Cigarette smoking, alcohol consumption, and risk of ARDS: a 15-year cohort study in a managed care setting

Smoking on the risk of acute respiratory distress syndrome: a systematic review and meta-analysis

BACKGROUND

The relationship between smoking and the risk of acute respiratory distress syndrome (ARDS) has been recognized, but the conclusions have been inconsistent. This systematic review and meta-analysis investigated the association between smoking and ARDS risk in adults.

METHODS

The PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched for eligible studies published from January 1, 2000, to December 31, 2023. We enrolled adult patients exhibiting clinical risk factors for ARDS and smoking condition. Outcomes were quantified using odds ratios (ORs) for binary variables and mean differences (MDs) for continuous variables, with a standard 95% confidence interval (CI).

RESULTS

A total of 26 observational studies involving 36,995 patients were included. The meta-analysis revealed a significant association between smoking and an increased risk of ARDS (OR 1.67; 95% CI 1.33-2.08; P < 0.001). Further analysis revealed that the associations between patient-reported smoking history and ARDS occurrence were generally similar to the results of all the studies (OR 1.78; 95% CI 1.38-2.28; P < 0.001). In contrast, patients identified through the detection of tobacco metabolites (cotinine, a metabolite of nicotine, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of tobacco products) showed no significant difference in ARDS risk (OR 1.19; 95% CI 0.69-2.05; P = 0.53). The smoking group was younger than the control group (MD - 7.15; 95% CI - 11.58 to - 2.72; P = 0.002). Subgroup analysis revealed that smoking notably elevated the incidence of ARDS with extrapulmonary etiologies (OR 1.85; 95% CI 1.43-2.38; P < 0.001). Publication bias did not affect the integrity of our conclusions. Sensitivity analysis further reinforced the reliability of our aggregated outcomes.

CONCLUSIONS

There is a strong association between smoking and elevated ARDS risk. This emphasizes the need for thorough assessment of patients' smoking status, urging healthcare providers to vigilantly monitor individuals with a history of smoking, especially those with additional extrapulmonary risk factors for ARDS.

The Impact of Donor Smoking on Primary Graft Dysfunction and Mortality after Lung Transplantation

Rationale: Primary graft dysfunction (PGD) is the leading cause of early morbidity and mortality after lung transplantation. Prior studies implicated proxy-defined donor smoking as a risk factor for PGD and mortality. Objectives: We aimed to more accurately assess the impact of donor smoke exposure on PGD and mortality using quantitative smoke exposure biomarkers. Methods: We performed a multicenter prospective cohort study of lung transplant recipients enrolled in the Lung Transplant Outcomes Group cohort between 2012 and 2018. PGD was defined as grade 3 at 48 or 72 hours after lung reperfusion. Donor smoking was defined using accepted thresholds of urinary biomarkers of nicotine exposure (cotinine) and tobacco-specific nitrosamine (4-[methylnitrosamino]-1-[3-pyridyl]-1-butanol [NNAL]) in addition to clinical history. The donor smoking-PGD association was assessed using logistic regression, and survival analysis was performed using inverse probability of exposure weighting according to smoking category. Measurements and Main Results: Active donor smoking prevalence varied by definition, with 34-43% based on urinary cotinine, 28% by urinary NNAL, and 37% by clinical documentation. The standardized risk of PGD associated with active donor smoking was higher across all definitions, with an absolute risk increase of 11.5% (95% confidence interval [CI], 3.8% to 19.2%) by urinary cotinine, 5.7% (95% CI, -3.4% to 14.9%) by urinary NNAL, and 6.5% (95% CI, -2.8% to 15.8%) defined clinically. Donor smoking was not associated with differential post-lung transplant survival using any definition. Conclusions: Donor smoking associates with a modest increase in PGD risk but not with increased recipient mortality. Use of lungs from smokers is likely safe and may increase lung donor availability. Clinical trial registered with www.clinicaltrials.gov (NCT00552357).

Acute respiratory distress syndrome heterogeneity and the septic ARDS subgroup

Acute respiratory distress syndrome (ARDS) is an acute diffuse inflammatory lung injury characterized by the damage of alveolar epithelial cells and pulmonary capillary endothelial cells. It is mainly manifested by non-cardiogenic pulmonary edema, resulting from intrapulmonary and extrapulmonary risk factors. ARDS is often accompanied by immune system disturbance, both locally in the lungs and systemically. As a common heterogeneous disease in critical care medicine, researchers are often faced with the failure of clinical trials. Latent class analysis had been used to compensate for poor outcomes and found that targeted treatment after subgrouping contribute to ARDS therapy. The subphenotype of ARDS caused by sepsis has garnered attention due to its refractory nature and detrimental consequences. Sepsis stands as the most predominant extrapulmonary cause of ARDS, accounting for approximately 32% of ARDS cases. Studies indicate that sepsis-induced ARDS tends to be more severe than ARDS caused by other factors, leading to poorer prognosis and higher mortality rate. This comprehensive review delves into the immunological mechanisms of sepsis-ARDS, the heterogeneity of ARDS and existing research on targeted treatments, aiming to providing mechanism understanding and exploring ideas for accurate treatment of ARDS or sepsis-ARDS.

Alveolar Hemorrhage Caused by the Combination of Immune Checkpoint Inhibitors (ICIs) and Angiogenesis Inhibitors: The Underlying Long-Term Vascular Endothelial Growth Factor (VEGF) Inhibition

The combination of immune checkpoint inhibitors (ICIs) and other anticancer agents is the standard of care for various cancers. Bevacizumab, an anti-angiogenesis inhibitor, causes serious adverse events such as pulmonary hemorrhage (PH). Here, we present a case of drug-induced diffuse alveolar hemorrhage (DAH), an adverse event, in a patient with hepatocellular carcinoma who was treated with a combination of ICIs and anti-angiogenesis inhibitors after long-term use of lenvatinib, which inhibits vascular endothelial growth factor (VEGF). An 85-year-old man with hepatocellular carcinoma initially received lenvatinib, a multi-kinase inhibitor, but the drug was later switched to bevacizumab-atezolizumab combination therapy owing to disease progression. After five cycles, he developed dyspnea and diffuse ground-glass opacities, which improved with discontinuation of the combination therapy and initiation of steroid pulse therapy. Our case findings indicate that both ICIs and anti-angiogenesis inhibitors cause drug-induced DAH, and their combination may increase the severity of DAH. Moreover, long-term VEGF inhibition may induce the development of DAH. Clinicians need to be aware that long-term VEGF inhibition may be associated with DAH and should consider the risk management of such adverse events while using this combination therapy.

Environmental Factors

The acute respiratory distress syndrome (ARDS) remains a major cause of morbidity and mortality in the intensive care unit. Improving outcomes depends on not only evidence-based care once ARDS has already developed but also preventing ARDS incidence. Several environmental exposures have now been shown to increase the risk of ARDS and related adverse outcomes. How environmental factors impact the risk of developing ARDS is a growing and important field of research that should inform the care of individual patients as well as public health policy.

Pretransplant Risk Factors Can Predict Development of Acute Respiratory Distress Syndrome after Hematopoietic Stem Cell Transplantation

Rationale: Acute respiratory distress syndrome (ARDS) is a common complication after hematopoietic stem cell transplantation (HCT) and is a major contributor to nonrelapse mortality. Objectives: To better understand pretransplant risk factors for developing ARDS after HCT. Methods: This is a single-center observational study comparing risk factors for ARDS development in 164 patients who went on to develop post-HCT ARDS compared with 492 patients who did not. The patients were matched 1 to 3 on age, sex, type of transplant (allogeneic vs. autologous), and underlying disease. Pertinent risk factors were analyzed separately in multivariable conditional logistic regression after adjustment for a priori variables known to be associated with ARDS development. Results: Patients with ARDS were more likely to have a lower pretransplant pulmonary function as measured by forced vital capacity (FVC) (odds ratio [OR], 0.54 [0.42-0.70] per liter increase in FVC; P < 0.001), forced expiratory volume in one second (FEV₁) (OR, 0.52 [0.38-0.71] per liter increase in FEV₁; P < 0.001) and diffusing capacity (OR, 0.92 [0.88-0.96] per ml/min/mm Hg increase in diffusing capacity; P < 0.001). Several laboratory indices were predictive of subsequent ARDS development including elevated AST (aspartate aminotransferase) (OR, 1.01 [1.00-1.01]; P < 0.008), lower serum albumin (OR, 0.44 [0.30-0.66]; P < 0.001), lower pretransplant hemoglobin (OR, 0.82 [0.73-0.92]; P = 0.001), and lower leukocyte count (OR, 0.88 [0.79-0.99]; P < 0.03). Patients who went on to develop ARDS were more likely to have been hospitalized in the year before the transplant (OR, 1.11 [1.04-1.20]; P = 0.003), and required invasive or noninvasive ventilation during that hospitalization. Lastly, patients with ARDS were significantly more likely to have received carboplatin, thalidomide, methotrexate, and cisplatin than the non-ARDS control subjects. Conclusions: Several risk factors for developing ARDS after HCT are identifiable at the time of transplantation, well before the development of critical illness and ARDS. The identification of risk factors long before ARDS develops is relatively unique to the HCT population. Further work is needed to develop usable risk prediction tools in this setting.

