Interobserver variation in interpreting chest radiographs for the diagnosis of acute respiratory distress syndrome

Extravascular lung water and acute lung injury

Acute lung injury carries a high burden of morbidity and mortality and is characterised by nonhydrostatic pulmonary oedema. The aim of this paper is to highlight the role of accurate quantification of extravascular lung water in diagnosis, management, and prognosis in "acute lung injury" and "acute respiratory distress syndrome". Several studies have verified the accuracy of both the single and the double transpulmonary thermal indicator techniques. Both experimental and clinical studies were searched in PUBMED using the term "extravascular lung water" and "acute lung injury". Extravascular lung water measurement offers information not otherwise available by other methods such as chest radiography, arterial blood gas, and chest auscultation at the bedside. Recent data have highlighted the role of extravascular lung water in response to treatment to guide fluid therapy and ventilator strategies. The quantification of extravascular lung water may predict mortality and multiorgan dysfunction. The limitations of the dilution method are also discussed.

Definition of ALI/ARDS

Although acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are caused by different injuries and conditions, their similar clinical picture makes a compelling case for them to be studied as a single entity. An array of potential specific targets for pharmacologic intervention can be applied to ALI/ARDS as one disease. Although a working definition of ALI/ARDS that includes pulmonary and extrapulmonary causes can have benefit in standardizing supportive care, it can also complicate assessments of the efficacy of therapeutic interventions. In this article, definitions that have been recently used for ALI/ARDS in various clinical studies are discussed individually.

Acute respiratory distress syndrome: A clinical review

The acute respiratory distress syndrome (ARDS) is a complex disorder of heterogeneous etiologies characterized by a consistent, recognizable pattern of lung injury. Extensive epidemiologic studies and clinical intervention trials have been conducted to address the high mortality of this disorder and have provided significant insight into the complexity of studying new therapies for this condition. The existing clinical investigations in ARDS will be highlighted in this review. The limitations to current definitions, patient selection, and outcome assessment will be considered. While significant attention has been focused on the parenchymal injury that characterizes this disorder and the clinical support of gas exchange function, relatively limited focus has been directed to hemodynamic and pulmonary vascular dysfunction equally prominent in the disease. The limited available clinical information in this area will also be reviewed. The current standards for cardiopulmonary management of the condition will be outlined. Current gaps in our understanding of the clinical condition will be highlighted with the expectation that continued progress will contribute to a decline in disease mortality.

[Acute lung injury and acute respiratory distress syndrome: a genomic perspective]

Genomics have allowed important advances in the knowledge of the etiology and pathogenesis of complex disease entities such as acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Genomic medicine aims to personalize and optimize diagnosis, prognosis and treatment by determining the influence of genetic polymorphisms in specific diseases. The scientific community must cope with the important challenge of securing rapid transfer of knowledge to clinical practice, in order to prevent patients from becoming exposed to unnecessary risks. In the present article we describe the main concepts of genomic medicine pertaining to ALI/ARDS, and its currently recognized clinical applications.

Genetic variation in the FAS gene and associations with acute lung injury

RATIONALE

Fas (CD95) modulates apoptosis and inflammation and is believed to play an important role in lung injury.

OBJECTIVES

To determine if common genetic variation in FAS is associated with acute lung injury (ALI) susceptibility, risk of death, and FAS gene expression.

METHODS

We genotyped 14 single nucleotide polymorphisms (tagSNPS) in FAS in samples from healthy white volunteers (control subjects, n = 294) and patients with ALI (cases, n = 324) from the ARDSnet Fluid and Catheter Treatment Trial (FACTT). FAS genotypes associated with ALI in the discovery study were confirmed in a nested case-control validation study of critically ill patients at risk for ALI (n = 657). We also tested for associations between selected tagSNPS and FAS mRNA levels in whole blood from healthy control subjects exposed to media alone or LPS ex vivo.

MEASUREMENTS AND MAIN RESULTS

We identified associations between four tagSNPs in FAS (FAS(-11341A>T) [rs17447140], FAS(9325G>A) [rs2147420], FAS(21541C>T) [rs2234978], and FAS(24484A>T) [rs1051070]) and ALI case status. Haplotype-based analyses suggested that three of the tagSNPs (FAS(9325G>A), FAS(21541C>T), and FAS(24484A>T)) function as a unit. The association with this haplotype and ALI was validated in a nested case-control study of at-risk subjects (P = 0.05). This haplotype was also associated with increased FAS mRNA levels in response to LPS stimulation. There was no association between FAS polymorphisms and risk of death among ALI cases.

