Acute lung injury outside of the ICU: incidence in respiratory isolation on a general ward

Predicting Persistent Acute Respiratory Failure in Acute Pancreatitis: The Accuracy of Two Lung Injury Indices

BACKGROUND/AIMS

Early and accurate identification of patients with acute pancreatitis (AP) at high risk of persistent acute respiratory failure (PARF) is crucial. We sought to determine the accuracy of simplified Lung Injury Prediction Score (sLIPS) and simplified Early Acute Lung Injury (sEALI) for predicting PARF in ward AP patients.

METHODS

Consecutive AP patients in a training cohort from West China Hospital of Sichuan University (n = 912) and a validation cohort from The First Affiliated Hospital of Nanchang University (n = 1033) were analyzed. PARF was defined as oxygen in arterial blood/fraction of inspired oxygen < 300 mmHg that lasts for > 48 h. The sLIPS was composed by shock (predisposing condition), alcohol abuse, obesity, high respiratory rate, low oxygen saturation, high oxygen requirement, hypoalbuminemia, and acidosis (risk modifiers). The sEALI was calculated from oxygen 2 to 6 L/min, oxygen > 6 L/min, and high respiratory rate. Both indices were calculated on admission.

RESULTS

PARF developed in 16% (145/912) and 22% (228/1033) (22%) of the training and validation cohorts, respectively. In these patients, sLIPS and sEALI were significantly increased. sLIPS ≥ 2 predicted PARF in the training (AUROC 0.87, 95% CI 0.84-0.89) and validation (AUROC 0.81, 95% CI 0.78-0.83) cohorts. sLIPS was significantly more accurate than sEALI and current clinical scoring systems in both cohorts (all P < 0.05).

CONCLUSIONS

Using routinely available clinical data, the sLIPS can accurately predict PARF in ward AP patients and outperforms the sEALI and current existing clinical scoring systems.

Long-term exposure to ambient air pollution is associated with an increased incidence and mortality of acute respiratory distress syndrome in a large French region

INTRODUCTION

Air pollution exposure is suspected to alter both the incidence and mortality in acute respiratory distress syndrome (ARDS). The impact of chronic air pollutant exposure on the incidence and mortality of ARDS from various aetiologies in Europe remains unknown. The main objective of this study was to evaluate the incidence of ARDS in a large European region, 90-day mortality being the main secondary outcome.

METHODS

The study was performed in the Provence-Alpes-Cote-d'Azur (PACA) region. Nitrogen dioxide (NO2), particulate matter (PM_2.5 and PM₁₀) and ozone (O3) were measured. The Programme de Médicalisation des Systèmes d'Information (PMSI), which captures all patient hospital stays in France, was used to identify adults coded as ARDS in an intensive care unit.

RESULTS

From 2016 to 2018, 4733 adults with ARDS treated in intensive care units were analysed. The incidence rate ratios for 1-year average exposure to PM_2.5 and PM₁₀ were 1.207 ([95% confidence interval (95% CI), 1.145-1.390]; P < 0.01) and 1.168 (95% CI, 1.083-1.259; P < 0.001), respectively. The same trend was observed for both 2- and 3-year exposures, while only chronic 1- and 2-year exposure NO₂ exposures were related to a higher incidence of ARDS. Increased PM_2.5 exposure was associated with a higher 90-day mortality for both 1- and 3-year exposures (OR 1.096 (95% CI, 1.001-1.201) and 1.078 (95% CI, 1.009-1.152), respectively). O₃ was not associated with either of incidence nor mortality.

CONCLUSIONS

While chronic exposure to NO2, PM2.5, and PM10 was associated with an increased ARDS incidence and a higher mortality rate (for PM2.5) in those patients presenting with ARDS, further research on this topic is required.

LTB4 Promotes Acute Lung Injury via Upregulating the PLCε-1/TLR4/NF-κB Pathway in One-Lung Ventilation

Background

Mechanical ventilation (MV) can provoke acute lung injury (ALI) by increasing inflammation activation and disrupting the barrier in lung tissues even causing death. However, the inflammation-related molecules and pathways in MV-induced ALI remain largely unknown. Hence, the purposes of this study are to examine the role and mechanism of a novel inflammation-related molecule, leukotriene B4 (LTB4), in ALI.