Influenza virus infection increases ACE2 expression and shedding in human small airway epithelial cells

Background

Patients with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demonstrate high rates of co-infection with respiratory viruses, including influenza A (IAV), suggesting pathogenic interactions.

Methods

We investigated how IAV may increase the risk of COVID-19 lung disease, focusing on the receptor angiotensin-converting enzyme (ACE)2 and the protease TMPRSS2, which cooperate in the intracellular uptake of SARS-CoV-2.

Results

We found, using single-cell RNA sequencing of distal human nondiseased lung homogenates, that at baseline, ACE2 is minimally expressed in basal, goblet, ciliated and secretory epithelial cells populating small airways. We focused on human small airway epithelial cells (SAECs), central to the pathogenesis of lung injury following viral infections. Primary SAECs from nondiseased donor lungs apically infected (at the air-liquid interface) with IAV (up to 3×10⁵ pfu; ~1 multiplicity of infection) markedly (eight-fold) boosted the expression of ACE2, paralleling that of STAT1, a transcription factor activated by viruses. IAV increased the apparent electrophoretic mobility of intracellular ACE2 and generated an ACE2 fragment (90 kDa) in apical secretions, suggesting cleavage of this receptor. In addition, IAV increased the expression of two proteases known to cleave ACE2, sheddase ADAM17 (TACE) and TMPRSS2 and increased the TMPRSS2 zymogen and its mature fragments, implicating proteolytic autoactivation.

Conclusion

These results indicate that IAV amplifies the expression of molecules necessary for SARS-CoV-2 infection of the distal lung. Furthermore, post-translational changes in ACE2 by IAV may increase vulnerability to lung injury such as acute respiratory distress syndrome during viral co-infections. These findings support efforts in the prevention and treatment of influenza infections during the COVID-19 pandemic.

Influenza virus infection of cells lining the small airways increases the expression of molecules required for SARS-CoV-2 uptake in a manner that predicts increased severity of lung disease in those co-infected with influenza and coronaviruses https://bit.ly/3nu1WAo

A critical review of outcomes of cancer during the COVID-19 pandemic

The recent outbreak of COVID-19 has created an alarming fear, apprehension, and worry world over. Cancer patients represent a subgroup that is vulnerable and is under high risk. It is, therefore, necessary to analyze factors that predict outcomes in these patients so that they can be triaged accordingly in order to mitigate the effects of COVID-19 on cancer management. To determine the factors affecting cancer patients in COVID-19. A systematic search was performed to identify all relevant studies on PubMed, Embase, and Google Scholar published until April 5, 2020. Relevant articles that reported the incidence, demographic and clinical characteristics, treatment, and outcomes of cancer patients infected by COVID-19 were included in the analysis. Among 559 articles that were further screened, 14 articles fulfilled the inclusion criteria. The incidence of cancer across various studies ranged from 0.5% to 2.43%. Males were more than females, and the mean age affected was 63.1–66 years. Lung cancer was the most common subtype (25%–58.3%). Cancer patients, as reported, had a higher risk of progressing to severe events (hazard ratio:3.56, 95% confidence interval: 1.65–7.69; P < 0.0001). Nearly 39%–53.6% of patients who had a recent history of anticancer therapy developed severe events. Individuals with cancer feared the risk of complications. Cancer patients have worse outcomes from COVID-19, compared to the general population, providing a reason to pay more timely attention. High-risk patients should have vigorous screening and intensive surveillance. Anticancer treatment during COVID-19 should be modified based on the type and prognosis of cancer.

Acute Respiratory Distress Syndrome Prediction Score: Derivation and Validation

BACKGROUND

Despite advances in treatment strategies, acute respiratory distress syndrome (ARDS) after cardiac surgery remains associated with high morbidity and mortality. A method of screening patients for risk of ARDS after cardiac surgery is needed.

OBJECTIVES

To develop and validate an ARDS prediction score designed to identify patients at high risk of ARDS after cardiac or aortic surgery.

METHODS

An ARDS prediction score was derived from a retrospective derivation cohort and validated in a prospective cohort. Discrimination and calibration of the score were assessed with area under the receiver operating characteristic curve and the Hosmer-Lemeshow goodness-of-fit test, respectively. A sensitivity analysis was conducted to assess model performance at different cutoff points.

RESULTS

The retrospective derivation cohort consisted of 201 patients with and 602 patients without ARDS who had undergone cardiac or aortic surgery. Nine routinely available clinical variables were included in the ARDS prediction score. In the derivation cohort, the score distinguished patients with versus without ARDS with area under the curve of 0.84 (95% CI, 0.81-0.88; Hosmer-Lemeshow P = .55). In the validation cohort, 46 of 1834 patients (2.5%) had ARDS develop within 7 days after cardiac or aortic surgery. Area under the curve was 0.78 (95% CI, 0.71-0.85), and the score was well calibrated (Hosmer-Lemeshow P = .53).

CONCLUSIONS

The ARDS prediction score can be used to identify high-risk patients from the first day after cardiac or aortic surgery. Patients with a score of 3 or greater should be closely monitored. The score requires external validation before clinical use.

Predictors and outcomes of acute respiratory failure in hospitalised patients with acute pancreatitis

BACKGROUND AND AIM

Acute pancreatitis (AP) is associated with organ failures and systemic complications, most commonly acute respiratory failure (ARF) and acute kidney injury. So far, no studies have analysed the predictors and hospitalisation outcomes, of patients with AP who developed ARF. The aim of this study was to measure the prevalence of ARF in AP and to determine the clinical predictors for ARF and mortality in AP.

METHODS

This is a retrospective cohort study using the Nationwide Inpatient Sample database from the year 2005-2014. The study population consisted of all hospitalisations with a primary or secondary discharge diagnosis of AP, which is further stratified based on the presence of ARF. The outcome measures include in-hospital mortality, hospital length of stay and hospitalisation cost.

RESULTS

In our study, about 5.4% of patients with AP had a codiagnosis of ARF, with a mortality rate of 26.5%. The significant predictors for ARF include sepsis, pleural effusion, pneumonia and cardiogenic shock. Key variables that were associated with a higher risk of mortality include mechanical ventilation, age more than 65 years, sepsis and cancer (excluding pancreatic cancer). The presence of ARF increased hospital stay by 8.3 days and hospitalisation charges by US$103 460.

CONCLUSION

In this study, we demonstrate that ARF is a significant risk factor for increased hospital mortality, greater length of stay and higher hospitalisation charges in patients with AP. This underlines significantly higher resource utilisation in patients with a dual diagnosis of AP-ARF.

Coronavirus Disease 2019 and Smoking: How and Why We Implemented a Tobacco Treatment Campaign

Smoking is associated with one of five deaths in the United States. Multimodality tobacco treatment increases rates of successful cessation by at least 20%. The coronavirus disease 2019 pandemic has put a halt to many inpatient and outpatient medical visits that have been deemed nonessential, including tobacco treatment. The transition to telehealth has been wrought with challenges. Although data on the association between coronavirus disease 2019 and tobacco products are mixed, the overall health consequences of tobacco point towards increased risk of morbidity and death that is associated with the virus. This leaves smoking as one of the few readily modifiable risk factors in an environment understandably not set up to prioritize cessation. A military health facility on Fort Eustis in Virginia runs a successful tobacco treatment program and adapted it to pandemic times. This article describes the process and lessons learned from this initiative. The model is applicable and scalable to government and civilian health centers as health care adapts to a new normal.

The effects of smoking on adolescent trauma patients: a propensity-score-matched analysis

PURPOSE

Cigarettes have been demonstrated to be toxic to the pulmonary connective tissue by impairing the lung's ability to clear debris, resulting in infection and acute respiratory distress syndrome (ARDS). Approximately 8% of adolescents are smokers. We hypothesized that adolescent trauma patients who smoke have a higher rate of ARDS and pneumonia when compared to non-smokers.

METHODS

The Trauma Quality Improvement Program (2014-2016) was queried for adolescent trauma patients aged 13-17 years. Adolescent smokers were 1:2 propensity-score-matched to non-smokers based on age, comorbidities, and injury type. Data were analyzed using chi square for categorical data and Mann-Whitney U test for continuous data.