CONCLUSIONS

Common genetic variants in FAS are associated with ALI susceptibility. This is the first genetic evidence supporting a role for FAS in ALI.

[Agreement between lung ultrasonography and chest radiography in the intensive care unit]

OBJECTIVE

Because the chest radiograph currently remains the routine choice of imaging for the examination of the chest in the intensive care unit, we compared lung ultrasonography with chest radiography.

STUDY DESIGN

Observational prospective study.

METHODS

An ultrasound examination and chest radiography were simultaneously ordered in 50 patients whose clinical exam justified a lung exploration. Each exam was interpreted independently by an intensivist. The abnormalities found were classified into interstitial syndrome, alveolar consolidation, and pleural effusion. An agreement analysis was performed between the results of the two techniques. The delay between the order and interpretation of both investigations, and the degree of interobserver agreement were also collected.

RESULTS

The kappa agreement between lung ultrasonography and chest radiography was 0.42. In total, 329 total abnormalities were detected, 156 abnormalities were found by both techniques, 31 by radiography alone, and 142 by ultrasonography alone. The interobserver agreement was 0.86. Ultrasonography was performed with a shorter delay (14.8 ± 6.9 min vs 44.2 ± 21.4 min).

CONCLUSION

There was only moderate agreement between lung ultrasonography and chest radiography for the diagnosis of interstitial syndrome, alveolar consolidation and pleural effusion in intensive care unit. This result is mainly explained by the higher number of ultrasound abnormalities. With the ability to provide fast diagnosis, good reproducibility and high feasibility, ultrasound scan could represent an alternative exam for chest exploration in intensive care unit.

Validation of extravascular lung water measurement by single transpulmonary thermodilution: human autopsy study

Introduction

Gravimetric validation of single-indicator extravascular lung water (EVLW) and normal EVLW values has not been well studied in humans thus far. The aims of this study were (1) to validate the accuracy of EVLW measurement by single transpulmonary thermodilution with postmortem lung weight measurement in humans and (2) to define the statistically normal EVLW values.

Methods

We evaluated the correlation between pre-mortem EVLW value by single transpulmonary thermodilution and post-mortem lung weight from 30 consecutive autopsies completed within 48 hours following the final thermodilution measurement. A linear regression equation for the correlation was calculated. In order to clarify the normal lung weight value by statistical analysis, we conducted a literature search and obtained the normal reference ranges for post-mortem lung weight. These values were substituted into the equation for the correlation between EVLW and lung weight to estimate the normal EVLW values.

Results

EVLW determined using transpulmonary single thermodilution correlated closely with post-mortem lung weight (r = 0.904, P < 0.001). A linear regression equation was calculated: EVLW (mL) = 0.56 × lung weight (g) - 58.0. The normal EVLW values indexed by predicted body weight were approximately 7.4 ± 3.3 mL/kg (7.5 ± 3.3 mL/kg for males and 7.3 ± 3.3 mL/kg for females).

Conclusions

A definite correlation exists between EVLW measured by the single-indicator transpulmonary thermodilution technique and post-mortem lung weight in humans. The normal EVLW value is approximately 7.4 ± 3.3 mL/kg.

Trial registration

UMIN000002780.

Acute lung injury: epidemiology, pathogenesis, and treatment

Acute lung injury (ALI) remains a significant source of morbidity and mortality in the critically ill patient population. Defined by a constellation of clinical criteria (acute onset of bilateral pulmonary infiltrates with hypoxemia without evidence of hydrostatic pulmonary edema), ALI has a high incidence (200,000 per year in the US) and overall mortality remains high. Pathogenesis of ALI is explained by injury to both the vascular endothelium and alveolar epithelium. Recent advances in the understanding of pathophysiology have identified several biologic markers that are associated with worse clinical outcomes. Phase III clinical trials by the NHLBI ARDS Network have resulted in improvement in survival and a reduction in the duration of mechanical ventilation with a lung-protective ventilation strategy and fluid conservative protocol. Potential areas of future treatments include nutritional strategies, statin therapy, and mesenchymal stem cells.

