Acute respiratory distress syndrome: a historical perspective

Imaging the Lung in ARDS: A Primer

Despite periodic changes in the clinical definition of ARDS, imaging of the lung remains a central component of its diagnostic identification. Several imaging modalities are available to the clinician to establish a diagnosis of the syndrome, monitor its clinical course, or assess the impact of treatment and management strategies. Each imaging modality provides unique insight into ARDS from structural and/or functional perspectives. This review will highlight several methods for lung imaging in ARDS, emphasizing basic operational and physical principles for the respiratory therapist. Advantages and disadvantages of each modality will be discussed in the context of their utility for clinical management and decision-making.

Hypoxia-Inducible Factor 1α and Its Role in Lung Injury: Adaptive or Maladaptive

Hypoxia-inducible factors (HIFs) are transcription factors critical for the adaptive response to hypoxia. There is also an essential link between hypoxia and inflammation, and HIFs have been implicated in the dysregulated immune response to various insults. Despite the prevalence of hypoxia in tissue trauma, especially involving the lungs, there remains a dearth of studies investigating the role of HIFs in clinically relevant injury models. Here, we summarize the effects of HIF-1α on the vasculature, metabolism, inflammation, and apoptosis in the lungs and review the role of HIFs in direct lung injuries, including lung contusion, acid aspiration, pneumonia, and COVID-19. We present data that implicates HIF-1α in the context of arguments both in favor and against its role as adaptive or injurious in the propagation of the acute inflammatory response in lung injuries. Finally, we discuss the potential for pharmacological modulation of HIFs as a new class of therapeutics in the modern intensive care unit.

Application of Neuromuscular Blockers in Patients with ARDS in ICU: A Retrospective Study Based on the MIMIC-III Database

BACKGROUND

Although neuromuscular blocker agents (NMBAs) are recommended by guidelines as a treatment for ARDS patients, the efficacy of NMBAs is still controversial. Our study aimed to investigate the association between cisatracurium infusion and the medium- and long-term outcomes of critically ill patients with moderate and severe ARDS.

METHODS

We performed a single-center, retrospective study of 485 critically ill adult patients with ARDS based on the Medical Information Mart for Intensive Care III (MIMIC-III) database. Propensity score matching (PSM) was used to match patients receiving NMBA administration with those not receiving NMBAs. The Cox proportional hazards model, Kaplan-Meier method, and subgroup analysis were used to evaluate the relationship between NMBA therapy and 28-day mortality.

RESULTS

A total of 485 moderate and severe patients with ARDS were reviewed and 86 pairs of patients were matched after PSM. NMBAs were not associated with reduced 28-day mortality (hazard ratio (HR) 1.44; 95% CI: 0.85~2.46; p = 0.20), 90-day mortality (HR = 1.49; 95% CI: 0.92~2.41; p = 0.10), 1-year mortality (HR = 1.34; 95% CI: 0.86~2.09; p = 0.20), or hospital mortality (HR = 1.34; 95% CI: 0.81~2.24; p = 0.30). However, NMBAs were associated with a prolonged duration of ventilation and the length of ICU stay.

CONCLUSIONS

NMBAs were not associated with improved medium- and long-term survival and may result in some adverse clinical outcomes.

COVID-19-Related ARDS: Key Mechanistic Features and Treatments

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome historically characterized by the presence of severe hypoxemia, high-permeability pulmonary edema manifesting as diffuse alveolar infiltrate on chest radiograph, and reduced compliance of the integrated respiratory system as a result of widespread compressive atelectasis and fluid-filled alveoli. Coronavirus disease 19 (COVID-19)-associated ARDS (C-ARDS) is a novel etiology caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that may present with distinct clinical features as a result of the viral pathobiology unique to SARS-CoV-2. In particular, severe injury to the pulmonary vascular endothelium, accompanied by the presence of diffuse microthrombi in the pulmonary microcirculation, can lead to a clinical presentation in which the severity of impaired gas exchange becomes uncoupled from lung capacity and respiratory mechanics. The purpose of this review is to highlight the key mechanistic features of C-ARDS and to discuss the implications these features have on its treatment. In some patients with C-ARDS, rigid adherence to guidelines derived from clinical trials in the pre-COVID era may not be appropriate.

Effects of early rehabilitation on motor function, dyspnoea intensity, respiratory muscle performance and handgrip strength in patients with COVID-19: an observational study

Background/Aims

Although an increasing volume of research is emerging, rehabilitative treatment of patients with COVID-19 still continues to be a matter of great importance that must be explored further. The purpose of the present study was to describe the effects of inpatient rehabilitation in acute patients treated in a sub-intensive hospital setting during the COVID-19 pandemic.

Methods

A retrospective analysis was conducted based on the prospectively collected data of 192 patients with COVID-19 undergoing a physiotherapeutic regimen during their hospitalisation. Patients were admitted because of COVID-19-related pneumonia from the periods of 25 March–12 June 2020 and 2 November 2020–9 June 2021. This study investigated dyspnoea intensity using the modified Borg scale, motor function through the 1-minute sit-to-stand test, and daily walked distance. In a subset of 57 patients, handgrip strength and respiratory muscle function was also evaluated. Measurements were taken at baseline and discharge.

Results

Patients were classified according to the severity of their ratio of arterial oxygen partial pressure to fractional inspired oxygen (mean 225 ± 82 mmHg). At discharge to home or to another hospital facility, patients performed a mean of 12 repetitions (1-minute sit-to-stand test); dyspnoea intensity was 1.4 (modified Borg scale), and they were able to walk a mean distance of 266.7 metres. The mean handgrip strength of the dominant hand was 29.3 kg, the maximal inspiratory pressure was 43.5 cmH2O, and the maximal expiratory pressure was 59.1 cmH2O. Overall, significant differences before and after treatment were detected for all clinical variables. Dyspnoea improved by 0.7 points; walked distance by 200 metres; the number of repetitions at the 1-minute sit-to-stand test by 5.6; the handgrip strength by 1.2 kg (right hand) and 1.7 kg (left hand); maximal inspiratory pressure by 7.7 cmH2O; and maximal expiratory pressure by 9.5 cmH2O.

Conclusions

Patients obtained significant improvements in functional capacity, dyspnoea perception, handgrip strength and respiratory muscle function. In addition, the treatment was feasible and well tolerated by patients, and no adverse related events were observed in a sub-intensive care setting.

Natural therapeutics and nutraceuticals for lung diseases: Traditional significance, phytochemistry, and pharmacology

BACKGROUND

Lung diseases including chronic obstructive pulmonary disease (COPD), infections like influenza, acute respiratory distress syndrome (ARDS), asthma and pneumonia lung cancer (LC) are common causes of sickness and death worldwide due to their remoteness, cold and harsh climatic conditions, and inaccessible health care facilities.