RESULTS

From 32,610 adolescent patients, 997 (3.1%) were smokers. After matching, 459 smokers were compared to 918 non-smokers. There were no differences in matched characteristics. Compared to non-smokers, smokers had an increased rate of pneumonia (3.1% vs. 1.1%, p = 0.01) but not ARDS (0.2% vs. 0%, p = 0.16). Compared to the non-smoking group, the smokers had a longer median total hospital length-of-stay (3 vs. 2 days, p = 0.01) and no difference in overall mortality (1.5% vs. 2.4%, p = 0.29).

CONCLUSION

Smoking is associated with an increased rate of pneumonia in adolescent trauma patients. Future research should target smoking cessation and/or interventions to mitigate the deleterious effects of smoking in this population.

The acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a prevalent cause of acute respiratory failure with high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of well-demonstrated therapeutic interventions are essential to change the natural course of this entity and bring about positive clinical outcomes. In this article, we review updated concepts in ARDS. Specifically, we discuss the current definition of ARDS, its risk factors, and the evidence supporting ventilation management, adjunctive therapies, and interventions required in refractory hypoxemia.

Nicotine Impairs the Response of Lung Epithelial Cells to IL-22

Smoking is a major risk factor for pulmonary diseases that include chronic obstructive pulmonary diseases (COPD) and cancer. Nicotine is the toxic and addictive component of tobacco products, like cigarettes, that negatively affects the immune system. Here, we examined the effect of nicotine on the IL-22 pathway that protects lung function by increasing transepithelial resistance and epithelial cell regeneration and repair. Our results indicate that exposure to nicotine impairs the regenerative capacity of primary bronchial epithelial cells in scratch assays. IL-22 at 100 ng/ml significantly improved wound healing in epithelial cells; however, the exposure to nicotine hampered the IL-22-mediated effect of wound healing. Investigation into the mechanisms showed that IL-22 receptor, IL-22Rα1, was downregulated in the presence of nicotine as determined by q-PCR and flow cytometry. We also investigated the effect of nicotine on IL-22 production by T cells. Results indicate that nicotine inhibited the secretion of IL-22 from T cells in response to aryl hydrocarbon receptor (AHR) ligand, FICZ. Altogether, the data suggests that nicotine negatively influences the IL-22-IL-22R axis. This impairment may contribute to the nicotine-mediated detrimental effects on lung function.

What factors predispose patients to acute respiratory distress syndrome?

Sepsis, pneumonia, and shock are the most common conditions predisposing to acute respiratory distress syndrome (ARDS) and certain host genetic variants have been associated with the development of ARDS. Risk modifiers include abuse of alcohol and tobacco, malnutrition, and obesity. The Lung Injury Prediction Score (LIPS) and the simplified Early Acute Lung Injury Score predict ARDS based on clinical and investigational criteria. Hospital-acquired ARDS may result from a medley factors of which high tidal volume ventilation, high oxygen concentration, and plasma transfusion are most commonly implicated. The Checklist for Lung Injury Prevention (CLIP) has been developed to ensure compliance with evidence-based practice that may affect ARDS occurrence. To date, no pharmacologic intervention has been shown to prevent ARDS

Pulmonary Endothelial Cell Apoptosis in Emphysema and Acute Lung Injury

Apoptosis plays an essential role in homeostasis and pathogenesis of a variety of human diseases. Endothelial cells are exposed to various environmental and internal stress and endothelial apoptosis is a pathophysiological consequence of these stimuli. Pulmonary endothelial cell apoptosis initiates or contributes to progression of a number of lung diseases. This chapter will focus on the current understanding of the role of pulmonary endothelial cell apoptosis in the development of emphysema and acute lung injury (ALI) and the factors controlling pulmonary endothelial life and death.

Lung injury prediction scores: Clinical validation and C-reactive protein involvement in high risk patients

OBJECTIVE

A study was made to validate two previously derived lung injury prediction scores (LIPS) for the prediction of acute respiratory distress syndrome (ARDS) in high risk intensive care patients, with the incorporation of C-reactive protein (CRP) for improving score accuracy.

DESIGN

A prospective, observational cohort study was carried out.

PATIENTS

A total of 200 patients with APACHE II score ≥15 and at least one ARDS risk factor upon ICU admission were included.

INTERVENTIONS

Calculation of LIPS using formulas developed by Cartin-Ceba et al. (2009) and Trillo-Alvarez et al. (2011) (LIPS-2009 and LIPS-2011). C-reactive protein was measured upon admission (CRP-0) and after 48h (CRP-48).

MAIN VARIABLES OF INTEREST

Independent variables: LIPS-2009, LIPS-2011 and CRP values. Dependent variable: development of ARDS.

RESULTS

Eighty-eight patients (44%) developed ARDS after a median (Q₁-Q₃) of 2.5 (1.3-6.8) days. The LIPS-2009 and LIPS-2011 scores were 4 (3-6) and 5 (3.6-6.5) in ARDS patients compared to 2 (1-4) and 3.5 (1.5-4.5) in non-ARDS patients (p<0.001). CRP-48 was 96 (67.5-150.3)mg/L and 48 (24-96)mg/L in the two groups, respectively (p<0.001). ΔCRP (i.e., CRP-48 minus CRP-0) was significantly higher in the ARDS patients (p<0.001). The AUC was 0.740 and 0.738 for LIPS-2011 and LIPS-2009, respectively - the difference being nonsignificant (p=0.9, 0.9 and 0.8 for pairwise comparison of the different ROC curves). Integrating ΔCRP with LIPS-2011 using binary logistic regression analysis identified a new score (LIPS-N) with AUC 0.803, which was significantly higher than the AUC of LIPS-2011 (p=0.01).

CONCLUSIONS

Both LIPS scores are equally effective in predicting ARDS in high risk ICU patients. Integrating the change in CRP within the score might improve its accuracy.

Risk factors and outcomes of acute respiratory distress syndrome in critically ill patients with cirrhosis

AIM

Prior randomized controlled trials of acute respiratory distress syndrome (ARDS) excluded critically ill patients with cirrhosis. Data regarding risk factors for ARDS development and outcomes from ARDS in patients with cirrhosis are scarce. We sought to characterize outcomes from ARDS in patients with cirrhosis.

METHODS

An observational cohort of patients with cirrhosis admitted to an intensive care unit at a high-volume liver transplant center between 1 January 2012 and 31 December 2014 were reviewed. ARDS cases were identified according to the Berlin definition. Potential risk factors were examined in multivariable logistic regression analysis for ARDS development. Outcomes including in-hospital mortality were compared between ARDS and non-ARDS patients.

RESULTS

A total of 559 patients met the inclusion criteria and 45 (8.1%) developed ARDS. Differences between ARDS and non-ARDS patients included sepsis, Model for End-Stage Liver Disease - Sodium score, and Sequential Organ Failure Assessment score. In-hospital mortality was higher in cirrhotic patients with ARDS compared with those without ARDS (82.2% vs. 27.6%, P < 0.001). In multivariable analysis, acute-on-chronic liver failure (OR 8.69, 95% CI 2.28-33.18, P < 0.01) and shock on intensive care unit admission (OR 3.13, 95% CI 1.57-6.24, P = 0.001) were associated with ARDS development, whereas etiology of cirrhosis or alcohol use were not.

CONCLUSIONS

Acute-on-chronic liver failure and shock on intensive care unit admission were risk factors for ARDS development, whereas etiology of cirrhosis and alcohol were not. Mortality from ARDS was markedly increased in patients with cirrhosis. Early recognition and treatment for infection might be important for improving the high mortality in this group of patients.

Acute pulmonary effects of aerosolized nicotine

Nicotine is a highly addictive principal component of both tobacco and electronic cigarette that is readily absorbed in blood. Nicotine-containing electronic cigarettes are promoted as a safe alternative to cigarette smoking. However, the isolated effects of inhaled nicotine are largely unknown. Here we report a novel rat model of aerosolized nicotine with a particle size (~1 μm) in the respirable diameter range. Acute nicotine inhalation caused increased pulmonary edema and lung injury as measured by enhanced bronchoalveolar lavage fluid protein, IgM, lung wet-to-dry weight ratio, and high-mobility group box 1 (HMGB1) protein and decreased lung E-cadherin protein. Immunohistochemical analysis revealed congested blood vessels and increased neutrophil infiltration. Lung myeloperoxidase mRNA and protein increased in the nicotine-exposed rats. Complete blood counts also showed an increase in neutrophils, white blood cells, eosinophils, and basophils. Arterial blood gas measurements showed an increase in lactate. Lungs of nicotine-inhaling animals revealed increased mRNA levels of IL-1A and CXCL1. There was also an increase in IL-1α protein. In in vitro air-liquid interface cultures of airway epithelial cells, there was a dose dependent increase in HMGB1 release with nicotine treatment. Air-liquid cultures exposed to nicotine also resulted in a dose-dependent loss of barrier as measured by transepithelial electrical resistance and a decrease in E-cadherin expression. Nicotine also caused a dose-dependent increase in epithelial cell death and an increase in caspase-3/7 activities. These results show that the nicotine content of electronic cigarettes may have adverse pulmonary and systemic effects.