An alternative method of acute lung injury classification for use in observational studies

BACKGROUND

In observational studies using acute lung injury (ALI) as an outcome, a spectrum of lung injury and difficult-to-interpret chest radiographs (CXRs) may hamper efforts to uncover risk factor associations. We assessed the impact of excluding patients with difficult-to-classify or equivocal ALI diagnosis on clinical and genetic risk factor associations for ALI after trauma.

METHODS

This study was of a prospective cohort of 280 critically ill trauma patients. The primary outcome was the development of ALI. Patients were classified into one of three groups: (1) definite ALI (patients who fulfilled the American-European Consensus Conference [AECC] criteria for ALI), (2)equivocal ALI (patients who had difficult-to-interpret CXRs), and (3) definite non-ALI. We compared clinical and genetic ALI risk factor associations between two classification schemes: AECC classification (definite ALI vs rest) and alternative classification (definite ALI vs definite non-ALI, excluding equivocal ALI).

RESULTS

Ninety-three (35%) patients were classified as definite ALI, 67 (25%) as equivocal, and 104 (39%) as definite non-ALI. Estimates of clinical and genetic ALI risk factor associations were farther from the null using the alternative classification. In a multivariable risk factor model, the C statistic of the alternative classification was significantly higher than that derived from the AECC classification (0.82 vs 0.74; P < .01).

CONCLUSIONS

The ability to detect ALI risk factors may be improved by excluding patients with equivocal or difficult-to-classify ALI. Such analyses may provide improved ability to detect clinical and genetic risk factor associations in future epidemiologic studies of ALI.

Review of a Large Clinical Series: The Value of Routinely Obtained Chest Radiographs on Admission to a Mixed Medical—Surgical Intensive Care Unit

Background and objectives: The efficacy of routinely obtained chest radiographs (CXRs) on admission to the intensive care unit (ICU) is largely unknown. The current study investigated the efficacy of routinely obtained admission CXRs and determined whether the value of this diagnostic test was dependent on patient category. Materials and Methods: Prospective nonrandomized controlled study. including 1081 admission CXRs of 1330 patients admitted to a 28-bed mixed medical—surgical university-affiliated ICU, over a 10-month period. To determine the value of admission CXRs, 2 categories of efficacy were used: diagnostic efficacy (the number of CXRs with a new or progressive major finding divided by the total number of CXRs) and therapeutic efficacy (the number of CXRs resulting in a change in clinical management divided by the total number of CXRs). Efficacy <15% was considered low. Patients were subclassified into subcategories on the basis of type of admission. Results: Of all admission CXRs, 227 were clinically indicated and 854 were routinely obtained to establish a baseline prior to admission to ICU. Diagnostic efficacy of routinely obtained admission CXRs was 11%. The majority of abnormalities were malposition of invasive devices and severe pulmonary congestion. Therapeutic efficacy of routinely obtained admission CXRs was only 5%. Subgroup analysis showed highest efficacy in nonsurgical patients. Conclusions: In our mixed medical—surgical ICU the diagnostic and therapeutic efficacy of routinely obtained admission CXRs is low, though not completely negligible. Highest efficacy of CXRs was found in nonsurgical patients. Prospective studies are needed to determine whether abolishing this diagnostic test is a safe strategy.

Efficacy and acceptability of mood stabilisers in the treatment of acute bipolar depression: systematic review

BACKGROUND

Although people with bipolar disorder spend more time in a depressed than manic state, little evidence is available to guide the treatment of acute bipolar depression.

AIMS

To compare the efficacy, acceptability and safety of mood stabiliser monotherapy with combination and antidepressant treatment in adults with acute bipolar depression.

METHOD

Systematic review and meta-analysis of randomised, double-blind controlled trials.

RESULTS

Eighteen studies with a total 4105 participants were analysed. Mood stabiliser monotherapy was associated with increased rates of response (relative risk (RR) = 1.30, 95% CI 1.16-1.44, number needed to treat (NNT) = 10, 95% CI 7-18) and remission (RR = 1.51, 95% CI 1.27-1.79, NNT = 8, 95% CI 5-14) relative to placebo. Combination therapy was not statistically superior to monotherapy. Weight gain, switching and suicide rates did not differ between groups. No differences were found between individual medications or drug classes for any outcome.