Methods

The functions of LTB4 in one-lung ventilation (OLV) model were detected by the loss-of-function experiments. H&E staining was used to examine the pathologic changes of lung tissues. Functionally, PLCε-1 knockdown and Toll-like receptor 4 (TLR4)/NF-κB pathway inhibitor were used to detect the regulatory effects of LTB4 on the phospholipase Cε (PLCε-1)/TLR4/nuclear factor-kappa B (NF-κB) pathway. The levels of genes and proteins were determined by RT-qPCR and western blotting assay. The levels of inflammation cytokines and chemokines were measured by ELISA.

Results

Here, we found LTA4H, leukotriene B (4) receptor 1 (BLT1), LTB4, and PLCε-1 upregulated in OLV rats and associated with inflammatory activation and lung permeability changes of lung tissues. Inhibition of LTB4 alleviated the OLV-induced ALI by inhibiting inflammatory activation and lung permeability changes of lung tissues. For mechanism analyses, LTB4 promoted OLV-induced ALI by activating the PLCε-1/TLR4/NF-κB pathway.

Conclusion

LTB4 induced ALI in OLV rats by activating the PLCε-1/TLR4/NF-κB pathway. Our findings might supply a new potential therapeutic for OLV-induced ALI.

Lian Hua Qing Wen Capsules, a Potent Epithelial Protector in Acute Lung Injury Model, Block Proapoptotic Communication Between Macrophages, and Alveolar Epithelial Cells

Besides pathogen evading, Acute Lung Injury (ALI), featuring the systematic inflammation and severe epithelial damages, is widely believed to be the central non-infectious factor controlling the progression of infectious diseases. ALI is partly caused by host immune responses. Under the inspiration of unsuccessful treatment in COVID-19, recent insights into pathogen–host interactions are leading to identification and development of a wide range of host-directed therapies with different mechanisms of action. The interaction unit consisting of macrophages and the alveolar epithelial cells has recently revealed as the therapeutic basis targeting ALI. Lian Hua Qing Wen capsule is the most effective and commonly-used clinical formula in treating respiratory infection for thousands of years in China. However, little is known about its relevance with ALI, especially its protective role against ALI-induced alveolar tissue damages. Aiming to evaluate its contribution in antibiotics-integrating therapies, this study pharmacologically verified whether LHQW could alleviate lipopolysaccharide (LPS)-induced ALI and explore its potential mechanisms in maintaining the physiology of macrophage-epithelial unit. In ALI mouse model, the pathological parameters, including the anal temperature, inflammation condition, lung edema, histopathological structures, have all been systematically analyzed. Results consistently supported the effectiveness of the combined strategy for LHQW and low-dose antibiotics. Furthermore, we established the macrophages-alveolar epithelial cells co-culture model and firstly proved that LHQW inhibited LPS-induced ER stress and TRAIL secretion in macrophages, thereby efficiently protected epithelial cells against TRAIL-induced apoptosis. Mechanistically, results showed that LHQW significantly deactivated NF-κB and reversed the SOCS3 expression in inflammatory macrophages. Furthermore, we proved that the therapeutic effects of LHQW were highly dependent on JNK-AP1 regulation. In conclusion, our data proved that LHQW is an epithelial protector in ALI, implying its promising potential in antibiotic alternative therapy.

Frequency of Pediatric Acute Respiratory Distress Syndrome Based on Oxygen Saturation Index in Pediatric Intensive Care Unit of a Developing Country

Objectives

To determine the frequency of pediatric acute respiratory distress syndrome based on oxygen saturation index in pediatric intensive care unit of a developing country.

Methods

We conducted a retrospective study of all children admitted in pediatric intensive care unit (PICU) of Aga Khan University Hospital, Karachi from July 2017 to June 2018 with respiratory rate >40 breaths/minute, shortness of breath, and bluish discoloration of skin and mucous membranes. The diagnosis of acute respiratory distress syndrome (ARDS) was made on the basis of standard operational definitions as mentioned (fulfilling criteria for ARDS).