PURPOSE

Many drugs have already been proposed for the treatment of lung diseases. Few of them are in clinical trials and have the potential to cure infectious diseases. Plant extracts or herbal products have been extensively used as Traditional Chinese Medicine (TCM) and Indian Ayurveda. Moreover, it has been involved in the inhibition of certain genes/protiens effects to promote regulation of signaling pathways. Natural remedies have been scientifically proven with remarkable bioactivities and are considered a cheap and safe source for lung disease.

METHODS

This comprehensive review highlighted the literature about traditional plants and their metabolites with their applications for the treatment of lung diseases through experimental models in humans. Natural drugs information and mode of mechanism have been studied through the literature retrieved by Google Scholar, ScienceDirect, SciFinder, Scopus and Medline PubMed resources against lung diseases.

RESULTS

In vitro, in vivo and computational studies have been explained for natural metabolites derived from plants (like flavonoids, alkaloids, and terpenoids) against different types of lung diseases. Probiotics have also been biologically active therapeutics against cancer, anti-inflammation, antiplatelet, antiviral, and antioxidants associated with lung diseases.

CONCLUSION

The results of the mentioned natural metabolites repurposed for different lung diseases especially for SARS-CoV-2 should be evaluated more by advance computational applications, experimental models in the biological system, also need to be validated by clinical trials so that we may be able to retrieve potential drugs for most challenging lung diseases especially SARS-CoV-2.

Surface mechanical behavior of water-spread poly(styrene)-poly(ethylene glycol) (PS-PEG) micelles at the air-water interface: Effect of micelle size and polymer end/linking group chemistry

HYPOTHESIS

The surface mechanical properties of poly(styrene)-poly(ethylene glycol) (PS-PEG) micelles are influenced by the PEG corona structure. Changes in micelle aggregation number as well as changes in the PEG end group and linking group chemistry of the PS-PEG block copolymer are expected to alter PEG corona characteristics and therefore affect surface mechanical properties of the resulting micelle film.

EXPERIMENTS

Different sized micelles comprised of PS-PEG block copolymer chains were formulated by equilibrating micelles in different ratios of acetone/water mixtures and subsequently removing acetone using dialysis. Additionally, micelles of a similar size and PS-PEG molecular weight but slightly different chemistry were formulated. The micelles were characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), ¹H NMR, surface pressure-area isotherms and Brewster angle microscopy (BAM).

FINDINGS

The reduction in micelle aggregation number results in the subsequent monolayer having higher compressibility moduli and bending stiffnesses and collapsing at lower surface pressures. Micelle hydrophobicity was shown to improve readsorption of micelles to interface after collapse. Analysis of Brewster angle microscopy images of out-of-plane wrinkle structures which formed upon monolayer collapse indicates the presence of continuous 1 nm thick PEG layer which allows micelle monolayers to bend under high compression.

The β3/5 Integrin-MMP9 Axis Regulates Pulmonary Inflammatory Response and Endothelial Leakage in Acute Lung Injury

Background

Acute lung injury (ALI) is a severe respiratory disease with high rates of morbidity and mortality. Many mediators regarding endogenous or exogenous are involved in the pathophysiology of ALI. Here, we have uncovered the involvement of integrins and matrix metalloproteinases, as critical determinants of excessive inflammation and endothelial permeability, in the regulation of ALI.

Methods

Inflammatory cytokines were measured by quantitative real-time PCR for mRNA levels and ELISA for secretion levels. Endothelial permeability assay was detected by the passage of rhodamine B isothiocyanate-dextran. Mice lung permeability was assayed by Evans blue albumin (EBA). Western blot was used for protein level measurements. The intracellular reactive oxygen species (ROS) were evaluated using a cell-permeable probe, DCFH-DA. Intratracheal injection of lipopolysaccharide (LPS) into mice was conducted to establish the lung injury model.

Results

Exogenous MMP-9 significantly aggravated the inflammatory response and permeability in mouse pulmonary microvascular endothelial cells (PMVECs) treated by LPS, whereas knockdown of MMP-9 exhibited the opposite phenotypes. Knockdown of integrin β3 or β5 in LPS-treated PMVECs significantly downregulated MMP-9 expression and decreased inflammatory response and permeability in the presence or absence of exogenous MMP-9. Additionally, the interaction of MMP-9 and integrin β5 was impaired by a ROS scavenger, which further decreased the pro-inflammatory cytokines production and endothelial leakage in PMVECs subjected to co-treatment (LPS with exogenous MMP-9). In vivo studies, exogenous MMP-9 treatment or knockdown β3 integrin significantly decreased survival in ALI mice. Notably, knockdown of β5 integrin alone had no remarkable effect on survival, but which combined with anti-MMP-9 treatment significantly improved the survival by ameliorating excessive lung inflammation and permeability in ALI mice.

Conclusion

These findings support the β3/5 integrin-MMP-9 axis as an endogenous signal that could play a pivotal role in regulating inflammatory response and alveolar-capillary permeability in ALI.

Therapeutic Potential of B-1a Cells in Intestinal Ischemia-reperfusion Injury

BACKGROUND

Acute mesenteric ischemia is a common surgical emergency. Restoration of blood flow is a critical objective of treating this pathology. However, many patients suffer from ischemia-reperfusion (I/R) injuries at the time of revascularization, requiring prolonged hospitalizations. B-1a cells are a subtype of B lymphocytes with roles in regulating inflammation and tissue injury by spontaneous release of natural IgM and IL-10. We hypothesized that treatment with B-1a cells protects mice from intestinal I/R.

METHODS

Mesenteric ischemia was induced in mice by placing a vascular clip on the superior mesenteric artery for 60 minutes. At the time of reperfusion, B-1a cells or PBS control were instilled into the peritoneal cavity (PerC) of mice. PerC lavage, blood, intestine, and lungs were collected 4 h after reperfusion. Serum organ injury and inflammatory markers such as ALT, AST, LDH, lactate, IL-6, as well as lung and gut histology and myeloperoxidase (MPO) were assessed.

RESULTS

In intestinal I/R, B-1a cell frequency and number in the PerC were significantly decreased compared to sham-operated mice. There was an increase in the serum levels of ALT, AST, LDH, lactate, and IL-6 when comparing the vehicle group with the sham group. These increases were significantly reduced in the B-1a cell treated group. B-1a cell treatment significantly decreased the intestine and lung injury scores as well as MPO content, compared to vehicle treated mice. B-1a cell treatment resulted in a reduction of apoptotic cells in these tissues. Serum IgM levels were decreased in intestinal I/R, while treatment with B-1a cells significantly increased their levels towards normal levels.

CONCLUSIONS

B-1a cell treatment at the time of mesenteric reperfusion ameliorates end organ damage and reduces systemic inflammation through the improvement of serum IgM levels. Preserving B-1a cells pool could serve as a novel therapeutic avenue in intestinal I/R injury.