CONCLUSIONS

Mood stabilisers are moderately efficacious for acute bipolar depression. Extant studies are few and limited by high rates of discontinuation and short duration. Further study of existing and novel agents is required.

Documentation of best interest by intensivists: a retrospective study in an Ontario critical care unit

BACKGROUND

Intensive care physicians often must rely on substitute decision makers to address all dimensions of the construct of "best interest" for incapable, critically ill patients. This task involves identifying prior wishes and to facilitate the substitute decision maker's understanding of the incapable patient's condition and their likely response to treatment. We sought to determine how well such discussions are documented in a typical intensive care unit.

METHODS

Using a quality of communication instrument developed from a literature search and expert opinion, 2 investigators transcribed and analyzed 260 handwritten communications for 105 critically ill patients who died in the intensive care unit between January and June 2006. Cohen's kappa was calculated before analysis and then disagreements were resolved by consensus. We report results on a per-patient basis to represent documented communication as a process leading up to the time of death in the ICU. We report frequencies and percentages for discrete data, median (m) and interquartile range (IQR) for continuous data.

RESULTS

Our cohort was elderly (m 72, IQR 58-81 years) and had high APACHE II scores predictive of a high probability of death (m 28, IQR 23-36). Length of stay in the intensive care unit prior to death was short (m 2, IQR 1-5 days), and withdrawal of life support preceded death for more than half (n 57, 54%). Brain death criteria were present for 18 patients (17%). Although intensivists' communications were timely (median 17 h from admission to critical care), the person consenting on behalf of the incapable patient was explicitly documented for only 10% of patients. Life support strategies at the time of communication were noted in 45% of charts, and options for their future use were presented in 88%. Considerations relevant to determining the patient's best interest in relation to the treatment plan were not well documented. While explicit survival estimates were noted in 50% of charts, physicians infrequently documented their own predictions of the patient's functional status (20%), anticipated need for chronic care (0%), or post ICU quality of life (3%). Similarly, documentation of the patient's own perspectives on these ranged from 2-18%.

CONCLUSIONS

Intensivists' documentation of their communication with substitute decision makers frequently outlined the proposed plan of treatment, but often lacked evidence of discussion relevant to whether the treatment plan was expected to improve the patient's condition. Legislative standards for determination of best interest, such as the Health Care Consent Act in Ontario, Canada, may provide guidance for intensivists to optimally document the rationales for proposed treatment plans.

Diagnosing acute lung injury in the critically ill: a national survey among critical care physicians

BACKGROUND

Incidence reports on acute lung injury (ALI) vary widely. An insight into the diagnostic preferences of critical care physicians when diagnosing ALI may improve identification of the ALI patient population.

METHODS

Critical care physicians in the Netherlands were surveyed using vignettes involving hypothetical patients and a questionnaire. The vignettes varied in seven diagnostic determinants based on the North American European Consensus Conference and the lung injury score. Preferences were analyzed using a mixed-effects logistic regression model and presented as an odds ratio (OR) with a 95% confidence interval.

RESULTS

From 243 surveys sent to 30 hospitals, 101 were returned (42%). ORs were as follows: chest X-ray consistent with ALI: OR 1.7 (1.3-2.3), high positive end-expiratory pressure (PEEP) (15 cmH(2)O): OR 5.0 (3.9-6.6), low pulmonary artery occlusion pressures (PAOP) (<18 mmHg): OR 4.7 (3.6-6.1), low compliance (30 ml/cmH(2)O): OR 0.7 (0.5-0.9), low PaO(2)/FiO(2) (<250 mmHg): OR 9.2 (6.9-12.3), absence of heart failure: OR 1.2 (0.9-1.5), presence of a risk factor for ALI (sepsis): OR 1.0 (0.8-1.3). The questionnaire revealed that critical care physicians with an anesthesiology background differed from physicians with an internal medicine background with regard to hemodynamic variables when considering an ALI diagnosis (P<0.05).

CONCLUSIONS

Dutch critical care physicians consider the PEEP level, but not the presence of a risk factor for ALI, as an important factor to diagnose ALI. Background specialty of critical care physicians influences diagnostic preferences and may account for variance in the reported incidence of ALI.