Cigarette smoke alters lung vascular permeability and endothelial barrier function (2017 Grover Conference Series)

Smoking of tobacco products continues to be widespread, despite recent progress in decreasing use. Both in the United States and worldwide, cigarette smoking is a major cause of morbidity and mortality. Growing evidence indicates that acute respiratory distress syndrome (ARDS) is among the consequences of cigarette smoking. Based on the topic from the 2017 Grover Conference, we review evidence that cigarette smoking increases lung vascular permeability using both acute and longer exposures of mice to cigarette smoke (CS). We also review studies indicating that CS extract disrupts cultured lung endothelial cell barrier function through effects on focal adhesion contacts, adherens junctions, actin cytoskeleton, and microtubules. Among the potentially injurious components of CS, the reactive aldehyde, acrolein, similarly increases lung vascular permeability and disrupts barrier function. We speculate that inhibition of aldehyde-induced lung vascular permeability may prevent CS-induced lung injury.

The Effect of Alcohol Consumption on the Risk of ARDS: A Systematic Review and Meta-Analysis

BACKGROUND

To conduct a systematic review and meta-analysis evaluating the association between alcohol consumption and the risk of ARDS in adults.

METHODS

Medline, EMBASE and Web of Science were searched to identify observational studies evaluating the association between prior alcohol intake and the occurrence of ARDS among adults, published between 1985 and 2015 and with no language restriction. Reference lists were also screened. Demographic baseline data were extracted independently by two reviewers and random-effects meta-analyses were used to estimate pooled effect sizes with 95% confidence intervals. Subgroup analyses were used to explore heterogeneity.

RESULTS

Seventeen observational studies (177,674 people) met the inclusion criteria. Meta-analysis of 13 studies showed that any measure of high relative to low alcohol consumption was associated with a significantly increased risk of ARDS (OR, 1.89; 95% CI, 1.45-2.48; I2 = 48%; 13 studies); no evidence of publication bias was seen (P = .150). Sensitivity analyses indicated that this association was attributable primarily to an effect of a history of alcohol abuse (OR, 1.90; 95% CI, 1.40-2.60; 10 studies). Also, subgroup analyses identified that heterogeneity was explained by predisposing condition (trauma, sepsis/septic shock, pneumonia; P = .003).

CONCLUSIONS

Chronic high alcohol consumption significantly increases the risk of ARDS. This finding suggests that patients admitted to hospital should be screened for chronic alcohol use.

Effects of cigarette smoke on pulmonary endothelial cells

Cigarette smoking is the leading cause of preventable disease and death in the United States. Cardiovascular comorbidities associated with both active and secondhand cigarette smoking indicate the vascular toxicity of smoke exposure. Growing evidence supports the injurious effect of cigarette smoke on pulmonary endothelial cells and the roles of endothelial cell injury in development of acute respiratory distress syndrome (ARDS), emphysema, and pulmonary hypertension. This review summarizes results from studies of humans, preclinical animal models, and cultured endothelial cells that document toxicities of cigarette smoke exposure on pulmonary endothelial cell functions, including barrier dysfunction, endothelial activation and inflammation, apoptosis, and vasoactive mediator production. The discussion is focused on effects of cigarette smoke-induced endothelial injury in the development of ARDS, emphysema, and vascular remodeling in chronic obstructive pulmonary disease.

ARDS following oesophagectomy: a comparison of two trials

Introduction

The Beta Agonist Lung Injury Trial-Prevention (BALTI-P) translational substudy and Vitamin D to Prevent Acute Lung Injury Following Oesophagectomy (VINDALOO) trials recruited patients undergoing oesophagectomy, 4 years apart. The acute respiratory distress syndrome (ARDS) rates were lower in the VINDALOO trial. We sought to identify changes between these two trials and identify risk factors for ARDS in oesophagectomy.

Methods

There were data available from 61 patients in the BALTI-P substudy and 68 from VINDALOO. Databases were available for both trials; additional data were collected. Multivariate logistic regression was used to analyse risk factors for ARDS and postoperative complications in the cohorts combined.

Results

Logistic regression analysis showed active smoking was associated with an increase in ARDS (OR 3.91; 95% CI 1.33 to 11.5) and dihydropyridine use (OR 5.34;95% CI 1.56 to 18.3). Hospital length of stay was longer for those who took dihydropyridines (median 29 days (IQR 17–42) vs 13 days (IQR 10–18), P=0.0007) or were diabetic (median 25 days (IQR 14–39) vs 13 (IQR 10–19), P=0.023) but not for current smokers (median in never/ex-smokers 13 (IQR 10–23) vs current smokers 15 (IQR 11–20), P=0.73).

Conclusions

Smoking cessation trials should be promoted. Dihydropyridine effects perioperatively require further clinical and mechanistic evaluation. Patients undergoing oesophagectomy are a useful model for studying perioperative ARDS.

Cigarette Smoke Disrupted Lung Endothelial Barrier Integrity and Increased Susceptibility to Acute Lung Injury via Histone Deacetylase 6

Epidemiologic evidence indicates that cigarette smoke (CS) is associated with the development of acute lung injury (ALI). We have previously shown that brief CS exposure exacerbates lipopolysaccharide (LPS)-induced ALI in vivo and endothelial barrier dysfunction in vitro. In this study, we found that CS also exacerbated Pseudomonas-induced ALI in mice. We demonstrated that lung microvascular endothelial cells (ECs) isolated from mice exposed to CS had a greater permeability or incomplete recovery after challenges by LPS and thrombin. Histone deacetylase (HDAC) 6 deacetylates proteins essential for maintenance of endothelial barrier function. We found that HDAC6 phosphorylation at serine-22 was increased in lung tissues of mice exposed to CS and in lung ECs exposed to cigarette smoke extract (CSE). Inhibition of HDAC6 attenuated CSE-induced increases in EC permeability and CS priming of ALI. Similar barrier protection was provided by the microtubule stabilizer taxol, which preserved α-tubulin acetylation. CSE decreased α-tubulin acetylation and caused microtubule depolymerization. In coordination with increased HDAC6 phosphorylation, CSE inhibited Akt and activated glycogen synthase kinase (GSK)-3β; these effects were ameliorated by the antioxidant N-acetyl cysteine. Our results suggest that CS increases lung EC permeability, thereby enhancing susceptibility to ALI, likely through oxidative stress-induced Akt inactivation and subsequent GSK-3β activation. Activated GSK-3β may activate HDAC6 via phosphorylation of serine-22, leading to α-tubulin deacetylation and microtubule disassembly. Inhibition of HDAC6 may be a novel therapeutic option for ALI in cigarette smokers.

Association between chronic exposure to air pollution and mortality in the acute respiratory distress syndrome

The impact of chronic exposure to air pollution and outcomes in the acute respiratory distress syndrome (ARDS) is unknown. The Nationwide Inpatient Sample (NIS) from 2011 was utilized for this analysis. The NIS is a national database that captures 20% of all US in-patient hospitalizations from 47 states. Patients with ARDS who underwent mechanical ventilation from the highest 15 ozone pollution cities were compared with the rest of the country. Secondary analyses assessed outcomes of ARDS patients for ozone pollution and particulate matter pollution on a continuous scale by county of residence. A total of 8,023,590 hospital admissions from the 2011 NIS sample were analyzed. There were 93,950 patients who underwent mechanical ventilation for ARDS included in the study. Patients treated in high ozone regions had significantly higher unadjusted hospital mortality (34.9% versus 30.8%, p < 0.01) than patients in cities with control levels of ozone. After controlling for all variables in the model, treatment in a hospital located in a high ozone pollution area was associated with an increased odds of in-hospital mortality (OR 1.11, 95% CI 1.08-1.15, p < 0.01). After adjustment for all variables in the model, for each increase in ozone exposure by 0.01 ppm the OR for death was 1.07 (95% CI 1.06-1.08, p < 0.01). Similarly, for each increase in particulate matter exposure by 10 μg/m³, the OR for death was 1.08 (95% CI 1.02-1.16, p < 0.01). Chronic exposure to both ozone and particulate matter pollution is associated with higher rates of mortality in ARDS. These preliminary findings need to be confirmed by further detailed studies.