Predicting the mortality risk of acute respiratory distress syndrome: radial basis function artificial neural network model versus logistic regression model

To predict the mortality of acute respiratory distress syndrome (ARDS) by using a radial basis function (RBF) artificial neural network (ANN) model. This study included 217 patients who were admitted between June 2013 and November 2019. The RBF ANN model and logistic regression (LR) model were based on twelve factors related to ARDS. Statistical indexes were used to determine the value of the prediction in the two models. The sensitivity, specificity and accuracy of the RBF ANN model to predict mortality were 83.6%, 88.5% and 82.5%, respectively. Significant differences were found between the RBF ANN and LR models (P < 0.05). When the RBF ANN model was used to identify ARDS, the area under the ROC curve was 0.854 ± 0.029. LDH, organ failure, SP-D and PaO2/FiO2 were the most important independent variables. The RBF ANN model was more likely to predict the mortality of ARDS than the LR model. In addition, it can extract informative risk factors for ARDS.

The HIV protease inhibitor Saquinavir attenuates sepsis-induced acute lung injury and promotes M2 macrophage polarization via targeting matrix metalloproteinase-9

Imbalance of macrophage polarization plays an indispensable role in acute lung injury (ALI), which is considered as a promising target. Matrix metalloproteinase-9 (MMP-9) is expressed in the macrophage, and has a pivotal role in secreting inflammatory cytokines. We reported that saquinavir (SQV), a first-generation human immunodeficiency virus-protease inhibitor, restricted exaggerated inflammatory response. However, whether MMP-9 could regulate macrophage polarization and inhibit by SQV is still unknown. We focused on the important role of macrophage polarization in CLP (cecal ligation puncture)-mediated ALI and determined the ability of SQV to maintain M2 over M1 phenotype partially through the inhibition of MMP-9. We also performed a limited clinical study to determine if MMP-9 is a biomarker of sepsis. Lipopolysaccharide (LPS) increased MMP-9 expression and recombinant MMP-9 (rMMP-9) exacerbated LPS-mediated M1 switching. Small interfering RNA to MMP-9 inhibited LPS-mediated M1 phenotype and SQV inhibition of this switching was reversed with rMMP-9, suggesting an important role for MMP-9 in mediating LPS-induced M1 phenotype. MMP-9 messenger RNA levels in peripheral blood mononuclear cells of these 14 patients correlated with their clinical assessment. There was a significant dose-dependent decrease in mortality and ALI after CLP with SQV. SQV significantly inhibited LPS-mediated M1 phenotype and increased M2 phenotype in cultured RAW 264.7 and primary murine bone marrow-derived macrophages as well as lung macrophages from CLP-treated mice. This study supports an important role for MMP-9 in macrophage phenotypic switching and suggests that SQV-mediated inhibition of MMP-9 may be involved in suppressing ALI during systemic sepsis.

Non-Invasive Delivery of Nano-Emulsified Sesame Oil-Extract of Turmeric Attenuates Lung Inflammation

Turmeric, the golden Indian spice, and the edible oil of sesame seeds are the essential ingredients of Indian food created by ancestors and established the belief of the curative effect of food for many generations. Considering the anti-inflammatory effects of turmeric, we formulated a nano-emulsion of turmeric infused in edible sesame oil, with a globule size of 200–250 nm using high-energy microfluidization. The product with a zeta potential of −11.5 mV showed spherical globules when imaged for scanning and transmission electron microscopy. We explored the anti-inflammatory potential of this edible nano-emulsion in lung inflammation. The lungs are the internal organ most vulnerable to infection, injury, and rapid inflammation from the external environment because of their constant exposure to pollutants, pathogenic microorganisms, and viruses. We evaluated the nano-emulsion for efficacy in ovalbumin-induced lung injury in mice with an oral treatment for two weeks. The therapeutic effect of nano-emulsion of the sesame oil-extract of turmeric was evident from biochemical analysis of bronchoalveolar lavage fluid, lung histopathology, and flow cytometric analysis. The developed nano-emulsion significantly reduced the inflammation and damage to the alveolar network in ovalbumin-injured mice. Significant reduction in the levels of neutrophils and inflammatory cytokines like IL-4, IL-6, and IL-13 in bronchoalveolar lavage fluid was observed in the nano-emulsion-treated group. Leukotriene B4 and IgE were also significantly altered in the treated group, thus suggesting the suitability of the formulation for the treatment of allergy and other inflammatory conditions. The nano-emulsification process potentiated the immunoregulatory effect of turmeric, as observed from the elevated levels of the natural anti-inflammatory cytokine, IL-10. The dietary constituents-based nano-emulsion of spice turmeric helped in scavenging the free radicals in the injured lungs, thus modulating the inflammation pathway. This easily scalable formulation technology approach can therefore serve as a potential noninvasive and safe treatment modality for reducing lung inflammation in lung injury cases.

Medical Conditions

An acute hypoxemic respiratory failure (AHRF) has high possibilities to develop acute respiratory distress syndrome (ARDS) and increased death risk. AHRF which represents a common end-point to multiple pathological processes either local or systemic may have many medical conditions as aetiology. The causes may be pulmonary and extrapulmonary. Between pulmonary determinants, pneumonia and bacterial and virus infection diseases are the most frequent disease associated with AHRF. On the other hand, many non-infectious etiologic conditions, such as blunt chest contusion, multiple injuries, aspiration of gastric contents, inhalation burns, pancreatitis, and blood transfusions may cause ARDS.

Acute Lung Injury and Non-infectious Pneumonias

Lung injury can occur secondary to a myriad of causes, including infection, immunologic disorders, drug toxicity, or inhalational injury among others. Although the list of causative agents is long, the lung’s response to injury is limited resulting in similar patterns of disease irrespective of the cause. From a pathological perspective, acute lung injury refers to a group of entities that present with acute or subacute disease. These conditions are characterized by particular histological patterns including diffuse alveolar damage, acute fibrinous and organizing pneumonia, organizing pneumonia, and eosinophilic pneumonia and clinically correspond to the varying degrees of acute respiratory distress syndrome (Patel et al, Chest 125:197–202, 2004; Beasley et al, Arch Pathol Lab Med 126:1064–1070, 2002; Avecillas et al, Clin Chest Med 27:549–557, 2006; Cottin, Cordier, Semin Respir Crit Care Med 33:462–475, 2012; Ferguson et al, Intensive Care Med 38:1573–1582, 2012). In most cases, the underlying cause will not be apparent from the histological findings requiring close correlation with clinical history and laboratory findings to determine the etiology. Nevertheless, careful search for infectious organisms with application of histochemical and immunohistochemical stains should be performed in all cases in order to identify cases that benefit from more targeted treatment.

Utility of Point-of-Care Lung Ultrasound for Initial Assessment of Acute Respiratory Distress Syndrome Patients in the Emergency Department

Aim

Lung ultrasound (LUS) has been extensively used in the evaluation of acute respiratory distress syndrome (ARDS) in the critical care setting. In our study, we aim to assess the utility of point-of-care ultrasound (POCUS)-LUS in the initial assessment of ARDS patients presenting to the emergency department (ED).