Body mass index is associated with the development of acute respiratory distress syndrome

BACKGROUND

The relationship between body mass index (BMI) and development of acute respiratory distress syndrome (ARDS) is unknown.

METHODS

A cohort study of critically ill patients at risk for ARDS was carried out. BMI was calculated from admission height and weight. Patients were screened daily for AECC (American European Consensus Committee)-defined ARDS and 60-day ARDS mortality.

RESULTS

Of 1795 patients, 83 (5%) patients were underweight (BMI <18.5 kg/m(2)), 627 (35%) normal (BMI 18.5-24.9), 605 (34%) overweight (BMI 25-29.9), 364 (20%) obese (BMI 30-39.9) and 116 (6%) severely obese (BMI > or =40). Increasing weight was associated with younger age (p<0.001), diabetes (p<0.0001), higher blood glucose (p<0.0001), lower prevalence of direct pulmonary injury (p<0.0001) and later development of ARDS (p = 0.01). BMI was associated with ARDS on multivariate analysis (OR(adj) 1.24 per SD increase; 95% CI 1.11 to 1.39). Similarly, obesity was associated with ARDS compared with normal weight (OR(adj) 1.66; 95% CI 1.21 to 2.28 for obese; OR(adj) 1.78; 95% CI 1.12 to 2.92 for severely obese). Exploratory analysis in a subgroup of intubated patients without ARDS on admission (n = 1045) found that obese patients received higher peak (p<0.0001) and positive end-expiratory pressures (p<0.0001) than non-obese patients. Among patients with ARDS, increasing BMI was associated with increased length of stay (p = 0.007) but not with mortality (OR(adj) 0.89 per SD increase; 95% CI 0.71 to 1.12).

CONCLUSION

BMI was associated with increased risk of ARDS in a weight-dependent manner and with increased length of stay, but not with mortality. Additional studies are needed to determine whether differences in initial ventilator settings may contribute to ARDS development in the obese.

Primary graft dysfunction; possible evaluation by high resolution computed tomography, and suggestions for a scoring system

We have reviewed and discussed current knowledge on existing scoring systems regarding high resolution computed tomography (HRCT) images for the assessment of primary graft dysfunction (PGD) after lung transplantation. Adult respiratory distress syndrome (ARDS) has been more widely studied and appears to have many morphological features similar to what is found in PGD, and might, therefore, be usefully extrapolated to PGD. Principles of HRCT, scoring systems based on HRCT and various terms describing PGD were reviewed and summarized. The sensitivity, inter-intra observer variability, and reproducibility of these systems were discussed. Lastly, the future perspectives for 64-multi-slice computed tomography (MSCT) in relation to PGD were discussed. Few studies on scoring systems of lung tissue by HRCT in ARDS patients and idiopathic pulmonary fibrosis (IPF) patients were found. Most studies were performed on patients with cystic fibrosis (CF). Sensitivity of HRCT for the detection of parenchymal changes is superior to other imaging methods. High levels of reproducibility are achievable amongst observers who score HRCT lung images. Development of standardized criteria that specify the inclusion/exclusion criteria of patients, pilot testing, and training investigators through review of disagreements, were possibilities suggested for decreasing inter/intra observer variability. Factors affecting the image attenuation (Hounsfield numbers) and thus, the reproducibility of CT densitometric measurements were of minimal influence. Studies have reported on how lung tissue images, derived by HRCT, can be scored and graded. There does not seem to be a golden standard for evaluating these images, which makes comparison between methods challenging. These scoring systems assess the presence, severity, and extent of parenchymal change in the lung. HRCT is considered relevant and superior in evaluating disease severity, disease progression, and in evaluating the effects of therapy regimes in the lung. It is, however, not clear to what extent these scoring methods may be implemented for grading PGD. Further efforts could be made to standardize scoring methods for lung tissue with regards to PGD.

Accuracy of clinical definitions of ventilator-associated pneumonia: comparison with autopsy findings

METHODS

We studied patients requiring mechanical ventilation for more than 48 hours who died in the intensive care unit and whose bodies were autopsied. We evaluated 3 clinical definitions of ventilator-associated pneumonia: loose definition, defined as chest radiograph infiltrates and 2 of 3 clinical criteria (leukocytosis, fever, purulent respiratory secretions); rigorous definition, defined as chest radiograph infiltrates and all of the clinical criteria; and a clinical pulmonary infection score higher than 6 points. Sensitivity, specificity, and likelihood ratios were calculated by using pathology pattern as criterion standard.

