Epidemiology and outcome of acute lung injury in European intensive care units. Results from the ALIVE study

Comparison of community-acquired, hospital-acquired, and intensive care unit-acquired acute respiratory distress syndrome: a prospective observational cohort study

Introduction

Acute respiratory distress syndrome (ARDS) is a syndrome characterized by diffuse pulmonary edema and severe hypoxemia that usually occurs after an injury such as sepsis, aspiration and pneumonia. Little is known about the relation between the setting where the syndrome developed and outcomes in ARDS patients.

Methods

This is a 1-year prospective observational study conducted at a tertiary referred hospital. ARDS was defined by the Berlin criteria. Community-acquired ARDS, hospital-acquired ARDS and intensive care unit (ICU)-acquired ARDS were defined as ARDS occurring within 48 hours of hospital or ICU admission, more than 48 hours after hospital admission and ICU admission. The primary and secondary outcomes were short- and long- term mortality rates and ventilator-free and ICU-free days.

Results

Of the 3002 patients screened, 296 patients had a diagnosis of ARDS, including 70 (23.7 %) with community-acquired ARDS, 83 (28 %) with hospital-acquired ARDS, and 143 (48.3 %) with ICU-acquired ARDS. The overall ICU mortality rate was not significantly different in mild, moderate and severe ARDS (50 %, 50 % and 56 %, p = 0.25). The baseline characteristics were similar other than lower rate of liver disease and metastatic malignancy in community-acquired ARDS than in hospital-acquired and ICU-acquired ARDS. A multiple logistic regression analysis indicated that age, sequential organ function assessment score and community-acquired ARDS were independently associated with hospital mortality. For community-acquired, hospital-acquired and ICU-acquired ARDS, ICU mortality rates were 37 % 61 % and 52 %; hospital mortality rates were 49 %, 74 % and 68 %. The ICU and hospital mortality rates of community-acquired ARDS were significantly lower than hospital-acquired and ICU-acquired ARDS (p = 0.001 and p = 0.001). The number of ventilator-free days was significantly lower in ICU-acquired ARDS than in community-acquired and hospital-acquired ARDS (11 ± 9, 16 ± 9, and 14 ± 10 days, p = 0.001). The number of ICU-free days was significantly higher in community-acquired ARDS than in hospital-acquired and ICU-acquired ARDS (8 ± 10, 4 ± 8, and 3 ± 6 days, p = 0.001).

Conclusions

Community-acquired ARDS have lower short- and long-term mortality rates than hospital-acquired or ICU-acquired ARDS.

Lung protective ventilation and hospital survival of cardiac intensive care patients

OBJECTIVE

To detect connections between parameters of ventilation and outcomes of cardiac intensive care patients.

DESIGN AND SETTING

Noninterventional study. Between 05/11 and 05/12 all patients with acute heart failure and post cardiopulmonary resuscitation were registered. Lung protective ventilation was defined as peak inspiratory pressure (PIP) < 30 mmHg and tidal volume (Vt) < = 6 ml/kg.

RESULTS

In total, 129 patients were included in the study, 68.2 % male, age 67.9 ± 13.4 years, weight 71.4 ± 37.2 kg, predictive body weight 66.9 ± 8.8 kg, mortality 47.3 %. Lung protective ventilated patients at day 1: 17.3 % with a significant difference between surviving and nonsurviving patients (24.1 % vs. 9.6 %; p < 0.05). Logistic regression models showed a strong connection between PIP and survival (odds ratio 1.13; p < 0.05). Vt showed no significant influence on survival.

CONCLUSION

Our data recommends a strict observance of a low PIP for cardiac intensive care patients, whereas Vt seems to be of secondary importance.

Soluble Receptor for Advanced Glycation End-Products Predicts Impaired Alveolar Fluid Clearance in Acute Respiratory Distress Syndrome

RATIONALE

Levels of the soluble form of the receptor for advanced glycation end-products (sRAGE) are elevated during acute respiratory distress syndrome (ARDS) and correlate with severity and prognosis. Alveolar fluid clearance (AFC) is necessary for the resolution of lung edema but is impaired in most patients with ARDS. No reliable marker of this process has been investigated to date.

OBJECTIVES

To verify whether sRAGE could predict AFC during ARDS.

METHODS

Anesthetized CD-1 mice underwent orotracheal instillation of hydrochloric acid. At specified time points, lung injury was assessed by analysis of blood gases, alveolar permeability, lung histology, AFC, and plasma/bronchoalveolar fluid measurements of proinflammatory cytokines and sRAGE. Plasma sRAGE and AFC rates were also prospectively assessed in 30 patients with ARDS.

MEASUREMENTS AND MAIN RESULTS

The rate of AFC was inversely correlated with sRAGE levels in the plasma and the bronchoalveolar fluid of acid-injured mice (Spearman's ρ = -0.73 and -0.69, respectively; P < 10(-3)), and plasma sRAGE correlated with AFC in patients with ARDS (Spearman's ρ = -0.59; P < 10(-3)). Similarly, sRAGE levels were significantly associated with lung injury severity, and decreased over time in mice, whereas AFC was restored and lung injury resolved.

CONCLUSIONS

Our results indicate that sRAGE levels could be a reliable predictor of impaired AFC during ARDS, and should stimulate further studies on the pathophysiologic implications of RAGE axis in the mechanisms leading to edema resolution. Clinical trial registered with www.clinicaltrials.gov (NCT 00811629).

Acute Respiratory Distress Syndrome: Mortality in a Single Center According to Different Definitions

BACKGROUND

Mortality in acute lung injury (ALI) remains high, with outcome data arising mostly from multicenter studies. We undertook this investigation to determine hospital mortality in patients with ALI in a single center.

METHODS

We studied patients admitted between 2005 and 2012 with ALI and acute respiratory distress syndrome (ARDS) according to the American European Consensus Conference (AECC) criteria and recorded clinical variables. Thereafter, patients were classified as subgroups according to the AECC and Berlin definition in order to compare the clinical characteristics and outcomes.

RESULTS

In the 93 patients comprising the study, hospital mortality was 38%. Mortality at 28 days was 36%. Multivariate analysis associated hospital mortality with age and Pao₂/Fio₂ on day 1 ( P < .001). Differences resulted between the subgroups of AECC (ALI vs ARDS) and Berlin (mild vs moderate vs severe ARDS) in the lung injury score, Pao₂/Fio₂, Pao₂/P_Ao₂, PaCo₂ on day 1, and hospital mortality.

CONCLUSION

The overall hospital mortality (38%) was similar to that of other studies and according to the presence of ARDS (Pao₂/Fio₂ ≤ 200), we found significant differences between ALI and ARDS (AECC) and between mild and moderate or severe ARDS (Berlin) in baseline respiratory variables and mortality.

Albuterol in the treatment of acute respiratory distress syndrome: A meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis of randomized controlled trials aimed to systematically evaluate the value of albuterol in the treatment of patients with acute respiratory distress syndrome (ARDS).

DATA SOURCES

Randomized controlled trials on albuterol treatment of ARDS from its inception to October 2014 were searched systematically. The databases searched included: PubMed, Ovid EMBASE, Ovid Cochrane, CNKI, WANFANG and VIP. The trials were screened according to the pre-designed inclusion and exclusion criteria. We performed a systematic review and meta-analysis of the randomized controlled trials (RCTs) on albuterol treatment, attempting to improve outcomes, i.e. lowering the 28-day mortality and ventilator-free days.

RESULTS

Three RCTs involving 646 patients met the inclusion criteria. There was no significant decrease in the 28-day mortality (risk difference=0.09; P=0.07, P for heterogeneity=0.22, I (2)=33%). The ventilator-free days and organ failure-free days were significantly lower in the patients who received albuterol (mean difference=-2.20; P<0.001, P for heterogeneity=0.49, I (2)=0% and mean difference=-1.71, P<0.001, P for heterogeneity=0.60, I (2)=0%).

CONCLUSIONS

Current evidences indicate that treatment with albuterol in the early course of ARDS was not effective in increasing the survival, but significantly decreasing the ventilator-free days and organ failure-free days. Owing to the limited number of included trails, strong recommendations cannot be made.

The association between the Th-17 immune response and pulmonary complications in a trauma ICU population

BACKGROUND

The overall immunopathology of the T-helper cell (Th)-17 immune response has been implicated in various inflammatory diseases including pulmonary inflammation; however its potential role in acute respiratory distress syndrome (ARDS) is not defined. This study aimed to evaluate the Th-17 response in bronchoalveolar lavage fluid (BALF) and blood and from trauma patients with pulmonary complications.

