The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome

Bronchoalveolar Lavage and Oleic Acid Two-hit Model for Inducing Acute Respiratory Distress Syndrome in Swine Models

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is a widespread and often fatal clinical syndrome marked by the acute onset of pulmonary edema and inflammatory-mediated disruptions in alveolar-capillary permeability resulting in impaired gas exchange and tissue oxygenation with subsequent acute respiratory failure that accounts for 10.4% of all intensive care unit admissions worldwide and boasts a mortality rate of 38.5%. The current treatment for ARDS remains largely supportive. This is largely because of the many challenges of achieving a stable and sustainable animal model that recreates the pathophysiology of ARDS experimentally in a controlled setting to allow research to elucidate potential treatments of ARDS moving forward.

MATERIALS AND METHODS

The bronchoalveolar lavage and oleic acid models are currently the 2 most frequently used experimental models in inducing ARDS in animal models. This study demonstrated that combining them into a "two-hit model" can produce sustained ARDS in swine models per the Horowitz index (PaO2/FiO2 ratio of ≤300 mmHg). Additionally, expected changes in pH, pCO2, lung compliance, cytokines, and tissue histopathology were observed and add to our confidence and reliability that the "two-hit model" produces symptomatic ARDS in a manner very similar to that observed in humans.

RESULTS AND CONCLUSIONS

In conclusion, we demonstrated a viable animal model of human ARDS that is maintained for a prolonged period, suitable for continuous monitoring of the progression, and evaluation of potential future treatments and procedures to reduce patient morbidity and mortality. To carry out this two-hit model, lung injury was induced through a combination of bronchoalveolar lavage and oleic acid administration and the disease process of ARDS is subsequently tracked through clinically relevant parameters such as respiratory mechanics, cytokine response, aretrial blood gas (ABG) changes, and observation of postmortem histopathologic changes. This promising new model has the capacity to successfully replicate human ARDS which is a well-known and notoriously multifactorial pathogenic process to reproduce experimentally for an extended period of time. The "two-hit model" is a viable and appropriate model for the research of novel treatments for ARDS.

Impact of obesity on outcomes of patients with acute respiratory distress syndrome: a retrospective analysis of a large clinical database

OBJECTIVE

To evaluate the link between obesity and mortality in patients with acute respiratory distress syndrome (ARDS).

METHODS

We performed a retrospective cohort study of a large clinical database. A Cox proportional hazards regression model was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for the relationship between body mass index (BMI) and mortality. The primary endpoint was 30-day death rate and the secondary endpoints were 90-day and 1‑year mortality.

RESULTS

Overall, 418 patients with ARDS were enrolled in the study, including 185 women and 233 men (age: 70.7 ± 44.1 years; BMI: 28.7 ± 8.1 kg/m2). Compared with patients with normal weight, obese patients were younger (60.1 ± 13.7, p = 0.003) and a higher percentage of these patients were women (51.3% vs. 49.0%, p = 0.001). The HRs (95% CI) of 30-day mortality in the underweight, overweight, and obese populations were 1.82 (0.85, 3.90), 0.59 (0.29, 1.20), and 3.85 (1.73, 8.57), respectively, after adjustment for other confounding factors. A similar pattern was also seen for death after 90 days and after 1 year. A U-shaped association between BMI and 30-day mortality was discovered by curve fitting.

CONCLUSION

Obesity had a significant impact on the short- and long-term mortality in patients with ARDS. There was a U-shaped relationship between BMI and mortality, while a higher BMI was associated with an increased risk of death in patients with ARDS.

Recapitulation of human pathophysiology and identification of forensic biomarkers in a translational model of chlorine inhalation injury

Chlorine gas (Cl2) has been repeatedly used as a chemical weapon, first in World War I and most recently in Syria. Life-threatening Cl2 exposures frequently occur in domestic and occupational environments, and in transportation accidents. Modeling the human etiology of Cl2-induced acute lung injury (ALI), forensic biomarkers, and targeted countermeasures development have been hampered by inadequate large animal models. The objective of this study was to develop a translational model of Cl2-induced ALI in swine to understand toxico-pathophysiology and evaluate whether it is suitable for screening potential medical countermeasures and to identify biomarkers useful for forensic analysis. Specific pathogen-free Yorkshire swine (30-40 kg) of either sex were exposed to Cl2 (≤240 ppm for 1 h) or filtered air under anesthesia and controlled mechanical ventilation. Exposure to Cl2 resulted in severe hypoxia and hypoxemia, increased airway resistance and peak inspiratory pressure, and decreased dynamic lung compliance. Cl2 exposure resulted in increased total leucocyte and neutrophil counts in bronchoalveolar lavage fluid, vascular leakage, and pulmonary edema compared with the air-exposed group. The model recapitulated all three key histopathological features of human ALI, such as neutrophilic alveolitis, deposition of hyaline membranes, and formation of microthrombi. Free and lipid-bound 2-chlorofatty acids and chlorotyrosine-modified proteins (3-chloro-l-tyrosine and 3,5-dichloro-l-tyrosine) were detected in plasma and lung tissue after Cl2 exposure. In this study, we developed a translational swine model that recapitulates key features of human Cl2 inhalation injury and is suitable for testing medical countermeasures, and validated chlorinated fatty acids and protein adducts as biomarkers of Cl2 inhalation.NEW & NOTEWORTHY We established a swine model of chlorine gas-induced acute lung injury that exhibits several features of human acute lung injury and is suitable for screening potential medical countermeasures. We validated chlorinated fatty acids and protein adducts in plasma and lung samples as forensic biomarkers of chlorine inhalation.

Setting positive end-expiratory pressure: using the pressure-volume curve

PURPOSE OF REVIEW

To discuss the role of pressure-volume curve (PV curve) in exploring elastic properties of the respiratory system and setting mechanical ventilator to reduce ventilator-induced lung injury.

RECENT FINDINGS

Nowadays, quasi-static PV curves and loops can be easily obtained and analyzed at the bedside without disconnection of the patient from the ventilator. It is shown that this tool can provide useful information to optimize ventilator setting. For example, PV curves can assess for patient's individual potential for lung recruitability and also evaluate the risk for lung injury of the ongoing mechanical ventilation setting.

SUMMARY

In conclusion, PV curve is an easily available bedside tool: its correct interpretation can be extremely valuable to enlighten potential for lung recruitability and select a high or low positive end-expiratory pressure (PEEP) strategy. Furthermore, recent studies have shown that PV curve can play a significant role in PEEP and driving pressure fine tuning: clinical studies are needed to prove whether this technique will improve outcome.

Prone Position Ventilation in Neurologically Ill Patients: A Systematic Review and Proposed Protocol

OBJECTIVES

Prone positioning has been shown to be a beneficial adjunctive supportive measure for patients who develop acute respiratory distress syndrome. Studies have excluded patients with reduced intracranial compliance, whereby patients with concomitant neurologic diagnoses and acute respiratory distress syndrome have no defined treatment algorithm or recommendations for management. In this study, we aim to determine the safety and feasibility of prone positioning in the neurologically ill patients.