RESULTS

One hundred forty-two (56%) of the 253 patients included had histological criteria of pneumonia. Patients who met the clinical criteria of ventilator-associated pneumonia were 163 (64%) for the loose definition, 32 (13%) for the rigorous definition, and 109 (43%) for the clinical pulmonary infection score. The operative indexes (sensitivity and specificity) of each definition were as follows: loose definition, 64.8% and 36%; rigorous definition, 91% and 15.5%; and clinical pulmonary infection score higher than 6, 45.8% and 60.4%. The addition of microbiological data to the clinical definitions increased the specificity and decreased the sensitivity but not significantly.

CONCLUSIONS

Accuracy of 3 commonly used clinical definitions of ventilator-associated pneumonia was poor taking the autopsy findings as reference standard.

Acute respiratory failure in intensive care units. FINNALI: a prospective cohort study

OBJECTIVE

To evaluate the incidence, treatment and mortality of acute respiratory failure (ARF) in Finnish intensive care units (ICUs).

STUDY DESIGN

Prospective multicentre cohort study.

METHODS

All adult patients in 25 ICUs were screened for use of invasive or non-invasive ventilatory support during an 8-week period. Patients needing ventilatory support for more than 6 h were included and defined as ARF patients. Risk factors for ARF and details of prior chronic health status were assessed. Ventilatory and concomitant treatments were evaluated and recorded daily throughout the ICU stay. ICU and 90-day mortalities were assessed.

RESULTS

A total of 958 (39%) from the 2,473 admitted patients were treated with ventilatory support for more than 6 h. Incidence of ARF, acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) was 149.5, 10.6 and 5.0/100,000 per year, respectively. Ventilatory support was started with non-invasive interfaces in 183 of 958 (19%) patients. Ventilatory modes allowing triggering of spontaneous breaths were preferred (81%). Median tidal volume/predicted body weight was 8.7 (7.6-9.9) ml/kg and plateau pressure 19 (16-23) cmH2O. The 90-day mortality of ARF was 31%.

CONCLUSIONS

While the incidence of ARF requiring ventilatory support is higher, the incidence of ALI and ARDS seems to be lower in Finland than previously reported in other countries. Tidal volumes are higher than recommended in the concept of lung protective strategy. However, restriction of peak airway pressure was used in the majority of ARF patients.

Clinician's use of the Statin Choice decision aid in patients with diabetes: a videographic study nested in a randomized trial

OBJECTIVE

To describe how clinicians use decision aids.

BACKGROUND

A 98-patient factorial-design randomized trial of the Statin Choice decision vs. standard educational pamphlet; each participant had a 1:4 chance of receiving the decision aid during the encounter with the clinician resulting in 22 eligible encounters.

DESIGN

Two researchers working independently and in duplicate reviewed and coded the 22 encounter videos.

SETTING AND PARTICIPANTS

Twenty-two patients with diabetes (57% of them on statins) and six endocrinologists working in a referral diabetes clinic randomly assigned to use the decision aid during the consultation.

MAIN OUTCOME MEASURES

Proportion and nature of unintended use of the Statin Choice decision aid.

RESULTS

We found eight encounters involving six clinicians who did not use the decision aid as intended either by not using it at all (n = 5; one clinician did use the decision aid in three encounters), offering inaccurate quantitative and probabilistic information about the risks and benefits of statins (n = 2), or using the decision aid to advance the agenda that all patients with diabetes should take statin (n = 1). Clinicians used the decision aid as intended in all other encounters.

CONCLUSIONS

Unintended decision aid use in the context of videotaped encounters in a practical randomized trial was common. These instances offer insights to researchers seeking to design and implement effective decision aids for use during the clinical visit, particularly when clinicians may prefer to proceed in ways that the decision aid apparently contradicts.