METHODS

A total of 21 severely injured intensive care unit (ICU) subjects, who were mechanically ventilated and undergoing bronchoscopy, were enrolled. BALF and blood were collected and analyzed for Th-1 (interferon [IFN]γ), Th-2 (interleukin [IL]-4, -10), Th-17 (IL-17A, -17F, -22, 23) and pro-inflammatory (IL-1β, IL-6, tumor necrosis factor [TNF]α) cytokine levels.

RESULTS

Significant levels of the Th-17 cytokines IL-17A, -17F and -21 and IL-6 (which can be classified as a Th-17 cytokine) were observed in the BALF of all subjects. There were no significant differences in Th-17 cytokines between those subjects with ARDS and those without, with the exception of plasma and BALF IL-6, which was markedly greater in ARDS subjects, as compared with controls and non-ARDS subjects.

CONCLUSIONS

Trauma patients with pulmonary complications exhibited a significant Th-17 response in the lung and blood, suggesting that this pro-inflammatory milieu may be a contributing factor to such complications.

Soluble Forms and Ligands of the Receptor for Advanced Glycation End-Products in Patients with Acute Respiratory Distress Syndrome: An Observational Prospective Study

BACKGROUND

The main soluble form of the receptor for advanced glycation end-products (sRAGE) is elevated during acute respiratory distress syndrome (ARDS). However other RAGE isoforms and multiple ligands have been poorly reported in the clinical setting, and their respective contribution to RAGE activation during ARDS remains unclear. Our goal was therefore to describe main RAGE isoforms and ligands levels during ARDS.

METHODS

30 ARDS patients and 30 mechanically ventilated controls were prospectively included in this monocenter observational study. Arterial, superior vena cava and alveolar fluid levels of sRAGE, endogenous-secretory RAGE (esRAGE), high mobility group box-1 protein (HMGB1), S100A12 and advanced glycation end-products (AGEs) were measured in duplicate ELISA on day 0, day 3 and day 6. In patients with ARDS, baseline lung morphology was assessed with computed tomography.

RESULTS

ARDS patients had higher arterial, central venous and alveolar levels of sRAGE, HMGB1 and S100A12, but lower levels of esRAGE and AGEs, than controls. Baseline arterial sRAGE, HMGB1 and S100A12 were correlated with nonfocal ARDS (AUC 0.79, 0.65 and 0.63, respectively). Baseline arterial sRAGE, esRAGE, S100A12 and AGEs were associated with severity as assessed by PaO2/FiO2.

CONCLUSIONS

This is the first kinetics study of levels of RAGE main isoforms and ligands during ARDS. Elevated sRAGE, HMGB1 and S100A12, with decreased esRAGE and AGEs, were found to distinguish patients with ARDS from those without. Our findings should prompt future studies aimed at elucidating RAGE/HMGB1/S100A12 axis involvement in ARDS.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01270295.

The Role of Omega-3 Polyunsaturated Fatty Acids in the Treatment of Patients with Acute Respiratory Distress Syndrome: A Clinical Review

Acute respiratory distress syndrome (ARDS) is defined as the acute onset of noncardiogenic edema and subsequent gas-exchange impairment due to a severe inflammatory process. Recent report on the prognostic value of eicosanoids in patients with ARDS suggests that modulating the inflammatory response through the use of polyunsaturated fatty acids may be a useful strategy for ARDS treatment. The use of enteral diets enriched with eicosapentaenoic acid (EPA) and gamma-linolenic acid (GLA) has reported promising results, showing an improvement in respiratory variables and haemodynamics. However, the interpretation of the studies is limited by their heterogeneity and methodology and the effect of ω-3 fatty acid-enriched lipid emulsion or enteral diets on patients with ARDS remains unclear. Therefore, the routine use of ω-3 fatty acid-enriched nutrition cannot be recommended and further large, homogeneous, and high-quality clinical trials need to be conducted to clarify the effectiveness of ω-3 polyunsaturated fatty acids.

Lung Injury Prediction Score Is Useful in Predicting Acute Respiratory Distress Syndrome and Mortality in Surgical Critical Care Patients

Background. Lung injury prediction score (LIPS) is valuable for early recognition of ventilated patients at high risk for developing acute respiratory distress syndrome (ARDS). This study analyzes the value of LIPS in predicting ARDS and mortality among ventilated surgical patients. Methods. IRB approved, prospective observational study including all ventilated patients admitted to the surgical intensive care unit at a single tertiary center over 6 months. ARDS was defined using the Berlin criteria. LIPS were calculated for all patients and analyzed. Logistic regression models evaluated the ability of LIPS to predict development of ARDS and mortality. A receiver operator characteristic (ROC) curve demonstrated the optimal LIPS value to statistically predict development of ARDS. Results. 268 ventilated patients were observed; 141 developed ARDS and 127 did not. The average LIPS for patients who developed ARDS was 8.8 ± 2.8 versus 5.4 ± 2.8 for those who did not (p < 0.001). An ROC area under the curve of 0.79 demonstrates LIPS is statistically powerful for predicting ARDS development. Furthermore, for every 1-unit increase in LIPS, the odds of developing ARDS increase by 1.50 (p < 0.001) and odds of ICU mortality increase by 1.22 (p < 0.001). Conclusion. LIPS is reliable for predicting development of ARDS and predicting mortality in critically ill surgical patients.

Prognostic factors in the acute respiratory distress syndrome

Despite improvements in critical care, acute respiratory distress syndrome (ARDS) remains a devastating clinical problem with high rates of morbidity and mortality. A better understanding of the prognostic factors associated with ARDS is crucial for facilitating risk stratification and developing new therapeutic interventions that aim to improve clinical outcomes. In this article, we present an up-to-date summary of factors that predict mortality in ARDS in four categories: (1) clinical characteristics; (2) physiological parameters and oxygenation; (3) genetic polymorphisms and biomarkers; and (4) scoring systems. In addition, we discuss how a better understanding of clinical and basic pathogenic mechanisms can help to inform prognostication, decision-making, risk stratification, treatment selection, and improve study design for clinical trials.

One-year experience with an acute respiratory distress syndrome standard operating procedure on intensive care unit

PURPOSE

Mortality in acute respiratory distress syndrome (ARDS) patients remains unacceptable high, and there is substantial variation in the diagnostic and management strategies used. We recently established a standardized algorithm for the early identification and guideline conform therapy of ARDS on intensive care units (ICUs). We here present the results of a first-year observatory period after implementation of the ARDS bundle on our ICU.

METHODS AND RESULTS

A retrospective, observative, single-center case control study over a period of 4 years was performed. We analyzed the effects after implementation of an ARDS standard operating procedure (SOP) on prevalence of the diagnosis ARDS, mortality from ARDS, and therapy strategies. Implementation of the SOP led to an increased frequency of ARDS diagnosis (P < .05), increased application of early prone positioning (P < .05), and use of neuromuscular blockers (P < .02) in ARDS patients. An influence on mortality in ARDS patients could not be detected after implementation of the SOP (P = not significant).

CONCLUSION

A standardized ARDS bundle fundamentally increases awareness of this clinical picture on ICU and facilitates application of evidence-based therapies like prone positioning and use of neuromuscular blockers. These data encourage evaluating our ARDS SOP in a prospective trial to identify potential effects on mortality.

Pediatric acute respiratory distress syndrome: definition, incidence, and epidemiology: proceedings from the Pediatric Acute Lung Injury Consensus Conference

OBJECTIVES

Although there are similarities in the pathophysiology of acute respiratory distress syndrome in adults and children, pediatric-specific practice patterns, comorbidities, and differences in outcome necessitate a pediatric-specific definition. We sought to create such a definition.

DESIGN

A subgroup of pediatric acute respiratory distress syndrome investigators who drafted a pediatric-specific definition of acute respiratory distress syndrome based on consensus opinion and supported by detailed literature review tested elements of the definition with patient data from previously published investigations.

SETTINGS

International PICUs.