Subjects and Methods

We evaluated a prospective convenience sample of 73 adult patients presenting to the ED. The bedside LUS was performed by the trained emergency physician on patients with undifferentiated dyspnea with a clinical diagnosis of ARDS according to the Berlin's criteria. The four major LUS findings were examined on structured 12-zone LUS. The observed profile consisted of A lines, well-separated B lines, coalescent B lines, and consolidation among patients who were clinically diagnosed as ARDS. These LUS findings may vary depending on the severity of ARDS. The findings were analyzed using IBM SPSS Statistics for Windows, Version 24.0 (IBM Corp., Armonk, NY, USA).

Results

Of the 73 study individuals, majority were male 46 (63%). The distributions of study individuals were as follows: 27% - mild ARDS, 37% - moderate ARDS, and 36% - severe ARDS. Coalescent B lines are present in about 70.4% and 92.3% of moderate and severe ARDS patients, respectively. Consolidations are predominantly present in moderate (100%) and severe (92.3%) ARDS.

Conclusion

LUS in the initial assessment of patients' with ARDS yielded significant findings in the three clinically designated categories. This study opens up the possibility of using POCUS as an adjunct in the initial assessment of ARDS patient in the ED.

Optimising mechanical ventilation through model-based methods and automation

Mechanical ventilation (MV) is a core life-support therapy for patients suffering from respiratory failure or acute respiratory distress syndrome (ARDS). Respiratory failure is a secondary outcome of a range of injuries and diseases, and results in almost half of all intensive care unit (ICU) patients receiving some form of MV. Funding the increasing demand for ICU is a major issue and MV, in particular, can double the cost per day due to significant patient variability, over-sedation, and the large amount of clinician time required for patient management. Reducing cost in this area requires both a decrease in the average duration of MV by improving care, and a reduction in clinical workload. Both could be achieved by safely automating all or part of MV care via model-based dynamic systems modelling and control methods are ideally suited to address these problems. This paper presents common lung models, and provides a vision for a more automated future and explores predictive capacity of some current models. This vision includes the use of model-based methods to gain real-time insight to patient condition, improve safety through the forward prediction of outcomes to changes in MV, and develop virtual patients for in-silico design and testing of clinical protocols. Finally, the use of dynamic systems models and system identification to guide therapy for improved personalised control of oxygenation and MV therapy in the ICU will be considered. Such methods are a major part of the future of medicine, which includes greater personalisation and predictive capacity to both optimise care and reduce costs. This review thus presents the state of the art in how dynamic systems and control methods can be applied to transform this core area of ICU medicine.

Lipids in the intensive care unit: Recommendations from the ESPEN Expert Group

This article summarizes the presentations given at an ESPEN Workshop on "Lipids in the ICU" held in Tel Aviv, Israel in November 2014 and subsequent discussions and updates. Lipids are an important component of enteral and parenteral nutrition support and provide essential fatty acids, a concentrated source of calories and building blocks for cell membranes. Whilst linoleic acid-rich vegetable oil-based enteral and parenteral nutrition is still widely used, newer lipid components such as medium-chain triglycerides and olive oil are safe and well tolerated. Fish oil (FO)-enriched enteral and parenteral nutrition appears to be well tolerated and confers additional clinical benefits, particularly in surgical patients, due to its anti-inflammatory and immune-modulating effects. Whilst the evidence base is not conclusive, there appears to be a potential for FO-enriched nutrition, particularly administered peri-operatively, to reduce the rate of complications and intensive care unit (ICU) and hospital stay in surgical ICU patients. The evidence for FO-enriched nutrition in non-surgical ICU patients is less clear regarding its clinical benefits and additional, well-designed large-scale clinical trials need to be conducted in this area. The ESPEN Expert Group supports the use of olive oil and FO in nutrition support in surgical and non-surgical ICU patients but considers that further research is required to provide a more robust evidence base.

Antihistone Properties of C1 Esterase Inhibitor Protect against Lung Injury

RATIONALE

Acute respiratory distress syndrome is characterized by alveolar epithelial cell injury, edema formation, and intraalveolar contact phase activation.

OBJECTIVES

To explore whether C1 esterase inhibitor (C1INH), an endogenous inhibitor of the contact phase, may protect from lung injury in vivo and to decipher the possible underlying mechanisms mediating protection.

METHODS

The ability of C1INH to control the inflammatory processes was studied in vitro and in vivo.

MEASUREMENTS AND MAIN RESULTS

Here, we demonstrate that application of C1INH alleviates bleomycin-induced lung injury via direct interaction with extracellular histones. In vitro, C1INH was found to bind all histone types. Interaction with histones was independent of its protease inhibitory activity, as demonstrated by the use of reactive-center-cleaved C1INH, but dependent on its glycosylation status. C1INH sialylated-N- and -O-glycans were not only essential for its interaction with histones but also to protect against histone-induced cell death. In vivo, histone-C1INH complexes were detected in bronchoalveolar lavage fluid from patients with acute respiratory distress syndrome and multiple models of lung injury. Furthermore, reactive-center-cleaved C1INH attenuated pulmonary damage evoked by intravenous histone instillation.

CONCLUSIONS

Collectively, C1INH administration provides a new therapeutic option for disorders associated with histone release.

Corticosteroids in ARDS: The Never-Ending Story

This feature examines the impact of pharmacologic interventions on the treatment of the critically ill patient — an area of health care that has become increasingly complex. Recent advances in drug therapy (including evolving and controversial data) for adult intensive-care-unit patients will be reviewed and assessed in terms of clinical, humanistic, and economic outcomes.

Correlation between nitric oxide content in exhaled breath condensate and the severity of acute respiratory distress syndrome

Nitric oxide (NO) can induce necrosis and detachment of branchial epithelium, aggregate inflammation and induce acute respiratory distress syndrome (ARDS). The detection of NO in exhaled breath condensate (EBC) has not been widely applied in evaluating ARDS condition. This study thus tested NO in EBC of ARDS patients, in order to provide non-invasive method to monitor disease condition of ARDS. ARDS patients in ICU of our hospital were recruited in parallel with healthy controls. NO contents in EBC and serum were measured in both control group and ARDS patients before/after treatment, and between survived and dead patients. APACHE II score, PaO₂/FiO₂, and PaO₂ were also quantified and analyzed for their correlation with NO contents. Correlation between EBC and serum NO contest was also analyzed. ARDS patients had significantly higher EBC/serum NO contents before treatment compared to control. NO levels were remarkably decreased after treatment (P<0.05). Survival patients had decreased APACHEII score, and EBC/serum NO, plus elevated PaO₂/FiO₂, and PaO₂ after treatment. Dead patients had elevated APACHEII score, EBC/serum NO with prolonged treatment, plus decreased PaO₂/FiO₂, and PaO₂ (P<0.05). EBC/serum NO in ARDS patients were positively correlated with APACHE II score, and negatively correlated with PaO₂/FiO₂, and PaO₂ (P<0.05). NO level in EBC was positively correlated with serum level in ARDS patients (P<0.05). The detection of EBC NO content can reflect hypoxia and disease condition of ARDS patients, and benefits treatment efficacy evaluation and prognostic judgement. EBC NO can replace serum NO due to satisfactory correlation.