DESIGN AND SETTING

A systematic review of the literature, performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses 2009 guidelines, yielded 10 articles for analysis. Using consensus from these articles, in combination with review of multi-institutional proning protocols for patients with nonneurologic conditions, a proning protocol for patients with intracranial pathology and concomitant acute respiratory distress syndrome was developed.

MEASUREMENTS AND MAIN RESULTS

Among 10 studies included in the final analysis, we found that prone positioning is safe and feasible in the neurologically ill patients with acute respiratory distress syndrome. Increased intracranial pressure and compromised cerebral perfusion pressure may occur with prone positioning. We propose a prone positioning protocol for the neurologically ill patients who require frequent neurologic examinations and intracranial monitoring.

CONCLUSIONS

Although elevations in intracranial pressure and reductions in cerebral perfusion pressure do occur during proning, they may not occur to a degree that would warrant exclusion of prone ventilation as a treatment modality for patients with acute respiratory distress syndrome and concomitant neurologic diagnoses. In cases where intracranial pressure, cerebral perfusion pressure, and brain tissue oxygenation can be monitored, prone position ventilation should be considered a safe and viable therapy.

Impact of obesity on outcomes in patients with acute respiratory syndrome

Objectives

We assessed the relationship between obesity and all-cause mortality in patients with acute respiratory distress syndrome (ARDS).

Methods

In this retrospective cohort study, patient data were extracted from the eICU Collaborative Research Database and the Medical Information Mart for Intensive Care Database III. Body mass index (BMI) was grouped according to World Health Organization classifications: underweight, normal weight, overweight, obese. Cox regression models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause mortality related to obesity.

Results

Participants included 185 women and 233 men, mean age 70.7 ± 44.1 years and mean BMI 28.7 ± 8.1 kg/m². Compared with normal weight patients, obese patients tended to be younger (60.1 ± 13.7 years) and included more women (51.3% vs. 49.0%). In the unadjusted model, HRs (95% CIs) of 30-day mortality for underweight, overweight, and obesity were 1.57 (0.76, 3.27), 0.64 (0.39, 1.08), and 4.83 (2.25, 10.35), respectively, compared with those for normal weight. After adjustment, HRs (95% CIs) of 30-day mortality for underweight, overweight, and obesity were 1.82 (0.85, 3.90), 0.59 (0.29, 1.20), and 3.85 (1.73, 8.57), respectively, compared with the reference group; 90-day and 1-year all-cause mortalities showed similar trends.

Conclusions

Obesity was associated with increased all-cause mortality in patients with ARDS.

Air pollution impairs recovery and tissue remodeling in a murine model of acute lung injury

Evidence regarding the impact of air pollution on acute respiratory distress syndrome (ARDS) is limited, and most studies focus on ARDS onset. Our study aimed to evaluate whether exposure to fine particulate matter interferes with lung recovery and remodeling in a murine model of acute lung injury. Forty-eight mice received nebulized LPS or the vehicle (controls). Blood, BALF, lungs and spleen were collected after 5 weeks of exposure to either PM_2.5 (PM and LPS + PM group) or filtered air (control and LPS5w groups). Inflammatory cells and cytokines were assessed in the blood, BALF, lungs and spleen. Stereological analyses and remodeling assessments were performed by histology. The LPS + PM group showed increased BALF leukocytes, characterized by increased macrophages, increased IL-1β and IL-6 levels, anemia and thrombocytopenia. Moreover, we also observed septal thickening, decreased alveolar air space total volume and, septa surface density. Finally, regarding tissue remodeling, we observed elastosis of the lung parenchyma, and unlike in the LPS5w group, we did not observe fibrosis in the LPS + PM group. In conclusion, the delayed inflammation resolution due to subchronic exposure to PM_2.5 could be influenced by low systemic and local lymphocyte counts, which lead to impaired lung injury recovery and tissue remodeling.

Anti-Allergic and Anti-Inflammatory Effects and Molecular Mechanisms of Thioredoxin on Respiratory System Diseases

Significance: The pathogenesis and progression of allergic inflammation in the respiratory system are closely linked to oxidative stress. Thioredoxin (TRX) is an essential redox balance regulator in organisms and is induced by various oxidative stress factors, including ultraviolet rays, radiation, oxidation, viral infections, ischemia reperfusion, and anticancer agents. Recent Advances: We demonstrated that systemic administration and transgenic overexpression of TRX is useful in a wide variety of in vivo inflammatory respiratory diseases models, such as viral pneumonia, interstitial lung disease, chronic obstructive pulmonary disease, asthma, acute respiratory distress syndrome, and obstructive sleep apnea syndrome, by removing reactive oxygen species, blocking production of inflammatory cytokines, inhibiting migration and activation of neutrophils and eosinophils, and regulating the cellular redox status. In addition, TRX's anti-inflammatory mechanism is different from the mechanisms associated with anti-inflammatory agents, such as glucocorticoids, which regulate the inflammatory reaction in association with suppressing immune responses. Critical Issues: Understanding the molecular mechanism of TRX is very helpful for understanding the role of TRX in respiratory diseases. In this review, we show the protective effect of TRX in various respiratory diseases. In addition, we discuss its anti-allergic and anti-inflammatory molecular mechanism in detail. Future Directions: The application of TRX may be useful for treating respiratory allergic inflammatory disorders. Antioxid. Redox Signal. 32, 785-801.

Obesity is a risk factor for preoperative hypoxemia in Stanford A acute aortic dissection

Obese individuals are apt to develop Stanford A acute aortic dissection (AAD) complicated with acute lung injury (ALI), but the mechanism is still not well defined. We aim to investigate whether oxidative stress and inflammatory are involved in the aortic dissection lung injury caused by obesity.Seventy-nine patients were categorized into AAD with obesity group (n = 17) and AAD without obesity group (n = 62) according to body mass index (BMI). Inflammatory reactions including interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-6, C-reactive protein (CRP) and white blood cell (WBC) count, and oxidative stress including malondialdehyde (MDA), superoxide dismutase were determined using enzyme-linked immunosorbent assays and chemiluminescence. All the patients received ascending aorta replacement combined with total arch replacement and stented elephant trunk. The postoperative complications were recorded.The incidence of preoperative hypoxemia (94.1% vs 35.5%, P < .01) and postoperative ALI (88.2% vs 40.3%, P < .01) in obese patients was significantly higher than that in non-obese patients. Besides, the ICU stay (119.2 ± 59.2 vs 87.8 ± 31.2 h, P < .01) and hospitalization duration (18.8 ± 8.5 vs 14.3 ± 8.1d, P = .048) were increased in the obese patients with AAD. The expression of IL-1β, TNF-α, IL-6, CRP, and WBC was remarkably increased (P < .01) in obese group compared with non-obese group.Oxidative stress and inflammatory response may be involved in the process of ALI of aortic dissection caused by obesity, which provides new ideas for the treatment of ALI of the aortic dissection.

