratory mechanics, respiratory indices and biomarkers

Postperfusion lung syndrome is rare but lethal. Secondary inflammatory response was the popularly accepted theory for the underlying etiology. Respiratory index (RI) and arterial oxygen tension/fractional inspired oxygen can be reliable indices for the diagnosis of this syndrome as X-ray appearance is always insignificant at the early stage of the onset. Evaluations of extravascular lung water content and pulmonary compliance are also helpful in the definite diagnosis. Multiorgan failure and triple acid-base disturbances that might develop secondary to postperfusion lung syndrome are responsible for the poor prognosis and increased mortality rather than postperfusion lung syndrome itself. Mechanical ventilation with low tidal volume (TV) and proper positive end-expiratory pressure can be an effective treatment strategy. Use of ulinastatin and propofol may benefit the patients through different mechanisms.

Synergistic Inhibition of β2-adrenergic Receptor-mediated Alveolar Epithelial Fluid Transport by Interleukin-8 and Transforming Growth Factor-β

BACKGROUND

Patients with acute respiratory distress syndrome who retain maximal alveolar fluid clearance (AFC) have better clinical outcomes. The release of endogenous catecholamines associated with shock or the administration of β2-adrenergic receptor (β2AR) agonists enhances AFC via a 3'-5'-cyclic adenosine monophosphate-dependent mechanism. The authors have previously reported that transforming growth factor-β1 (TGF-β1) and interleukin-8 (IL-8), two major mediators of alveolar inflammation associated with the early phase of acute respiratory distress syndrome, inhibit AFC upregulation by β2AR agonists via a phosphoinositol-3-kinase (PI3K)-dependent mechanism. However, whether TGF-β1 and IL-8 cause an additive or synergistic inhibition of AFC is unclear. Thus, the central hypothesis of the study was to determine whether they synergistically inhibit the β2AR-stimulated AFC by activating two different isoforms of PI3K.

METHODS

The effects of TGF-β1 or IL-8 on β2AR agonist-stimulated net alveolar fluid transport were studied using short-circuit current studies. Molecular pathways of inhibition were confirmed by pharmacologic inhibitors and Western blotting of p-Akt, G-protein-coupled receptor kinase 2, protein kinase C-ζ, and phospho-β2AR. Finally, our observations were confirmed by an in vivo model of AFC.

RESULTS

Combined exposure to TGF-β1 and IL-8/cytokine-induced neutrophil chemoattractant-1 caused synergistic inhibition of β2AR agonist-stimulated vectorial Cl across alveolar epithelial type II cells (n = 12 in each group). This effect was explained by activation of different isoforms of PI3K by TGF-β1 and IL-8/cytokine-induced neutrophil chemoattractant-1 (n = 12 in each group). Furthermore, the inhibitory effect of TGF-β1 on 3'-5'-cyclic adenosine monophosphate-stimulated alveolar epithelial fluid transport required the presence of IL-8/cytokine-induced neutrophil chemoattractant-1 (n = 12 in each group). Inhibition of cytokine-induced neutrophil chemoattractant-1 prevented TGF-β1-mediated heterologous β2AR downregulation and restored physiologic β2AR agonist-stimulated AFC in rats (n = 6 in each group).

CONCLUSIONS

TGF-β1 and IL-8 have a synergistic inhibitory effect on β2AR-mediated stimulation of pulmonary edema removal by the alveolar epithelium. This result may, in part, explain why a large proportion of the patients with acute respiratory distress syndrome have impaired AFC.

Passive targeting of phosphatiosomes increases rolipram delivery to the lungs for treatment of acute lung injury: An animal study

A novel nanovesicle carrier, phosphatiosomes, was developed to enhance the targeting efficiency of phosphodiesterase 4 (PDE4) inhibitor to the lungs for treating acute lung injury (ALI) by intravenous administration. Phosphatiosomes were the basis of a niosomal system containing phosphatidylcholine (PC) and distearoylphosphatidylethanolamine polyethylene glycol (DSPE-PEG). Rolipram was used as the model drug loaded in the phosphatiosomes. Bioimaging, biodistribution, activated neutrophil inhibition, and ALI treatment were performed to evaluate the feasibility of phosphatiosomes as the lung-targeting carriers. An encapsulation percentage of >90% was achieved for rolipram-loaded nanovesicles. The vesicle size and zeta potential of the phosphatiosomes were 154 nm and -34 mV, respectively. Real-time imaging in rats showed a delayed and lower uptake of phosphatiosomes by the liver and spleen. Ex vivo bioimaging demonstrated a high accumulation of phosphatiosomes in the lungs. In vivo biodistribution exhibited increased lung accumulation and reduced brain penetration of rolipram in phosphatiosomes relative to the control solution. Phosphatiosomes improved the lungs/brain ratio of the drug by more than 7-fold. Interaction with pulmonary lipoprotein surfactants and the subsequent aggregation may be the mechanisms for facilitating lung targeting by phosphatiosomes. Rolipram could continue to inhibit active neutrophils after inclusion in the nanovesicles by suppressing O2(-) generation and elevating cAMP. Phosphatiosomes significantly alleviated ALI in mice as revealed by examining their pulmonary appearance, edema, myeloperoxidase (MPO) activity, and histopathology. This study highlights the potential of nanovesicles to deliver the drug for targeting the lungs and attenuating nervous system side effects.