SUBJECTS

Children enrolled in published investigations of pediatric acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Several aspects of the proposed pediatric acute respiratory distress syndrome definition align with the Berlin Definition of acute respiratory distress syndrome in adults: timing of acute respiratory distress syndrome after a known risk factor, the potential for acute respiratory distress syndrome to coexist with left ventricular dysfunction, and the importance of identifying a group of patients at risk to develop acute respiratory distress syndrome. There are insufficient data to support any specific age for "adult" acute respiratory distress syndrome compared with "pediatric" acute respiratory distress syndrome. However, children with perinatal-related respiratory failure should be excluded from the definition of pediatric acute respiratory distress syndrome. Larger departures from the Berlin Definition surround 1) simplification of chest imaging criteria to eliminate bilateral infiltrates; 2) use of pulse oximetry-based criteria when PaO2 is unavailable; 3) inclusion of oxygenation index and oxygen saturation index instead of PaO2/FIO2 ratio with a minimum positive end-expiratory pressure level for invasively ventilated patients; 4) and specific inclusion of children with preexisting chronic lung disease or cyanotic congenital heart disease.

CONCLUSIONS

This pediatric-specific definition for acute respiratory distress syndrome builds on the adult-based Berlin Definition, but has been modified to account for differences between adults and children with acute respiratory distress syndrome. We propose using this definition for future investigations and clinical care of children with pediatric acute respiratory distress syndrome and encourage external validation with the hope for continued iterative refinement of the definition.

Management and outcome of mechanically ventilated patients after cardiac arrest

Introduction

The aim of this study was to describe and compare the changes in ventilator management and complications over time, as well as variables associated with 28-day hospital mortality in patients receiving mechanical ventilation (MV) after cardiac arrest.

Methods

We performed a secondary analysis of three prospective, observational multicenter studies conducted in 1998, 2004 and 2010 in 927 ICUs from 40 countries. We screened 18,302 patients receiving MV for more than 12 hours during a one-month-period. We included 812 patients receiving MV after cardiac arrest. We collected data on demographics, daily ventilator settings, complications during ventilation and outcomes. Multivariate logistic regression analysis was performed to calculate odds ratios, determining which variables within 24 hours of hospital admission were associated with 28-day hospital mortality and occurrence of acute respiratory distress syndrome (ARDS) and pneumonia acquired during ICU stay at 48 hours after admission.

Results

Among 812 patients, 100 were included from 1998, 239 from 2004 and 473 from 2010. Ventilatory management changed over time, with decreased tidal volumes (V_T) (1998: mean 8.9 (standard deviation (SD) 2) ml/kg actual body weight (ABW), 2010: 6.7 (SD 2) ml/kg ABW; 2004: 9 (SD 2.3) ml/kg predicted body weight (PBW), 2010: 7.95 (SD 1.7) ml/kg PBW) and increased positive end-expiratory pressure (PEEP) (1998: mean 3.5 (SD 3), 2010: 6.5 (SD 3); P <0.001). Patients included from 2010 had more sepsis, cardiovascular dysfunction and neurological failure, but 28-day hospital mortality was similar over time (52% in 1998, 57% in 2004 and 52% in 2010). Variables independently associated with 28-day hospital mortality were: older age, PaO₂ <60 mmHg, cardiovascular dysfunction and less use of sedative agents. Higher V_T, and plateau pressure with lower PEEP were associated with occurrence of ARDS and pneumonia acquired during ICU stay.

Conclusions

Protective mechanical ventilation with lower V_T and higher PEEP is more commonly used after cardiac arrest. The incidence of pulmonary complications decreased, while other non-respiratory organ failures increased with time. The application of protective mechanical ventilation and the prevention of single and multiple organ failure may be considered to improve outcome in patients after cardiac arrest.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0922-9) contains supplementary material, which is available to authorized users.

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.

Development and validation of severe hypoxemia associated risk prediction model in 1,000 mechanically ventilated patients*

OBJECTIVES

Patients with severe, persistent hypoxemic respiratory failure have a higher mortality. Early identification is critical for informing clinical decisions, using rescue strategies, and enrollment in clinical trials. The objective of this investigation was to develop and validate a prediction model to accurately and timely identify patients with severe hypoxemic respiratory failure at high risk of death, in whom novel rescue strategies can be efficiently evaluated.

DESIGN

Electronic medical record analysis.

SETTING

Medical, surgical, and mixed ICU setting at a tertiary care institution.

PATIENTS

Mechanically-ventilated ICU patients.

MEASUREMENTS AND MAIN RESULTS

Mechanically ventilated ICU patients were screened for severe hypoxemic respiratory failure (Murray lung injury score of ≥ 3). Survival to hospital discharge was the dependent variable. Clinical predictors within 24 hours of onset of severe hypoxemia were considered as the independent variables. An area under the curve and a Hosmer-Lemeshow goodness-of-fit test were used to assess discrimination and calibration. A logistic regression model was developed in the derivation cohort (2005-2007). The model was validated in an independent cohort (2008-2010). Among 79,341 screened patients, 1,032 met inclusion criteria. Mortality was 41% in the derivation cohort (n = 464) and 35% in the validation cohort (n = 568). The final model included hematologic malignancy, cirrhosis, aspiration, estimated dead space, oxygenation index, pH, and vasopressor use. The area under the curve of the model was 0.85 (0.82-0.89) and 0.79 (0.75-0.82) in the derivation and validation cohorts, respectively, and showed good calibration. A modified model, including only physiologic variables, performed similarly. It had comparable performance in patients with acute respiratory distress syndrome and outperformed previous prognostic models.

CONCLUSIONS

A model using comorbid conditions and physiologic variables on the day of developing severe hypoxemic respiratory failure can predict hospital mortality.

Effects of a recruitment maneuver on plasma levels of soluble RAGE in patients with diffuse acute respiratory distress syndrome: a prospective randomized crossover study

PURPOSE

The soluble form of the receptor for advanced glycation end-products (sRAGE) is a promising marker for epithelial dysfunction, but it has not been fully characterized as a biomarker of acute respiratory distress syndrome (ARDS). Whether sRAGE could inform on the response to ventilator settings has been poorly investigated, and whether a recruitment maneuver (RM) may influence plasma sRAGE remains unknown.

METHODS

Twenty-four patients with moderate/severe, nonfocal ARDS were enrolled in this prospective monocentric crossover study and randomized into a "RM-SHAM" group when a 6-h-long RM sequence preceded a 6-h-long sham evaluation period, or a "SHAM-RM" group (inverted sequences). Protective ventilation was applied, and RM consisted of the application of 40 cmH2O airway pressure for 40 s. Arterial blood was sampled for gas analyses and sRAGE measurements, 5 min pre-RM (or 40-s-long sham period), 5, 30 min, 1, 4, and 6 h after the RM (or 40-s-long sham period).

RESULTS

Mean PaO2/FiO2, tidal volume, PEEP, and plateau pressure were 125 mmHg, 6.8 ml/kg (ideal body weight), and 13 and 26 cmH2O, respectively. Median baseline plasma sRAGE levels were 3,232 pg/ml. RM induced a significant decrease in sRAGE (-1,598 ± 859 pg/ml) in 1 h (p = 0.043). At 4 and 6 h post-RM, sRAGE levels increased back toward baseline values. Pre-RM sRAGE was associated with RM-induced oxygenation improvement (AUC 0.84).

CONCLUSIONS

We report the first kinetics study of plasma sRAGE after RM in ARDS. Our findings reinforce the value of plasma sRAGE as a biomarker of ARDS.

Systemic combined melatonin-mitochondria treatment improves acute respiratory distress syndrome in the rat

Despite high in-hospital mortality associated with acute respiratory distress syndrome (ARDS), there is no effective therapeutic strategy. We tested the hypothesis that combined melatonin-mitochondria treatment ameliorates 100% oxygen-induced ARDS in rats. Adult male Sprague-Dawley rats (n = 40) were equally categorized into normal controls, ARDS, ARDS-melatonin, ARDS with intravenous liver-derived mitochondria (1500 μg per rat 6 hr after ARDS induction), and ARDS receiving combined melatonin-mitochondria. The results showed that 22 hr after ARDS induction, oxygen saturation (saO2 ) was lowest in the ARDS group and highest in normal controls, significantly lower in ARDS-melatonin and ARDS-mitochondria than in combined melatonin-mitochondria group, and significantly lower in ARDS-mitochondria than in ARDS-melatonin group. Conversely, right ventricular systolic blood pressure and lung weight showed an opposite pattern compared with saO2 among all groups (all P < 0.001). Histological integrity of alveolar sacs showed a pattern identical to saO2 , whereas lung crowding score exhibited an opposite pattern (all P < 0.001). Albumin level and inflammatory cells (MPO+, CD40+, CD11b/c+) from bronchoalveolar lavage fluid showed a pattern opposite to saO2 (all P < 0.001). Protein expression of indices of inflammation (MMP-9, TNF-α, NF-κB), oxidative stress (oxidized protein, NO-1, NOX-2, NOX-4), apoptosis (mitochondrial Bax, cleaved caspase-3, and PARP), fibrosis (Smad3, TGF-β), mitochondrial damage (cytochrome C), and DNA damage (γ-H2AX+) exhibited an opposite pattern compared to saO2 in all groups, whereas protein (HO-1, NQO-1, GR, GPx) and cellular (HO-1+) expressions of antioxidants exhibited a progressively increased pattern from normal controls to ARDS combined melatonin-mitochondria group (all P < 0.001). In conclusion, combined melatonin-mitochondrial was superior to either treatment alone in attenuating ARDS in this rat model.