Results

During the one-year study period 150 patients with age range of one month to 16 years were admitted fulfilling the inclusion criteria. Mean age was 38.27 ± 53.13 months, and 92 (61.33%) were male with male to female ratio of 1.6:1. Mean duration of symptoms was 1.23 ± 0.42 days. Frequency of pediatric acute respiratory distress syndrome using oxygen saturation index admitted in a pediatric ICU was 23 (15.33%) patients.

Conclusion

This study has shown that the frequency of pediatric acute respiratory distress syndrome is quite high.

Epidemiology of mechanically ventilated patients treated in ICU and non-ICU settings in Japan: a retrospective database study

BACKGROUND

In most countries, patients receiving mechanical ventilation (MV) are treated in intensive care units (ICUs). However, in some countries, including Japan, many patients on MV are not treated in ICUs. There are insufficient epidemiological data on these patients. Here, we sought to describe the epidemiology of patients on MV in Japan by comparing and contrasting patients on MV treated in ICUs and in non-ICU settings. A preliminary comparison of patient outcomes between ICU and non-ICU patients was a secondary objective.

METHODS

Data on adult patients receiving MV for at least 3 days in ICUs or non-ICU settings from April 2010 through March 2012 were obtained from the Quality Indicator/Improvement Project, a voluntary data-administration project covering more than 400 acute-care hospitals in Japan. We excluded patients with cancer-related diagnoses. Patient demographic data and the critical care provided were compared between groups.

RESULTS

Over the study period, 17,775 patients on MV were treated only in non-ICU settings, whereas 20,516 patients were treated at least once in ICUs (46.4% vs. 53.6%). Average age was higher in non-ICU patients than in ICU patients (72.8 vs. 70.2, P < 0.001). Mean number of ventilation days was greater in non-ICU patients (11.7 vs. 9.5, P < 0.001). Hospital mortality was higher in non-ICU patients (41.4% vs. 38.8%, P < 0.001). Standard critical care (e.g., arterial line placement, enteral nutrition, and stress-ulcer prevention) was provided significantly less often in non-ICU patients. Multivariate analysis showed that ICU admission significantly decreased hospital mortality (adjusted odds ratio 0.713, 95% CI 0.676 to 0.753).

CONCLUSIONS

A large proportion of Japanese patients on MV were treated in non-ICU settings. Analysis of administrative data indicated preliminarily that hospital mortality rates in these patients were higher in non-ICU settings than in ICUs. Prospective analyses comparing non-ICU and ICU patients on MV by severity scoring are needed.

Preadmission Oral Corticosteroids Are Associated With Reduced Risk of Acute Respiratory Distress Syndrome in Critically Ill Adults With Sepsis

OBJECTIVES

To determine the association between preadmission oral corticosteroid receipt and the development of acute respiratory distress syndrome in critically ill patients with sepsis.

DESIGN

Retrospective observational study.

SETTING

Medical, surgical, trauma, and cardiovascular ICUs of an academic medical center.

PATIENTS

A total of 1,080 critically ill patients with sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The unadjusted occurrence rate of acute respiratory distress syndrome within 96 hours of ICU admission was 35% among patients who had received oral corticosteroids compared with 42% among those who had not (p = 0.107). In a multivariable analysis controlling for prespecified confounders, preadmission oral corticosteroids were associated with a lower incidence of acute respiratory distress syndrome in the 96 hours after ICU admission (odds ratio, 0.53; 95% CI, 0.33-0.84; p = 0.008), a finding that persisted in multiple sensitivity analyses. The median daily dose of oral corticosteroids among the 165 patients receiving oral corticosteroids, in prednisone equivalents, was 10 mg (interquartile range, 5-30 mg). Higher doses of preadmission oral corticosteroids were associated with a lower incidence of acute respiratory distress syndrome (odds ratio for 30 mg of prednisone compared with 5 mg 0.53; 95% CI, 0.32-0.86). In multivariable analyses, preadmission oral corticosteroids were not associated with in-hospital mortality (odds ratio, 1.41; 95% CI, 0.87-2.28; p = 0.164), ICU length of stay (odds ratio, 0.90; 95% CI, 0.63-1.30; p = 0.585), or ventilator-free days (odds ratio, 1.06; 95% CI, 0.71-1.57; p = 0.783).