Vitamin D deficiency contributes directly to the acute respiratory distress syndrome (ARDS)

Rationale

Vitamin D deficiency has been implicated as a pathogenic factor in sepsis and intensive therapy unit mortality but has not been assessed as a risk factor for acute respiratory distress syndrome (ARDS). Causality of these associations has never been demonstrated.

Objectives

To determine if ARDS is associated with vitamin D deficiency in a clinical setting and to determine if vitamin D deficiency in experimental models of ARDS influences its severity.

Methods

Human, murine and in vitro primary alveolar epithelial cell work were included in this study.

Findings

Vitamin D deficiency (plasma 25(OH)D levels <50 nmol/L) was ubiquitous in patients with ARDS and present in the vast majority of patients at risk of developing ARDS following oesophagectomy. In a murine model of intratracheal lipopolysaccharide challenge, dietary-induced vitamin D deficiency resulted in exaggerated alveolar inflammation, epithelial damage and hypoxia. In vitro, vitamin D has trophic effects on primary human alveolar epithelial cells affecting >600 genes. In a clinical setting, pharmacological repletion of vitamin D prior to oesophagectomy reduced the observed changes of in vivo measurements of alveolar capillary damage seen in deficient patients.

Conclusions

Vitamin D deficiency is common in people who develop ARDS. This deficiency of vitamin D appears to contribute to the development of the condition, and approaches to correct vitamin D deficiency in patients at risk of ARDS should be developed.

Trial registration

UKCRN ID 11994.

Extravascular lung water and pulmonary vascular permeability index as markers predictive of postoperative acute respiratory distress syndrome: a prospective cohort investigation

OBJECTIVE

Robust markers of subclinical perioperative lung injury are lacking. Extravascular lung water indexed to predicted body weight and pulmonary vascular permeability index are two promising early markers of lung edema. We aimed to evaluate whether extravascular lung water indexed to predicted body weight and pulmonary vascular permeability index would identify patients at risk for clinically significant postoperative pulmonary edema, particularly resulting from the acute respiratory distress syndrome.

DESIGN

Prospective cohort study.

SETTING

Tertiary care academic medical center.

PATIENTS

Adults undergoing high-risk cardiac or aortic vascular surgery (or both) with risk of acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Extravascular lung water indexed to predicted body weight and pulmonary vascular permeability index measurements were obtained intraoperatively and in the early postoperative period. We assessed the accuracy of peak extravascular lung water indexed to predicted body weight and pulmonary vascular permeability index as predictive markers of clinically significant pulmonary edema (defined as acute respiratory distress syndrome or cardiogenic pulmonary edema) using area under the receiver-operating characteristic curves. Associations between extravascular lung water indexed to predicted body weight and pulmonary vascular permeability patient-important with important outcomes were assessed. Of 150 eligible patients, 132 patients (88%) had extravascular lung water indexed to predicted body weight and pulmonary vascular permeability index measurements. Of these, 13 patients (9.8%) had postoperative acute respiratory distress syndrome and 15 patients (11.4%) had cardiogenic pulmonary edema. Extravascular lung water indexed to predicted body weight effectively predicted development of clinically significant pulmonary edema (area under the receiver-operating characteristic curve, 0.79; 95% CI, 0.70-0.89). Pulmonary vascular permeability index discriminated acute respiratory distress syndrome from cardiogenic pulmonary edema alone or no edema (area under the receiver-operating characteristic curve, 0.77; 95% CI, 0.62-0.93). Extravascular lung water indexed to predicted body weight was associated with the worst postoperative PaO2/FIO2, duration of mechanical ventilation, ICU stay, and hospital stay. Peak values for extravascular lung water indexed to predicted body weight and pulmonary vascular permeability index were obtained within 2 hours of the primary intraoperative insult for the majority of patients (> 80%).

CONCLUSIONS

Perioperative extravascular lung water indexed to predicted body weight is an early marker that predicts risk of clinically significant postoperative pulmonary edema in at-risk surgical patients. Pulmonary vascular permeability index effectively discriminated postoperative acute respiratory distress syndrome from cardiogenic pulmonary edema. These measures will aid in the early detection of subclinical lung injury in at-risk surgical populations.

Fluids in ARDS: from onset through recovery

PURPOSE OF REVIEW

Early acute respiratory distress syndrome (ARDS) is characterized by protein-rich inflammatory lung edema often associated with a hydrostatic component. Mechanical ventilation with positive intrathoracic pressure further induces salt and water retention, while impairing the pathways designed for edema clearance. In this framework, we will review the recent findings on fluid strategy and edema clearance in ARDS.

RECENT FINDINGS

Consistently, conservative strategies lead to better oxygenation and reduce the length of mechanical ventilation. A possible drawback associated with conservative strategy is the impaired cognitive function. Echography may be used for safer use of furosemide or hemofiltration therapy during edema clearance. Albumin and furosemide techniques may accelerate edema clearance, particularly when pulmonary capillary permeability is restored. Beta-2 agonist therapy does not accelerate edema clearance and is potentially dangerous.

SUMMARY

Lung edema is likely the single pathogenic factor more relevant for ARDS severity and outcome. Fluid overload must be avoided. Several monitoring techniques are available to reach this target. No specific studies are available to recommend a given fluid composition in ARDS. In our opinion, the general recommendations for fluid composition suggested for severe sepsis and septic shock should be applied to ARDS that may be considered an organ-confined sepsis.