Beta-Agonist Lung injury TrIal-2 (BALTI-2): a multicentre, randomised, double-blind, placebo-controlled trial and economic evaluation of intravenous infusion of salbutamol versus placebo in patients with acute respiratory distress syndrome

Signaling pathways and potential therapeutic targets in acute respiratory distress syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a common condition associated with critically ill patients, characterized by bilateral chest radiographical opacities with refractory hypoxemia due to noncardiogenic pulmonary edema. Despite significant advances, the mortality of ARDS remains unacceptably high, and there are still no effective targeted pharmacotherapeutic agents. With the outbreak of coronavirus disease 19 worldwide, the mortality of ARDS has increased correspondingly. Comprehending the pathophysiology and the underlying molecular mechanisms of ARDS may thus be essential to developing effective therapeutic strategies and reducing mortality. To facilitate further understanding of its pathogenesis and exploring novel therapeutics, this review provides comprehensive information of ARDS from pathophysiology to molecular mechanisms and presents targeted therapeutics. We first describe the pathogenesis and pathophysiology of ARDS that involve dysregulated inflammation, alveolar-capillary barrier dysfunction, impaired alveolar fluid clearance and oxidative stress. Next, we summarize the molecular mechanisms and signaling pathways related to the above four aspects of ARDS pathophysiology, along with the latest research progress. Finally, we discuss the emerging therapeutic strategies that show exciting promise in ARDS, including several pharmacologic therapies, microRNA-based therapies and mesenchymal stromal cell therapies, highlighting the pathophysiological basis and the influences on signal transduction pathways for their use.

Acute Respiratory Distress Syndrome; A Review of Recent Updates and a Glance into the Future

Acute respiratory distress syndrome (ARDS) is a rapidly progressive form of respiratory failure that accounts for 10% of admissions to the ICU and is associated with approximately 40% mortality in severe cases. Despite significant mortality and healthcare burden, the mainstay of management remains supportive care. The recent pandemic of SARS-CoV-2 has re-ignited a worldwide interest in exploring the pathophysiology of ARDS, looking for innovative ideas to treat this disease. Recently, many trials have been published utilizing different pharmacotherapy targets; however, the long-term benefits of these agents remain unknown. Metabolomics profiling and stem cell transplantation offer strong enthusiasm and may completely change the outlook of ARDS management in the near future.

Pulmonary drug delivery for acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a life-threatening condition that causes respiratory failure. Despite numerous clinical trials, there are no molecularly targeted pharmacologic therapies to prevent or treat ARDS. Drug delivery during ARDS is challenging due to the heterogenous nature of lung injury and occlusion of lung units by edema fluid and inflammation. Pulmonary drug delivery during ARDS offers several potential advantages including limiting the off-target and off-organ effects and directly targeting the damaged and inflamed lung regions. In this review we summarize recent ARDS clinical trials using both systemic and pulmonary drug delivery. We then discuss the advantages of pulmonary drug delivery and potential challenges to its implementation. Finally, we discuss the use of nanoparticle drug delivery and surfactant-based drug carriers as potential strategies for delivering therapeutics to the injured lung in ARDS.

Challenges in ARDS Definition, Management, and Identification of Effective Personalized Therapies

Over the last decade, the management of acute respiratory distress syndrome (ARDS) has made considerable progress both regarding supportive and pharmacologic therapies. Lung protective mechanical ventilation is the cornerstone of ARDS management. Current recommendations on mechanical ventilation in ARDS include the use of low tidal volume (V_T) 4-6 mL/kg of predicted body weight, plateau pressure (P_PLAT) < 30 cmH₂O, and driving pressure (∆P) < 14 cmH₂O. Moreover, positive end-expiratory pressure should be individualized. Recently, variables such as mechanical power and transpulmonary pressure seem promising for limiting ventilator-induced lung injury and optimizing ventilator settings. Rescue therapies such as recruitment maneuvers, vasodilators, prone positioning, extracorporeal membrane oxygenation, and extracorporeal carbon dioxide removal have been considered for patients with severe ARDS. Regarding pharmacotherapies, despite more than 50 years of research, no effective treatment has yet been found. However, the identification of ARDS sub-phenotypes has revealed that some pharmacologic therapies that have failed to provide benefits when considering all patients with ARDS can show beneficial effects when these patients were stratified into specific sub-populations; for example, those with hyperinflammation/hypoinflammation. The aim of this narrative review is to provide an overview on current advances in the management of ARDS from mechanical ventilation to pharmacological treatments, including personalized therapy.

“Rogue” neutrophil-subset [DEspR+CD11b+/CD66b+] immunotype is an actionable therapeutic target for neutrophilic inflammation-mediated tissue injury – studies in human, macaque and rat LPS-inflammation models

Background and objective

The correlation (Rs > 0.7) of neutrophils expressing the dual endothelin1/signal peptide receptor (DEspR+CD11b+/CD66b+) with severity of hypoxemia (SF-ratio) and multi-organ failure (SOFA-score) in patients with acute respiratory distress syndrome (ARDS) suggest the hypothesis that the DEspR+ neutrophil-subset is an actionable therapeutic target in ARDS. To test this hypothesis, we conducted in vivo studies to validate DEspR+ neutrophil-subset as therapeutic target and test efficacy of DEspR-inhibition in acute neutrophilic hyperinflammation models.

Methods

We performed tests in lipopolysaccharide (LPS)-induced acute neutrophilic inflammation in three species – human, rhesus macaque, rat – with increasing dose-dependent severity. We measured DEspR+CD66b+ neutrophils in bronchoalveolar lavage fluid (BALF) in healthy volunteers (HVs) 24-hours after segmental LPS-challenge by ChipCytometry, and DEspR+CD11b+ neutrophils in whole blood and BALF in an LPS-induced transient acute lung injury (ALI) model in macaques. We determined anti-DEspR antibody efficacy in vivo in LPS-ALI macaque model and in high-mortality LPS-induced encephalopathy in hypertensive rats.

Results

ChipCytometry detected increased BALF total neutrophil and DEspR+CD66b+ neutrophil counts after segmental LPS-challenge compared to baseline (P =0.034), as well as increased peripheral neutrophil counts and neutrophil-lymphocyte ratio (NLR) compared to pre-LPS level (P <0.05). In the LPS-ALI macaque model, flow cytometry detected increased DEspR+ and DEspR[-] neutrophils in BALF, which was associated with moderate-severe hypoxemia. After determining pharmacokinetics of single-dose anti-DEspR[hu6g8] antibody, one-time pre-LPS anti-DEspR treatment reduced hypoxemia (P =0.03) and neutrophil influx into BALF (P =0.0001) in LPS-ALI vs vehicle mock-treated LPS-ALI macaques. Ex vivo live cell imaging of macaque neutrophils detected greater “intrinsic adhesion to hard-surface” in DEspR+ vs DEspR[-] neutrophils (P <0.001). Anti-DEspR[hu6g8] antibody abrogated intrinsic high adhesion in DEspR+ neutrophils, but not in DEspR[-] neutrophils (P <0.001). In the LPS-encephalopathy rat model, anti-DEspR[10a3] antibody treatment increased median survival (P =0.0007) and exhibited brain target engagement and bioeffects.

Conclusion

Detection of increased DEspR+ neutrophil-subset in human BALF after segmental LPS-challenge supports the correlation of circulating DEspR+ neutrophil counts with severity measure (SOFA-score) in ARDS. Efficacy and safety of targeted inhibition of DEspR+CD11b+ neutrophil-subset in LPS-induced transient-ALI and high-mortality encephalopathy models identify a potential therapeutic target for neutrophil-mediated secondary tissue injury.

Acute respiratory distress syndrome in adults: diagnosis, outcomes, long-term sequelae, and management

Acute respiratory distress syndrome (ARDS) is characterised by acute hypoxaemic respiratory failure with bilateral infiltrates on chest imaging, which is not fully explained by cardiac failure or fluid overload. ARDS is defined by the Berlin criteria. In this Series paper the diagnosis, management, outcomes, and long-term sequelae of ARDS are reviewed. Potential limitations of the ARDS definition and evidence that could inform future revisions are considered. Guideline recommendations, evidence, and uncertainties in relation to ARDS management are discussed. The future of ARDS strives towards a precision medicine approach, and the framework of treatable traits in ARDS diagnosis and management is explored.

Treatment for acute respiratory distress syndrome in adults: A narrative review of phase 2 and 3 trials

INTRODUCTION

Ventilatory management and general supportive care of acute respiratory distress syndrome (ARDS) in the adult population have led to significant clinical improvements, but morbidity and mortality remain high. Pharmacologic strategies acting on the coagulation cascade, inflammation, oxidative stress, and endothelial cell injury have been targeted in the last decade for patients with ARDS, but only a few of these have shown potential benefits with a meaningful clinical response and improved patient outcomes. The lack of availability of specific pharmacologic treatments for ARDS can be attributed to its complex pathophysiology, different risk factors, huge heterogeneity, and difficult classification into specific biological phenotypes and genotypes.

AREAS COVERED

In this narrative review, we briefly discuss the relevance and current advances in pharmacologic treatments for ARDS in adults and the need for the development of new pharmacological strategies.

EXPERT OPINION

Identification of ARDS phenotypes, risk factors, heterogeneity, and pathophysiology may help to design clinical trials personalized according to ARDS-specific features, thus hopefully decreasing the rate of failed clinical pharmacologic trials. This concept is still under clinical investigation and needs further development.

Inhaled β2 Adrenergic Agonists and Other cAMP-Elevating Agents: Therapeutics for Alveolar Injury and Acute Respiratory Disease Syndrome?

Inhaled long-acting β-adrenergic agonists (LABAs) and short-acting β-adrenergic agonists are approved for the treatment of obstructive lung disease via actions mediated by β2 adrenergic receptors (β2-ARs) that increase cellular cAMP synthesis. This review discusses the potential of β2-AR agonists, in particular LABAs, for the treatment of acute respiratory distress syndrome (ARDS). We emphasize ARDS induced by pneumonia and focus on the pathobiology of ARDS and actions of LABAs and cAMP on pulmonary and immune cell types. β2-AR agonists/cAMP have beneficial actions that include protection of epithelial and endothelial cells from injury, restoration of alveolar fluid clearance, and reduction of fibrotic remodeling. β2-AR agonists/cAMP also exert anti-inflammatory effects on the immune system by actions on several types of immune cells. Early administration is likely critical for optimizing efficacy of LABAs or other cAMP-elevating agents, such as agonists of other Gs-coupled G protein-coupled receptors or cyclic nucleotide phosphodiesterase inhibitors. Clinical studies that target lung injury early, prior to development of ARDS, are thus needed to further assess the use of inhaled LABAs, perhaps combined with inhaled corticosteroids and/or long-acting muscarinic cholinergic antagonists. Such agents may provide a multipronged, repurposing, and efficacious therapeutic approach while minimizing systemic toxicity. SIGNIFICANCE STATEMENT: Acute respiratory distress syndrome (ARDS) after pulmonary alveolar injury (e.g., certain viral infections) is associated with ∼40% mortality and in need of new therapeutic approaches. This review summarizes the pathobiology of ARDS, focusing on contributions of pulmonary and immune cell types and potentially beneficial actions of β2 adrenergic receptors and cAMP. Early administration of inhaled β2 adrenergic agonists and perhaps other cAMP-elevating agents after alveolar injury may be a prophylactic approach to prevent development of ARDS.

Sodium-coupled neutral amino acid transporter SNAT2 counteracts cardiogenic pulmonary edema by driving alveolar fluid clearance

The constant transport of ions across the alveolar epithelial barrier regulates alveolar fluid homeostasis. Dysregulation or inhibition of Na⁺ transport causes fluid accumulation in the distal airspaces resulting in impaired gas exchange and respiratory failure. Previous studies have primarily focused on the critical role of amiloride-sensitive epithelial sodium channel (ENaC) in alveolar fluid clearance (AFC), yet activation of ENaC failed to attenuate pulmonary edema in clinical trials. Since 40% of AFC is amiloride-insensitive, Na⁺ channels/transporters other than ENaC such as Na⁺-coupled neutral amino acid transporters (SNATs) may provide novel therapeutic targets. Here, we identified a key role for SNAT2 (SLC38A2) in AFC and pulmonary edema resolution. In isolated perfused mouse and rat lungs, pharmacological inhibition of SNATs by HgCl₂ and α-methylaminoisobutyric acid (MeAIB) impaired AFC. Quantitative RT-PCR identified SNAT2 as the highest expressed System A transporter in pulmonary epithelial cells. Pharmacological inhibition or siRNA-mediated knockdown of SNAT2 reduced transport of l-alanine across pulmonary epithelial cells. Homozygous Slc38a2^-/- mice were subviable and died shortly after birth with severe cyanosis. Isolated lungs of Slc38a2^+/- mice developed higher wet-to-dry weight ratios (W/D) as compared to wild type (WT) in response to hydrostatic stress. Similarly, W/D ratios were increased in Slc38a2^+/- mice as compared to controls in an acid-induced lung injury model. Our results identify SNAT2 as a functional transporter for Na⁺ and neutral amino acids in pulmonary epithelial cells with a relevant role in AFC and the resolution of lung edema. Activation of SNAT2 may provide a new therapeutic strategy to counteract and/or reverse pulmonary edema.

Pharmacological management of adult patients with acute respiratory distress syndrome

INTRODUCTION

There is still no definite drug for acute respiratory distress syndrome (ARDS) that is capable of reducing either short-term or long-term mortality. Therefore, great efforts are being made to identify a pharmacological approach that can be really effective.

AREAS COVERED

This review focuses on current challenges and future directions in the pharmacological management of ARDS, regardless of anti-infective treatments. The authors have excluded small randomized controlled trials (RCTs) with less than 60 patients because those studies do not have statistical power for outcome data, and also anecdotal trials but have considered the last meta-analysis on any drug.

EXPERT OPINION

There has been substantial progress in our knowledge of ARDS over the past two decades and many drugs have been used in its treatment. Nevertheless, effective targeted pharmacological treatments for ARDS are still lacking. The likely reason why a pharmacological approach is beneficial for some patients, but harmful for others is that ARDS is an extremely heterogeneous syndrome. To overcome this issue, a precision approach for ARDS, whereby therapies are specifically targeted to patients most likely to benefit, has been proposed. At present, however, the application of this approach seems to be a difficult task.

Personalized pharmacological therapy for ARDS: a light at the end of the tunnel

Introduction: Pharmacotherapy for the acute respiratory distress syndrome (ARDS) has been tested in preclinical and clinical studies. However, to date, no pharmacological interventions have proven effective. This may be attributed to lack of proper identification of different ARDS phenotypes.Areas covered: We designed inclusive search strings and searched four bibliographic databases (Cochrane Database of Systematic Reviews, PubMed, Web of Science, and clinicaltrials.gov) to identify relevant research. Search results were mainly restricted to papers published from 2009 through 2019. ARDS is a heterogeneous syndrome, and its different phenotypes - defined according to clinical, radiological, and biological parameters - may affect response to therapy. The most promising pharmacological approaches to date have been based on ARDS pathophysiology. They focus on reducing inflammation and pulmonary edema, promoting selective vasodilation, and repairing alveolar epithelial and endothelial cells.Expert opinion: Pharmacotherapeutic approaches targeting ARDS pathophysiology have failed to exert beneficial effects. Personalized medicine targeting the different ARDS phenotypes has emerged as an option to improve survival. Identification of specific ARDS patient phenotypes that respond to specific therapies seems to be the most important challenge for the next decade. Additional research is warranted before personalized medicine approaches can be applied at bedside for ARDS patients.

Recent advances in the understanding and management of ARDS

The acute respiratory distress syndrome (ARDS) remains a common and highly morbid condition despite advances in the understanding and management of this complex critical illness. Recent work has illuminated the heterogeneity within ARDS and demonstrated the likely impact of heterogeneity on the identification of effective therapeutic interventions. Despite these challenges, new data have also informed the standard of care for ARDS and have resulted in the re-evaluation of previously established therapies, including ventilation strategies, pharmacologic interventions, and rescue therapies. As the field of ARDS continues to evolve, innovative approaches will be needed to further define phenotypes within ARDS and design targeted clinical trials.

Pharmacological agents for adults with acute respiratory distress syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a life-threatening condition caused by direct or indirect injury to the lungs. Despite improvements in clinical management (for example, lung protection strategies), mortality in this patient group is at approximately 40%. This is an update of a previous version of this review, last published in 2004.

OBJECTIVES

To evaluate the effectiveness of pharmacological agents in adults with ARDS on mortality, mechanical ventilation, and fitness to return to work at 12 months.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and CINAHL on 10 December 2018. We searched clinical trials registers and grey literature, and handsearched reference lists of included studies and related reviews.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing pharmacological agents with control (placebo or standard therapy) to treat adults with established ARDS. We excluded trials of nitric oxide, inhaled prostacyclins, partial liquid ventilation, neuromuscular blocking agents, fluid and nutritional interventions and medical oxygen. We excluded studies published earlier than 2000, because of changes to lung protection strategies for people with ARDS since this date.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data, and assessed risks of bias. We assessed the certainty of evidence with GRADE.

MAIN RESULTS

We included 48 RCTs with 6299 participants who had ARDS; two included only participants with mild ARDS (also called acute lung injury). Most studies included causes of ARDS that were both direct and indirect injuries. We noted differences between studies, for example the time of administration or the size of dose, and because of unclear reporting we were uncertain whether all studies had used equivalent lung protection strategies.We included five types of agents as the primary comparisons in the review: corticosteroids, surfactants, N-acetylcysteine, statins, and beta-agonists. We included 15 additional agents (sivelestat, mesenchymal stem cells, ulinastatin, anisodimine, angiotensin-converting enzyme (ACE) inhibitor, recombinant human ACE2 (palifermin), AP301, granulocyte-macrophage colony stimulating factor (GM-CSF), levosimendan, prostacyclins, lisofylline, ketaconazole, nitroglycerins, L-2-oxothiazolidine-4-carboxylic acid (OTZ), and penehyclidine hydrochloride).We used GRADE to downgrade outcomes for imprecision (because of few studies and few participants), for study limitations (e.g. high risks of bias) and for inconsistency (e.g. differences between study data).Corticosteroids versus placebo or standard therapyCorticosteroids may reduce all-cause mortality within three months by 86 per 1000 patients (with as many as 161 fewer to 19 more deaths); however, the 95% confidence interval (CI) includes the possibility of both increased and reduced deaths (risk ratio (RR) 0.77, 95% CI 0.57 to 1.05; 6 studies, 574 participants; low-certainty evidence). Due to the very low-certainty evidence, we are uncertain whether corticosteroids make little or no difference to late all-cause mortality (later than three months) (RR 0.99, 95% CI 0.64 to 1.52; 1 study, 180 participants), or to the duration of mechanical ventilation (mean difference (MD) -4.30, 95% CI -9.72 to 1.12; 3 studies, 277 participants). We found that ventilator-free days up to day 28 (VFD) may be improved with corticosteroids (MD 4.09, 95% CI 1.74 to 6.44; 4 studies, 494 participants; low-certainty evidence). No studies reported adverse events leading to discontinuation of study medication, or fitness to return to work at 12 months (FTR).Surfactants versus placebo or standard therapyWe are uncertain whether surfactants make little or no difference to early mortality (RR 1.08, 95% CI 0.91 to 1.29; 9 studies, 1338 participants), or whether they reduce late all-cause mortality (RR 1.28, 95% CI 1.01 to 1.61; 1 study, 418 participants). Similarly, we are uncertain whether surfactants reduce the duration of mechanical ventilation (MD -2.50, 95% CI -4.95 to -0.05; 1 study, 16 participants), make little or no difference to VFD (MD -0.39, 95% CI -2.49 to 1.72; 2 studies, 344 participants), or to adverse events leading to discontinuation of study medication (RR 0.50, 95% CI 0.17 to 1.44; 2 studies, 88 participants). We are uncertain of these effects because we assessed them as very low-certainty. No studies reported FTR.N-aceytylcysteine versus placeboWe are uncertain whether N-acetylcysteine makes little or no difference to early mortality, because we assessed this as very low-certainty evidence (RR 0.64, 95% CI 0.32 to 1.30; 1 study, 36 participants). No studies reported late all-cause mortality, duration of mechanical ventilation, VFD, adverse events leading to study drug discontinuation, or FTR.Statins versus placeboStatins probably make little or no difference to early mortality (RR 0.99, 95% CI 0.78 to 1.26; 3 studies, 1344 participants; moderate-certainty evidence) or to VFD (MD 0.40, 95% CI -0.71 to 1.52; 3 studies, 1342 participants; moderate-certainty evidence). Statins may make little or no difference to duration of mechanical ventilation (MD 2.70, 95% CI -3.55 to 8.95; 1 study, 60 participants; low-certainty evidence). We could not include data for adverse events leading to study drug discontinuation in one study because it was unclearly reported. No studies reported late all-cause mortality or FTR.Beta-agonists versus placebo controlBeta-blockers probably slightly increase early mortality by 40 per 1000 patients (with as many as 119 more or 25 fewer deaths); however, the 95% CI includes the possibility of an increase as well as a reduction in mortality (RR 1.14, 95% CI 0.91 to 1.42; 3 studies, 646 participants; moderate-certainty evidence). Due to the very low-certainty evidence, we are uncertain whether beta-agonists increase VFD (MD -2.20, 95% CI -3.68 to -0.71; 3 studies, 646 participants), or make little or no difference to adverse events leading to study drug discontinuation (one study reported little or no difference between groups, and one study reported more events in the beta-agonist group). No studies reported late all-cause mortality, duration of mechanical ventilation, or FTR.

AUTHORS' CONCLUSIONS

We found insufficient evidence to determine with certainty whether corticosteroids, surfactants, N-acetylcysteine, statins, or beta-agonists were effective at reducing mortality in people with ARDS, or duration of mechanical ventilation, or increasing ventilator-free days. Three studies awaiting classification may alter the conclusions of this review. As the potential long-term consequences of ARDS are important to survivors, future research should incorporate a longer follow-up to measure the impacts on quality of life.

Esmolol infusion in patients with septic shock and tachycardia: a prospective, single-arm, feasibility study

Background

High adrenergic tone appears to be associated with mortality in septic shock, while adrenergic antagonism may improve survival. In preparation for a randomized trial, we conducted a prospective, single-arm pilot study of esmolol infusion for patients with septic shock and tachycardia that persists after adequate volume expansion.

Methods

From April 2016 to March 2017, we enrolled patients admitted to an intensive care unit with sepsis who were receiving vasopressor infusion and were tachycardic despite adequate volume expansion. All patients received a continuous intravenous infusion of esmolol, targeted to heart rate 80–90/min, while receiving vasopressors. The feasibility outcomes were proportion of eligible patients consented, compliance with pre-infusion safety check, and compliance with the titration protocol. The primary clinical outcome was organ-failure-free days (OFFD) at 28 days.

Results

We enrolled 7 of 10 eligible patients. Mean age was 46 (± 19) years, and mean admission APACHE II was 28 (± 8). Median norepinephrine infusion rate at the initiation of esmolol infusion was 0.20 (0.14–0.23) μg/kg/min. Compliance with the safety check was 100%; compliance with components of the titration protocol was 98–100%. OFFD were 26 (24.5–26); all patients survived to day 90. Median peak esmolol infusion was 50 (25–50) μg/kg/min. Median peak norepinephrine infusion rate during esmolol infusion was 0.46 (0.13–0.50) μg/kg/min. Four patients achieved target heart rate. Protocol-defined stop events, suggesting possible intolerance to a given infusion rate, occurred in three patients, all of whom were receiving at least 50 μg/kg/min of esmolol.

Conclusions

In a pilot, single-arm study, we report the first published experience with esmolol infusion in tachycardic patients with septic shock in the United States. These findings support a phase 2 trial of esmolol infusion for septic shock. Lower infusion rates of esmolol infusion may be better tolerated and more feasible than higher infusion rates for such a trial.

Trial registration

This study was retrospectively registered at ClinicalTrials.gov (NCT02841241) on 19 July 2016.

Electronic supplementary material

The online version of this article (10.1186/s40814-018-0321-5) contains supplementary material, which is available to authorized users.

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.

Cytokine-Ion Channel Interactions in Pulmonary Inflammation

The lungs conceptually represent a sponge that is interposed in series in the bodies’ systemic circulation to take up oxygen and eliminate carbon dioxide. As such, it matches the huge surface areas of the alveolar epithelium to the pulmonary blood capillaries. The lung’s constant exposure to the exterior necessitates a competent immune system, as evidenced by the association of clinical immunodeficiencies with pulmonary infections. From the in utero to the postnatal and adult situation, there is an inherent vital need to manage alveolar fluid reabsorption, be it postnatally, or in case of hydrostatic or permeability edema. Whereas a wealth of literature exists on the physiological basis of fluid and solute reabsorption by ion channels and water pores, only sparse knowledge is available so far on pathological situations, such as in microbial infection, acute lung injury or acute respiratory distress syndrome, and in the pulmonary reimplantation response in transplanted lungs. The aim of this review is to discuss alveolar liquid clearance in a selection of lung injury models, thereby especially focusing on cytokines and mediators that modulate ion channels. Inflammation is characterized by complex and probably time-dependent co-signaling, interactions between the involved cell types, as well as by cell demise and barrier dysfunction, which may not uniquely determine a clinical picture. This review, therefore, aims to give integrative thoughts and wants to foster the unraveling of unmet needs in future research.

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.

Simvastatin for patients with acute respiratory distress syndrome: long-term outcomes and cost-effectiveness from a randomised controlled trial

Background

Simvastatin therapy for patients with acute respiratory distress syndrome (ARDS) has been shown to be safe and associated with minimal adverse effects, but it does not improve clinical outcomes. The aim of this research was to report on mortality and cost-effectiveness of simvastatin in patients with ARDS at 12 months.

Methods

This was a cost-utility analysis alongside a multicentre, double-blind, randomised controlled trial carried out in the UK and Ireland. Five hundred and forty intubated and mechanically ventilated patients with ARDS were randomly assigned (1:1) to receive once-daily simvastatin (at a dose of 80 mg) or identical placebo tablets enterally for up to 28 days.

Results

Mortality was lower in the simvastatin group (31.8%, 95% confidence interval (CI) 26.1–37.5) compared to the placebo group (37.3%, 95% CI 31.6–43.0) at 12 months, although this was not significant. Simvastatin was associated with statistically significant quality-adjusted life year (QALY) gain (incremental QALYs 0.064, 95% CI 0.002–0.127) compared to placebo. Simvastatin was also less costly (incremental total costs –£3601, 95% CI –8061 to 859). At a willingness-to-pay threshold of £20,000 per QALY, the probability of simvastatin being cost-effective was 99%. Sensitivity analyses indicated that the results were robust to changes in methodological assumptions with the probability of cost-effectiveness never dropping below 90%.

Conclusion

Simvastatin was found to be cost-effective for the treatment of ARDS, being associated with both a significant QALY gain and a cost saving. There was no significant reduction in mortality at 12 months,

Trial registration

ISRCTN, 88244364. Registered 26 November 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1695-0) contains supplementary material, which is available to authorized users.

Methodological Issues Surrounding the Use of Baseline Health-Related Quality of Life Data to Inform Trial-Based Economic Evaluations of Interventions Within Emergency and Critical Care Settings: A Systematic Literature Review

BACKGROUND

Trial-based cost-utility analyses require health-related quality of life data that generate utility values in order to express health outcomes in terms of quality-adjusted life years (QALYs). Assessments of baseline health-related quality of life are problematic where trial participants are incapacitated or critically ill at the time of randomisation. This review aims to identify and critique methods for handling non-availability of baseline health-related quality of life data in trial-based cost-utility analyses within emergency and critical illness settings.