CONCLUSIONS

Among ICU patients with sepsis, preadmission oral corticosteroids were independently associated with a lower incidence of early acute respiratory distress syndrome.

Timing of Intubation and Clinical Outcomes in Adults With Acute Respiratory Distress Syndrome

OBJECTIVE

The prevalence, clinical characteristics, and outcomes of critically ill, nonintubated patients with evidence of the acute respiratory distress syndrome remain inadequately characterized.

DESIGN

Secondary analysis of a prospective observational cohort study.

SETTING

Vanderbilt University Medical Center.

PATIENTS

Among adult patients enrolled in a large, multi-ICU prospective cohort study between the years of 2006 and 2011, we studied intubated and nonintubated patients with acute respiratory distress syndrome as defined by acute hypoxemia (PaO2/FIO2 ≤ 300 or SpO2/FIO2 ≤ 315) and bilateral radiographic opacities not explained by cardiac failure. We excluded patients not committed to full respiratory support.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 457 patients with acute respiratory distress syndrome, 106 (23%) were not intubated at the time of meeting all other acute respiratory distress syndrome criteria. Nonintubated patients had lower morbidity and severity of illness than intubated patients; however, mortality at 60 days was the same (36%) in both groups (p = 0.91). Of the 106 nonintubated patients, 36 (34%) required intubation within the subsequent 3 days of follow-up; this late-intubation subgroup had significantly higher 60-day mortality (56%) when compared with the both early intubation group (36%, P<0.03) and patients never requiring intubation (26%; p = 0.002). Increased mortality in the late intubation group persisted at 2-year follow-up. Adjustment for baseline clinical and demographic differences did not change the results.

CONCLUSIONS

A substantial proportion of critically ill adults with acute respiratory distress syndrome were not intubated in their initial days of intensive care, and many were never intubated. Late intubation was associated with increased mortality. Criteria defining the acute respiratory distress syndrome prior to need for positive pressure ventilation are required so that these patients can be enrolled in clinical studies and to facilitate early recognition and treatment of acute respiratory distress syndrome.

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.

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.

Early non-invasive ventilation treatment for respiratory failure due to severe community-acquired pneumonia

BACKGROUND AND AIMS

Severe community-acquired pneumonia (sCAP) have been as defined pneumonia requiring admission to the intensive care unit or carrying a high risk of death. Currently, the treatment of sCAP consists of antibiotic therapy and ventilator support. The use of invasive ventilation causes several complications as does admission to ICU. For this reason, non-invasive ventilation (NIV) has been used for acute respiratory failure to avoid endotracheal intubation. However, few studies have currently assessed the usefulness of NIV in sCAP.

METHODS

We prospectively assessed 127 patients with sCAP and severe acute respiratory failure [oxygen arterial pressure/oxygen inspiratory fraction ratio (PaO2/FiO2) <250]. We defined successful NIV as avoidance of intubation and the achievement of PaO2/FiO2 >250 with spontaneous breathing. We assessed predictors of NIV failure and hospital mortality using univariate and multivariate analyses.

RESULTS

NIV failed in 32 patients (25.1%). Higher chest X-ray score at admission, chest X-ray worsening, and a lower PaO2/FiO2 and higher alveolar-arteriolar gradient (A-aDO2) after 1 h of NIV all independently predicted NIV failure. Higher lactate dehydrogenase and confusion, elevated blood urea, respiratory rate, blood pressure plus age ≥65 years at admission, higher A-aDO2, respiratory rate and lower PaO2/FiO2 after 1 h of NIV and intubation rate were directly related to hospital mortality.