Acute and Chronic Respiratory Failure in Cancer Patients

In 2016, there was an estimated 1.8 million new cases of cancer diagnosed in the United States. Remarkable advances have been made in cancer therapy and the 5-year survival has increased for most patients affected by malignancy. There are growing numbers of patients admitted to intensive care units (ICU) and up to 20% of all patients admitted to an ICU carry a diagnosis of malignancy. Respiratory failure remains the most common reason for ICU admission and remains the leading causes of death in oncology patients. There are many causes of respiratory failure in this population. Pneumonia is the most common cause of respiratory failure, yet there are many causes of respiratory insufficiency unique to the cancer patient. These causes are often a result of immunosuppression, chemotherapy, radiation treatment, or hematopoietic stem cell transplant (HCT). Treatment is focused on supportive care and specific therapy for the underlying cause of respiratory failure. Noninvasive modalities of respiratory support are available; however, careful patient selection is paramount as indiscriminate use of noninvasive positive pressure ventilation is associated with a higher mortality if mechanical ventilation is later required. Historically, respiratory failure in the cancer patient had a grim prognosis. Outcomes have improved over the past 20 years. Survivors are often left with significant disability.

Metabolomic Profile of ARDS by Nuclear Magnetic Resonance Spectroscopy in Patients With H1N1 Influenza Virus Pneumonia

PURPOSE

The integrated analysis of changes in the metabolic profile could be critical for the discovery of biomarkers of lung injury, and also for generating new pathophysiological hypotheses and designing novel therapeutic targets for the acute respiratory distress syndrome (ARDS). This study aimed at developing a nuclear magnetic resonance (NMR)-based approach for the identification of the metabolomic profile of ARDS in patients with H1N1 influenza virus pneumonia.

METHODS

Serum samples from 30 patients (derivation set) diagnosed of H1N1 influenza virus pneumonia were analyzed by unsupervised principal component analysis to identify metabolic differences between patients with and without ARDS by NMR spectroscopy. A predictive model of partial least squares discriminant analysis (PLS-DA) was developed for the identification of ARDS. PLS-DA was trained with the derivation set and tested in another set of samples from 26 patients also diagnosed of H1N1 influenza virus pneumonia (validation set).

RESULTS

Decreased serum glucose, alanine, glutamine, methylhistidine and fatty acids concentrations, and elevated serum phenylalanine and methylguanidine concentrations, discriminated patients with ARDS versus patients without ARDS. PLS-DA model successfully identified the presence of ARDS in the validation set with a success rate of 92% (sensitivity 100% and specificity 91%). The classification functions showed a good correlation with the Sequential Organ Failure Assessment score (R = 0.74, P < 0.0001) and the PaO2/FiO2 ratio (R = 0.41, P = 0.03).

CONCLUSIONS

The serum metabolomic profile is sensitive and specific to identify ARDS in patients with H1N1 influenza A pneumonia. Future studies are needed to determine the role of NMR spectroscopy as a biomarker of ARDS.

Biomedical engineer's guide to the clinical aspects of intensive care mechanical ventilation

Background

Mechanical ventilation is an essential therapy to support critically ill respiratory failure patients. Current standards of care consist of generalised approaches, such as the use of positive end expiratory pressure to inspired oxygen fraction (PEEP–FiO₂) tables, which fail to account for the inter- and intra-patient variability between and within patients. The benefits of higher or lower tidal volume, PEEP, and other settings are highly debated and no consensus has been reached. Moreover, clinicians implicitly account for patient-specific factors such as disease condition and progression as they manually titrate ventilator settings. Hence, care is highly variable and potentially often non-optimal. These conditions create a situation that could benefit greatly from an engineered approach. The overall goal is a review of ventilation that is accessible to both clinicians and engineers, to bridge the divide between the two fields and enable collaboration to improve patient care and outcomes. This review does not take the form of a typical systematic review. Instead, it defines the standard terminology and introduces key clinical and biomedical measurements before introducing the key clinical studies and their influence in clinical practice which in turn flows into the needs and requirements around how biomedical engineering research can play a role in improving care. Given the significant clinical research to date and its impact on this complex area of care, this review thus provides a tutorial introduction around the review of the state of the art relevant to a biomedical engineering perspective.

Discussion

This review presents the significant clinical aspects and variables of ventilation management, the potential risks associated with suboptimal ventilation management, and a review of the major recent attempts to improve ventilation in the context of these variables. The unique aspect of this review is a focus on these key elements relevant to engineering new approaches. In particular, the need for ventilation strategies which consider, and directly account for, the significant differences in patient condition, disease etiology, and progression within patients is demonstrated with the subsequent requirement for optimal ventilation strategies to titrate for patient- and time-specific conditions.

Conclusion

Engineered, protective lung strategies that can directly account for and manage inter- and intra-patient variability thus offer great potential to improve both individual care, as well as cohort clinical outcomes.

Mild to Moderate to Severe: What Drives the Severity of ARDS in Trauma Patients?

Acute respiratory distress syndrome (ARDS) is a complex inflammatory process with multifactorial etiologies. Risk factors for its development have been extensively studied, but factors associated with worsening severity of disease, as defined by the Berlin criteria, are poorly understood. A retrospective chart and trauma registry review identified trauma patients in our surgical intensive care unit who developed ARDS, defined according to the Berlin definition, between 2010 and 2015. The primary outcome was development of mild, moderate, or severe ARDS. A logistic regression model identified risk factors associated with developing ARDS and with worsening severity of disease. Of 2704 total patients, 432 (16%) developed ARDS. Of those, 100 (23%) were categorized as mild, 176 (41%) as moderate, and 156 (36%) as severe. Two thousand two hundred and seventy-two patients who did not develop ARDS served as controls. Male gender, blunt trauma, severe head and chest injuries, and red blood cell as well as total blood product transfusions are independent risk factors associated with ARDS. Worsening severity of disease is associated with severe chest trauma and volume of plasma transfusion. Novel findings in our study include the association between plasma transfusions and specifically severe chest trauma with worsening severity of ARDS in trauma patients.

Knockdown of TNF‑α alleviates acute lung injury in rats with intestinal ischemia and reperfusion injury by upregulating IL‑10 expression

Intestinal ischemia and reperfusion (II/R) injury often triggers severe injury in remote organs, with the lungs being considered the main target. Excessive elevation of proinflammatory cytokines is a major contributor in the occurrence and development of II/R-induced acute lung injury (ALI). Therefore, the present study aimed to investigate whether blocking tumor necrosis factor-α (TNF-α) expression could protect the lungs from injury following II/R, and to explore the possible underlying mechanism involving interleukin-10 (IL-10). Briefly, II/R was induced in rats by 40 min occlusion of the superior mesenteric artery and celiac artery, followed by 8, 16 or 24 h of reperfusion. Subsequently, lentiviral vectors containing TNF-α short hairpin (sh)RNA were injected into the right lung tissues, in order to induce TNF-α knockdown. The severity of ALI was determined according to lung injury scores and lung edema (lung wet/dry weight ratio). The expression levels of TNF-α were analyzed by quantitative polymerase chain reaction (qPCR), western blotting and immunofluorescence (IF) staining. IL-10 expression, in response to TNF-α knockdown, was detected in lung tissues by qPCR and IF. The results detected marked inflammatory responses, and increased levels of lung wet/dry weight ratio and TNF-α expression, in the lungs of II/R rats. Conversely, treatment with TNF-α shRNA significantly alleviated the severity of ALI and upregulated the expression levels of IL-10 in lung tissues. These findings suggested that TNF-α RNA interference may exert a protective effect on II/R-induced ALI via the upregulation of IL-10. Therefore, TNF-α knockdown may be considered a potential strategy for the prevention or treatment of ALI induced by II/R in future clinical trials.

Effects of Prone Position and Positive End-Expiratory Pressure on Noninvasive Estimators of ICP: A Pilot Study

BACKGROUND

Prone positioning and positive end-expiratory pressure can improve pulmonary gas exchange and respiratory mechanics. However, they may be associated with the development of intracranial hypertension. Intracranial pressure (ICP) can be noninvasively estimated from the sonographic measurement of the optic nerve sheath diameter (ONSD) and from the transcranial Doppler analysis of the pulsatility (ICPPI) and the diastolic component (ICPFVd) of the velocity waveform.

METHODS

The effect of the prone positioning and positive end-expiratory pressure on ONSD, ICPFVd, and ICPPI was assessed in a prospective study of 30 patients undergoing spine surgery. One-way repeated measures analysis of variance, fixed-effect multivariate regression models, and receiver operating characteristic analyses were used to analyze numerical data.

RESULTS

The mean values of ONSD, ICPFVd, and ICPPI significantly increased after change from supine to prone position. Receiver operating characteristic analyses demonstrated that, among the noninvasive methods, the mean ONSD measure had the greatest area under the curve signifying it is the most effective in distinguishing a hypothetical change in ICP between supine and prone positioning (0.86±0.034 [0.79 to 0.92]). A cutoff of 0.43 cm was found to be a best separator of ONSD value between supine and prone with a specificity of 75.0 and a sensitivity of 86.7.

CONCLUSIONS

Noninvasive ICP estimation may be useful in patients at risk of developing intracranial hypertension who require prone positioning.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016)

BACKGROUND AND PURPOSE

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in February 2017 and published in the Journal of JSICM, [2017; Volume 24 (supplement 2)] 10.3918/jsicm.24S0001 and Journal of Japanese Association for Acute Medicine [2017; Volume 28, (supplement 1)] http://onlinelibrary.wiley.com/doi/10.1002/jja2.2017.28.issue-S1/issuetoc.This abridged English edition of the J-SSCG 2016 was produced with permission from the Japanese Association of Acute Medicine and the Japanese Society for Intensive Care Medicine.

METHODS

Members of the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine were selected and organized into 19 committee members and 52 working group members. The guidelines were prepared in accordance with the Medical Information Network Distribution Service (Minds) creation procedures. The Academic Guidelines Promotion Team was organized to oversee and provide academic support to the respective activities allocated to each Guideline Creation Team. To improve quality assurance and workflow transparency, a mutual peer review system was established, and discussions within each team were open to the public. Public comments were collected once after the initial formulation of a clinical question (CQ) and twice during the review of the final draft. Recommendations were determined to have been adopted after obtaining support from a two-thirds (> 66.6%) majority vote of each of the 19 committee members.

RESULTS

A total of 87 CQs were selected among 19 clinical areas, including pediatric topics and several other important areas not covered in the first edition of the Japanese guidelines (J-SSCG 2012). The approval rate obtained through committee voting, in addition to ratings of the strengths of the recommendation, and its supporting evidence were also added to each recommendation statement. We conducted meta-analyses for 29 CQs. Thirty-seven CQs contained recommendations in the form of an expert consensus due to insufficient evidence. No recommendations were provided for five CQs.

CONCLUSIONS

Based on the evidence gathered, we were able to formulate Japanese-specific clinical practice guidelines that are tailored to the Japanese context in a highly transparent manner. These guidelines can easily be used not only by specialists, but also by non-specialists, general clinicians, nurses, pharmacists, clinical engineers, and other healthcare professionals.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016)

Background and Purpose

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2016 (J-SSCG 2016), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in February 2017 in Japanese. An English-language version of these guidelines was created based on the contents of the original Japanese-language version.

Methods

Members of the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine were selected and organized into 19 committee members and 52 working group members. The guidelines were prepared in accordance with the Medical Information Network Distribution Service (Minds) creation procedures. The Academic Guidelines Promotion Team was organized to oversee and provide academic support to the respective activities allocated to each Guideline Creation Team. To improve quality assurance and workflow transparency, a mutual peer review system was established, and discussions within each team were open to the public. Public comments were collected once after the initial formulation of a clinical question (CQ), and twice during the review of the final draft. Recommendations were determined to have been adopted after obtaining support from a two-thirds (>66.6%) majority vote of each of the 19 committee members.

Results

A total of 87 CQs were selected among 19 clinical areas, including pediatric topics and several other important areas not covered in the first edition of the Japanese guidelines (J-SSCG 2012). The approval rate obtained through committee voting, in addition to ratings of the strengths of the recommendation and its supporting evidence were also added to each recommendation statement. We conducted meta-analyses for 29 CQs. Thirty seven CQs contained recommendations in the form of an expert consensus due to insufficient evidence. No recommendations were provided for 5 CQs.

Conclusions

Based on the evidence gathered, we were able to formulate Japanese-specific clinical practice guidelines that are tailored to the Japanese context in a highly transparent manner. These guidelines can easily be used not only by specialists, but also by non-specialists, general clinicians, nurses, pharmacists, clinical engineers, and other healthcare professionals.

Early and late pulmonary effects of nebulized LPS in mice: An acute lung injury model

Background and objective

Acute respiratory distress syndrome (ARDS) has a high mortality rate of 35–46% depending on its severity. Animal models are crucial to better understand the pathophysiology of diseases, including ARDS. This study presents a feasible animal model of acute lung injury (ALI) using nebulized lipopolysaccharide (LPS) in a non-invasive approach, focusing on its short and long-term effects.

Methods

Mice received nebulized LPS or vehicle only (control group). Blood, BALF and lung tissue were collected 24 hours (LPS 24h) or 5 weeks (LPS 5w) after the nebulized LPS-induced lung injury. Inflammatory cytokines were assessed in the blood serum, BALF and lung tissue. Stereological analyses and remodeling changes were assessed by histology and immunohistochemistry at the specified time points.

Results

The LPS 24h group showed increased pro-inflammatory cytokine levels, intense cell influx, increased total septal volume, septal thickening and decreased surface density of the alveolar septa. The LPS 5w group showed persistent lung inflammation, septal thickening, increased total lung volume, accentuated collagen deposition, especially of collagen type I, and decreased MMP-2 protein expression.

Conclusion

We present a feasible, reproducible and non-invasive nebulized-LPS animal model that allows the assessment of both the acute and late phases of acute lung injury. The presence of lung remodeling with collagen deposition after 5 weeks makes it useful to study the pathophysiology, complications, and possible therapeutic intervention studies that aim to understand and reduce pulmonary fibrosis in the late phases of ALI.

Geraniol alleviates LPS-induced acute lung injury in mice via inhibiting inflammation and apoptosis

Geraniol (GOH), a special type of acyclic monoterpene alcohol, has been widely used to treat many diseases associated with inflammation and apoptosis. Acute lung injury (ALI) is a common clinical disease in humans characterized by pulmonary inflammation and apoptosis. In the present study, we investigated the protective effects of GOH in a mouse model of ALI induced by the intranasal administration of lipopolysaccharide (LPS) and elucidated the underlying molecular mechanisms in RAW 264.7 cells. In vivo, GOH treatment markedly ameliorated pathological injury and pulmonary cell apoptosis and reduced the wet/dry (W/D) weight ratio of lungs, myeloperoxidase (MPO) activity and the production of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α). In vitro, the levels of pro-inflammatory cytokines, iNOS and COX-2 were significantly increased in LPS-stimulated RAW 264.7 cells, an effect that was decreased by GOH treatment. Moreover, GOH treatment dramatically reduced the expression of Toll-like receptor 4 (TLR4) and then prevented the nuclear factor-κB (NF-κB) activation. GOH treatment also promoted anti-apoptotic Bcl-2 expression and inhibited pro-apoptotic Bax and Caspase-3 expression. Furthermore, knockdown of TLR4 expression exerted a similar effect and inhibited the phosphorylation of p65, as well as the Bax and Caspase-3 expression. Taken together, these results suggest that GOH treatment alleviates LPS-induced ALI via inhibiting pulmonary inflammation and apoptosis, a finding that might be associated with the inhibition of TLR4-mediated NF-κB and Bcl-2/Bax signalling pathways.

Inhaled AP301 for treatment of pulmonary edema in mechanically ventilated patients with acute respiratory distress syndrome: a phase IIa randomized placebo-controlled trial

Background

High-permeability pulmonary edema is a hallmark of acute respiratory distress syndrome (ARDS) and is frequently accompanied by impaired alveolar fluid clearance (AFC). AP301 enhances AFC by activating epithelial sodium channels (ENaCs) on alveolar epithelial cells, and we investigated its effect on extravascular lung water index (EVLWI) in mechanically ventilated patients with ARDS.

Methods

Forty adult mechanically ventilated patients with ARDS were included in a randomized, double-blind, placebo-controlled trial for proof of concept. Patients were treated with inhaled AP301 (n = 20) or placebo (0.9% NaCl; n = 20) twice daily for 7 days. EVLWI was measured by thermodilution (PiCCO®), and treatment groups were compared using the nonparametric Mann–Whitney U test.

Results

AP301 inhalation was well tolerated. No differences in mean baseline-adjusted change in EVLWI from screening to day 7 were found between the AP301 and placebo group (p = 0.196). There was no difference in the PaO₂/FiO₂ ratio, ventilation pressures, Murray lung injury score, or 28-day mortality between the treatment groups. An exploratory subgroup analysis according to severity of illness showed reductions in EVLWI (p = 0.04) and ventilation pressures (p < 0.05) over 7 days in patients with initial sequential organ failure assessment (SOFA) scores ≥11 inhaling AP301 versus placebo, but not in patients with SOFA scores ≤10.

Conclusions

There was no difference in mean baseline-adjusted EVLWI between the AP301 and placebo group. An exploratory post-hoc subgroup analysis indicated reduced EVLWI in patients with SOFA scores ≥11 receiving AP301. These results suggest further confirmation in future clinical trials of inhaled AP301 for treatment of pulmonary edema in patients with ARDS.

Trial registration

The study was prospectively registered at clinicaltrials.gov, NCT01627613. Registered 20 June 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1795-x) contains supplementary material, which is available to authorized users.

Deficiency in cold-inducible RNA-binding protein attenuates acute respiratory distress syndrome induced by intestinal ischemia-reperfusion

BACKGROUND

Intestinal ischemia-reperfusion can occur in shock and mesenteric occlusive diseases, causing significant morbidity and mortality. Aside from local injury, intestinal ischemia-reperfusion can result in remote organ damage, particularly in the lungs. Cold-inducible RNA-binding protein (CIRP) was identified as a novel inflammatory mediator. We hypothesized that a deficiency in CIRP would protect the lungs during intestinal ischemia-reperfusion injury.

METHODS

Intestinal ischemia was induced in adult male C57BL/6 wild-type and CIRP knock-out (CIRP^-/-) mice via clamping of the superior mesenteric artery for 60 minutes. Reperfusion was allowed for 4 hours or 20 hours, and blood, gut, and lung tissues were harvested for various analyses.

RESULTS

After intestinal ischemia-reperfusion, the elevated levels of serum lactate dehydrogenase and inflammatory cytokine interleukin-6 were reduced by 68% and 98%, respectively, at 20 hours after ischemia-reperfusion in CIRP^-/- mice compared with the wild-type mice. In the gut, mRNA levels of inflammatory cytokine interleukin-6 were reduced by 67% at 4 hours after ischemia-reperfusion in CIRP^-/- mice. In the lungs, inflammatory cytokine interleukin-6 protein and myeloperoxidase activity were reduced by 78% and 26% at 20 hours and 4 hours after ischemia-reperfusion, respectively, in CIRP^-/- mice. Finally, the elevated lung caspase-3 was significantly decreased by 55%, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells decreased by 91%, and lung injury score decreased by 37% in CIRP^-/- mice at 20 hours after ischemia-reperfusion.

CONCLUSION

Increased levels of proinflammatory cytokines, myeloperoxidase, and apoptosis are the hallmarks of acute respiratory distress syndrome. We noticed after intestinal ischemia-reperfusion the proinflammatory milieu in lungs was elevated significantly, while the CIRP^-/- mice had significantly decreased levels of proinflammatory cytokine, myeloperoxidase, and apoptotic cells leading to decreased lung injury. These findings strongly established a causal link between CIRP and acute respiratory distress syndrome during intestinal ischemia-reperfusion injuries. Targeting CIRP may therefore be beneficial for treatment of intestinal ischemia-reperfusion-associated acute respiratory distress syndrome acute respiratory distress syndrome.

The negative effect of initial high-dose methylprednisolone and tapering regimen for acute respiratory distress syndrome: a retrospective propensity matched cohort study

Background

The efficacy of corticosteroid use in acute respiratory distress syndrome (ARDS) remains controversial. Generally, short-term high-dose corticosteroid therapy is considered to be ineffective in ARDS. On the other hand, low-dose, long-term use of corticosteroids has been reported to be effective since they provide continued inhibition of the systemic inflammatory response syndrome (SIRS) that accompanies ARDS. Thus far, no reports have been published on the efficacy of initiating treatment with a high-dose corticosteroid regimen with tapering.

Methods

We conducted a retrospective observational study involving 186 patients treated at a teaching hospital (68% had sepsis, pneumonia, or aspiration pneumonia). ARDS was diagnosed according to the Berlin definition. Patients were divided into a high-dose (n = 21) or low-dose corticosteroid group (n = 165) to compare the effectiveness of a down-titration regimen. The primary medical team chose which treatment a patient would receive. We were careful to conduct a differential diagnosis of interstitial pneumonia (e.g., acute eosinophilic pneumonia) since corticosteroid treatment has been proven effective in that patient population. The primary outcome was the 60-day mortality rate. The secondary outcome was the number of ventilator-free days (VFD).

Results

Those started on a high-dose regimen had a significantly higher 60-day mortality rate (P = 0.031) with significantly fewer VFD (P = 0.021). Propensity scores were used to adjust patient backgrounds in a variable analysis that also showed the high-dose regimen was a factor in decreasing VFD (OR, 95.63; 95% CI, 1.74–5271.07; P = 0.026) and worsening the 60-day mortality rate (OR, 2.54; 95% CI, 0.92–7.02; P = 0.072).

Conclusions

A tapering regimen after high-dose corticosteroids is likely to increase ventilator dependency and might aggravate the prognosis of patients with ARDS diagnosed according to the Berlin definition.

Prone Positioning of Patients With Acute Respiratory Distress Syndrome

Effectively treating critically ill patients with acute respiratory distress syndrome (ARDS) is a challenge for many intensive care nurses. Multiple disease processes and injuries contribute to the complexity of ARDS and often complicate therapy. As a means of supportive care for ARDS, practitioners resort to rescue therapies to improve oxygenation and salvage the patient. The pathophysiology of ARDS and the use of prone positioning to improve pulmonary ventilation and oxygenation in ARDS patients are described. Educating nursing and medical staff on the use of prone positioning allows ease of patient placement with an emphasis on safety of both patients and staff. Scrupulous assessment of patients coupled with judicious timing of prone positioning expedites weaning from ventilatory support and contributes to positive outcomes for patients.

The Use of Specialized Enteral Formulas in Pulmonary Disease

The relationship between pulmonary disease and nutrition is significant. Malnutrition and its associated adverse pulmonary effects can directly affect outcomes in the individual with pulmonary disease. The use of nutrition support is common for these patients as a supportive or therapeutic measure. Historical reports of adverse respiratory function associated with high parenteral carbohydrate intakes have led to the controversial use of high-fat enteral products in patients with chronic pulmonary dysfunction. The rationale for using this type of formula is that by providing less carbohydrates, carbon dioxide production will be reduced, respiratory quotient will therefore decrease, and a favorable respiratory outcome will result. In the patient with acute respiratory distress syndrome, an inflammatory state exists in which proinflammatory mediators are produced and affect the course of the disease. An enteral formula with modified lipids designed to modulate eicosanoid production and therefore influence the inflammatory cascade is available. This article reviews the rationale for use of modified enteral formulas in both chronic and acute pulmonary disease, reviews the available studies evaluating the efficacy of these formulas, and provides overall recommendations for the use of specialized enteral formulas in individuals with pulmonary disease.

Dephosphorylation of Y685-VE-Cadherin Involved in Pulmonary Microvascular Endothelial Barrier Injury Induced by Angiotensin II

Angiotensin II (AngII) caused pulmonary microvascular endothelial barrier injury, which induced acute aortic dissection (AAD) combined with acute lung injury (ALI). However, the exact mechanism is unclear. We investigated the role of dephosphorylation of Y685-VE-cadherin in the AngII induced pulmonary microvascular endothelial barrier injury. Mice or pulmonary microvascular endothelial cells (PMVECs) were divided into control group, AngII group, AngII+PP2 (Src kinase inhibitor) group, and PP2 group. PP2 was used to inhibit the phosphorylation of Y685-VE-cadherin. Pathological changes, infiltration of macrophages and neutrophils, and pulmonary microvascular permeability were used to determine the pulmonary microvascular endothelial barrier function. Flow cytometry was used to determine the apoptosis of PMVECs, and immunofluorescence was used to determine the skeletal arrangement. Transendothelial resistance was used to detect the permeability of endothelial barrier. Phosphorylation of Y685-VE-cadherin was significantly reduced after AngII stimulation (P < 0.05), together with skeletal rearrangement, and elevation of endothelial permeability which finally induced endothelial barrier injury. After PP2 interference, the phosphorylation of Y685-VE-cadherin was further reduced and the endothelial permeability was further elevated. These data indicated that AngII could induce pulmonary injury by triggering endothelial barrier injury, and such process may be related to the dephosphorylation of Y685-VE-cadherin and the endothelial skeletal rearrangement.

Rapid Reduction of Oxygenation Index by Employment of a Recruitment Technique in Patients with Severe ARDS

Mechanical ventilation of patients with acute respiratory distress syndrome (ARDS) may contribute to pulmonary injury and systemic inflammation. The objective of this study was to examine the safety and efficacy of a recruitment maneuver that rapidly improves atelectasis and oxygenation, and in so doing may reduce the potential for ventilator-induced lung injury. Nineteen patients with severe ARDS (defined as PaO2: FiO2 ≤ 150) from diverse etiologies were turned prone and a positive pressure of 40 cmH2O was applied for a period of 90 seconds. This pressure was increased in 5 cmH2O increments in subsequent maneuvers to a maximum of 50 cmH2O if there was an inadequate initial response. Subsequently pressure-limited mechanical ventilation with a PEEP of 15 cmH2O was instituted to prevent derecruitment. Peak pressures were maintained at ≤35 cmH2O. Outcome measures were oxygenation index, PaO2: FiO2 ratio, and alveolar-arterial oxygen difference. The oxygenation index decreased from a median of 31 cmH2O/mmHg to 14 cmH2O/mmHg immediately after recruitment and to 11 cmH2O/mmHg (p < 0.0001) 24 hours later. The A-aDO2 improved from 454 mmHg to 128 mmHg (p < 0.0001) and the PaO2:FiO2 ratio from 75 to 218 (p < 0.0001) 24 hours later. Twenty-five percent of patients had PaO2:FiO2 ratios of more than 300 mmHg at 24 hours. Mean airway pressure increased by 3 cmH2O initially, from 23 cmH2O to 26 cmH2O as a consequence of the increase in PEEP, but this had decreased to 25 cmH2O after 24 hours. There were no significant complications. Rapid reductions in FiO2 can be achieved safely by the implementation of a relatively simple recruitment technique.

Direct hemoperfusion with polymyxin B-immobilized fiber improves shock and hypoxemia during endotoxemia in anesthetized sheep

This study evaluates the effect of direct hemoperfusion (DHP) using polymyxin B-immobilized fibers (PMX-F) as an extracorporeal blood filter on systemic hypotension and lung injury during endotoxemia. Sheep were anesthetized, intubated, mechanically ventilated with 50% oxygen and connected to the DHP system between the right femoral artery and left jugular vein. Group 1 ( n = 6) sheep were infused with 10 μg/kg Escherichia coli endotoxin over a 30 min period. At the same time, sheep underwent DHP with PMX-F (Toraymyxin®: PMX-20R) for 2 h at a flow rate of 60 ml/h. Group 2 ( n = 6) sheep were infused with the same dose of endotoxin and treated with a sham column, in the same manner as those in group 1. DHP with PMX-F significantly improved and restored systemic pressure and arterial oxygen tension in group 1 sheep, although these values never returned to the baseline levels of group 2 sheep. Pulmonary hypertension and leukocytopenia were observed after endotoxin infusion in both groups, but there were no significant differences between these values. DHP with PMX-F significantly decreased the elevation of plasma nitric oxide products. The treatment with PMX-F improves shock and deteriorated oxygenation during endotoxemia, probably through the suppression of nitric oxide production.