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

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

The Effect of Omega-3 Fatty Acids on ARDS: A Randomized Double-Blind Study

PURPOSE

The aim of this study was to evaluate the effect of an enteral nutrition diet, enriched with omega-3 fatty acids because of its anti-inflammatory effects on treatment of patients with mild to moderate ARDS.

METHODS

This randomized clinical trial was performed in two ICUs of Tabriz University of Medical Sciences from Jun 2011 until Sep 2013 in north west of Iran. Fifty-eight patients with mild to moderate ARDS were enroled in this clinical trial. All patients received standard treatment for ARDS based on ARDS network trial. In intervention group, patients received 6 soft-gels of omega-3/day in addition to the standard treatment.

RESULTS

Tidal volume, PEEP, pH, PaO2/FiO2 , SaO2, P platue and PaCO2 on the 7(th) and 14(th) days didn't have significant difference between two groups. Indices of lung mechanics (Resistance, Compliance) had significant difference between the groups on the 14(th) day. Pao2 had significant difference between two groups on both 7(th) and 14(th) days. Trend of PaO2 changes during the study period in two groups were significant. We showed that adjusted mortality rate did not have significant difference between two groups.

CONCLUSION

It seems that adding omega-3 fatty acids to enteral diet of patients with ARDS has positive results in term of ventilator free days, oxygenation, lung mechanic indices; however, we need more multi center trials with large sample size and different doses of omega-3 fatty acids for their routine usage as an adjuant for ARDS treatment.

Prone position

PURPOSE OF REVIEW

Prone position can prevent ventilator-induced lung injury in acute respiratory distress syndrome (ARDS) patients receiving conventional mechanical ventilation and, hence, may have the potential to improve survival from this basis. Even though no single randomized controlled trial has proven benefit on patient outcome until recently, two meta-analyses, one on grouped data and the other on individual data, have shown that patients with PaO2/FIO2 ratio less than 100 mmHg at the time of inclusion did benefit from prone position. As a fifth trial completed recently has shown a significant reduction in mortality in patients with severe and confirmed ARDS from using prone position, the purpose of this review is to revisit prone positioning in ARDS in the light of these new findings.

RECENT FINDINGS

In this trial done in patients with severe ARDS severity criteria (PaO2/FIO2 ratio less than 150 mmHg with positive end expiratory pressure of 5 cmH2O or more, FIO2 of 60% or more and tidal volume around 6 ml/kg predicted body weight) confirmed 12-24 h after the onset of ARDS, the day 28 mortality in the supine group (229 patients) was 32.8 versus 16% in the prone group (237 patients) (P < 0.001). Significant reduction in mortality was confirmed at day 90.

SUMMARY

From the combined results of the two meta-analyses and the last randomized controlled trial, there is a very strong signal to use prone position in patients with severe ARDS, as early as possible and for long sessions.

Propofol pretreatment attenuates lipopolysaccharide-induced acute lung injury in rats by activating the phosphoinositide-3-kinase/Akt pathway

The aim of this study was to investigate the effect of propofol pretreatment on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the role of the phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) pathway in this procedure. Survival was determined 48 h after LPS injection. At 1 h after LPS challenge, the lung wet- to dry-weight ratio was examined, and concentrations of protein, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in bronchoalveolar lavage fluid (BALF) were determined using the bicinchoninic acid method or ELISA. Lung injury was assayed via lung histological examination. PI3K and p-Akt expression levels in the lung tissue were determined by Western blotting. Propofol pretreatment prolonged survival, decreased the concentrations of protein, TNF-α, and IL-6 in BALF, attenuated ALI, and increased PI3K and p-Akt expression in the lung tissue of LPS-challenged rats, whereas treatment with wortmannin, a PI3K/Akt pathway specific inhibitor, blunted this effect. Our study indicates that propofol pretreatment attenuated LPS-induced ALI, partly by activation of the PI3K/Akt pathway.

Perceptions of diagnosis and management of patients with acute respiratory distress syndrome: a survey of United Kingdom intensive care physicians

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a potentially devastating refractory hypoxemic illness with multi-organ involvement. Although several randomised controlled trials into ventilator and fluid management strategies have provided level 1 evidence to guide supportive therapy, there are few, established guidelines on how to manage patients with ARDS. In addition, and despite their continued use, pharmacotherapies for ARDS disease modulation have no proven benefit in improving mortality. Little is known however about the variability in diagnostic and treatment practices across the United Kingdom (UK). The aim of this survey, therefore, was to assess the use of diagnostic criteria and treatment strategies for ARDS in critical care units across the UK.

METHODS

The survey questionnaire was developed and internally piloted at University Hospital Southampton NHS Foundation Trust. Following ethical approval from University of Southampton Ethics and Research Committee, a link to an online survey engine (Survey Monkey) was then placed on the Intensive Care Society (UK) website. Fellows of The Intensive Care Society were subsequently personally approached via e-mail to encourage participation. The survey was conducted over a period of 3 months.

RESULTS

The survey received 191 responses from 125 critical care units, accounting for 11% of all registered intensive care physicians at The Intensive Care Society. The majority of the responses were from physicians managing general intensive care units (82%) and 34% of respondents preferred the American European Consensus Criteria for ARDS. There was a perceived decline in both incidence and mortality in ARDS. Primary ventilation strategies were based on ARDSnet protocols, though frequent deviations from ARDSnet positive end expiratory pressure (PEEP) recommendations (51%) were described. The majority of respondents set permissive blood gas targets (hypoxia (92%), hypercapnia (58%) and pH (90%)). The routine use of pharmacological agents is rare. Neuromuscular blockers and corticosteroids are considered occasionally and on a case-by-case basis. Routine (58%) or late (64%) tracheostomy was preferred to early tracheostomy insertion. Few centres offered routine follow-up or dedicated rehabilitation programmes following hospital discharge.

CONCLUSIONS

There is substantial variation in the diagnostic and management strategies employed for patients with ARDS across the UK. National and/or international guidelines may help to improve standardisation in the management of ARDS.

Evolving epidemiology and definitions of the acute respiratory distress syndrome and early acute lung injury

This article reviews the evolving definitions and epidemiology of the acute respiratory distress syndrome (ARDS) and highlights current efforts to improve identification of high-risk patients, thus to target prevention and early treatment before progression to ARDS. This information will be important for general practitioners and intensivists interested in improving the care of patients at risk for ARDS, and clinical researchers interested in designing clinical trials targeting the prevention and early treatment of acute lung injury.

Clinical and biological heterogeneity in acute respiratory distress syndrome: direct versus indirect lung injury

The acute respiratory distress syndrome (ARDS) is a heterogeneous group of illnesses affecting the pulmonary parenchyma with acute onset bilateral inflammatory pulmonary infiltrates with associated hypoxemia. ARDS occurs after 2 major types of pulmonary injury: direct lung injury affecting the lung epithelium or indirect lung injury disrupting the vascular endothelium. Greater understanding of the differences between direct and indirect lung injury may refine the classification of patients with ARDS and lead to development of new therapeutics targeted at specific subpopulations of patients with ARDS.