Interobserver variability in antroduodenal manometry

Interobserver variability affects investigations involving assessment of complex visual data, such as histopathology, radiology and motility. This study assessed interobserver variation for interpretation of antroduodenal manometry (ADM), as this has not been previously investigated. Thirty-five ADM recordings from children aged 0.3-18 years were independently evaluated by five experienced paediatric gastroenterologists who were blinded to cases' clinical histories. Intra-class correlation (ICC) was analysed for detection and measurement of phase three of the migrating motor complex (MMC) and Cohen's kappa statistic was calculated between observer pairs for detection of specific motility features and final diagnosis. Observers were unanimous on the differentiation of normal and abnormal motility in 63% of cases. There was excellent interobserver agreement for the number of phase three of the MMC in fasting (ICC = 0.82, P < 0.0001) and for measurements of phase three of the MMC (ICC = 0.9999, P < 0.0001). Detection of other normal and abnormal motility patterns varied more. Objective findings such as the presence of phase three of the MMC correlated more closely than findings that involved the integration of several variables, such as final diagnosis. However, these data overall indicate that agreement between expert observers for the distinction of normal and abnormal antroduodenal motility compares favourably with other standard medical assessments.

Occupational exposures and asthma in health-care workers: comparison of self-reports with a workplace-specific job exposure matrix

The authors compared self-reported occupational exposures with a workplace-specific job exposure matrix (JEM) in a 2004 survey of Texas health-care professionals (n = 3,650), by asthma status. Sensitivity, specificity, chance-corrected (kappa) and chance-independent (phi) agreement, and associations of self-reported exposures with asthma were compared with those for the JEM. Among asthmatics, the median sensitivity of self-reported exposures was 74% (range, 53-90); specificity was 64% (range, 27-74). For nonasthmatics, median sensitivity was 67% (range, 40-88) and specificity was 70% (range, 33-82). Sensitivity was higher among asthmatics for exposures involving perceptible odors. Specificity was higher among nonasthmatics for instrument cleaning and exposure to adhesives/solvents. Asthmatics showed better agreement with the JEM for patient-care-related cleaning (phi = 0.51 vs. 0.40); there was little difference for other exposures. In all cases, confidence intervals overlapped. Prevalence ratios were higher with self-reported exposures than with the JEM; differences were greatest for cleaning products, adhesives/solvents, and gases/vapors. However, confidence intervals overlapped with those obtained using the JEM. In asthma studies, differential reporting bias by health status should be taken into consideration. Findings favor using externally developed methods of exposure classification, although information gleaned from examining distributions of exposure self-reports, particularly among nondiseased persons, can provide useful information for improving the reliability of exposure ascertainment.

Acute respiratory distress syndrome 40 years later: time to revisit its definition

OBJECTIVE

Acute respiratory distress syndrome is a common disorder associated with significant mortality and morbidity. The aim of this article is to critically evaluate the definition of acute respiratory distress syndrome and examine the impact the definition has on clinical practice and research.

DATA SOURCES

Articles from a MEDLINE search (1950 to August 2007) using the Medical Subject Heading respiratory distress syndrome, adult, diagnosis, limited to the English language and human subjects, their relevant bibliographies, and personal collections, were reviewed.

DATA SYNTHESIS

The definition of acute respiratory distress syndrome is important to researchers, clinicians, and administrators alike. It has evolved significantly over the last 40 years, culminating in the American-European Consensus Conference definition, which was published in 1994. Although the American-European Consensus Conference definition is widely used, it has some important limitations that may impact on the conduct of clinical research, on resource allocation, and ultimately on the bedside management of such patients. These limitations stem partially from the fact that as defined, acute respiratory distress syndrome is a heterogeneous entity and also involve the reliability and validity of the criteria used in the definition. This article critically evaluates the American-European Consensus Conference definition and its limitations. Importantly, it highlights how these limitations may contribute to clinical trials that have failed to detect a potential true treatment effect. Finally, recommendations are made that could be considered in future definition modifications with an emphasis on the significance of accurately identifying the target population in future trials and subsequently in clinical care.

CONCLUSION

How acute respiratory distress syndrome is defined has a significant impact on the results of randomized, controlled trials and epidemiologic studies. Changes to the current American-European Consensus Conference definition are likely to have an important role in advancing the understanding and management of acute respiratory distress syndrome.