Radiologic, Neurologic and Cardiopulmonary Aspects of Submersion Injury

Many indices and scores are used in critical care medicine to aid management and predict risk of mortality. We report 2 cases of submersion injury and discuss the usefulness and application of common respiratory and critical care indices. The respiratory indices help better understand the pulmonary pathophysiology and characterize the severity of lung injury and ventilation/perfusion mismatch. Severe lung injury resolved after ventilation support with appropriate positive end-expiratory pressure in both cases. The 6-year-old girl survived the near-fatal submersion injury intact despite grossly abnormal initial Glasgow Coma Scale (GCS) and high Pediatric Index of Mortality 2 scores, whereas the 5-year-old boy with grossly abnormal GCS and Pediatric Index of Mortality 2 scores died despite resolution of lung injury. These cases illustrate that resuscitation should be promptly instituted at the scene to ensure optimal outcome because initial pulmonology and neurology indices may not reliably predict mortality or intact survival. The GCS score was not initially designed for prognostication. Nevertheless, 2 serial GCS scores of 3, one performed at emergency department and one at the pediatric intensive care unit, were associated with nonsurvival in our second patient.

Lung Protective Ventilation Strategies

While traditional ventilation approaches are appropriate for the patient without significant lung disease and only requiring short-term mechanical ventilatory support, the strategy should be altered for the patient with severe lung disease. Research on the mechanisms of ventilator-induced lung injury has led to the development of mechanical ventilation strategies that imrove patient outcomes. The trend toward using lower tidal volmes, limited airway pressures, and PEEP have produced imroved outcome results. Predictive indices of outcome using laboratory values, biologic markers, and mediators of lung inury are being evaluated for early identification of patients at risk for lung injury. Nonconventional ventilatory approaches, such as noninvasive positive pressure ventilation and high freuency ventilation, as well as adjunctive therapies (inhaled niric oxide and extracorporeal circulation) are being explored as alternatives in ARDS and ALI. While more clinical studies outine outcomes in specific subgroups of patients, the ventilatoy strategy should continually be revised at the bedside.

Pediatric Acute Hypoxemic Respiratory Failure: Management of Oxygenation

Acute hypoxemic respiratory failure (AHRF) is one of the hallmarks of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which are caused by an inflammatory process initiated by any of a number of potential systemic and/or pulmonary insults that result in heterogeneous disruption of the capillary-pithelial interface. In these critically sick patients, optimizing the management of oxygenation is crucial. Physicians managing pediatric patients with ALI or ARDS are faced with a complex array of options influencing oxygenation. Certain treatment strategies can influence clinical outcomes, such as a lung protective ventilation strategy that specifies a low tidal volume (6 mL/kg) and a plateau pressure limit (30 cm H2O). Other strategies such as different levels of positive end expiratory pressure, altered inspiration to expiration time ratios, recruitment maneuvers, prone positioning, and extraneous gases or drugs may also affect clinical outcomes. This article reviews state-of-the-art strategies on the management of oxygenation in acute hypoxemic respiratory failure in children.

The systemic inflammatory response syndrome

The systemic inflammatory response syndrome (SIRS) describes the clinical presentation of patients with systemic activation of the inflammatory response from any underlying cause. SIRS is a common problem in acute medical and surgical practice and an important cause of morbidity and mortality. As a consequence of SIRS, patients may develop multiple organ dysfunction syndrome and acute respiratory distress syndrome (ARDS). Over the recent years our understanding of the inflammatory response in SIRS has increased, but as yet specific immunomodulatory therapies have not proved useful. The mainstay of treatment for patients with SIRS and ARDS remains a general supportive care. It is in this area that more encouraging advances are being made, particularly in the management of invasive ventilation and nutrition. In this review we summarize the definitions, epidemiology and pathophysiology of SIRS, ARDS and related conditions. We then give a description of the clinical consequences and treatment of SIRS and ARDS with an emphasis on current aspects of supportive care.

High-frequency oscillatory ventilation versus conventional ventilation for acute respiratory distress syndrome

BACKGROUND

High-frequency oscillation (HFO) is an alternative to conventional mechanical ventilation that is sometimes used to treat people with acute respiratory distress syndrome, but effects on oxygenation, mortality and adverse clinical outcomes are uncertain. This review was originally published in 2004 and was updated in 2013 and again in 2015.

OBJECTIVES

To determine the effects of HFO compared to conventional mechanical ventilation on physiological outcomes, clinical outcomes, and mortality when used for the treatment of acute respiratory distress syndrome (ARDS).

SEARCH METHODS

We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Ovid), MEDLINE (Ovid), EMBASE (Ovid), and ISI, from inception to December 2015. We conducted the original search in 2002. We manually searched reference lists from included studies and review articles; searched conference proceedings of the American Thoracic Society (1994 to 2015), Society of Critical Care Medicine (1994 to 2015), European Society of Intensive Care Medicine (1994 to 2015), and American College of Chest Physicians (1994 to 2015); contacted clinical experts in the field; and searched for unpublished and ongoing trials in clinicaltrials.gov and controlled-trials.com.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing treatment using HFO with conventional mechanical ventilation for children and adults diagnosed with ARDS.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data on clinical, physiological, and safety outcomes according to a predefined protocol. We contacted investigators of all included studies to clarify methods and obtain additional data. We used random-effects models in the analyses.

MAIN RESULTS

We include 10 RCTs (n = 1850); almost all participants had moderate or severe ARDS. For the primary analysis, the risk of bias was low in three studies and unclear in five studies; the overall quality of evidence was very low due to imprecision, inconsistency, indirectness and methodologic limitations. In participants randomized to HFO, there was no significant difference in hospital or 30-day mortality (risk ratio (RR) 0.92, 95% confidence interval (CI) 0.72 to 1.16; P = 0.46, I² = 66%; 8 trials, 1779 participants, 807 deaths) compared with conventional ventilation. One large multicentre RCT was terminated early because of increased mortality in participants randomized to HFO compared to mechanical ventilation with low tidal volume and high positive end expiratory pressure, with HFO reserved only as a rescue therapy. We found substantial between-trial statistical heterogeneity (I² = 0% to 66%) for clinical outcomes, including mortality. 

AUTHORS' CONCLUSIONS

The findings of this systematic review suggest that HFO does not reduce hospital and 30-day mortality due to ARDS; the quality of evidence was very low. Our findings do not support the use of HFO as a first-line strategy in people undergoing mechanical ventilation for ARDS.

Transforming growth factor-beta 1 in humidifier disinfectant-associated children's interstitial lung disease

BACKGROUND

Humidifier disinfectant-associated children's interstitial lung disease has an unpredictable clinical course with a high morbidity and mortality.

OBJECTIVES

To evaluate the differences in clinical findings between survivors and non-survivors of humidifier disinfectant-associated children's interstitial lung disease. To evaluate dynamic changes in serum cytokines related to inflammation and fibrosis in lung injury, and to determine whether these changes are predictive of survival in this disease.

METHODS

We evaluated 17 children with humidifier disinfectant-associated children's interstitial lung disease, from whom serum samples were obtained weekly during hospitalization. The severity of chest tomographic and lung pathologic findings was scored. Levels of several cytokines were measured in the serial serum samples.

RESULTS

Seven of the 17 children were survivors. Compared to survivors, non-survivors had greater ground-glass attenuation on follow-up chest tomography, higher admission neutrophil counts, and more macrophages on pathologic findings. Transforming growth factor-beta 1 persisted at an elevated level (1,000-1,500 pg/ml) in survivors, whereas it decreased abruptly in non-survivors. At the time of this decrease, non-survivors had clinical worsening of their respiratory failure. Transforming growth factor-beta 1 was positively correlated with PaO2 /FiO2 (r = 0.481, P < 0.0001).