Plasminogen activator inhibitor-1 regulates LPS induced inflammation in rat macrophages through autophagy activation

Background. The mechanisms by which plasminogen activator inhibitor-1 (PAI-1) regulates inflammation, especially in acute respiratory distress syndrome (ARDS), are largely unknown. Objective. To assess the relationship between PAI-1 and autophagy in inflammatory reactions induced by LPS in rat NR8383 cells. Methods. ELISA was used to assess the amounts of TNF-α, IL-1β, and PAI-1 in cell culture supernatants; TLR4, MyD88, PAI-1, LC3, Beclin1, and mTOR protein and mRNA levels were determined by western blot and quantitative RT-PCR, respectively; western blot was used to determine NF-κB protein levels. To further evaluate the role of PAI-1, the PAI-1 gene was downregulated and overexpressed using the siRNA transfection technology and the pCDH-PAI-1, respectively. Finally, the GFP Positive Expression Rate Method was used to determine the rate of GFP-LC3 positive NR8383 cells. Results. In LPS-induced NR8383 cells, TNF-α, IL-1β, and PAI-1 expression levels increased remarkably. Upon PAI-1 knockdown, TNF-α, IL-1β, PAI-1, TLR4, MyD88, NF-κB, LC3, and Beclin1 levels were decreased, while mTOR increased. Conversely, overexpression of PAI-1 resulted in increased amounts of TNF-α, IL-1β, PAI-1, TLR4, MyD88, NF-κB, LC3, and Beclin1. However, no significant change was observed in mTOR expression. Conclusions. In NR8383 cells, PAI-1 contributes in the regulation of LPS-induced inflammation, likely by promoting autophagy.

Immunomodulation by fish-oil containing lipid emulsions in murine acute respiratory distress syndrome

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is a major cause of mortality in intensive care units. Patients with ARDS often require parenteral nutrition with lipid emulsions as essential components. Besides being an energy supply, these lipid emulsions might display differential modulatory effects on lung integrity and inflammation.

METHODS

In a pre-emptive strategy, we investigated the impact of three different intravenously infused lipid emulsions on lung morphology, leukocyte invasion, protein leakage and cytokines in a murine model of ARDS. Mice received an infusion of normal saline solution, a pure long-chain triglycerides (LCT) emulsion, a medium-chain triglycerides (MCT) containing mixed emulsion (LCT/MCT), or a fish oil (FO) containing mixed emulsion (LCT/MCT/FO) before lipopolysaccharide (LPS) challenge.

RESULTS

Mice pre-infused with fish oil-containing lipid emulsion showed decreased leukocyte invasion, protein leakage, myeloperoxidase activity, and cytokine production in their alveolar space after LPS challenge compared to mice receiving LCT or LCT/MCT. In line with these findings, lung morphology assessed by histological staining after LPS-induced lung injury improved faster in the LCT/MCT/FO group. Concerning the above mentioned parameters, no significant difference was observed between mice infused with LCT or the combination of LCT and MCT.

CONCLUSION

Fish oil-containing lipid emulsions might exert anti-inflammatory and pro-resolving effects in the murine model of acute lung injury. Partial replacement of n-6 fatty acids with n-3 fatty acids may thus be of benefit for critically ill patients at risk for ARDS which require parenteral nutrition.

Lung injury and its prognostic significance in acute liver failure

OBJECTIVE

Hypoxemia is a feared complication of acute liver failure, and high oxygen requirements will frequently lead to removal of patients from the transplant list. As data regarding the prevalence and outcome of acute respiratory distress syndrome in acute liver failure are scant and hypoxemia being a commonly encountered systemic complication, we analyzed radiological, gas exchange, and ventilator data in consecutive patients admitted with acute liver failure.

PATIENTS

Acute liver failure patients receiving mechanical ventilation admitted between January 2007 and February 2011 were included.

INTERVENTIONS

Patients were categorized according to the Berlin definition as: no acute respiratory distress syndrome, acute respiratory distress syndrome (PaO2/FIO2 < 300 mm Hg), and subdivisions of mild, moderate, and severe acute respiratory distress syndrome (200-300 mm Hg, 100-200 mm Hg, and < 100 mm Hg, respectively). Chest radiographs were independently assessed by two observers for the presence or absence of acute respiratory distress syndrome. Absence of left atrial pressure elevation was based on combined hemodynamic and echocardiographic assessment.

MEASUREMENTS AND MAIN RESULTS

Two hundred acute liver failure patients were admitted during the study period of whom 148, median age 39 years (16-74 yr), were included. Thirty-one (21%) had acute respiratory distress syndrome (17 mild acute respiratory distress syndrome [12%], 9 moderate acute respiratory distress syndrome [12%], and 5 severe acute respiratory distress syndrome) within the first 72 hours following admission. Acute respiratory distress syndrome patients required higher positive end-expiratory pressure (7 vs 6 vs 10 vs 15 cm H2O for no, mild, moderate, or severe acute respiratory distress syndrome, p = 0.014), had reduced respiratory system compliance (34 vs 29 vs 30 vs 23 L/cm H2O, p = 0.028), and an increased number of ventilator days (no acute respiratory distress syndrome, 10 d; mild acute respiratory distress syndrome acute lung injury, 12 d; moderate acute respiratory distress syndrome, 23 d; severe acute respiratory distress syndrome, 22 d; p = 0.097). Duration of liver intensive therapy unit stay (p = 0.175), survival (p = 0.877), inotrope requirements (p = 0.495), need for extracorporeal renal support (p = 0.565), and severity of organ failure scores were not affected. Extravascular lung water index had a moderate sensitivity of 65% and specificity of 77% for the prediction of acute respiratory distress syndrome.

CONCLUSION

The prevalence of lung injury is relatively low in acute liver failure, where 21% fulfilled acute respiratory distress syndrome criteria. Overall presence of acute respiratory distress syndrome appeared to have a limited impact on outcome.

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.

Difference in pulmonary permeability between indirect and direct acute respiratory distress syndrome assessed by the transpulmonary thermodilution technique: a prospective, observational, multi-institutional study

BACKGROUND

Acute respiratory distress syndrome (ARDS) is characterized by the increased pulmonary permeability secondary to diffuse alveolar inflammation and injuries of several origins. Especially, the distinction between a direct (pulmonary injury) and an indirect (extrapulmonary injury) lung injury etiology is gaining more attention as a means of better comprehending the pathophysiology of ARDS. However, there are few reports regarding the quantitative methods distinguishing the degree of pulmonary permeability between ARDS patients due to pulmonary injury and extrapulmonary injury.

METHODS

A prospective, observational, multi-institutional study was performed in 23 intensive care units of academic tertiary referral hospitals throughout Japan. During a 2-year period, all consecutive ARDS-diagnosed adult patients requiring mechanical ventilation were collected in which three experts retrospectively determined the pathophysiological mechanisms leading to ARDS. Patients were classified into two groups: patients with ARDS triggered by extrapulmonary injury (ARDSexp) and those caused by pulmonary injury (ARDSp). The degree of pulmonary permeability using the transpulmonary thermodilution technique was obtained during the first three intensive care unit (ICU) days.

RESULTS

In total, 173 patients were assessed including 56 ARDSexp patients and 117 ARDSp patients. Although the Sequential Organ Failure Assessment (SOFA) score was significantly higher in the ARDSexp group than in the ARDSp group, measurements of the pulmonary vascular permeability index (PVPI) were significantly elevated in the ARDSp group on all days: at day 0 (2.9 ± 1.3 of ARDSexp vs. 3.3 ± 1.3 of ARDSp, p = .008), at day 1 (2.8 ± 1.5 of ARDSexp vs. 3.2 ± 1.2 of ARDSp, p = .01), at day 2 (2.4 ± 1.0 of ARDSexp vs. 2.9 ± 1.3 of ARDSp, p = .01). There were no significant differences in mortality at 28 days, mechanical ventilation days, and hospital length of stay between the two groups.

CONCLUSIONS

The results of this study suggest the existence of several differences in the increased degree of pulmonary permeability between patients with ARDSexp and ARDSp.

TRIAL REGISTRATION

This report is a sub-group analysis of the study registered with UMIN-CTR (IDUMIN000003627).

Netrin-1 promotes epithelial sodium channel-mediated alveolar fluid clearance via activation of the adenosine 2B receptor in lipopolysaccharide-induced acute lung injury

BACKGROUND

The epithelial sodium channel (ENaC) is the driving force for pulmonary edema absorption in acute lung injury (ALI). Netrin-1 is a newly found anti-inflammatory factor that works by activating the adenosine 2B receptor (A2BAR). Meanwhile, activated A2BAR has the potential to enhance ENaC-dependent alveolar fluid clearance (AFC). However, whether netrin-1 can increase ENaC-mediated AFC by activating A2BAR remains unclear.