Cigarette smoke extract induces the epithelial-to-mesenchymal transition via the PLTP/TGF-β1/Smad2 pathway in RLE-6TN cells

Aim: The role of phospholipid transfer protein (PLTP) in the pathogenesis of the cigarette smoke extract (CSE)-induced epithelial-to-mesenchymal transition (EMT) has not been well described. In this study we investigated the effect of PLTP on the CSE-induced EMT of rat alveolar epithelial cells (RLE-6TN). Methods: The rats were exposed to air and cigarette smoke (CS) for 3 d and then the lungs were sectioned and examined using immunohistochemistry techniques. RLE-6TN cells were treated with different concentrations of CSE. PLTP siRNA was transfected into cells or SB431542 - an inhibitor of the transforming growth factor-β1 (TGF-β1) type I receptor - was administered prior to CSE exposure. The expression of EMT markers and PLTP was detected by qRT-PCR. The levels of PLTP, TGF-β1, p-Smad2, Smad2, and EMT proteins were analyzed by western blotting. Results: Lung injury and EMT were accompanied by up-regulation of PLTP and TGF-β1 in the CS-exposed rat model. EMT was induced by CSE in vitro, and the expression of PLTP, TGF-β1, and p-Smad2 was significantly increased after exposure to CSE (P < 0.05). Moreover, knockdown of PLTP and blocking of the TGF-β1/Smad2 pathway restrained the CSE-induced activation of the TGF-β1/Smad2 pathway and partly inhibited EMT by reversing E-cadherin expression and retarding the induction of N-cadherin and vimentin. In contrast, SB431542 had no effect on the expression of PLTP, while it ameliorated CSE-induced EMT. Conclusion: PLTP promotes the CSE-induced EMT process, in which the TGF-β1/Smad2 pathway is activated.

Double-hit mouse model of cigarette smoke priming for acute lung injury

Epidemiological studies indicate that cigarette smoking (CS) increases the risk and severity of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). The mechanism is not understood, at least in part because of lack of animal models that reproduce the key features of the CS priming process. In this study, using two strains of mice, we characterized a double-hit mouse model of ALI induced by CS priming of injury caused by lipopolysaccharide (LPS). C57BL/6 and AKR mice were preexposed to CS briefly (3 h) or subacutely (3 wk) before intratracheal instillation of LPS and ALI was assessed 18 h after LPS administration by measuring lung static compliance, lung edema, vascular permeability, inflammation, and alveolar apoptosis. We found that as little as 3 h of exposure to CS enhanced LPS-induced ALI in both strains of mice. Similar exacerbating effects were observed after 3 wk of preexposure to CS. However, there was a strain difference in susceptibility to CS priming for ALI, with a greater effect in AKR mice. The key features we observed suggest that 3 wk of CS preexposure of AKR mice is a reproducible, clinically relevant animal model that is useful for studying mechanisms and treatment of CS priming for a second-hit-induced ALI. Our data also support the concept that increased susceptibility to ALI/ARDS is an important adverse health consequence of CS exposure that needs to be taken into consideration when treating critically ill individuals.

The Relationship Between Airway Antioxidant Levels, Alcohol Use Disorders, and Cigarette Smoking

BACKGROUND

Alcohol use disorders (AUDs) and cigarette smoking are associated with pulmonary oxidative stress, likely related to antioxidant depletion. Pulmonary oxidative stress may adversely affect innate immunity, leading to increased pneumonia susceptibility and severity, including development of the acute respiratory distress syndrome. In people with AUDs, most of whom smoke, antioxidant therapy can potentially restore immune cell function and attenuate pneumonia development. Challenges to human investigations of antioxidant therapies include an inability to identify pulmonary oxidative stress noninvasively and the optimal route to deliver pulmonary antioxidants. We sought to determine whether bronchoalveolar lavage (BAL) measures of thiol antioxidants from a 50-ml upper airway aliquot approximated those in the alveolar space and to determine whether AUDs and/or smoking affected these relationships.

METHODS

Healthy human subjects with and without AUDs, including smokers and nonsmokers, underwent BAL. Samples obtained after the first 50-ml normal saline aliquot were analyzed as representing bronchial airways; subsequent 50-ml aliquots were analyzed as representative of the alveolar space. Reduced and oxidized (GSSG) glutathione, cysteine (Cys), and its oxidized species, cystine, along with mixed disulfides (MDs) were quantified using high-performance liquid chromatography. The percent of total thiols present in their oxidized forms, and thiol redox potentials, were calculated.

RESULTS

Positive correlations between upper and lower BAL fluid thiol species were observed that were most robust for GSSG (ρ = 0.85), Cys (ρ = 0.83), and MDs (ρ = 0.69), but poor for thiol redox potential measures. In contrast to nonsmokers (either with or without AUDs), in subjects with AUDs who smoked, upper BAL fluid %GSSG, Cys, and MD measures were relatively increased compared to lower.

CONCLUSIONS

A small volume BAL procedure may be suitable to assess intrapulmonary oxidative stress related to thiol depletion. Factors including AUDs and smoking may disproportionately increase upper airways oxidative stress that could be relevant for therapeutic interventions.

Extremes of Interferon-Stimulated Gene Expression Associate with Worse Outcomes in the Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome (ARDS) severity may be influenced by heterogeneity of neutrophil activation. Interferon-stimulated genes (ISG) are a broad gene family induced by Type I interferons, often as a response to viral infections, which evokes extensive immunomodulation. We tested the hypothesis that over- or under-expression of immunomodulatory ISG by neutrophils is associated with worse clinical outcomes in patients with ARDS. Genome-wide transcriptional profiles of circulating neutrophils isolated from patients with sepsis-induced ARDS (n = 31) and healthy controls (n = 19) were used to characterize ISG expression. Hierarchical clustering of expression identified 3 distinct subject groups with Low, Mid and High ISG expression. ISG accounting for the greatest variability in expression were identified (MX1, IFIT1, and ISG15) and used to analyze a prospective cohort at the Colorado ARDS Network site. One hundred twenty ARDS patients from four urban hospitals were enrolled within 72 hours of initiation of mechanical ventilation. Circulating neutrophils were isolated from patients and expression of ISG determined by PCR. Samples were stratified by standard deviation from the mean into High (n = 21), Mid, (n = 82) or Low (n = 17) ISG expression. Clinical outcomes were compared between patients with High or Low ISG expression to those with Mid-range expression. At enrollment, there were no differences in age, gender, co-existing medical conditions, or type of physiologic injury between cohorts. After adjusting for age, race, gender and BMI, patients with either High or Low ISG expression had significantly worse clinical outcomes than those in the Mid for number of 28-day ventilator- and ICU-free days (P = 0.0006 and 0.0004), as well as 90-day mortality and 90-day home with unassisted breathing (P = 0.02 and 0.004). These findings suggest extremes of ISG expression by circulating neutrophils from ARDS patients recovered early in the syndrome are associated with poorer clinical outcomes.

Where You Live Matters: The Impact of Place of Residence on Severe Sepsis Incidence and Mortality

BACKGROUND

Medically underserved areas are composed of vulnerable populations with reduced access to ambulatory care services. Our goal was to determine the association between residence in a medically underserved area and severe sepsis incidence and mortality.

METHODS

Using administrative data, we identified adults admitted with severe sepsis to nonfederal hospitals in South Carolina. We determined whether each resident lived in a medically underserved area or nonmedically underserved area from US Census and Department of Health and Human Services data. Age-adjusted severe sepsis incidence and mortality rates were calculated and compared between both residential classifications. Multivariate logistic regression measured the association between residence in a medically underserved area and mortality while adjusting for confounders.

RESULTS

In 2010, 24,395 adults were admitted with severe sepsis and 1,446,987 (43%) adults lived in a medically underserved area. Residents of medically underserved areas were admitted more frequently with severe sepsis (8.6 vs 6.8 cases/1,000 people, P < .01) and were more likely to die (15.5 vs 11.9 deaths/10,000 people, P < .01), with increased odds of severe sepsis-related death (OR, 1.12) after adjustment for age, race, and severity of illness. ZIP code-based surrogates of socioeconomic status, including median income, proportion below poverty level, and educational attainment, however, had minimal association with sepsis mortality.

CONCLUSIONS

Residence in a medically underserved area is associated with higher incidence and mortality rates of severe sepsis and represents a novel method of access-to-care adjustment. Traditional access-to-care surrogates, however, are poorly associated with sepsis mortality.

Evolution, Development, and Function of the Pulmonary Surfactant System in Normal and Perturbed Environments

Surfactant lipids and proteins form a surface active film at the air-liquid interface of internal gas exchange organs, including swim bladders and lungs. The system is uniquely positioned to meet both the physical challenges associated with a dynamically changing internal air-liquid interface, and the environmental challenges associated with the foreign pathogens and particles to which the internal surface is exposed. Lungs range from simple, transparent, bag-like units to complex, multilobed, compartmentalized structures. Despite this anatomical variability, the surfactant system is remarkably conserved. Here, we discuss the evolutionary origin of the surfactant system, which likely predates lungs. We describe the evolution of surfactant structure and function in invertebrates and vertebrates. We focus on changes in lipid and protein composition and surfactant function from its antiadhesive and innate immune to its alveolar stability and structural integrity functions. We discuss the biochemical, hormonal, autonomic, and mechanical factors that regulate normal surfactant secretion in mature animals. We present an analysis of the ontogeny of surfactant development among the vertebrates and the contribution of different regulatory mechanisms that control this development. We also discuss environmental (oxygen), hormonal and biochemical (glucocorticoids and glucose) and pollutant (maternal smoking, alcohol, and common "recreational" drugs) effects that impact surfactant development. On the adult surfactant system, we focus on environmental variables including temperature, pressure, and hypoxia that have shaped its evolution and we discuss the resultant biochemical, biophysical, and cellular adaptations. Finally, we discuss the effect of major modern gaseous and particulate pollutants on the lung and surfactant system.

Gemcitabine-Related Pneumonitis in Pancreas Adenocarcinoma--An Infrequent Event: Elucidation of Risk Factors and Management Implications

BACKGROUND

Gemcitabine-related pneumonitis (GRP) has been reported relatively frequently for pancreas cancer in the literature; however, underlying risk factors and optimal management remain to be defined. We studied a cohort of patients with GRP and investigated potential predisposing factors in pancreatic cancer patients.

PATIENTS AND METHODS

A total 2440 patients at Memorial Sloan Kettering Cancer Center were identified between January 1, 2000, and December 31, 2012, and were screened for grade 2 or higher GRP in an institutional tumor registry and using an ICD billing code database. Demographic and clinical information was extracted by electronic chart review.

RESULTS

A total of 28 patients (1.1%) with GRP were identified. Incidence of grade 2, 3, and 4 reactions were 7 (25%), 18 (64%), and 3 (11%), respectively. No GRP-related mortality was observed. Twenty-one patients (75%) reported a history of cigarette smoking. Seventeen patients (61%) were alcohol users. Six patients (21%) were either regular or heavy drinkers. Most patients (93%) had either locally advanced or metastatic disease. Three patients (11%) underwent a diagnostic bronchoscopy, and in 1 patient a diagnosis of organizing pneumonia was established. Morbidity was significant; 3 patients (11%) required treatment in the intensive care unit. All hospitalized patients received steroid treatment.

CONCLUSION

GRP is relatively uncommon but incurs significant morbidity. Potential risk factors include advanced-stage disease, along with smoking and alcohol consumption and possibly underlying lung disease. We recommend a high level of clinical alertness regarding the diagnosis, early pulmonary referral, and cessation of gemcitabine on suspicion of GRP.

Cigarette smoke extract induces apoptosis of rat alveolar Type II cells via the PLTP/TGF-β1/Smad2 pathway

Apoptosis of alveolar epithelial cells has been implicated in the pathogenesis of acute lung injury. Phospholipid transfer protein (PLTP) may play a role in apoptosis. In the present study, the effect of the novel function of PLTP in cigarette smoke extract (CSE)-induced apoptosis of alveolar epithelial cells and the possible mechanism were examined. Male Wistar rats were exposed to air and cigarette smoke (n=10/exposure) for 6h/day on 3 consecutive days, then the lungs were sectioned and examined. To investigate effects on alveolar epithelial cells, rat alveolar epithelial cells (RLE-6TN) were treated with different concentrations of CSE for various times. siRNA for PLTP was transfected into cells and an inhibitor of the transforming growth factor-β1 (TGF-β1) type I receptor was administered prior to CSE exposure. Apoptosis was measured, and mRNA expression of PLTP and TGF-β1 and protein levels of PLTP, TGF-β1, p-Smad2 and cleaved caspase-3 were analyzed. The results showed that apoptosis, as well as expression of PLTP, TGF-β1, p-Smad2 and cleaved caspase-3 were all significantly increased after CSE stimulation (P<0.05). Furthermore, the expression of TGF-β1, p-Smad2 and cleaved caspase-3 induced by CSE could be partly abrogated by knockdown of PLTP. The expression of PLTP showed no significant change as a result of TGF-β1 receptor inhibition, while cleaved caspase-3 showed a remarkable reduction. PLTP may act as an upstream signal molecule of the TGF-β1/Smad2 pathway and is likely to be involved in CSE-induced apoptosis of alveolar epithelial cells.

Role of angiotensin-converting enzyme (ACE) and ACE2 in a rat model of smoke inhalation induced acute respiratory distress syndrome

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Smoke inhalation results in lung injury manifestations and blood gas changes.

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This is associated with increased protein and leukocytes content in BALF.

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Smoke inhalation elevated W/D weights associated with pathological changes.

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Abnormal expression of ACE and ACE2 pathway in lung was found after smoke injury.

Smoke inhalation induced acute respiratory distress syndrome (ARDS) has become more and more common throughout the world and it is hard to improve the outcome. The present research was to investigate possible roles of angiotensin-converting enzyme (ACE) and ACE2 in lung injury resulted from smoke exposure. Rats were exposed to dense smoke to induce ARDS. Histological changes, blood gases, bronchoalveolar lavage fluids (BALF) and wet-to-dry weight were analyzed to evaluate lung injury after smoke inhalation; beside, we also measured the expression of ACE and ACE2 at different time points to explore the possible mechanism of those changes. The results showed that pH of arterial blood, partial blood oxygen (PaO₂) and blood oxygen saturation (SO₂) decreased after smoke inhalation at different time points (P < 0.01); while, partial blood carbon dioxide (PaCO₂), wet-to-dry weight ratio, leukocytes count, protein concentration and inflammatory cytokines in BALF increased after smoke exposure (P < 0.01). More importantly, both immunohistochemical staining and Western blot results showed that ACE and ACE2 expression in lungs from the experimental groups significantly increased compared with that of the control group (P < 0.05). This study indicated that inflammation pulmonary edema and histological changes resulted from smoke inhalation induced lung injury were possibly attributed to abnormal expression of ACE and ACE2 related pathway.

The acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a major cause of acute respiratory failure. Its development leads to high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of demonstrated therapeutic interventions are essential to change the natural course of this devastating entity. In this review article, we describe updated concepts in ARDS. Specifically, we discuss the new definition of ARDS, its risk factors and pathophysiology, and current evidence regarding ventilation management, adjunctive therapies, and intervention required in refractory hypoxemia.

Prescribing Patterns of Drugs in Acute Respiratory Distress Syndrome (ARDS): An Observational Study

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is characterized by acute respiratory failure and is associated with wide range of clinical disorders. Controversy prevails over the pharmacological intervention in this disease. The aim of the study was to observe the prescribing pattern of drugs in patients with ARDS managed at a tertiary care hospital.

MATERIALS AND METHODS

This observational study was conducted at tertiary care hospital in India. Data of patients admitted from January 2010 to December 2012 was collected. Patients aged more than 18 years admitted in ICU, who were diagnosed to have ARDS during the study period, were included. A total of 150 patients of ARDS were selected. Data was collected as per the pre designed proforma and it included patients' age, gender, clinical disorders precipitating ARDS, prescribing pattern of drugs and outcome. The data of the subjects was collected till discharge from hospital or death.

RESULTS

Infection was the cause of ARDS in 81.3% (n=122) of subjects. Antibiotics were prescribed in all the subjects and beta-lactams were prescribed in 97.3% (n=146). 41.3% (n=62) were prescribed corticosteroids, 39.3% (n=59) diuretics and 89.3% (n=134) intravenous fluids.

CONCLUSION

The outcome of patients on different pharmacological treatment did not show any statistically significant difference.

Recipient clinical risk factors predominate in possible transfusion-related acute lung injury

BACKGROUND

Possible transfusion-related acute lung injury (pTRALI) cases by definition have a clear temporal relationship to an alternative recipient risk factor for acute respiratory distress syndrome (ARDS). We questioned whether transfusion factors are important for the development of pTRALI.

STUDY DESIGN AND METHODS

In this nested case-control study, we prospectively identified 145 consecutive patients with pTRALI and randomly selected 163 transfused controls over a 4-year period at the University of California at San Francisco and the Mayo Clinic (Rochester, Minnesota).

RESULTS

For pTRALI, we found evidence against transfusion being important: receipt of plasma from female donors (odds ratio [OR], 0.82; 95% confidence interval [CI], 0.29-2.3; p = 0.70), total number of units transfused (OR, 0.99; 95% CI, 0.89-1.10; p = 0.86), and number of red blood cell and whole blood units transfused (OR, 0.78; 95% CI, 0.59-1.03; p = 0.079). In contrast, we found that risk for pTRALI was associated with additional recipient factors: chronic alcohol abuse (OR, 12.5; 95% CI, 2.8-55; p < 0.001), current smoker (OR, 4.2; 95% CI, 1.67-10.8; p = 0.0024), shock before transfusion (OR, 4.6; 95% CI, 2.0-10.7; p < 0.001), and positive fluid balance before transfusion (OR, 1.32/L; 95% CI, 1.20-1.44; p < 0.001).