CONCLUSIONS

Non-survivors exhibited more inflammatory clinical findings than survivors. Transforming growth factor-beta 1 remained elevated in survivors, suggesting that it affected the clinical course of humidifier disinfectant-associated children's interstitial lung disease. The prognosis of this lung disease may depend more on controlling excessive inflammation and repairing damaged lung than on fibrosis, and transforming growth factor-beta 1 may play a key role in this process.

Progress and perspectives in pediatric acute respiratory distress syndrome

Acute respiratory distress syndrome is a disease of acute onset characterized by hypoxemia and infiltrates on chest radiographs that affects both adults and children of all ages. It is an important cause of respiratory failure in pediatric intensive care units and is associated with significant morbidity and mortality. Nevertheless, until recently, the definitions and diagnostic criteria for acute respiratory distress syndrome have focused on the adult population. In this article, we review the evolution of the definition of acute respiratory distress syndrome over nearly five decades, with a special focus on the new pediatric definition. We also discuss recommendations for the implementation of mechanical ventilation strategies in the treatment of acute respiratory distress syndrome in children and the use of adjuvant therapies.

Feasibility of titrating PEEP to minimum elastance for mechanically ventilated patients

Background

Selecting positive end-expiratory pressure (PEEP) during mechanical ventilation is important, as it can influence disease progression and outcome of acute respiratory distress syndrome (ARDS) patients. However, there are no well-established methods for optimizing PEEP selection due to the heterogeneity of ARDS. This research investigates the viability of titrating PEEP to minimum elastance for mechanically ventilated ARDS patients.

Methods

Ten mechanically ventilated ARDS patients from the Christchurch Hospital Intensive Care Unit were included in this study. Each patient underwent a stepwise PEEP recruitment manoeuvre. Airway pressure and flow data were recorded using a pneumotachometer. Patient-specific respiratory elastance (E_rs) and dynamic functional residual capacity (dFRC) at each PEEP level were calculated and compared. Optimal PEEP for each patient was identified by finding the minima of the PEEP-E_rs profile.

Results

Median E_rs and dFRC over all patients and PEEP values were 32.2 cmH₂O/l [interquartile range (IQR) 25.0–45.9] and 0.42 l [IQR 0.11–0.87]. These wide ranges reflect patient heterogeneity and variable response to PEEP. The level of PEEP associated with minimum E_rs corresponds to a high change of functional residual capacity, representing the balance between recruitment and minimizing the risk of overdistension.

Conclusions

Monitoring patient-specific E_rs can provide clinical insight to patient-specific condition and response to PEEP settings. The level of PEEP associated with minimum-E_rs can be identified for each patient using a stepwise PEEP recruitment manoeuvre. This ‘minimum elastance PEEP’ may represent a patient-specific optimal setting during mechanical ventilation.

Trial registration

Australian New Zealand Clinical Trials Registry: ACTRN12611001179921.

Electronic supplementary material

The online version of this article (doi:10.1186/s40814-015-0006-2) contains supplementary material, which is available to authorized users.

Impact of Corticosteroids on Mortality in Patients with Acute Respiratory Distress Syndrome: A Systematic Review and Meta-analysis

OBJECTIVE

The impact of corticosteroids on acute respiratory distress syndrome (ARDS) mortality remains controversial following the publication of numerous trials, observational studies and meta-analyses. An updated meta-analysis is warranted, as a few original studies on this topic have been published since the last meta-analysis.

METHODS

We searched for eligible articles using four databases. In particular, we included full-length original articles providing sufficient data for evaluating the impact of corticosteroid treatment on adult ARDS mortality in the form of odds ratios. A fixed model with the confidence interval method was used. An assessment of publication bias and sensitivity analyses were also conducted.

RESULTS

We included 11 of 185 articles. The pooled odds ratio for corticosteroids with respect to all-cause mortality involving 949 patients was 0.77 [95% confidence interval (CI): 0.58-1.03, p=0.079] with strong heterogeneity(I2=70%, p<0.001). The results of the sensitivity analysis, Begg-Kendall test (τ=0.53, p=0.024)and funnel plot consistently suggested the existence of strong publication bias. After six potentially unpublished cohorts were filled using Duval's trim and fill method, the pooled odds ratio shifted to 1.11 (95% CI0.86-1.44, p=0.427). In addition, the sensitivity analyses suggested that corticosteroid treatment has a different impact on mortality depending on the comorbidities and trigger events.

CONCLUSION

We were unable to confirm, based on the data of published studies, the favorable impact of corticosteroid therapy on mortality in overall ARDS cases. Published articles exhibit strong publication bias,and previous meta-analyses may be affected by this publication bias. Further research focusing on pathophysiology- or trigger event-specific ARDS is anticipated.

The use of paralytics in patients with acute respiratory distress syndrome

Interest in the role of neuromuscular blocking agents (NMBAs) in the treatment of acute respiratory distress syndrome (ARDS) has been renewed since a recent randomized clinical trial showed a reduction in mortality associated with the use of NMBAs. However, the role of paralytics in a protective mechanical ventilation strategy should be detailed. This review summarizes data in the literature concerning the clinical effects of NMBAs on the outcome of patients with ARDS, in an attempt to explain some pathophysiologic hypotheses concerning their action and to integrate them into the overall management strategy for the mechanical ventilation of ARDS patients.

Beyond low tidal volumes: ventilating the patient with acute respiratory distress syndrome

The cornerstone of lung protective ventilation in patients with acute respiratory distress syndrome (ARDS) is a pressure- and volume-limited strategy. Other interventions have also been investigated. Although no method for positive end-expiratory pressure (PEEP) titration has proven most advantageous, experimental and clinical data support the use of higher PEEP in patients with moderate/severe ARDS. There is no benefit to the early use of high-frequency oscillatory ventilation (HFOV) in patients with moderate/severe ARDS, although it may be considered as rescue therapy. Further investigations of novel methods of bedside monitoring of mechanical ventilation may help identify the optimal ventilatory strategy.

Centers for disease control and prevention expert panel meetings on prevention and treatment of anthrax in adults

The Centers for Disease Control and Prevention convened panels of anthrax experts to review and update guidelines for anthrax postexposure prophylaxis and treatment. The panels included civilian and military anthrax experts and clinicians with experience treating anthrax patients. Specialties represented included internal medicine, pediatrics, obstetrics, infectious disease, emergency medicine, critical care, pulmonology, hematology, and nephrology. Panelists discussed recent patients with systemic anthrax; reviews of published, unpublished, and proprietary data regarding antimicrobial drugs and anthrax antitoxins; and critical care measures of potential benefit to patients with anthrax. This article updates antimicrobial postexposure prophylaxis and antimicrobial and antitoxin treatment options and describes potentially beneficial critical care measures for persons with anthrax, including clinical procedures for infected nonpregnant adults. Changes from previous guidelines include an expanded discussion of critical care and clinical procedures and additional antimicrobial choices, including preferred antimicrobial drug treatment for possible anthrax meningitis.