Pulmonary Manifestations of Acute Lung Injury: More Than Just Diffuse Alveolar Damage

CONTEXT

- Acute pulmonary injury may occur as a result of myriad direct or indirect pulmonary insults, often resulting in hypoxemic respiratory failure and clinical acute respiratory distress syndrome. Histologically, most patients will exhibit diffuse alveolar damage on biopsy, but other histologic patterns may be encountered, such as acute eosinophilic pneumonia, acute fibrinous and organizing pneumonia, and diffuse alveolar hemorrhage with capillaritis.

OBJECTIVE

- To review the diagnostic features of various histologic patterns associated with a clinical picture of acute lung injury, and to discuss key features in the differential diagnosis.

DATA SOURCES

- The review is drawn from pertinent peer-reviewed literature and the personal experience of the authors.

CONCLUSIONS

- Acute pulmonary injury is a significant cause of morbidity and mortality. In addition to diffuse alveolar damage, pathologists should be aware of alternate histologic patterns of lung disease that may present with a similar clinical presentation because this may impact treatment decisions and disease outcome.

Evidences of Herbal Medicine-Derived Natural Products Effects in Inflammatory Lung Diseases

Pulmonary inflammation is a hallmark of many respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory syndrome distress (ARDS). Most of these diseases are treated with anti-inflammatory therapy in order to prevent or to reduce the pulmonary inflammation. Herbal medicine-derived natural products have been used in folk medicine and scientific studies to evaluate the value of these compounds have grown in recent years. Many substances derived from plants have the biological effects in vitro and in vivo, such as flavonoids, alkaloids, and terpenoids. Among the biological activities of natural products derived from plants can be pointed out the anti-inflammatory, antiviral, antiplatelet, antitumor anti-allergic activities, and antioxidant. Although many reports have evaluated the effects of these compounds in experimental models, studies evaluating clinical trials are scarce in the literature. This review aims to emphasize the effects of these different natural products in pulmonary diseases in experimental models and in humans and pointing out some possible mechanisms of action.

MiR-15a/16 Regulates Apoptosis of Lung Epithelial Cells after Oxidative Stress

Lung epithelial cell apoptosis is an important feature of hyperoxia-induced lung injury. Death receptor-associated extrinsic pathway and mitochondria-associated intrinsic pathway both mediate the development of lung epithelial cell apoptosis. Despite decades of research, molecular mechanisms of hyperoxia-induced epithelial cell apoptosis remain incompletely understood. Here we report a novel regulatory paradigm in response to hyperoxia-associated oxidative stress. Hyperoxia markedly up-regulated miR-15a/16 levels in lung epithelial cells, broncho-alveolar lavage fluid (BALF) and lung tissue. This effect was mediated by hyperoxia-induced reactive oxygen species (ROS). Functionally, miR-15a/16 inhibitors induced caspase 3-mediated lung epithelial cell apoptosis, in the presence of hyperoxia. MiR-15a/16 inhibitors robustly enhanced FADD level and down-regulated Bcl-2 expression. Consistently, cleaved caspase 8 and 9 were highly induced in the miR-15a/16 deficient cells, after hyperoxia. Using airway epithelial cell specific, miR-15a/16^-/- mice, we found that Bcl-2 significantly reduced in lung epithelial cells in vivo after hyperoxia. In contrast, caspase 3, 8 and Bcl-2 associated death promoter (BAD) were highly elevated in the miR-15a/16^-/- epithelial cells in vivo. Interestingly, in lung epithelial malignant cells, rather than benign cells, deletion of miR-15a/16 prevented apoptosis. Furthermore, deletion of miR-15a/16 in macrophages also prohibited apoptosis, opposite to what we have found in normal lung epithelial cells. Taken together, our data suggested that miR-15a/16 may exert differential roles in different cell types. MiR-15a/16 deficiency result in lung epithelial cell apoptosis in response to hyperoxia, via modulating both intrinsic and extrinsic apoptosis pathways.

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.

Polymorphisms in key pulmonary inflammatory pathways and the development of acute respiratory distress syndrome

PURPOSE/AIM

Acute Respiratory Distress Syndrome (ARDS) is an important clinical and public health problem. Why some at-risk individuals develop ARDS and others do not is unclear but may be related to differences in inflammatory and cell signaling systems. The Receptor for Advanced Glycation Endproducts (RAGE) and Granulocyte-Monocyte Stimulating Factor (GM-CSF) pathways have recently been implicated in pulmonary pathophysiology; whether genetic variation within these pathways contributes to ARDS risk or outcome is unknown.

MATERIALS AND METHODS

We studied 842 patients from three centers in Utah and 14 non-Utah ARDS Network centers. We studied patients at risk for ARDS and patients with ARDS to determine whether Single Nucleotide Polymorphisms (SNPs) in the RAGE and GM-CSF pathways were associated with development of ARDS. We studied 29 SNPs in 5 genes within the two pathways and controlled for age, sepsis as ARDS risk factor, and severity of illness, while targeting a false discovery rate of ≤ 5%. In a secondary analysis we evaluated associations with mortality.

RESULTS

Of 842 patients, 690 had ARDS, and 152 were at-risk. Sepsis was the risk factor for ARDS in 250 (30%) patients. When controlling for age, APACHE III score, sepsis as risk factor, and multiple comparisons, no SNPs were significantly associated with ARDS. In a secondary analysis, only rs743564 in CSF2 approached significance with regard to mortality (OR 2.17, unadjusted p = 0.005, adjusted p = 0.15).

CONCLUSIONS

Candidate SNPs within 5 genes in the RAGE and GM-CSF pathways were not significantly associated with development of ARDS in this multi-centric cohort.

Sodium thiosulfate attenuates acute lung injury in mice

BACKGROUND

Acute lung injury is characterized by neutrophilic inflammation and increased lung permeability. Thiosulfate is a stable metabolite of hydrogen sulfide, a gaseous mediator that exerts antiinflammatory effects. Although sodium thiosulfate (STS) has been used as an antidote, the effect of STS on acute lung injury is unknown. The authors assessed the effects of STS on mice lung and vascular endothelial cells subjected to acute inflammation.