CONCLUSION

Recipient risk factors for ARDS rather than transfusion risk factors predominate in pTRALI.

Environmental risk factors for acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) remains a major cause of morbidity and mortality in critically ill patients. Over the past several decades, alcohol abuse and cigarette smoke exposure have been identified as risk factors for the development of ARDS. The mechanisms underlying these relationships are complex and remain under investigation but are thought to involve pulmonary immune impairment and alveolar epithelial and endothelial dysfunction. This review summarizes the epidemiologic data supporting links between these exposures and ARDS susceptibility and outcomes and highlights key mechanistic investigations that provide insight into the pathways by which each exposure is linked to ARDS.

Approach to the patient with the acute respiratory distress syndrome

Given the high incidence and mortality of acute respiratory distress syndrome (ARDS) in critically ill patients, every practitioner needs a bedside approach both for early identification of patients at risk for ARDS and for the appropriate evaluation of patients who meet the diagnostic criteria of ARDS. Recent advances such as the Lung Injury Prediction score, the Early Acute Lung Injury score, and validation of the SpO(2)/Fio(2) ratio for assessing the degree of hypoxemia are all practical tools to aid the practitioner in caring for patients at risk of ARDS.

Prevalence and impact of active and passive cigarette smoking in acute respiratory distress syndrome

OBJECTIVES

Cigarette smoke exposure has recently been found to be associated with increased susceptibility to trauma- and transfusion-associated acute respiratory distress syndrome. We sought to determine 1) the incidence of cigarette smoke exposure in a diverse multicenter sample of acute respiratory distress syndrome patients and 2) whether cigarette smoke exposure is associated with severity of lung injury and mortality in acute respiratory distress syndrome.

DESIGN

Analysis of the Albuterol for the Treatment of Acute Lung Injury and Omega Acute Respiratory Distress Syndrome Network studies.

SETTING

Acute Respiratory Distress Syndrome Network hospitals.

PATIENTS

Three hundred eighty-one patients with acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol, a validated tobacco-specific marker, was measured in urine samples from subjects enrolled in two National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome Network randomized controlled trials. Urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol levels were consistent with active smoking in 36% of acute respiratory distress syndrome patients and with passive smoking in 41% of nonsmokers (vs 20% and 40% in general population, respectively). Patients with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol levels in the active smoking range were younger and had a higher incidence of alcohol misuse, fewer comorbidities, lower severity of illness, and less septic shock at enrollment compared with patients with undetectable 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol levels. Despite this lower severity of illness, the severity of lung injury did not significantly differ based on biomarker-determined smoking status. Cigarette smoke exposure was not significantly associated with death after adjusting for differences in age, alcohol use, comorbidities, and severity of illness.

CONCLUSIONS

In this first multicenter study of biomarker-determined cigarette smoke exposure in acute respiratory distress syndrome patients, we found that active cigarette smoke exposure was significantly more prevalent among acute respiratory distress syndrome patients compared to population averages. Despite their younger age, better overall health, and lower severity of illness, smokers by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol had similar severity of lung injury as patients with undetectable 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol. These findings suggest that active cigarette smoking may increase susceptibility to acute respiratory distress syndrome in younger, healthier patients.

Loss of cystic fibrosis transmembrane conductance regulator impairs lung endothelial cell barrier function and increases susceptibility to microvascular damage from cigarette smoke

Abnormal lung microvascular endothelial vascular barrier function may contribute to pulmonary inflammation, such as that occurring during inhalation of cigarette smoke (CS). Cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel expressed in both epithelial and endothelial cells, regulates the organization of tight junctions between epithelial cells and has also been implicated in the transport of sphingosine-1 phosphate (S1P), a vascular barrier-enhancing sphingolipid. Because CS has been shown to affect CFTR function, we hypothesized that CFTR function contributes to lung endothelial cell barrier and that CFTR dysfunction worsens CS-induced injury. CFTR inhibitors GlyH-101 or CFTRinh172 caused a dose-dependent increase in pulmonary or bronchial endothelial monolayer permeability, which peaked after 4 hours. CFTR inhibition was associated with both intercellular gaps and actin stress fiber formation compared with vehicle-treated cells. Increasing endothelial S1P, either by exogenous treatment or by inhibition of its degradation, significantly improved the barrier function in CFTR-inhibited monolayers. Both cultured lung endothelia and the lung microcirculation visualized in vivo with intravital two-photon imaging of transgenic mice deficient in CFTR showed that CFTR dysfunction increased susceptibility to CS-induced permeability. These results suggested that CFTR function might be required for lung endothelial barrier, including adherence junction stability. Loss of CFTR function, especially concomitant to CS exposure, might promote lung inflammation by increasing endothelial cell permeability, which could be ameliorated by S1P.

Predicting risk of postoperative lung injury in high-risk surgical patients: a multicenter cohort study

BACKGROUND

Acute respiratory distress syndrome (ARDS) remains a serious postoperative complication. Although ARDS prevention is a priority, the inability to identify patients at risk for ARDS remains a barrier to progress. The authors tested and refined the previously reported surgical lung injury prediction (SLIP) model in a multicenter cohort of at-risk surgical patients.

METHODS

This is a secondary analysis of a multicenter, prospective cohort investigation evaluating high-risk patients undergoing surgery. Preoperative ARDS risk factors and risk modifiers were evaluated for inclusion in a parsimonious risk-prediction model. Multiple imputation and domain analysis were used to facilitate development of a refined model, designated SLIP-2. Area under the receiver operating characteristic curve and the Hosmer-Lemeshow goodness-of-fit test were used to assess model performance.

RESULTS

Among 1,562 at-risk patients, ARDS developed in 117 (7.5%). Nine independent predictors of ARDS were identified: sepsis, high-risk aortic vascular surgery, high-risk cardiac surgery, emergency surgery, cirrhosis, admission location other than home, increased respiratory rate (20 to 29 and ≥30 breaths/min), FIO2 greater than 35%, and SpO2 less than 95%. The original SLIP score performed poorly in this heterogeneous cohort with baseline risk factors for ARDS (area under the receiver operating characteristic curve [95% CI], 0.56 [0.50 to 0.62]). In contrast, SLIP-2 score performed well (area under the receiver operating characteristic curve [95% CI], 0.84 [0.81 to 0.88]). Internal validation indicated similar discrimination, with an area under the receiver operating characteristic curve of 0.84.

CONCLUSIONS

In this multicenter cohort of patients at risk for ARDS, the SLIP-2 score outperformed the original SLIP score. If validated in an independent sample, this tool may help identify surgical patients at high risk for ARDS.

Impact of distinct definitions of acute lung injury on its incidence and outcomes in Brazilian ICUs: prospective evaluation of 7,133 patients*

OBJECTIVES

Evaluation of prevalence and outcomes of acute lung injury in a large cohort of critically ill patients in Brazil and comparison of predictive receiver operating characteristic curve mortality of American European Consensus conference definition with new Berlin definition of acute respiratory distress syndrome.

DESIGN

A 15-month prospective, multicenter, observational study.

SETTING

Fourteen medical ICUs in Espirito Santo, a state of Brazil.

PATIENTS

Mechanically ventilated patients who fulfilled American European Consensus conference criteria of acute lung injury or Berlin definition of acute respiratory distress syndrome.

INTERVENTIONS

Clinical and respiratory data were collected for 7 consecutive days and on the 14 and 28 days. Twenty-eight day mortality, hospital mortality, and predictive receiver operating characteristic curve mortality were calculated.

MEASUREMENTS AND MAIN RESULTS

Of 7,133 patients, 130 patients (1.8%) fulfilled criteria for acute lung injury (American European Consensus conference) or acute respiratory distress syndrome (Berlin definition). Median time for diagnosis was 2 days (interquartile range, 0-3 d). Main risk factors were pneumonia (35.3%) and nonpulmonary sepsis (31.5%). Mean age was 44.2 ± 15.9 years, and 61.5% were men. Mean Acute Physiology and Chronic Health Evaluation II score was 20.7 ± 7.9. Mean PaO2/FIO2 was 206 ± 61.5, significantly lower in nonsurvivors on day 7 (p = 0.003). Mean mechanical ventilation time was 21 ± 15 days. Length of ICU stay was 26.4 ± 18.7 days. Twenty-eight-day mortality was 38.5% (95% CI, 30.1-46.8); hospital mortality was 49.2% (95% CI, 40.6-57.8). Predictive 28-day mortality area under the receiver operating characteristic curve for American European Consensus conference definition was 0.5625 (95% CI, 0.4783-0.6467) and for the Berlin definition 0.5664 (95% CI, 0.4759-0.6568; p = 0.9510).