OBJECTIVES

To investigate the effect of netrin-1 on AFC in ALI and clarify the pathway via which netrin-1 regulates the expression of ENaC in vivo and in vitro.

METHODS

An ALI model was established by intratracheal instillation of lipopolysaccharide (LPS; 5 mg/kg) in C57BL/J mice, followed by netrin-1 with or without pretreatment with PSB1115, via the caudal vein. Twenty-four hours later, the lungs were isolated for determination of the bronchoalveolar lavage fluid, the lung wet/dry weight (W/D) ratio, AFC, the expressions of α-, β-, and γ-ENaC, and cyclic adenosine monophosphate (cAMP) levels. LPS-stimulated MLE-12 cells were incubated with netrin-1 with or without preincubation with PSB1115. Twenty-four hours later, the expressions of α-, β-, and γ-ENaC were detected.

RESULTS

In vivo, netrin-1 expression was significantly decreased during ALI. Substituted netrin-1 significantly dampened the lung injury, decreased the W/D ratio, and enhanced AFC, the expressions of α-, β-, and γ-ENaC, and cAMP levels in ALI, which were abolished by specific A2BAR inhibitor PSB1115. In vitro, netrin-1 increased the expressions of α-, β-, and γ-ENaC, which were prevented by PSB1115.

CONCLUSION

These results indicate that netrin-1 dampens pulmonary inflammation and increases ENaC-mediated AFC to alleviate pulmonary edema in LPS-induced ALI by enhancing cAMP levels through the activation of A2BAR.

Impact of serum biomarkers and clinical factors on intensive care unit mortality and 6-month outcome in relatively healthy patients with severe pneumonia and acute respiratory distress syndrome

Objectives. This study aimed to identify the independent biomarkers and clinical factors that could predict ICU mortality and 6-month outcomes in relatively healthy patients with severe pneumonia and acute respiratory distress syndrome (ARDS). Patients and Methods. We prospectively enrolled patients with severe pneumonia-related ARDS that required mechanical ventilation. Patients were excluded if they were unable to take care of themselves. Several biomarkers and clinical factors were evaluated prospectively on day 1 and day 3 after ICU admission. All biomarkers and clinical factors were collected for analysis. Results. 56 patients were enrolled in this study. We determined that the initial appropriate antibiotics use was an independent clinical factor and day 1 high-mobility group protein B1 (HMGB1) concentration was an independent biomarker for ICU mortality. Interestingly, we also found that a low day 1 albumin level was an independent biomarker for predicting patient life dependence 6 months after a pneumonia event. Conclusion. Patients with severe pneumonia and ARDS requiring mechanical ventilation experience high rates of ICU mortality or disability, even if they were quite healthy before. Initial appropriate antibiotics use and day 1 level of HMGB1 were independent factors for predicting ICU mortality. Day 1 albumin level was predictive of 6-month patient life dependence.

The postoperative airway: unique challenges?

PURPOSE OF REVIEW

The review is focused on the challenge of managing airway and ventilation in the intraoperative and postoperative period.

RECENT FINDINGS

In past years, a lot of attention was focused on tracheal intubation in difficult airway, whereas only in recent years extubation time of difficult airway is also covering an important role. Protective ventilation strategies have been studied in acute respiratory distress syndrome and then in general anesthesia, either for thoracic or bariatric surgery, whereas in general abdominal surgery, in healthy lung, few studies are present demonstrating the effective protective role of low tidal volume, lung recruitment maneuvers (LRM) and positive end-expiratory pressure (PEEP). In the early postoperative period, the role of noninvasive ventilation is growing as it reduces postoperative pulmonary complications, postoperative length of stay and costs.

SUMMARY

The combination of planning extubation of predicted and unpredicted difficult airway, both intraoperative low tidal volume and low FiO2 with LRM and PEEP at different points of surgery and postoperative noninvasive ventilation should be considered in patients undergoing surgery to decrease the rate of postoperative pulmonary complications and major fatal complications such as brain damage and death.

Etiology and Outcomes of ARDS in a Rural-Urban Fringe Hospital of South India

Objectives. Etiology and outcomes of acute lung injury in tropical countries may be different from those of western nations. We describe the etiology and outcomes of illnesses causing acute lung injury in a rural populace. Study Design. A prospective observational study. Setting. Medical ICU of a teaching hospital in a rural-urban fringe location. Patients. Patients ≥13 years, admitted between December 2011 and May 2013, satisfying AECC criteria for ALI/ARDS. Results. Study had 61 patients; 46 had acute lung injury at admission. Scrub typhus was the commonest cause (7/61) and tropical infections contributed to 26% of total cases. Increasing ARDS severity was associated with older age, higher FiO₂ and APACHE/SOFA scores, and longer duration of ventilation. Nonsurvivors were generally older, had shorter duration of illness, a nontropical infection, and higher total WBC counts, required longer duration of ventilation, and had other organ dysfunction and higher mean APACHE scores. The mortality rate of ARDS was 36.6% (22/61) in our study. Conclusion. Tropical infections form a major etiological component of acute lung injury in a developing country like India. Etiology and outcomes of ARDS may vary depending upon the geographic location and seasonal illnesses.

Non-invasive ventilation for acute hypoxemic respiratory failure: intubation rate and risk factors

Introduction

We assessed rates and predictive factors of non-invasive ventilation (NIV) failure in patients admitted to the intensive care unit (ICU) for non-hypercapnic acute hypoxemic respiratory failure (AHRF).

Methods

This is an observational cohort study using data prospectively collected over a three-year period in a medical ICU of a university hospital.

Results

Among 113 patients receiving NIV for AHRF, 82 had acute respiratory distress syndrome (ARDS) and 31 had non-ARDS. Intubation rates significantly differed between ARDS and non-ARDS patients (61% versus 35%, P = 0.015) and according to clinical severity of ARDS: 31% in mild, 62% in moderate, and 84% in severe ARDS (P = 0.0016). In-ICU mortality rates were 13% in non-ARDS, and, respectively, 19%, 32% and 32% in mild, moderate and severe ARDS (P = 0.22). Among patients with moderate ARDS, NIV failure was lower among those having a PaO₂/FiO₂ >150 mmHg (45% vs. 74%, p = 0.04). NIV failure was associated with active cancer, shock, moderate/severe ARDS, lower Glasgow coma score and lower positive end-expiratory pressure level at NIV initiation. Among intubated patients, ICU mortality rate was 46% overall and did not differ according to the time to intubation.

Conclusions

With intubation rates below 35% in non-ARDS and mild ARDS, NIV stands as the first-line approach; NIV may be attempted in ARDS patients with a PaO₂/FiO₂ > 150. By contrast, 84% of severe ARDS required intubation and NIV did not appear beneficial in this subset of patients. However, the time to intubation had no influence on mortality.

Intraoperative ventilatory strategies to prevent postoperative pulmonary complications: a meta-analysis

PURPOSE OF REVIEW

It is uncertain whether patients undergoing short-lasting mechanical ventilation for surgery benefit from lung-protective intraoperative ventilatory settings including the use of lower tidal volumes, higher levels of positive end-expiratory pressure (PEEP) and/or recruitment maneuvers. We meta-analyzed trials testing the effect of lung-protective intraoperative ventilatory settings on the incidence of postoperative pulmonary complications.

RECENT FINDINGS

Eight articles (1669 patients) were included. Meta-analysis showed a decrease in lung injury development [risk ratio (RR) 0.40; 95% confidence interval (CI) 0.22-0.70; I 0%; number needed to treat (NNT) 37], pulmonary infection (RR 0.64; 95% CI 0.43-0.97; I 0%; NNT 27) and atelectasis (RR 0.67; 95% CI 0.47-0.96; I 48%; NNT 31) in patients receiving intraoperative mechanical ventilation with lower tidal volumes. Meta-analysis also showed a decrease in lung injury development (RR 0.29; 95% CI 0.14-0.60; I 0%; NNT 29), pulmonary infection (RR 0.62; 95% CI 0.40-0.96; I 15%; NNT 33) and atelectasis (RR 0.61; 95% CI 0.41-0.91; I 0%; NNT 29) in patients ventilated with higher levels of PEEP, with or without recruitment maneuvers.

SUMMARY

Lung-protective intraoperative ventilatory settings have the potential to protect against postoperative pulmonary complications.