Inter-observer variability in chest radiograph reading for diagnosing acute lung injury in children

Acute lung injury (ALI), including its most serious form called acute respiratory distress syndrome (ARDS), is a devastating disease that can occur at any age. ALI/ARDS accounts for only 5-8% of admissions to pediatric intensive care units (PICUs) but is fatal in 30-60% of cases. International multicenter prospective studies are needed to better understand pediatric ALI/ARDS. However, a reproducible definition of ALI/ARDS is crucial to ensure that study populations are homogeneous. We designed a retrospective review to test the inter-observer variability of chest radiograph interpretation for presence of the American-European Consensus Conference (AECC) radiographic criterion for ALI/ARDS. The medical files of 24 children ventilated for ALI/ARDS in our PICU between January 1993 and December 2002 were reviewed. Five pediatric radiologists and five pediatric intensivists interpreted one frontal chest radiograph (FCR) per patient taken on the day of ALI/ARDS diagnosis. Each reader indicated whether the radiograph showed the AECC radiographic criterion for ALI/ARDS. Data analysis involved comparing each reader to all the others based on the raw agreement and Kappa coefficient (kappa). Features in the 24 patients were consistent with earlier studies. Global inter-observer agreement beyond chance was fair (kappa = 0.29 +/- 0.02) among the five radiologists (kappa = 0.26 +/- 0.05) and among the five intensivists (kappa = 0.29 +/- 0.05). Thus, considerable inter-observer variability occurred in assessing the radiographic criterion for ALI/ARDS, as previously shown in adults. Given the low incidence of ALI/ARDS in children, this variability may have a large impact in studies of pediatric ALI/ARDS.

Implications of early versus late bilateral pulmonary infiltrates in patients with aneurysmal subarachnoid hemorrhage

INTRODUCTION

Bilateral pulmonary infiltrates occur frequently following aneurysmal subarachnoid hemorrhage (SAH), and may be associated with worse outcomes. The etiology, natural history, and prognosis of infiltrates occurring soon after SAH may differ from the characteristics of infiltrates developing at a later time.

METHODS

We performed a retrospective cohort study involving 245 consecutive patients with a ruptured cerebral aneurysm to assess the association between "early" (< or = 72 h) or "late" (>72 h) bilateral pulmonary infiltrates and subsequent death or neurologic impairment. We used logistic regression models to adjust for baseline differences in age, level of consciousness, amount of blood on computed tomography, and the presence or absence of clinical vasospasm.

RESULTS

Sixty-seven patients (27%) developed bilateral pulmonary infiltrates. Of these, 36 (54%) had early infiltrates, 24 (36%) had late infiltrates, and 7 (10%) had both. Twenty-eight patients (11% of entire cohort) met criteria for acute respiratory distress syndrome (ARDS). Patients with early infiltrates were more likely to have presented with stupor or coma than patients who developed infiltrates later (64% vs. 29%, P < 0.01). In multivariable analysis, late pulmonary infiltrates were strongly predictive of poor outcome (OR 5.0, 95% CI 1.9-13.6, P < 0.01), while early infiltrates were not (OR 1.2, 95% CI 0.5-3.0, P = 0.66).

CONCLUSIONS

Bilateral pulmonary infiltrates after SAH most often occur within three days of aneurysm rupture. However, only infiltrates occurring beyond this time are independently associated with poor outcome. Increased emphasis on the prevention of late pulmonary complications has the potential to improve outcomes in SAH.

Outcomes of Tube Thoracostomies Performed by Advanced Practice Providers vs Trauma Surgeons

Background The role of advanced registered nurse practitioners and physician assistants in emergency departments, trauma centers, and critical care is becoming more widely accepted. These personnel, collectively known as advanced practice providers, expand physicians’ capabilities and are being increasingly recruited to provide care and perform invasive procedures that were previously performed exclusively by physicians.

Objectives To determine whether the quality of tube thoracostomies performed by advanced practice providers is comparable to that performed by trauma surgeons and to ascertain whether the complication rates attributable to tube thoracostomies differ on the basis of who performed the procedure.

Methods Retrospective blinded reviews of patients’ charts and radiographs were conducted to determine differences in quality indicators, complications, and outcomes of tube thoracostomies by practitioner type: trauma surgeons vs advanced practice providers.

Results Differences between practitioner type in insertion complications, complications requiring additional interventions, hospital length of stay, and morbidity were not significant. The only significant difference was a complication related to placement of the tube: when the tube extended caudad, toward the feet, from the insertion site. Interrater reliability ranged from good to very good.

Conclusions Use of advanced practice providers provides consistent and quality tube thoracostomies. