Acute Respiratory Distress Syndrome Phenotypes

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute respiratory illness characterised by bilateral chest radiographical opacities with severe hypoxaemia due to non-cardiogenic pulmonary oedema. The COVID-19 pandemic has caused an increase in ARDS and highlighted challenges associated with this syndrome, including its unacceptably high mortality and the lack of effective pharmacotherapy. In this Seminar, we summarise current knowledge regarding ARDS epidemiology and risk factors, differential diagnosis, and evidence-based clinical management of both mechanical ventilation and supportive care, and discuss areas of controversy and ongoing research. Although the Seminar focuses on ARDS due to any cause, we also consider commonalities and distinctions of COVID-19-associated ARDS compared with ARDS from other causes.

Cisatracurium Continuous Infusion Versus No Neuromuscular Blockade for Acute Respiratory Distress Syndrome on Venovenous Extracorporeal Membrane Oxygenation

The benefit of continuous infusion neuromuscular blockade concurrently with venovenous (VV) extracorporeal membrane oxygenation (ECMO) in patients with acute respiratory distress syndrome who are receiving mechanical ventilation remains unclear. Adult patients with severe acute respiratory distress syndrome requiring VV ECMO were analyzed in 2 groups: continuous infusion neuromuscular blockade with cisatracurium vs no neuromuscular blockade. Similar mechanical ventilation strategies were used. The primary end point was duration of VV ECMO. This single-center, retrospective observational cohort included a total of 47 patients, 28 of whom received continuous infusion cisatracurium and 19 patients who did not receive neuromuscular blockade. There was no difference in the duration of VV ECMO in patients who received cisatracurium, 226.5 hours (interquartile range, 119-362.3) vs 187.0 hours (interquartile range, 108-374) in the group who did not receive a paralytic (P = .64). There were no differences in secondary outcomes of days in the hospital, days free of organ dysfunction, ECMO survival, or discharged alive. Among patients with severe ARDS who were managed with VV ECMO, patients who received continuous infusion cisatracurium had no difference in the duration of VV ECMO compared to the nonparalytic comparator group.

[Is it really an acute respiratory distress syndrome? : Current definitions, pathophysiology and differentiated diagnoses]

Although the Berlin definition of the acute respiratory distress syndrome (ARDS) is generally recognized, the differentiation from other diseases with severe gas exchange disturbances is often difficult in clinical practice. In particular, the assessment of radiological findings and identification of primary noncardiogenic lung edema pose problems. In ARDS typical inflammatory processes can be found with involvement of activated neutrophilic granulocytes. Anti-inflammatory treatment strategies were unsuccessful. Lung protective ventilation strategies and prone positioning are the only evidence-based treatment options. Identifying ARDS phenotypes according to the etiology or disease progression can possibly provide a targeted individualized treatment option. The control of various biomarkers for assessment and treatment is the main focus of scientific interest. The results of appropriate studies remain to be seen.

Redox signaling and antioxidant therapies in acute respiratory distress syndrome: a systematic review and meta-analysis

Objectives: No pharmacologic treatment that targets the pathophysiologic alterations of acute respiratory distress syndrome (ARDS) has proven effective. Previous studies have revealed overactive oxidative stress as a potential therapeutic target. Thus we conducted this systematic review to assess the efficacyof antioxidant therapy on the clinical outcomes of ARDS patients.Methods: We retrieved clinical trials from electronic databases. Articles and conference abstracts about antioxidant therapies for patients with ARDS were identified in which the overall effect of each antioxidant therapy on the mortality of ARDS patients was summarized.Results: We identified 18 relevant studies that met the inclusion criteria, including 899 patients in the experimental group and 870 patients in the control group. The pooled results indicated that most antioxidant therapies could not improve all-cause mortality and might even be harmful in ARDS patients at low risk of death.Conclusion: Unclassified patients could not benefit from the antioxidant therapies, and thus discretion must be exercised when using these therapies.Abbreviations ARDS: Acute respiratory distress syndrome; ICU: Intensive care unit; NAC: N-acetylcysteine; ROS: Reactive oxygen species; RNS: Reactive nitrogen species; RR: Relative risk; CI: Confidence interval; OTC: L-2-oxothiazolidine-4-carboxylic acid; EPA: Eicosapentaenoic acid; DHA: Docosahexaenoic acid; GLA: Gamma-linolenic acid; NA: Not applicable; PaO₂/FiO₂ ratio: The ratio of partial pressure arterial oxygen and fraction of inspired oxygen; ALI: Acute lung injury.

Etiology-associated heterogeneity in acute respiratory distress syndrome: a retrospective cohort study

Background

Heterogeneity in acute respiratory distress syndrome (ARDS) has led to many statistically negative clinical trials. Etiology is considered an important source of pathogenesis heterogeneity in ARDS but previous studies have usually adopted a dichotomous classification, such as pulmonary versus extrapulmonary ARDS, to evaluate it. Etiology-associated heterogeneity in ARDS remains poorly described.

Methods

In this retrospective cohort study, we described etiology-associated heterogeneity in gas exchange abnormality (PaO₂/FiO₂ [P/F] and ventilatory ratios), hemodynamic instability, non-pulmonary organ dysfunction as measured by the Sequential Organ Failure Assessment (SOFA) score, biomarkers of inflammation and coagulation, and 30-day mortality. Linear regression was used to model the trajectory of P/F ratios over time. Wilcoxon rank-sum tests, Kruskal–Wallis rank tests and Chi-squared tests were used to compare between-etiology differences.

Results

From 1725 mechanically ventilated patients in the ICU, we identified 258 (15%) with ARDS. Pneumonia (48.4%) and non-pulmonary sepsis (11.6%) were the two leading causes of ARDS. Compared with pneumonia associated ARDS, extra-pulmonary sepsis associated ARDS had a greater P/F ratio recovery rate (difference = 13 mmHg/day, p = 0.01), more shock (48% versus 73%, p = 0.01), higher non-pulmonary SOFA scores (6 versus 9 points, p < 0.001), higher d-dimer levels (4.2 versus 9.7 mg/L, p = 0.02) and higher mortality (43% versus 67%, p = 0.02). In pneumonia associated ARDS, there was significant difference in proportion of shock (p = 0.005) between bacterial and non-bacterial pneumonia.

Conclusion

This study showed that there was remarkable etiology-associated heterogeneity in ARDS. Heterogeneity was also observed within pneumonia associated ARDS when bacterial pneumonia was compared with other non-bacterial pneumonia. Future studies on ARDS should consider reporting etiology-specific data and exploring possible effect modification associated with etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01557-9.

Comparison of fixed dose versus train-of-four titration of cisatracurium in acute respiratory distress syndrome

PURPOSE

To compare the ventilatory and clinical outcomes associated with a fixed-dose cisatracurium infusion versus a titrated infusion strategy in patients with Acute Respiratory Distress Syndrome (ARDS).

MATERIALS AND METHODS

Single-center, retrospective, cohort study in a medical ICU of a tertiary care academic medical center. Adult patients ≥18 years old with a continuous infusion of cisatracurium for ≥12 h for treatment of ARDS were included. The primary outcome was the PaO2 /FiO2 ratio assessed at 24 and 48 h following cisatracurium initiation. Secondary outcomes included amount of average dose of drug administered, 28-day ventilator-free days, LOS, and hospital mortality.

RESULTS

167 patients were included; median baseline PaO2/FiO2 was 97 (76-146), median SOFA score of 9 (7-11), and ICU mortality was 71/167 (43%). In a mixed-effects model, fixed dose and titrated cisatracurium associated with similar changes in PaO2/FiO2 assessed at 24 and 48 h (p = 0.316). Fixed-dose was associated with a >3-fold increase in drug exposure (average dose 6.4 (5.4-8.0) vs. 2.0 (1.5-2.8) mcg/kg/min; p < 0.001, respectively). No differences were observed in secondary clinical endpoints.

CONCLUSION

Fixed-dose cisatracurium was associated with similar ventilatory and clinical outcomes compared to titrated strategy, yet it was associated with a 3-fold increase in dose administered.

NETosis in the pathogenesis of acute lung injury following cutaneous chemical burns

Despite the high morbidity and mortality among patients with extensive cutaneous burns in the intensive care unit due to the development of acute respiratory distress syndrome, effective therapeutics remain to be determined. This is primarily because the mechanisms leading to acute lung injury (ALI) in these patients remain unknown. We test the hypothesis that cutaneous chemical burns promote lung injury due to systemic activation of neutrophils, in particular, toxicity mediated by the deployment of neutrophil extracellular traps (NETs). We also demonstrate the potential benefit of a peptidyl arginine deiminase 4 (PAD4) inhibitor to prevent NETosis and to preserve microvascular endothelial barrier function, thus reducing the severity of ALI in mice. Our data demonstrated that phenylarsine oxide (PAO) treatment of neutrophils caused increased intracellular Ca²⁺-associated PAD4 activity. A dermal chemical burn by lewisite or PAO resulted in PAD4 activation, NETosis, and ALI. NETs disrupted the barrier function of endothelial cells in human lung microvascular endothelial cell spheroids. Citrullinated histone 3 alone caused ALI in mice. Pharmacologic or genetic abrogation of PAD4 inhibited lung injury following cutaneous chemical burns. Cutaneous burns by lewisite and PAO caused ALI by PAD4-mediated NETosis. PAD4 inhibitors may have potential as countermeasures to suppress detrimental lung injury after chemical burns.

Analysis of the Efficacy and Mechanism of Action of Xuebijing Injection on ARDS Using Meta-Analysis and Network Pharmacology

Objective

Acute respiratory distress syndrome (ARDS) is defined as the acute onset of noncardiogenic edema and subsequent gas-exchange impairment due to a severe inflammatory process known as cytokine storm. Xuebijing injection (hereinafter referred to as Xuebijing) is a patent drug that was used to treat ARDS or severe pneumonia (SP) in China. However, its efficacy and mechanism of actions remain unclear. In this study, we used meta-analysis and network pharmacology to assess these traits of Xuebijing.

Methods

We searched PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Wanfang databases for randomized controlled trials (RCTs) that evaluated Xuebijing therapy for ARDS or SP. The outcomes were total mortality, intensive care unit (ICU) stay time, and TNF-α and IL-6 levels. We performed a meta-analysis using RevMan 5.3 software. The putative targets, top 10 proteins, and possible pathway of Xuebinjing on ARDS were analyzed by network pharmacology. TNF-α and IL-6 were further docked with the six main active components of Xuebinjing using AutoDock 4.2.6 and PyMol 1.5.0.3 software.

Results

Fifteen RCTs involving 2778 patients (13 ARDS and 2 SP) were included. Compared with the control, Xuebijing treatment significantly reduced the mortality rate (risk ratio, 0.64 (95% credible interval (CrI), 0.54-0.77)), reduced the ICU stay time (mean difference (MD), -4.51 (95% CrI, -4.97--4.06)), reduced the TNF-α ((MD), -1.23 (95% CrI, -1.38--1.08)) and IL-6 ((MD), -1.15 (95% CrI, -1.52--0.78)) levels. The 56 putative targets, top 10 proteins (MAPK1 (mitogen-activated protein kinase 1), MAPK8 (mitogen-activated protein kinase 8), RELA (transcription factor p65), NFKB1 (nuclear factor NF-kappa-B p105 subunit), JUN (transcription factor AP-1), SRC (proto-oncogene tyrosine-protein kinase), TNF (tumor necrosis factor), HRAS (GTPase HRas), IL6 (interleukin-6), and APP (amyloid-beta A4 protein)), and possible pathways (Ret tyrosine kinase, IL2-mediated signaling events, CD4+/CD8+ T cell-related TCR signaling, p75(NTR)-mediated signaling, CXCR4-mediated signaling events, LPA receptor-mediated events, IL12-mediated signaling events, FAS (CD95) signaling pathway, and immune system) of Xuebinjing's action on ARDS were obtained. The molecular docking results showed that all the six components of Xuebinjing docked with TNF-α, and two components docked with IL-6 got the binding energies lower than -5.

Conclusion

Our results recommended Xuebijing treatment for patients with ARDS. Xuebijing has therapeutic effects on ARDS patients partly by regulating the immune cell/cytokine pathways and thus inhibiting the cytokine storm. TNF-α is the cytokine both directly and indirectly inhibited by Xuebijing, and IL-6 is the cytokine mainly indirectly inhibited by Xuebijing.

Radiological pattern in ARDS patients: partitioned respiratory mechanics, gas exchange and lung recruitability

BACKGROUND

The ARDS is characterized by different degrees of impairment in oxygenation and distribution of the lung disease. Two radiological patterns have been described: a focal and a diffuse one. These two patterns could present significant differences both in gas exchange and in the response to a recruitment maneuver. At the present time, it is not known if the focal and the diffuse pattern could be characterized by a difference in the lung and chest wall mechanical characteristics. Our aims were to investigate, at two levels of PEEP, if focal vs. diffuse ARDS patterns could be characterized by different lung CT characteristics, partitioned respiratory mechanics and lung recruitability.

METHODS

CT patterns were analyzed by two radiologists and were classified as focal or diffuse. The changes from 5 to 15 cmH₂O in blood gas analysis and partitioned respiratory mechanics were analyzed. Lung CT scan was performed at 5 and 45 cmH₂O of PEEP to evaluate lung recruitability.

RESULTS

One-hundred and ten patients showed a diffuse pattern, while 58 showed a focal pattern. At 5 cmH₂O of PEEP, the driving pressure and the elastance, both the respiratory system and of the lung, were significantly higher in the diffuse pattern compared to the focal (14 [11-16] vs 11 [9-15 cmH₂O; 28 [23-34] vs 21 [17-27] cmH₂O/L; 22 [17-28] vs 14 [12-19] cmH₂O/L). By increasing PEEP, the driving pressure and the respiratory system elastance significantly decreased in diffuse pattern, while they increased or did not change in the focal pattern (Δ_15-5: - 1 [- 2 to 1] vs 0 [- 1 to 2]; - 1 [- 4 to 2] vs 1 [- 2 to 5]). At 5 cmH₂O of PEEP, the diffuse pattern had a lower lung gas (743 [537-984] vs 1222 [918-1974] mL) and higher lung weight (1618 [1388-2001] vs 1222 [1059-1394] g) compared to focal pattern. The lung recruitability was significantly higher in diffuse compared to focal pattern 21% [13-29] vs 11% [6-16]. Considering the median of lung recruitability of the whole population (16.1%), the recruiters were 65% and 22% in the diffuse and focal pattern, respectively.

CONCLUSIONS

An early identification of lung morphology can be useful to choose the ventilatory setting. A diffuse pattern has a better response to the increase of PEEP and to the recruitment maneuver.

Effects of 45° prone position ventilation in the treatment of acute respiratory distress syndrome: A protocol for a randomized controlled trial study

BACKGROUND

Acute respiratory distress syndrome (ARDS) is an increasingly common acute respiratory failure that seriously threaten people's health. ARDS has a case fatality rate of up to 40%. ARDS is a serious threat to the life safety of patients and the quality of life, causing a huge economic burden to individuals, families and society. ARDS has become a large worldwide public health problem. Prone position ventilation (PPV) is an important auxiliary treatment for ARDS, which could improve oxygenation. However, PPV could cause Pressure injuries (PI) and other complications easily. We found that 45° PPV could reduce the incidence of PI, but lack of robust Evidence-based medicine evidence proving its efficacy. Therefore, we designed a randomized controlled trial to evaluate the efficacy of 45° PPV in the treatment of ARDS.

METHODS

A total of 268 patients will be randomly assigned to the control group and the test group (n = 134 each) in a ratio of 1:1. The treatment period is 7 days. The primary outcome measure will be the incidence of PI. The secondary outcomes will include APACHE II score, Braden Scale score, heart rate, systolic blood pressure, diastolic blood pressure, central venous pressure, mean arterial pressure, pH of arterial blood, oxygenation index, oxygen partial pressure, and carbon dioxide partial pressure. The evaluation will be performed at baseline, 1 hour, 12 hour, 48 hour, 5days, 7days after PPPV.

RESULTS

This study is helpful to evaluate the efficacy of 45° PPV in the treatment of ARDS.

CONCLUSION

45° PPV may reduce the incidence of PI and improve oxygenation in patients with ARDS, which has important value in practical application.

TRIAL REGISTRATION

ChiCTR2000040436, registration time: November 28, 2020.

Research Progress on Strategies that can Enhance the Therapeutic Benefits of Mesenchymal Stromal Cells in Respiratory Diseases With a Specific Focus on Acute Respiratory Distress Syndrome and Other Inflammatory Lung Diseases

Recent advances in cell based therapies for lung diseases and critical illnesses offer significant promise. Despite encouraging preclinical results, the translation of efficacy to the clinical settings have not been successful. One of the possible reasons for this is the lack of understanding of the complex interaction between mesenchymal stromal cells (MSCs) and the host environment. Other challenges for MSC cell therapies include cell sources, dosing, disease target, donor variability, and cell product manufacturing. Here we provide an overview on advances and current issues with a focus on MSC-based cell therapies for inflammatory acute respiratory distress syndrome varieties and other inflammatory lung diseases.

Inhibition of Caspase-1 with Tetracycline Ameliorates Acute Lung Injury

Rationale: Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome with a mortality of up to 40%. Precision medicine approaches targeting patients on the basis of their molecular phenotypes of ARDS might help to identify effective pharmacotherapies. The inflammasome-caspase-1 pathway contributes to the development of ARDS via IL-1β and IL-18 production. Recent studies indicate that tetracycline can be used to treat inflammatory diseases mediated by IL-1β and IL-18, although the molecular mechanism by which tetracycline inhibits inflammasome-caspase-1 signaling remains unknown. Objectives: To identify patients with ARDS characterized by IL-1β and IL-18 expression and investigate the ability of tetracycline to inhibit inflammasome-caspase-1 signaling in ARDS. Methods: IL-1β and IL-18 concentrations were quantified in BAL fluid from patients with ARDS. Tetracycline's effects on lung injury and inflammation were assessed in two mouse models of direct (pulmonary) acute lung injury, and its effects on IL-1β and IL-18 production were assessed by alveolar leukocytes from patients with direct ARDS ex vivo. Murine macrophages were used to further characterize the effect of tetracycline on the inflammasome-caspase-1 pathway. Measurements and Main Results: BAL fluid concentrations of IL-1β and IL-18 are significantly higher in patients with direct ARDS than those with indirect (nonpulmonary) ARDS. In experimental acute lung injury, tetracycline significantly diminished lung injury and pulmonary inflammation by selectively inhibiting caspase-1-dependent IL-1β and IL-18 production, leading to improved survival. Tetracycline also reduced the production of IL-1β and IL-18 by alveolar leukocytes from patients with direct ARDS. Conclusions: Tetracycline may be effective in the treatment of direct ARDS in patients with elevated caspase-1 activity. Clinical Trial registered with www.clinicaltrials.gov (NCT04079426).

Biomarkers in acute respiratory distress syndrome

PURPOSE OF REVIEW

This article provides an overview of protein biomarkers for acute respiratory distress syndrome (ARDS) and their potential use in future clinical trials.

RECENT FINDINGS

The protein biomarkers studied as indices of biological processes involved in the pathogenesis of ARDS may have diagnostic and/or prognostic value. Recently, they also proved useful for identifying ARDS phenotypes and assessing heterogeneity of treatment effect in retrospective analyses of completed clinical trials.

SUMMARY

This article summarizes the current research on ARDS biomarkers and provides insights into how they should be integrated as prognostic and predictive enrichment tools in future clinical trials.

ABO blood type: a window into the genetics of acute respiratory distress syndrome susceptibility

The genetic factors that determine a patient's risk for developing the acute respiratory distress syndrome (ARDS) remain understudied. In this issue of the JCI, Reilly and colleagues analyzed data from three cohorts of critically ill patients and observed an association between the ABO allele A1 and the onset of moderate-severe ARDS. This association was most notable in patients with non-pulmonary sepsis (an indirect, vasculature-targeted mechanism of lung injury) and persisted in patients who lacked epithelial expression of the A antigen, suggesting an endothelial mechanism of A1-associated ARDS susceptibility. Critically ill patients with blood type A had increased circulating concentrations of endothelium-derived glycoproteins such as von Willebrand factor and soluble thrombomodulin, and marginal lungs from blood type A donors were less likely to recover function during ex vivo perfusion. These findings implicate A antigen glycosylation of endothelial cells as a critical, genetically determined risk factor for indirect lung injury that may contribute to the mechanistic heterogeneity of ARDS.

The ABO histo-blood group, endothelial activation, and acute respiratory distress syndrome risk in critical illness

BACKGROUNDThe ABO histo-blood group is defined by carbohydrate modifications and is associated with risk for multiple diseases, including acute respiratory distress syndrome (ARDS). We hypothesized that genetically determined blood subtype A1 is associated with increased risk of ARDS and markers of microvascular dysfunction and coagulation.METHODSWe conducted analyses in 3 cohorts of critically ill trauma and sepsis patients (n = 3710) genotyped on genome-wide platforms to determine the association of the A1 blood type genotype with ARDS risk. We subsequently determined whether associations were present in FUT2-defined nonsecretors who lack ABO antigens on epithelium, but not endothelium. In a patient subgroup, we determined the associations of blood type with plasma levels of endothelial glycoproteins and disseminated intravascular coagulation (DIC). Lastly, we tested whether blood type A was associated with less donor lung injury recovery during human ex vivo lung perfusion (EVLP).RESULTSThe A1 genotype was associated with a higher risk of moderate to severe ARDS relative to type O in all 3 populations. In sepsis, this relationship was strongest in nonpulmonary infections. The association persisted in nonsecretors, suggesting a vascular mechanism. The A1 genotype was also associated with higher DIC risk as well as concentrations of thrombomodulin and von Willebrand factor, which in turn were associated with ARDS risk. Blood type A was also associated with less lung injury recovery during EVLP.CONCLUSIONWe identified a replicable association between ABO blood type A1 and risk of ARDS among the critically ill, possibly mediated through microvascular dysfunction and coagulation.FUNDINGNIH HL122075, HL125723, HL137006, HL137915, DK097307, HL115354, HL101779, and the University of Pennsylvania McCabe Fund Fellowship Award.

Plasma Insulin-like Growth Factor Binding Protein 7 Contributes Causally to ARDS 28-Day Mortality: Evidence From Multistage Mendelian Randomization

BACKGROUND

ARDS is a devastating syndrome with heterogeneous subtypes, but few causal biomarkers have been identified.

RESEARCH QUESTION

Would multistage Mendelian randomization identify new causal protein biomarkers for ARDS 28-day mortality?

STUDY DESIGN AND METHODS

Three hundred moderate to severe ARDS patients were selected randomly from the Molecular Epidemiology of ARDS cohort for proteomics analysis. Orthogonal projections to latent structures discriminant analysis was applied to detect the association between proteins and ARDS 28-day mortality. Candidate proteins were analyzed using generalized summary data-based Mendelian randomization (GSMR). Protein quantitative trait summary statistics were retrieved from the Efficiency and safety of varying the frequency of whole blood donation (INTERVAL) study (n = 2,504), and a genome-wide association study for ARDS was conducted from the Identification of SNPs Predisposing to Altered Acute Lung Injury Risk (iSPAAR) consortium study (n = 534). Causal mediation analysis detected the role of platelet count in mediating the effect of protein on ARDS prognosis.

RESULTS

Plasma insulin-like growth factor binding protein 7 (IGFBP7) moderately increased ARDS 28-day mortality (OR, 1.11; 95% CI, 1.04-1.19; P = .002) per log2 increase. GSMR analysis coupled with four other Mendelian randomization methods revealed IGFBP7 as a causal biomarker for ARDS 28-day mortality (OR, 2.61; 95% CI, 1.33-5.13; P = .005). Causal mediation analysis indicated that the association between IGFBP7 and ARDS 28-day mortality is mediated by platelet count (OR, 1.03; 95% CI, 1.02-1.04; P = .01).

INTERPRETATION

We identified plasma IGFBP7 as a novel causal protein involved in the pathogenesis of ARDS 28-day mortality and platelet function in ARDS, a topic for further experimental and clinical investigation.

Disease-modifying treatment of chemical threat agent-induced acute lung injury

Acute respiratory distress syndrome (ARDS) is a highly morbid lung pathology induced by exposure to chemical warfare agents, including vesicants, phosgene, chlorine, and ricin. In this review, we describe the pathology associated with the development of ARDS in humans and experimental models of acute lung injury following animal exposure to these high-priority threat agents. Potential future approaches to disease-modifying treatment used in preclinical animal studies, including antioxidants, anti-inflammatories, biologics, and mesenchymal stem cells, are also described. As respiratory pathologies, including ARDS, are the major cause of morbidity and mortality following exposure to chemical threat agents, understanding mechanisms of disease pathogenesis is key to the development of efficacious therapeutics beyond the primary intervention principle, which remains mechanical ventilation.

COVID-19 in Human, Animal, and Environment: A Review

The medical authority in China, especially in Wuhan city, reported on December 2019 a large number of highly fatal, rapidly spreading viral pneumonia caused by an unknown coronavirus. The common history of all the patients was their visiting a Wuhan's whole food store, where live animals and seafood are sold. Irrespective of the efforts of the Chinese authorities, the virus spread rapidly all over the world by travelers, provoking widespread attention by the media and panic. Many previous coronavirus epidemics had been recorded, such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), and the recently newly discovered epidemic is named coronavirus disease of 2019 (COVID-19). This disease is caused by SARS Coronavirus-2 (SARS-CoV-2), and this virus is antigenically related to the SARS virus (SARS-CoV), which had been detected in 2002, depending on clinical, serological, and molecular findings. There is rapid competition among the researchers to discover the source of the virus, understand the mechanism of the disease development, establish treatment strategies, and determine the factors affecting the incidence of infection and severity of the disease, and focus on the production of a vaccine. Coronaviruses are a group of single-stranded, positive-sense RNA genome viruses; its genome length varies from 26 to 32 kb. Coronavirus causes mild to severe respiratory disorders. In December 2019, several cases of pneumonia of unknown causes were found in Wuhan city, which is located in the Hubei province in China. Chinese health authorities investigated the problem and found that a new virus caused such infection and, using next-generation sequencing, found the 2019 novel coronavirus (2019-nCoV). It has been transferred from humans to humans and animals to humans (zoonotic). Coronaviruses cause multiple respiratory problems, varying from common cold to severe infections such as SARS. General symptoms of infection include fatigue, cough, and breathing problems such as shortness of breath, as described by World Health Organization. Serious cases may result in pneumonia, renal failure, and even death. We address current information about the new SARS Coronavirus-2 as well as the COVID-19 disease caused by it in this review.

Perioperative Precision Medicine: Where Are We in 2020?

PURPOSE OF REVIEW

The present review examines how targeted approaches to care, based on individual variability in patient characteristics, could be applied in the perioperative setting. Such an approach would enhance individualized risk assessment and allow for targeted preventive and therapeutic decision-making in patients at increased risk for adverse perioperative events.

RECENT FINDINGS

Prior and current studies highlight valuable lessons on how future investigations attempting to link specific patient-related characteristics or treatment modalities with outcomes and adverse drug responses might be designed in the perioperative setting.

SUMMARY

Our review highlights the past, present, and future directions of perioperative precision medicine. Current evidence provides important lessons on how a specific patient and disease tailored approach can help perioperative physicians in delivering the most appropriate and safest perioperative care.

SARS-CoV-2 and Coronavirus Disease 2019: What We Know So Far

In December 2019, a cluster of fatal pneumonia cases presented in Wuhan, China. They were caused by a previously unknown coronavirus. All patients had been associated with the Wuhan Wholefood market, where seafood and live animals are sold. The virus spread rapidly and public health authorities in China initiated a containment effort. However, by that time, travelers had carried the virus to many countries, sparking memories of the previous coronavirus epidemics, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), and causing widespread media attention and panic. Based on clinical criteria and available serological and molecular information, the new disease was called coronavirus disease of 2019 (COVID-19), and the novel coronavirus was called SARS Coronavirus-2 (SARS-CoV-2), emphasizing its close relationship to the 2002 SARS virus (SARS-CoV). The scientific community raced to uncover the origin of the virus, understand the pathogenesis of the disease, develop treatment options, define the risk factors, and work on vaccine development. Here we present a summary of current knowledge regarding the novel coronavirus and the disease it causes.

Microvesicles as new therapeutic targets for the treatment of the acute respiratory distress syndrome (ARDS)

Introduction: Acute respiratory distress syndrome (ARDS) is a heterogeneous and multifactorial disease; it is a common and devastating condition that has a high mortality. Treatment is limited to supportive measures hence novel pharmacological approaches are necessary. We propose a new direction in ARDS research; this means moving away from thinking about individual inflammatory mediators and instead investigating how packaged information is transmitted between cells. Microvesicles (MVs) represent a novel vehicle for inter-cellular communication with an emerging role in ARDS pathophysiology.Areas covered: This review examines current approaches to ARDS and emerging MV research. We describe advances in our understanding of microvesicles and focus on their pro-inflammatory roles in airway and endothelial signaling. We also offer reasons for why MVs are attractive therapeutic targets.Expert opinion: MVs have a key role in ARDS pathophysiology. Preclinical studies must move away from simple models toward more realistic scenarios while clinical studies must embrace patient heterogeneity. Microvesicles have the potential to aid identification of patients who may benefit from particular treatments and act as biomarkers of cellular status and disease progression. Understanding microvesicle cargoes and their cellular interactions will undoubtedly uncover new targets for ARDS.

Synthetic surfactant with a recombinant surfactant protein C analogue improves lung function and attenuates inflammation in a model of acute respiratory distress syndrome in adult rabbits

AIM

In acute respiratory distress syndrome (ARDS) damaged alveolar epithelium, leakage of plasma proteins into the alveolar space and inactivation of pulmonary surfactant lead to respiratory dysfunction. Lung function could potentially be restored with exogenous surfactant therapy, but clinical trials have so far been disappointing. These negative results may be explained by inactivation and/or too low doses of the administered surfactant. Surfactant based on a recombinant surfactant protein C analogue (rSP-C33Leu) is easy to produce and in this study we compared its effects on lung function and inflammation with a commercial surfactant preparation in an adult rabbit model of ARDS.

METHODS

ARDS was induced in adult New Zealand rabbits by mild lung-lavages followed by injurious ventilation (V_T 20 m/kg body weight) until P/F ratio < 26.7 kPa. The animals were treated with two intratracheal boluses of 2.5 mL/kg of 2% rSP-C33Leu in DPPC/egg PC/POPG, 50:40:10 or poractant alfa (Curosurf®), both surfactants containing 80 mg phospholipids/mL, or air as control. The animals were subsequently ventilated (V_T 8-9 m/kg body weight) for an additional 3 h and lung function parameters were recorded. Histological appearance of the lungs, degree of lung oedema and levels of the cytokines TNFα IL-6 and IL-8 in lung homogenates were evaluated.

RESULTS

Both surfactant preparations improved lung function vs. the control group and also reduced inflammation scores, production of pro-inflammatory cytokines, and formation of lung oedema to similar degrees. Poractant alfa improved compliance at 1 h, P/F ratio and PaO₂ at 1.5 h compared to rSP-C33Leu surfactant.

CONCLUSION

This study indicates that treatment of experimental ARDS with synthetic lung surfactant based on rSP-C33Leu improves lung function and attenuates inflammation.

Mesenchymal stem cell-derived extracellular vesicles for the treatment of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a serious and potentially fatal acute inflammatory lung condition which currently has no specific treatments targeting its pathophysiology. However, mesenchymal stem cells have been shown to have very promising therapeutic potential, and recently, it has been established that their effect is largely due to the transfer of extracellular vesicles (EVs). EVs have been shown to transfer a variety of substances such as mRNA, miRNA, and even organelles such as mitochondria in order to ameliorate ARDS in preclinical models. In addition, the fact that they have been proven to have the same effect as their parent cells combined with their numerous advantages over whole cell administration means that they are a promising candidate for clinical application that merits further research.

Prone position for acute respiratory failure in adults

BACKGROUND

Acute hypoxaemia de novo or on a background of chronic hypoxaemia is a common reason for admission to intensive care and for provision of mechanical ventilation. Various refinements of mechanical ventilation or adjuncts are employed to improve patient outcomes. Mortality from acute respiratory distress syndrome, one of the main contributors to the need for mechanical ventilation for hypoxaemia, remains approximately 40%. Ventilation in the prone position may improve lung mechanics and gas exchange and could improve outcomes.

OBJECTIVES

The objectives of this review are (1) to ascertain whether prone ventilation offers a mortality advantage when compared with traditional supine or semi recumbent ventilation in patients with severe acute respiratory failure requiring conventional invasive artificial ventilation, and (2) to supplement previous systematic reviews on prone ventilation for hypoxaemic respiratory failure in an adult population.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 1), Ovid MEDLINE (1950 to 31 January 2014), EMBASE (1980 to 31 January 2014), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 31 January 2014) and Latin American Caribbean Health Sciences Literature (LILACS) (1992 to 31 January 2014) in Ovid MEDLINE for eligible randomized controlled trials. We also searched for studies by handsearching reference lists of relevant articles, by contacting colleagues and by handsearching published proceedings of relevant journals. We applied no language constraints, and we reran the searches in CENTRAL, MEDLINE, EMBASE, CINAHL and LILACS in June 2015. We added five new studies of potential interest to the list of "Studies awaiting classification" and will incorporate them into formal review findings during the review update.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that examined the effects of prone position versus supine/semi recumbent position during conventional mechanical ventilation in adult participants with acute hypoxaemia.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed all trials identified by the search and assessed them for suitability, methods and quality. Two review authors extracted data, and three review authors reviewed the data extracted. We analysed data using Review Manager software and pooled included studies to determine the risk ratio (RR) for mortality and the risk ratio or mean difference (MD) for secondary outcomes; we also performed subgroup analyses and sensitivity analyses.

MAIN RESULTS

We identified nine relevant RCTs, which enrolled a total of 2165 participants (10 publications). All recruited participants suffered from disorders of lung function causing moderate to severe hypoxaemia and requiring mechanical ventilation, so they were fairly comparable, given the heterogeneity of specific disease diagnoses in intensive care. Risk of bias, although acceptable in the view of the review authors, was inevitable: Blinding of participants and carers to treatment allocation was not possible (face-up vs face-down).Primary analyses of short- and longer-term mortality pooled from six trials demonstrated an RR of 0.84 to 0.86 in favour of the prone position (PP), but findings were not statistically significant: In the short term, mortality for those ventilated prone was 33.4% (363/1086) and supine 38.3% (395/1031). This resulted in an RR of 0.84 (95% confidence interval (CI) 0.69 to 1.02) marginally in favour of PP. For longer-term mortality, results showed 41.7% (462/1107) for prone and 47.1% (490/1041) for supine positions, with an RR of 0.86 (95% CI 0.72 to 1.03). The quality of the evidence for both outcomes was rated as low as a result of important potential bias and serious inconsistency.Subgroup analyses for mortality identified three groups consistently favouring PP: those recruited within 48 hours of meeting entry criteria (five trials; 1024 participants showed an RR of 0.75 (95% CI 0.59 to 94)); those treated in the PP for 16 or more hours per day (five trials; 1005 participants showed an RR of 0.77 (95% CI 0.61 to 0.99)); and participants with more severe hypoxaemia at trial entry (six trials; 1108 participants showed an RR of 0.77 (95% CI 0.65 to 0.92)). The quality of the evidence for these outcomes was rated as moderate as a result of potentially important bias.Prone positioning appeared to influence adverse effects: Pressure sores (three trials; 366 participants) with an RR of 1.37 (95% CI 1.05 to 1.79) and tracheal tube obstruction with an RR of 1.78 (95% CI 1.22 to 2.60) were increased with prone ventilation. Reporting of arrhythmias was reduced with PP, with an RR of 0.64 (95% CI 0.47 to 0.87).

AUTHORS' CONCLUSIONS

We found no convincing evidence of benefit nor harm from universal application of PP in adults with hypoxaemia mechanically ventilated in intensive care units (ICUs). Three subgroups (early implementation of PP, prolonged adoption of PP and severe hypoxaemia at study entry) suggested that prone positioning may confer a statistically significant mortality advantage. Additional adequately powered studies would be required to confirm or refute these possibilities of subgroup benefit but are unlikely, given results of the most recent study and recommendations derived from several published subgroup analyses. Meta-analysis of individual patient data could be useful for further data exploration in this regard. Complications such as tracheal obstruction are increased with use of prone ventilation. Long-term mortality data (12 months and beyond), as well as functional, neuro-psychological and quality of life data, are required if future studies are to better inform the role of PP in the management of hypoxaemic respiratory failure in the ICU.