METHODS

A systematic literature review was conducted, following PRISMA guidelines, to identify trial-based cost-utility analyses of interventions within emergency and critical care settings. Databases searched included the National Institute for Health Research (NIHR) Journals Library (1991-July 2016), Cochrane Library (all years); National Health Service (NHS) Economic Evaluation Database (all years) and Ovid MEDLINE/Embase (without time restriction). Strategies employed to handle non-availability of baseline health-related quality of life data in final QALY estimations were identified and critiqued.

RESULTS

A total of 4224 published reports were screened, 19 of which met the study inclusion criteria (mean trial size 1670): 14 (74 %) from the UK, four (21%) from other European countries and one (5%) from India. Twelve studies (63%) were based in emergency departments and seven (37%) in intensive care units. Only one study was able to elicit patient-reported health-related quality of life at baseline. To overcome the lack of baseline data when estimating QALYs, eight studies (42%) assigned a fixed utility weight corresponding to either death, an unconscious health state or a country-specific norm to patients at baseline, four (21%) ignored baseline utilities, three (16%) applied values from another study, one (5%) generated utility values via retrospective recall and one (5%) elicited utilities from experts. A preliminary exploration of these methods shows that incremental QALY estimation is unlikely to be biased if balanced trial allocation is achieved and subsequent collection of health-related quality of life data occurs at the earliest possible opportunity following commencement of treatment, followed by an adequate number of follow-up assessments.

CONCLUSION

Trial-based cost-utility analyses within emergency and critical illness settings have applied different methods for QALY estimation, employing disparate assumptions about the health-related quality of life of patients at baseline. Where baseline measurement is not practical, measurement at the earliest opportunity following commencement of treatment should minimise bias in QALY estimation.

Blinded randomised controlled trial of low-dose Adjuvant Steroids in Adults admitted to hospital with Pandemic influenza (ASAP): a trial 'in hibernation', ready for rapid activation

BACKGROUND

There are no completed randomised trials of the use of corticosteroids in patients with severe influenza infection. Corticosteroid use in influenza is widespread, non-systematic and marked by controversy. A recent meta-analysis of observational studies of adjuvant corticosteroids in influenza found an association with increased mortality but there were important concerns regarding the risks of bias.

OBJECTIVES

To (1) evaluate whether or not low-dose corticosteroids given as an adjunct to standard treatment is beneficial in patients who are hospitalised with severe pandemic influenza and (2) develop an 'off-the-shelf' clinical trial that is ready to be activated in a future pandemic.

DESIGN

Multicentre, pragmatic, blinded, randomised placebo-controlled trial.

SETTING

Thirty to 40 hospitals in the UK.

PARTICIPANTS

Adults (≥ 16 years) admitted to hospital with an influenza-like illness during a pandemic.

INTERVENTION

Five-day course of dexamethasone (Dexsol®, Rosemont Pharmaceuticals Ltd) 6 mg daily, started within 24 hours of admission.

MAIN OUTCOME MEASURE

Admission to Intensive Care Unit, or death, within 30 days of admission to hospital.

RESULTS

This trial has not yet been activated. It is currently set up with full ethics and regulatory approvals in place, ready for rapid activation at the onset of the next pandemic. Hurdles to setting up a pandemic trial include planning for pandemic-level pressures on UK NHS resources and co-enrolment of patients to multiple pandemic studies, ensuring adequate geographical distribution of participating sites, maintaining long-term low-level engagement with site investigators, addressing future trial-specific training needs of local investigators and resilience planning in trial management. Identified threats to trial delivery include changes to research capabilities or policies during the hibernation phase, lack of staff resources during a pandemic and the influence of media at the time of a pandemic. A mismatch in the approach to informed consent required by current regulations to that preferred by patients and the public was identified.

CONCLUSIONS

This study demonstrates that advance set-up of a trial to be conducted during a pandemic, with full regulatory approvals in place, is possible. Regular review during the hibernation phase will be required. This study serves as a model for the development of other 'off-the-shelf' trials as part of preparedness planning for public health emergencies.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN72331452. European Union Drug Regulating Authorities Clinical Trials number: 2013-001051-12.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 16. See the NIHR Journals Library website for further project information.

Is It Time to Beta Block the Septic Patient?

Beta blockers are some of the most studied drugs in the pharmacopoeia. They are already widely used in medicine for treating hypertension, chronic heart failure, tachyarrhythmias, and tremor. Whilst their use in the immediate perioperative patient has been questioned, the use of esmolol in the patients with established septic shock has been recently reported to have favourable outcomes. In this paper, we review the role of the adrenergic system in sepsis and the evidence for the use of beta stimulation and beta blockers from animal models to critically ill patients.

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.

Pressure-controlled versus volume-controlled ventilation for acute respiratory failure due to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS)

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) account for one-quarter of cases of acute respiratory failure in intensive care units (ICUs). A third to half of patients will die in the ICU, in hospital or during follow-up. Mechanical ventilation of people with ALI/ARDS allows time for the lungs to heal, but ventilation is invasive and can result in lung injury. It is uncertain whether ventilator-related injury would be reduced if pressure delivered by the ventilator with each breath is controlled, or whether the volume of air delivered by each breath is limited.

OBJECTIVES

To compare pressure-controlled ventilation (PCV) versus volume-controlled ventilation (VCV) in adults with ALI/ARDS to determine whether PCV reduces in-hospital mortality and morbidity in intubated and ventilated adults.

SEARCH METHODS

In October 2014, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Isssue 9), MEDLINE (1950 to 1 October 2014), EMBASE (1980 to 1 October 2014), the Latin American Caribbean Health Sciences Literature (LILACS) (1994 to 1 October 2014) and Science Citation Index-Expanded (SCI-EXPANDED) at the Institute for Scientific Information (ISI) Web of Science (1990 to 1 October 2014), as well as regional databases, clinical trials registries, conference proceedings and reference lists.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and quasi-RCTs (irrespective of language or publication status) of adults with a diagnosis of acute respiratory failure or acute on chronic respiratory failure and fulfilling the criteria for ALI/ARDS as defined by the American-European Consensus Conference who were admitted to an ICU for invasive mechanical ventilation, comparing pressure-controlled or pressure-controlled inverse-ratio ventilation, or an equivalent pressure-controlled mode (PCV), versus volume-controlled ventilation, or an equivalent volume-controlled mode (VCV).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened and selected trials, assessed risk of bias and extracted data. We sought clarification from trial authors when needed. We pooled risk ratios (RRs) for dichotomous data and mean differences (MDs) for continuous data with their 95% confidence intervals (CIs) using a random-effects model. We assessed overall evidence quality using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach.

MAIN RESULTS

We included three RCTs that randomly assigned a total of 1089 participants recruited from 43 ICUs in Australia, Canada, Saudi Arabia, Spain and the USA. Risk of bias of the included studies was low. Only data for mortality and barotrauma could be combined in the meta-analysis. We downgraded the quality of evidence for the three mortality outcomes on the basis of serious imprecision around the effect estimates. For mortality in hospital, the RR with PCV compared with VCV was 0.83 (95% CI 0.67 to 1.02; three trials, 1089 participants; moderate-quality evidence), and for mortality in the ICU, the RR with PCV compared with VCV was 0.84 (95% CI 0.71 to 0.99; two trials, 1062 participants; moderate-quality evidence). One study provided no evidence of clear benefit with the ventilatory mode for mortality at 28 days (RR 0.88, 95% CI 0.73 to 1.06; 983 participants; moderate-quality evidence). The difference in effect on barotrauma between PCV and VCV was uncertain as the result of imprecision and different co-interventions used in the studies (RR 1.24, 95% CI 0.87 to 1.77; two trials, 1062 participants; low-quality evidence). Data from one trial with 983 participants for the mean duration of ventilation, and from another trial with 78 participants for the mean number of extrapulmonary organ failures that developed with PCV or VCV, were skewed. None of the trials reported on infection during ventilation or quality of life after discharge.

AUTHORS' CONCLUSIONS

Currently available data from RCTs are insufficient to confirm or refute whether pressure-controlled or volume-controlled ventilation offers any advantage for people with acute respiratory failure due to acute lung injury or acute respiratory distress syndrome. More studies including a larger number of people given PCV and VCV may provide reliable evidence on which more firm conclusions can be based.

The evaluation and management of thermal injuries: 2014 update

Burns are among the most common injuries presenting to the emergency department. While burns, especially large ones, may be associated with significant morbidity and mortality, most are minor and can be managed by emergency practitioners and discharged home with close follow-up. In contrast, patients with large burns require aggressive management of their airway, breathing and circulation in order to reduce mortality and morbidity. While early endotracheal intubation of patients with actual or impending airway compromise and aggressive fluid resuscitation have been emphasized, it appears that the pendulum may have swung a bit too far towards the extreme. The current review will briefly cover the epidemiology, pathogenesis and diagnosis of burn injuries with greater emphasis on airway and fluid management. We will also discuss the local management of the burn wound, which is all that is required for most burn patients in the emergency department.

Is there a need for emerging drugs for the acute respiratory distress syndrome?

The acute respiratory distress syndrome (ARDS) is a common and devastating syndrome of acute respiratory failure for which little effective pharmacotherapy exists. The authors describe some interventions that show promise as potential therapies for this condition, with particular reference to clinically relevant human models of ARDS. Aspirin, mesenchymal stromal (stem) cells, keratinocyte growth factor, IFN-β and oncostatin M inhibition are discussed.