METHODS

Lung injury was assessed in mice challenged with intratracheal lipopolysaccharide or subjected to cecal ligation and puncture with or without STS. Effects of STS on endothelial permeability and the production of inflammatory cytokines and reactive oxygen species were examined in cultured endothelial cells incubated with lipopolysaccharide or tumor necrosis factor-α. Levels of sulfide and sulfane sulfur were measured using novel fluorescence probes.

RESULTS

STS inhibited lipopolysaccharide-induced production of cytokines (interleukin-6 [pg/ml]; 313±164, lipopolysaccharide; 79±27, lipopolysaccharide+STS [n=10]), lung permeability, histologic lung injury, and nuclear factor-κB activation in the lung. STS also prevented up-regulation of interleukin-6 in the mouse lung subjected to cecal ligation and puncture. In endothelial cells, STS increased intracellular levels of sulfide and sulfane sulfur and inhibited lipopolysaccharide or tumor necrosis factor-α-induced production of cytokines and reactive oxygen species. The beneficial effects of STS were associated with attenuation of the lipopolysaccharide-induced nuclear factor-κB activation through the inhibition of tumor necrosis factor receptor-associated factor 6 ubiquitination.

CONCLUSIONS

STS exerts robust antiinflammatory effects in mice lung and vascular endothelium. The results suggest a therapeutic potential of STS in acute lung injury.

Alveolar Hemorrhage

Diffuse alveolar hemorrhage (DAH) is a clinical syndrome characterized by generalized intra-alveolar bleeding originating from the pulmonary microcirculation. The finding of DAH carries an extended differential diagnosis and may be associated with a number of histopathologic patterns. The prompt recognition and diagnosis of DAH is of critical importance to the practicing clinician as accurate diagnosis and prompt initiation of therapy may dramatically improve patient outcomes. This chapter reviews the diagnosis and management of diffuse alveolar hemorrhage.

Surface-active drug loaded lipopolymeric nanohybrid aerosol therapy: potential non-invasive way to mitigate lipopolysaccharide mediated inflammation in murine lungs

Non-invasive aerosol therapy of surface-active lipopolymeric nanohybrids co-delivers two drugs in inflamed lungs and also replenishes the depleted lung surfactant pool in inflamed alveoli following cellular uptake by the cells.

Sepsis in vulnerable populations

Despite the acquisition of a large body of evidence, there are many unanswered questions about sepsis. The definition of this disease is plagued by the lack of a simple pathophysiological description linking cause to effect and the activation of host immune responses that hinders disease progression at the same time producing multiorgan dysfunction. A plethora of inconsistent clinical features has served to obfuscate rather than illuminate. The Surviving Sepsis Guidelines (SSG) are a major advance because it comprehensively interrogates all aspects of care for the critically ill. For vulnerable populations living in low- and middle-income countries, this guideline is ineffectual because of the lack of region-specific data, differences in etiology of sepsis and burden of disease, limited human capacity and infrastructure, as well as socioeconomic realities. Appropriate care must be guided by common sense guidelines that are sensitive to local realities and adapted as relevant data are acquired.

Pulmonary hypertension due to acute respiratory distress syndrome

Our aims were to describe the prevalence of pulmonary hypertension in patients with acute respiratory distress syndrome (ARDS), to characterize their hemodynamic cardiopulmonary profiles, and to correlate these parameters with outcome. All consecutive patients over 16 years of age who were in the intensive care unit with a diagnosis of ARDS and an in situ pulmonary artery catheter for hemodynamic monitoring were studied. Pulmonary hypertension was diagnosed when the mean pulmonary artery pressure was >25 mmHg at rest with a pulmonary artery occlusion pressure or left atrial pressure <15 mmHg. During the study period, 30 of 402 critically ill patients (7.46%) who were admitted to the ICU fulfilled the criteria for ARDS. Of the 30 patients with ARDS, 14 met the criteria for pulmonary hypertension, a prevalence of 46.6% (95% CI; 28-66%). The most common cause of ARDS was pneumonia (56.3%). The overall mortality was 36.6% and was similar in patients with and without pulmonary hypertension. Differences in patients' hemodynamic profiles were influenced by the presence of pulmonary hypertension. The levels of positive end-expiratory pressure and peak pressure were higher in patients with pulmonary hypertension, and the PaCO2 was higher in those who died. The level of airway pressure seemed to influence the onset of pulmonary hypertension. Survival was determined by the severity of organ failure at admission to the intensive care unit.

microRNAs mediate oleic acid-induced acute lung injury in rats using an alternative injury mechanism

Intravenous (IV) infusion of oleic acid (OA) distributes OA microemboli in the pulmonary capillaries, which results in severe vascular congestion, hemorrhage vascular congestion, interstitial edema, intravascular coagulation and bleeding. The immune response to acute lung injury (ALI) is known to be associated with rapid and widespread changes in microRNA (miRNA) expression in the lung. The present study of a model of rat lung injury aimed to investigate how the lung miRNA profile changes to mediate ALI. For the induction of ALI, OA (200 µl/kg) suspended in 20% ethyl alcohol was injected through the tail vein for 20 min. Lung tissue samples were acquired at 3, 6 and 24 h, and miRNA microarray and quantitative polymerase chain reaction were performed using these samples. The activation of phosphatase and tensin homolog (PTEN), protein kinase B (Akt), extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK) were analyzed by western blot analysis. There were 75 miRNAs that demonstrated >1.5‑fold changes in expression levels. miR-101a was highly upregulated at 3 h. miR-21 was upregulated in the OA group throughout the 24 h following OA challenge. miR-1 was the most downregulated miRNA at 24 h. In order to examine the expression levels of PTEN and Akt as targets of miR-21, western blot analysis was performed. At 3 h, the levels of PTEN were attenuated in the OA group as compared with those in the control group; however, p-Akt/Akt levels were increased at 3 h for the OA group. PTEN and p-Akt/Akt were significantly higher in the OA group at 3 h and were rapidly decreased at 6 h. The immunohistochemical stain of α-smooth muscle actin in the bronchial and alveolar wall increased 24 h after OA‑induced ALI. These results indicated that the profile of miRNAs dynamically changed throughout the OA-induced ALI process, and mitogen-activated protein kinase activation, PTEN/Akt pathway alteration and smooth muscle actin activation were observed in this ALI model.

Supplementation of parenteral nutrition with fish oil attenuates acute lung injury in a rat model

Fish oil rich in n-3 polyunsaturated fatty acids has diverse immunomodulatory properties and attenuates acute lung injury when administered in enternal nutrition. However, enteral nutrition is not always feasible. Therefore, we investigated the ability of parenteral nutrition supplemented with fish oil to ameliorate acute lung injury. Rats were infused with parenteral nutrition solutions (without lipids, with soybean oil, or with soybean oil and fish oil) for three days. Lipopolysaccharide (15 mg/kg) was then administered intratracheally to induce acute lung injury, characterized by impaired lung function, polymorphonuclear leukocyte recruitment, parenchymal tissue damage, and upregulation of mRNAs for inflammatory mediators. Administration of parenteral nutrition supplemented with fish oil prior to lung insult improved gas exchange and inhibited neutrophil recruitment and upregulation of mRNAs for inflammatory mediators. Parenteral nutrition supplemented with fish oil also prolonged survival. To investigate the underlying mechanisms, leukotriene B₄ and leukotriene B₅ secretion was measured in neutrophils from the peritoneal cavity. The neutrophils from rats treated with fish oil-rich parenteral nutrition released significantly more leukotriene B₅, an anti-inflammatory eicosanoid, than neutrophils isolated from rats given standard parenteral nutrition. Parenteral nutrition with fish oil significantly reduced lipopolysaccharide-induced lung injury in rats in part by promoting the synthesis of anti-inflammatory eicosanoids.