Veno-venous extracorporeal membrane oxygenation with a bicaval dual-lumen catheter in a SynCardia total artificial heart patient

We report the case of a 55 years old caucasian male patient with cardiogenic shock due to an extended myocardial infarction who underwent SynCardia Total Artificial Heart implantation and veno-venous extracorporeal membrane oxygenation with a bicaval dual-lumen cannula for the treatment of adult respiratory distress syndrome.

Apoptotic and inflammatory signaling via Fas and tumor necrosis factor receptor I contribute to the development of chest trauma-induced septic acute lung injury

BACKGROUND

Direct acute lung injury (ALI) is still associated with a high mortality, whereas the underlying pathomechanisms are not yet fully understood. In this regard, epithelial cell death in the lungs has been attributed an important role in the pathogenesis of this clinical entity. Based on this background here, we hypothesized that signaling through Fas and tumor necrosis factor receptor 1 (TNFR-1) is involved in mediating apoptosis and inflammation in chest trauma induced septic ALI.

METHODS

Male C57BL/6 mice (wild-type [WT]), male mutant mice expressing nonfunctional Fas receptor (B6.MRL-Faslpr/J [lpr]) (lpr) and male TNFR-1-deficient mice (TNFR-1(-/-)) were subjected to a model of direct ALI consisting of blunt chest trauma followed by cecal ligation and puncture.Cytokine/chemokine concentrations of plasma, bronchoalveolar lavage (BAL) fluids, and lung tissue were investigated as well as BAL protein and lung myeloperoxidase. Lung histology was assessed; lung caspase 3, TUNEL-positive cells, and apoptotic polymorphonuclear neutrophil were measured, followed by a survival study.

RESULTS

Cytokine/chemokine levels in plasma, BAL, and lung tissue were markedly increased in WT animals following ALI, whereas lpr and TNFR-1((-/-) showed significantly decreased levels. BAL protein levels were substantially elevated following ALI, but lpr animals presented markedly diminished protein levels compared with WT and TNFR-1(-/-) animals. Lung myeloperoxidase level was only increased 12 hours after ALI in WT animals, whereas lung myeloperoxidase levels in lpr and TNFR-1(-/-) animals were not increased compared with sham. Lung histology revealed beneficial effects in lpr and TNFR-1(-/-). Lung active caspase 3 after ALI was substantially decreased in lpr and TNFR-1(-/-) mice compared with WT. Interestingly, an early but not persisting survival benefit was observed in lpr and TNFR-1 animals(-/-).

CONCLUSION

Pathomechanistically, Fas and TNFR-1 signaling contributed to the apoptotic and inflammatory response in a clinically relevant double-hit model of trauma-induced septic ALI. Moreover, this was associated with a temporary survival benefit.

Establishment and evaluation of a simplified evaluation system of acute respiratory distress syndrome

PURPOSE

In recent years, a variety of acute respiratory distress syndrome (ARDS) evaluation systems have been developed worldwide; however, they are not so convenient for the doctors clinically, we decided to establish and evaluate a simplified evaluation system of ARDS (SESARDS).

MATERIALS AND METHODS

Data from 140 ARDS patients (derivation data set) were collected to screen for prognostic factors affecting outcomes in ARDS patients. By logistic regression analysis, scores were allocated to corresponding intervals of the variables, respectively, by means of analysis of the frequency distribution to establish a preliminary scoring system. Based on this primary scoring system, a definitive evaluation scheme was created through consultation with a panel of experts. The scores for the validation data set (92 cases) were assigned and calculated by their predictive mortality with the SESARDS and acute physiology and chronic health evaluation II (APACHE II). The performance of SESARDS was compared with that of APACHE II by means of statistical analysis.

RESULTS

The factors of age, pH, Glasgow coma scale (GCS), oxygenation index (OI), and the lobes of lung were associated with prognosis of ARDS respectively. The sensitivity and specificity of SESARDS for the validation data set were 96.43% and 58.33%, respectively. On the AUC, no significant difference between APACHE II and SESARDS was detected. There were no significant differences between the prediction and the actuality obtained by SESARDS for the validation data set the SESARDS scores were positively correlated with the actual mortality.

CONCLUSION

SESARDS was shown to be simple, accurate and effective in predicting ARDS progression.

Mechanisms of acute respiratory distress syndrome in children and adults: a review and suggestions for future research

OBJECTIVES

To provide a current overview of the epidemiology and pathophysiology of acute respiratory distress syndrome in adults and children, and to identify research questions that will address the differences between adults and children with acute respiratory distress syndrome.

DATA SOURCES

Narrative literature review and author-generated data.

DATA SELECTION

The epidemiology of acute respiratory distress syndrome in adults and children, lung morphogenesis, and postnatal lung growth and development are reviewed. The pathophysiology of acute respiratory distress syndrome is divided into eight categories: alveolar fluid transport, surfactant, innate immunity, apoptosis, coagulation, direct alveolar epithelial injury by bacterial products, ventilator-associated lung injury, and repair.

DATA EXTRACTION AND SYNTHESIS

Epidemiologic data suggest significant differences in the prevalence and mortality of acute respiratory distress syndrome between children and adults. Postnatal lung development continues through attainment of adult height, and there is overlap between the regulation of postnatal lung development and inflammatory, apoptotic, alveolar fluid clearance, and repair mechanisms. Therefore, there is a different biological baseline network of gene and protein expression in children as compared with adults.

CONCLUSIONS

There are significant obstacles to performing research on children with acute respiratory distress syndrome. However, epidemiologic, clinical, and animal studies suggest age-dependent differences in the pathophysiology of acute respiratory distress syndrome. In order to reduce the prevalence and improve the outcome of patients with acute respiratory distress syndrome, translational studies of inflammatory, apoptotic, alveolar fluid clearance, and repair mechanisms are needed. Understanding the differences in pathophysiologic mechanisms in acute respiratory distress syndrome between children and adults should facilitate identification of novel therapeutic interventions to prevent or modulate lung injury and improve lung repair.

The prevalence and impact of mortality of the acute respiratory distress syndrome on admissions of patients with ischemic stroke in the United States

PURPOSE

To determine the epidemiology of the acute respiratory distress syndrome (ARDS) and impact on in-hospital mortality in admissions of patients with acute ischemic stroke (AIS) in the United States.

METHODS

Retrospective cohort study of admissions with a diagnosis of AIS and ARDS from 1994 to 2008 identified through the Nationwide Inpatient Sample.

RESULTS

During the 15-year study period, we found 55 58 091 admissions of patients with AIS. The prevalence of ARDS in admissions of patients with AIS increased from 3% in 1994 to 4% in 2008 (P < .001). The ARDS was more common among younger men, nonwhites, and associated with history of congestive heart failure, hypertension, chronic obstructive pulmonary disease, renal failure, chronic liver disease, systemic tissue plasminogen activator, craniotomy, angioplasty or stent, sepsis, and multiorgan failures. Mortality due to AIS and ARDS decreased from 8% in 1994 to 6% in 2008 (P < .001) and 55% in 1994 to 45% in 2008 (P < .001), respectively. The ARDS in AIS increased in-hospital mortality (odds ratio, 14; 95% confidence interval, 13.5-14.3). A significantly higher length of stay was seen in admissions of patients with AIS having ARDS.

CONCLUSION

Our analysis demonstrates that ARDS is rare after AIS. Despite an overall significant reduction in mortality after AIS, ARDS carries a higher risk of death in this patient population.

Interhospital transfer of seriously sick ARDS patients using veno-venous Extracorporeal Membrane Oxygenation (ECMO): Concept of an ECMO transport team

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) therapy constitutes the last option for patients with acute respiratory distress syndrome (ARDS) refractory to conservative treatment. Since primary care centers are unable to provide this therapy, such patients need a transfer to a tertiary care center, which may be life-threatening without extracorporeal support.

METHODS

An ECMO transport team implanted an ECMO at the site of the primary care center with subsequent transport of the patient to the tertiary care center. Between September 2009 and March 2011, six patients with ARDS were treated by our ECMO transport team. Mean age was 39.5±12.0 years. All implantations were done percutaneously in a veno-venous configuration.

RESULTS

No complications occurred during the implant procedure and the subsequent transport. Four patients (67%) were successfully weaned from ECMO-therapy, and discharged from hospital.

CONCLUSION

With a specialized ECMO transport team, ECMO-implantation can be achieved successfully in a peripheral hospital, and patients can be transported safely.