CONCLUSIONS

In our population, prevalence of acute lung injury was low, most cases were diagnosed 2 days after ICU admission, and Berlin definition was not different from American European Consensus conference definition in predicting mortality. There are still several problems with the global epidemiology, definition, and mortality predictive indices that should be added to the classification of this still lethal syndrome to improve its predictive mortality power in the future.

Double impact of cigarette smoke and mechanical ventilation on the alveolar epithelial type II cell

INTRODUCTION

Ventilator-induced lung injury (VILI) impacts clinical outcomes in acute respiratory distress syndrome (ARDS), which is characterized by neutrophil-mediated inflammation and loss of alveolar barrier function. Recent epidemiological studies suggest that smoking may be a risk factor for the development of ARDS. Because alveolar type II cells are central to maintaining the alveolar epithelial barrier during oxidative stress, mediated in part by neutrophilic inflammation and mechanical ventilation, we hypothesized that exposure to cigarette smoke and mechanical strain have interactive effects leading to the activation of and damage to alveolar type II cells.

METHODS

To determine if cigarette smoke increases susceptibility to VILI in vivo, a clinically relevant rat model was established. Rats were exposed to three research cigarettes per day for two weeks. After this period, some rats were mechanically ventilated for 4 hours. Bronchoalveolar lavage (BAL) and differential cell count was done and alveolar type II cells were isolated. Proteomic analysis was performed on the isolated alveolar type II cells to discover alterations in cellular pathways at the protein level that might contribute to injury. Effects on levels of proteins in pathways associated with innate immunity, oxidative stress and apoptosis were evaluated in alveolar type II cell lysates by enzyme-linked immunosorbent assay. Statistical comparisons were performed by t-tests, and the results were corrected for multiple comparisons using the false discovery rate.

RESULTS

Tobacco smoke exposure increased airspace neutrophil influx in response to mechanical ventilation. The combined exposure to cigarette smoke and mechanical ventilation significantly increased BAL neutrophil count and protein content. Neutrophils were significantly higher after smoke exposure and ventilation than after ventilation alone. DNA fragments were significantly elevated in alveolar type II cells. Smoke exposure did not significantly alter other protein-level markers of cell activation, including Toll-like receptor 4; caspases 3, 8 and 9; and heat shock protein 70.

CONCLUSIONS

Cigarette smoke exposure may impact ventilator-associated alveolar epithelial injury by augmenting neutrophil influx. We found that cigarette smoke had less effect on other pathways previously associated with VILI, including innate immunity, oxidative stress and apoptosis.

Berberine attenuates cigarette smoke-induced acute lung inflammation

Berberine (Ber), the major constituent of Coptidis Rhizoma, possesses anti-inflammatory properties. In this study, we investigated the effects of Ber on cigarette smoke (CS)-mediated acute lung inflammation. C57BL/6 mice (6-8 weeks) were exposed to CS to induce acute lung injury. Ber was used to pretreat CS-exposed mice (50 mg/kg, intragastrically). Lung tissues were collected for histological examination, myeloperoxidase (MPO) activity assay, Western blot analysis, and electrophoretic mobility shift assay. Bronchoalveolar lavage fluid (BALF) was measured for cell counts and cytokine analysis. Histological examination showed that CS exposure caused infiltration of inflammatory cells into alveolar spaces and interstitial edema. Pretreatment with Ber significantly attenuated CS-induced lung inflammation. The numbers of total cells, macrophages, and neutrophils in BALF were decreased by 43, 40, and 53 %, respectively, by Ber pretreatment in CS-exposed mice, accompanied by decreased MPO activity, a marker of neutrophil accumulation. Ber pretreatment also profoundly diminished CS-induced secretions of macrophage inflammatory protein 2, tumor necrosis factor alpha, interleukin-6, and monocyte chemotactic protein-1 in BALF, along with less nuclear translocation of the pro-inflammatory transcription factor nuclear factor-kappa B (NF-κB) p65 subunit and lower NF-κB DNA-binding activity (P < 0.01). Thus, our results indicated that Ber ameliorates CS-induced acute lung injury through its anti-inflammatory activity.

Early acute lung injury: criteria for identifying lung injury prior to the need for positive pressure ventilation*

OBJECTIVE

Mortality associated with acute lung injury remains high. Early identification of acute lung injury prior to onset of respiratory failure may provide a therapeutic window to target in future clinical trials. The recently validated Lung Injury Prediction Score identifies patients at risk for acute lung injury but may be limited for routine clinical use. We sought to empirically derive clinical criteria for a pragmatic definition of early acute lung injury to identify patients with lung injury prior to the need for positive pressure ventilation.

DESIGN

Prospective observational cohort study.

SETTING

Stanford University Hospital.

PATIENTS

We prospectively evaluated 256 patients admitted to Stanford University Hospital with bilateral opacities on chest radiograph without isolated left atrial hypertension.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 256 patients enrolled, 62 patients (25%) progressed to acute lung injury requiring positive pressure ventilation. Clinical variables (through first 72 hr or up to 6 hr prior to acute lung injury) associated with progression to acute lung injury were analyzed by backward regression. Oxygen requirement, maximal respiratory rate, and baseline immune suppression were independent predictors of progression to acute lung injury. A simple three-component early acute lung injury score (1 point for oxygen requirement > 2-6 L/min or 2 points for > 6 L/min; 1 point each for a respiratory rate ≥ 30 and immune suppression) accurately identified patients who progressed to acute lung injury requiring positive pressure ventilation (area under the receiver-operator characteristic curve, 0.86) and performed similarly to the Lung Injury Prediction Score. An early acute lung injury score greater than or equal to 2 identified patients who progressed to acute lung injury with 89% sensitivity and 75% specificity. Median time of progression from early acute lung injury criteria to acute lung injury requiring positive pressure ventilation was 20 hours.

CONCLUSIONS

This pragmatic definition of early acute lung injury accurately identified patients who progressed to acute lung injury prior to requiring positive pressure ventilation. Pending further validation, these criteria could be useful for future clinical trials targeting early treatment of acute lung injury.

Risk factors for the development of acute lung injury in patients with infectious pneumonia

INTRODUCTION

Although pneumonia has been identified as the single most common risk factor for acute lung injury (ALI), we have a limited knowledge as to why ALI develops in some patients with pneumonia and not in others. The objective of this study was to determine frequency, risk factors, and outcome of ALI in patients with infectious pneumonia.

METHODS

A retrospective cohort study of adult patients with microbiologically positive pneumonia, hospitalized at two Mayo Clinic Rochester hospitals between January 1, 2005, and December 31, 2007. In a subsequent nested case-control analysis, we evaluated the differences in prehospital and intrahospital exposures between patients with and without ALI/acute respiratory distress syndrome (ARDS) matched by specific pathogen, isolation site, gender, and closest age in a 1:1 manner.

RESULTS

The study included 596 patients; 365 (61.2%) were men. The median age was 65 (IQR, 53 to 75) years. In total, 171 patients (28.7%) were diagnosed with ALI. The occurrence of ALI was less frequent in bacterial (n = 99 of 412, 24%) compared with viral (n = 19 of 55, 35%), fungal (n = 39 of 95, 41%), and mixed isolates pneumonias (n = 14 of 34, 41%; P = 0.002). After adjusting for baseline severity of illness and comorbidities, patients in whom ALI developed had a markedly increased risk of hospital death (ORadj 9.7; 95% CI, 6.0 to 15.9). In a nested case-control study, presence of shock (OR, 8.9; 95% CI, 2.8 to 45.9), inappropriate initial antimicrobial treatment (OR, 3.2; 95% CI, 1.3 to 8.5), and transfusions (OR, 4.8; 95% CI, 1.5 to 19.6) independently predicted ALI development.

CONCLUSIONS

The development of ALI among patients hospitalized with infectious pneumonia varied among pulmonary pathogens and was associated with increased mortality. Inappropriate initial antimicrobial treatment and transfusion predict the development of ALI independent of pathogen.

[Alcohol and acute respiratory distress syndrome: casuality or causality?]

Alcohol has been considered an important risk factor for the development of pneumonia since the last century. Nevertheless, it was not thought that it had relevant effects on lung structure and functions until recently. Recent studies have shown that the risk for acute respiratory distress syndrome (ARDS) is 2-4 times higher among alcoholic patients with sepsis or trauma, and that alcoholism can play a roll in more than 50% of cases in the pathogenesis of this syndrome. Although alcoholism per se does not cause acute lung injury it predisposes to pulmonary dysfunction after inflammatory stress, that is present in clinical situations that cause ARDS leading to its development and complicating its outcome. Recent investigations in animals and humans with alcohol abuse have uncovered several alterations currently known as the "alcoholic lung". This revision discusses the association between alcohol abuse and lung injury/ARDS and tries to explain the physiopathology along with possible treatments.