PEEP role in ICU and operating room: from pathophysiology to clinical practice

Positive end expiratory pressure (PEEP) may prevent cyclic opening and collapsing alveoli in acute respiratory distress syndrome (ARDS) patients, but it may play a role also in general anesthesia. This review is organized in two sections. The first one reports the pathophysiological effect of PEEP on thoracic pressure and hemodynamic and cerebral perfusion pressure. The second section summarizes the knowledge and evidence of the use of PEEP in general anesthesia and intensive care. More specifically, for intensive care this review refers to ARDS and traumatic brain injured patients.

Highly pathogenic porcine reproductive and respiratory syndrome virus infection results in acute lung injury of the infected pigs

Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) was firstly characterized in 2006 in China. The virus has caused great economic loss to the Chinese swine production during the past years. Herein, we experimentally infected SPF pigs using two strains of PRRSV with different pathogenicity and observed the lung pathological changes looking for new sights on the possible pathogenesis associated with the virulence of HP-PRRSV. The results indicated that the HP-PRRSV-infected pigs died and exhibited severe pathological changes of lungs featuring increased neutrophils, mast cells and mononuclear macrophages, compared with the pigs inoculated with low pathogenic (LP-) PRRSV. Furthermore, the pigs infected with HP-PRRSV showed the higher levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interleukin (IL)-8 and histamine, leukotriene B4 (LTB4), platelet activation factor (PAF) in sera than those inoculated with LP-PRRSV. Additionally, the fibrosis of lung was observed in the HP-PRRSV-infected pigs. At present, our findings suggest that the aberrant immune responses triggered by HP-PRRSV infection are closely related to acute lung injury (ALI), and especially the pathological changes in lung vascular system are of particular significance. These associated pathological changes of lung are in part responsible for the additional morbidity and mortality observed in HP-PRRSV infection.

Histologic Patterns of Acute Lung Injury and Issues in Forensic Medicine

Context

Acute lung injury and acute respiratory distress syndrome are significant causes of pulmonary morbidity and are frequently fatal. These two entities have precise definitions from a clinical standpoint. Histologically, cases from patients with clinical acute lung injury typically exhibit diffuse alveolar damage, but other histologic patterns may occasionally be encountered such as acute fibrinous and organizing pneumonia, acute eosinophilic pneumonia, and diffuse hemorrhage with capillaritis.

Objective

To review the diagnostic criteria for various histologic patterns associated with a clinical presentation of acute lung injury and to provide diagnostic aids and discuss the differential diagnosis.

Data Sources

The review is drawn from pertinent peer-reviewed literature and the author's personal experience.

Conclusions

Acute lung injury remains a significant cause of morbidity and mortality. The pathologist should be aware of histologic patterns of lung disease other than diffuse alveolar damage which are associated with a clinical presentation of acute lung injury. Identification of these alternate histologic findings as well as identification of potential etiologic agents, especially infection, may impact patient treatment and disease outcome.

High-resolution computed tomography findings of acute respiratory distress syndrome, acute interstitial pneumonia, and acute exacerbation of idiopathic pulmonary fibrosis

Diffuse alveolar damage (DAD) is the pathologic feature of rapidly progressive lung diseases, including acute respiratory distress syndrome, acute interstitial pneumonia, and acute exacerbation of idiopathic pulmonary fibrosis. The clinical significance and limitation of high-resolution computed tomography (HRCT) findings in these diseases were reviewed. The HRCT findings correlate well with pathologic phases (exudative, proliferative, and fibrotic) of DAD, although it cannot detect early exudative phase. Traction bronchiolectasis or bronchiectasis within areas of increased attenuation on HRCT scan is a sign of progression from the exudative to the proliferative and fibrotic phase of DAD. Extensive abnormalities seen on HRCT scans, which are indicative of fibroproliferative changes, were independently predictive of poor prognosis in patients with clinically early acute respiratory distress syndrome, acute interstitial pneumonia, and acute exacerbation of idiopathic pulmonary fibrosis.

The relationship between positive end-expiratory pressure and cardiac index in patients with acute respiratory distress syndrome

PURPOSE

The purpose of the study is to evaluate the association between positive end-expiratory pressure (PEEP) and cardiac index in patients with acute respiratory distress syndrome (ARDS).

METHODS

This is a secondary cross-sectional analysis of the multicenter randomized controlled Fluid and Catheter Treatment Trial enrolling adult patients within 48 hours of ARDS onset. Patients randomized to the pulmonary artery catheter arm, who had PEEP and cardiac index measurements performed within a short period of each other during the first 3 days of the FACTT study enrollment, were included in this study. Because FACTT had a 2 × 2 factorial design, half of the patients were in a "liberal fluids" study arm, and the other half were in a "conservative fluids" study arm.

RESULTS

The final study population (833 measurements or observations, in 367 patients) was comparable with the original overall FACTT study population. The mean PEEP level used was 8.2 ± 3.4 cm H2O, and the mean cardiac index was 4.2 ± 1.2 L/min per square meter. There was no association between PEEP and cardiac index in patients with ARDS, even when adjusted for Acute Physiology and Chronic Health Evaluation score, age, fluid study arm in FACTT, and sepsis.

CONCLUSION

In patients with ARDS who are managed with liberal or conservative fluid management protocols, PEEP is not associated with lower cardiac index.

Mesenchymal stromal (stem) cell therapy fails to improve outcomes in experimental severe influenza

Rationale

Severe influenza remains a major public health threat and is responsible for thousands of deaths annually. Increasing antiviral resistance and limited effectiveness of current therapies highlight the need for new approaches to influenza treatment. Extensive pre-clinical data have shown that mesenchymal stromal (stem) cell (MSC) therapy can induce anti-inflammatory effects and enhance repair of the injured lung. We hypothesized that MSC therapy would improve survival, dampen lung inflammation and decrease acute lung injury (ALI) in a murine model of severe influenza.