Macrophage A2A adenosinergic receptor modulates oxygen-induced augmentation of murine lung injury

Acute respiratory distress syndrome (ARDS) causes significant morbidity and mortality. Exacerbating factors increasing the risk of ARDS remain unknown. Supplemental oxygen is often necessary in both mild and severe lung disease. The potential effects of supplemental oxygen may include augmentation of lung inflammation by inhibiting anti-inflammatory pathways in alveolar macrophages. We sought to determine oxygen-derived effects on the anti-inflammatory A2A adenosinergic (ADORA2A) receptor in macrophages, and the role of the ADORA2A receptor in lung injury. Wild-type (WT) and ADORA2A(-/-) mice received intratracheal lipopolysaccharide (IT LPS), followed 12 hours later by continuous exposure to 21% oxygen (control mice) or 60% oxygen for 1 to 3 days. We measured the phenotypic endpoints of lung injury and the alveolar macrophage inflammatory state. We tested an ADORA2A-specific agonist, CGS-21680 hydrochloride, in LPS plus oxygen-exposed WT and ADORA2A(-/-) mice. We determined the specific effects of myeloid ADORA2A, using chimera experiments. Compared with WT mice, ADORA2A(-/-) mice exposed to IT LPS and 60% oxygen demonstrated significantly more histologic lung injury, alveolar neutrophils, and protein. Macrophages from ADORA2A(-/-) mice exposed to LPS plus oxygen expressed higher concentrations of proinflammatory cytokines and cosignaling molecules. CGS-21680 prevented the oxygen-induced augmentation of lung injury after LPS only in WT mice. Chimera experiments demonstrated that the transfer of WT but not ADORA2A(-/-) bone marrow cells into irradiated ADORA2A(-/-) mice reduced lung injury after LPS plus oxygen, demonstrating myeloid ADORA2A protection. ADORA2A is protective against lung injury after LPS and oxygen. Oxygen after LPS increases macrophage activation to augment lung injury by inhibiting the ADORA2A pathway.

Extravascular lung water is an independent prognostic factor in patients with acute respiratory distress syndrome

OBJECTIVE

Acute respiratory distress syndrome might be associated with an increase in extravascular lung water index and pulmonary vascular permeability index, which can be measured by transpulmonary thermodilution. We tested whether extravascular lung water index and pulmonary vascular permeability index are independent prognostic factors in patients with acute respiratory distress syndrome.

DESIGN

Retrospective study.

SETTING

Medical intensive care unit.

PATIENTS

Two hundred consecutive acute respiratory distress syndrome patients (age = 57 ± 17, Simplified Acute Physiology Score II = 57 ± 20, overall day-28 mortality = 54%).

MEASUREMENTS

Extravascular lung water index and pulmonary vascular permeability index were collected (PiCCO device, Pulsion Medical Systems) at each day of the acute respiratory distress syndrome episode.

MAIN RESULTS

The maximum values of extravascular lung water index and pulmonary vascular permeability index recorded during the acute respiratory distress syndrome episode (maximum value of extravascular lung water index and maximum value of pulmonary vascular permeability index, respectively) were significantly higher in nonsurvivors than in survivors at day-28 (mean ± SD: 24 ± 10 mL/kg vs. 19 ± 7 mL/kg of predicted body weight, p < 0.001 [t-test] for maximum value of extravascular lung water index and median [interquartile range]: 4.4 [3.3-6.1] vs. 3.5 [2.8-4.4], p = 0.001 for maximum value of pulmonary vascular permeability index, Wilcoxon's test). In multivariate analyses, maximum value of extravascular lung water index or maximum value of pulmonary vascular permeability index, Simplified Acute Physiology Score II, maximum blood lactate, mean positive end-expiratory pressure, mean cumulative fluid balance, and the minimal ratio of arterial oxygen pressure over the inspired oxygen fraction were all independently associated with day-28 mortality. A maximum value of extravascular lung water index >21 mL/kg predicted day-28 mortality with a sensitivity of (mean [95% confidence interval]) 54% (44-63)% and a specificity of 73% (63-82)%. The mortality rate was 70% in patients with a maximum value of extravascular lung water index >21 mL/kg and 43% in the remaining patients (p = 0.0003). A maximum value of pulmonary vascular permeability index >3.8 predicted day-28 mortality with a sensitivity of (mean [95% confidence interval]) 67% (57-76)% and a specificity of 65% (54-75)%. The mortality rate was 69% in patients with a maximum value of pulmonary vascular permeability index >3.8 and 37% in the group with a maximum value of pulmonary vascular permeability index ≤ 3.8 (p < 0.0001).

CONCLUSIONS

Extravascular lung water index and pulmonary vascular permeability index measured by transpulmonary thermodilution are independent risk factors of day-28 mortality in patients with acute respiratory distress syndrome.

[Quality of results of therapy of acute respiratory failure : changes over a period of two decades]

Progress in intensive care (ICU) treatment of acute respiratory distress syndrome (ARDS) over the last 20 years includes the introduction of extracorporeal membrane oxygenation (ECMO) for CO2 removal and the widespread use of evidence-based lung-protective ventilatory strategies. Little is known, however, about whether these changes have resulted in improvements in short-term and long-term outcome of acute respiratory distress syndrome (ARDS) within the two decades after introduction. In a retrospective study 167 long-term survivors of severe ARDS who were transferred to the clinic for anesthesiology of the University of Munich, Campus Großhadern by means of specialized intensive care unit (ICU) transport teams and treated over a period of 20 years (1985-2005) were evaluated to investigate whether significant improvements in outcome as a consequence of the above mentioned progress in ARDS therapy have occurred. The ARDS patient cohort studied was characterized with regard to demographic variables, initial acute physiology and chronic health evaluation (APACHE) II score, duration of ICU treatment, the duration of mechanical ventilation and mortality. Data on long-term outcome were collected in a subcohort (n = 125) of patients who responded to mailed questionnaires and included health-related quality of life (HRQL, SF-36 questionnaire), symptoms of post-traumatic stress disorder (PTSD), traumatic memories from ICU treatment (PTSS-10 instrument) and current state of employment. During the observation period no significant changes regarding patient age (39 ± 16 years, mean ± SD), disease severity on admission to the ICU (APACHE II scores 22 ± 5), duration of ICU treatment (47 ± 39 days) or duration of mechanical ventilation (39 ± 38 days) were found. Overall ICU mortality during the two decades was 37.3 % (range 25.0 %-38.1 %) between 1995 and 2001 and a non-significant increase in values between 36.8 % and 58.3 % during the time interval from 2002 und 2005. The paO2/FIO2-ratio on ICU admittance improved significantly between 1990 and 2000 (69 ± 5 between 1990 and 1994 versus 101 ± 12 between 1995 and 2000, p < 0.01) and remained nearly unchanged thereafter. Long-term outcome was evaluated on average 5.0 ± 3.1 years after discharge from the ICU. During the time period between 1985 and 1994 survivors of ARDS showed significant impairments in all 8 categories of the SF-36 HRQL instrument when compared to an age and sex-matched normal population with maximal differences regarding physical function (z = -1.01), general health perception (z = -1.17) and mental health (z = -1.3). Patients who were treated from 1995 to 2005 were still impaired in 7 out of 8 categories of HRQL but reported significantly better mental health (49.6 ± 16.5 vs. 68.6 ± 17.8, p < 0,01) and better physical function than individuals from the previous decade (49.6 ± 16.5 vs. 73.4 ± 27.5, p = 0,03). The difference of mental health was no longer significant when compared to a healthy age and sex matched control group (p = 0.14) but the difference in physical function still was (z = -0.48, p < 0.01). The incidence of severe post-traumatic stress defined as a PTSS-10 score ≥ 35 was 20.4 % and remained unchanged throughout the 2 decades of observation. The PTSS-10 scores correlated with the number of traumatic memories present (r = 0.43, p < 0.01, n = 125). More than 50 % of long-term survivors were able to return to full time work with no significant changes during the 2 decades of observation. The introduction of new modalities of ARDS treatment were associated with higher paO2/FIO2-ratios on ICU admittance but had no effect on short-term outcomes including duration of ICU therapy, mechanical ventilation or mortality. The ARDS patients are still at risk for post-traumatic stress and persistent impairments in HRQL. Apart from some improvements in HRQL, the outcome of ARDS therapy remained largely unchanged during two decades.