CONCLUSIONS

Successful treatment is strongly related to less severe illness as well as to a good initial and sustained response to medical therapy and NIV treatment. Constant monitoring of these patients is mandatory.

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.

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

OBJECTIVE

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

DESIGN

Prospective observational cohort study.

SETTING

Stanford University Hospital.

PATIENTS

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

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSIONS

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

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.

Clinical review: Early treatment of acute lung injury--paradigm shift toward prevention and treatment prior to respiratory failure

Acute lung injury (ALI) remains a major cause of morbidity and mortality in critically ill patients. Despite improved understanding of the pathogenesis of ALI, supportive care with a lung protective strategy of mechanical ventilation remains the only treatment with a proven survival advantage. Most clinical trials in ALI have targeted mechanically ventilated patients. Past trials of pharmacologic agents may have failed to demonstrate efficacy in part due to the resultant delay in initiation of therapy until several days after the onset of lung injury. Improved early identification of at-risk patients provides new opportunities for risk factor modification to prevent the development of ALI and novel patient groups to target for early treatment of ALI before progression to the need for mechanical ventilation. This review will discuss current strategies that target prevention of ALI and some of the most promising pharmacologic agents for early treatment of ALI prior to the onset of respiratory failure that requires mechanical ventilation.

The utility of clinical predictors of acute lung injury: towards prevention and earlier recognition

Despite significant advances in our understanding of the pathophysiology of acute lung injury, a lung-protective strategy of mechanical ventilation remains the only therapy with a proven survival advantage. Numerous pharmacologic therapies have failed to show benefit in multicenter clinical trials. The paradigm of early, goal-directed therapy of sepsis suggests greater clinical benefit may derive from initiating therapy prior to the onset of respiratory failure that requires mechanical ventilation. Thus, there is heightened interest in more accurate and complete characterization of high-risk patient populations and identification of patients in the early stage of acute lung injury, prior to the need for mechanical ventilation. This article discusses the growing literature on clinical predictors of acute lung injury (including risk factors for specific subgroups) with an emphasis on transfusion-related risk factors and recent research targeting the early identification of high-risk patients and those with early acute lung injury prior to the onset of respiratory failure.

Use of intensive care, mechanical ventilation, both, or neither by patients with acute lung injury

OBJECTIVE

Reports of acute lung injury and acute respiratory distress syndrome have generally been restricted to mechanically ventilated intensive care unit patients, creating an incomplete picture of the epidemiologies of the syndromes. We sought to determine the incidence and outcomes of acute lung injury and acute respiratory distress syndromes throughout an entire hospital population.

DESIGN

Retrospective cohort study.

SETTING

A Department of Veterans Affairs medical center.

PATIENTS

All patients satisfying criteria for acute lung injury or acute respiratory distress syndrome during a 2-yr period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 11,465 acute medical and surgical admissions during the study period; 156 patients had acute lung injury or acute respiratory distress syndrome. Only 74 (47%) were invasively ventilated in an intensive care unit for acute lung injury. Another 15 (10%) patients were ventilated for other reasons, 41 (26%) were admitted to an intensive care unit at approximately the time of acute lung injury onset but were not invasively ventilated, and 26 (17%) were managed with neither invasive ventilation nor admission to an intensive care unit. Four-week mortality differed by group (p = .023), ranging from 22% among those managed in an intensive care unit without invasive ventilation to 50% among those ventilated for acute lung injury or acute respiratory distress syndrome. By 2 yrs, differences in survival between groups were no longer significant. Notably, only 53 (34%) patients would have been eligible for widely cited acute lung injury intervention trials. Ten patients had a second episode of acute lung injury during the study period, equating to a 16%-per-year risk of recurrence.

CONCLUSIONS

Acute lung injury and acute respiratory distress syndrome studies restricted to patients mechanically ventilated in intensive care units substantially underestimate the incidence of the syndromes. Nonventilated patients and those cared for outside of intensive care units may still be at substantial risk for death. Further characterization of previously overlooked acute lung injury and acute respiratory distress syndrome patients may suggest new therapeutic opportunities.