Methods

C57Bl/6 mice were infected with influenza A/PuertoRico/8/34 (mouse-adapted H1N1) or influenza A/Mexico/4108/2009 (swine-origin pandemic H1N1) and administered human or mouse MSCs via the tail vein, either pre- or post- infection. MSC efficacy was evaluated as both an independent and adjunctive treatment strategy in combination with the antiviral agent, oseltamivir. Weight loss and survival were monitored. Inflammatory cells, cytokine/chemokines (IFN-γ, CXCL10, CCL2 and CCL5) and markers of ALI (total protein and IgM), were measured in bronchoalveolar lavage fluid and lung parenchyma.

Results

Administration of murine MSCs or human MSCs in a prophylactic or therapeutic regimen failed to improve survival, decrease pulmonary inflammation/inflammatory cell counts or prevent ALI in influenza virus-infected mice. MSCs administered in combination with oseltamivir also failed to improve outcomes.

Conclusions

Despite similarities in the clinical presentation and pathobiology of ALI and severe influenza, our findings suggest that MSC therapy may not be effective for prevention and/or treatment of acute severe influenza.

p62 sequestosome 1/light chain 3b complex confers cytoprotection on lung epithelial cells after hyperoxia

Lung epithelial cell death is a prominent feature of hyperoxic lung injury, and has been considered a very important underlying mechanism of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Here we report on a novel mechanism involved in epithelial cytoprotection and homeostasis after oxidative stress. p62 (sequestosome 1; SQSTM1) is a ubiquitously expressed cellular protein. It interacts with ubiquitinated proteins and autophagic marker light chain 3b (LC3b), thus mediating the degradation of selective targets. In this study, we explored the role of p62 in mitochondria-mediated cell death after hyperoxia. Lung alveolar epithelial cells demonstrate abundant p62 expression, and p62 concentrations are up-regulated by oxidative stress at both the protein and mRNA levels. The p62/LC3b complex interacts with Fas and truncated BID (tBID) physically. These interactions abruptly diminish after hyperoxia. The deletion of p62 robustly increases tBID and cleaved caspase-3, implying an antiapoptotic effect. This antiapoptotic effect of p62 is further confirmed by measuring caspase activities, cleaved poly ADP ribose polymerase, and cell viability. The deletion of the p62 PBI domain or the ubiquitin-associated domain both lead to elevated tBID, cleaved caspase-3, and significantly more cell death after hyperoxia. Moreover, p62 traffics in an opposite direction with LC3b after hyperoxia, leading to the dissociation of the p62/Cav-1/LC3b/BID complex. Subsequently, the LC3b-mediated lysosomal degradation of tBID is eliminated. Taken together, our data suggest that the p62/LC3b complex regulates lung alveolar epithelial cell homeostasis and cytoprotection after hyperoxia.

Updates in the Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in medical and surgical ICUs, totaling an estimated 200 000 cases per year in the United States. Despite improved supportive care, the mortality associated with ARDS remains high (30% to 40%). ARDS results from a variety of direct or indirect insults, including sepsis, aspiration, and trauma, all of which lead to pulmonary endothelial and epithelial injury. Several recent trials have led to improvements in the care of patients with ARDS, including the use of a fluid conservative treatment strategy and the use of neuromuscular blockade for severe ARDS. Patients with refractory hypoxemia due to ARDS may benefit from advanced therapies, including inhaled nitric oxide and extracorporeal life support; however, evidence from large clinical trials is lacking. Currently, clinical trials are underway for the treatment of ARDS with statins and inhaled heparin and preclinical evidence is promising for adoptive cellular therapy with mesenchymal stem cells.

Acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) is defined by bilateral diffuse infiltrates on chest radiography, a PO2/FiO2 ratio < 200, and noncardiogenic pulmonary edema. Pathophysiologically it is characterized by disruption of the alveolar lining and capillary endothelium, alveolar edema, protein exudation coupled with a marked inflammatory response and subsequent fibrosis and a resultant ventilation-perfusion mismatch. Effective treatment strategies include low tidal volume ventilation with positive end expiratory pressure, careful fluid management and good supportive care.

Respiratory Impairment after Early Red Cell Transfusion in Pediatric Patients with ALI/ARDS

Introduction. In the first 48 hours of ventilating patients with acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), a multipronged approach including packed red blood cell (PRBC) transfusion is undertaken to maintain oxygen delivery. Hypothesis. We hypothesized children with ALI/ARDS transfused within 48 hours of initiating mechanical ventilation would have worse outcome. The course of 34 transfused patients was retrospectively compared to 45 nontransfused control patients admitted to the PICU at Helen DeVos Children's Hospital between January 1st 2008 and December 31st 2009. Results. Mean hemoglobin (Hb) prior to transfusion was 8.2 g/dl compared to 10.1 g/dl in control. P/F ratio decreased from 135.4 ± 7.5 to 116.5 ± 8.8 in transfused but increased from 148.0 ± 8.0 to 190.4 ± 17.8 (P < 0.001) in control. OI increased in the transfused from 11.7 ± 0.9 to 18.7 ± 1.6 but not in control. Ventilator days in the transfused were 15.6 ± 1.7 versus 9.5 ± 0.6 days in control (P < 0.001). There was a trend towards higher rates of MODS in transfused patients; 29.4% versus 17.7%, odds ratio 1.92, 95% CI; 0.6–5.6 Fisher exact P < 0.282. Conclusion. This study suggests that early transfusions of patients with ALI/ARDS were associated with increased ventilatory needs.

Acute lung injury and acute respiratory distress syndrome: experimental and clinical investigations

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) can be associated with various disorders. Recent investigation has involved clinical studies in collaboration with clinical investigators and pathologists on the pathogenetic mechanisms of ALI or ARDS caused by various disorders. This literature review includes a brief historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the long-term experimental studies and clinical investigations from our laboratory, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

Goal-oriented respiratory management for critically ill patients with acute respiratory distress syndrome

This paper, based on relevant literature articles and the authors' clinical experience, presents a goal-oriented respiratory management for critically ill patients with acute respiratory distress syndrome (ARDS) that can help improve clinicians' ability to care for these patients. Early recognition of ARDS modified risk factors and avoidance of aggravating factors during hospital stay such as nonprotective mechanical ventilation, multiple blood products transfusions, positive fluid balance, ventilator-associated pneumonia, and gastric aspiration can help decrease its incidence. An early extensive clinical, laboratory, and imaging evaluation of “at risk patients” allows a correct diagnosis of ARDS, assessment of comorbidities, and calculation of prognostic indices, so that a careful treatment can be planned. Rapid administration of antibiotics and resuscitative measures in case of sepsis and septic shock associated with protective ventilatory strategies and early short-term paralysis associated with differential ventilatory techniques (recruitment maneuvers with adequate positive end-expiratory pressure titration, prone position, and new extracorporeal membrane oxygenation techniques) in severe ARDS can help improve its prognosis. Revaluation of ARDS patients on the third day of evolution (Sequential Organ Failure Assessment (SOFA), biomarkers and response to infection therapy) allows changes in the initial treatment plans and can help decrease ARDS mortality.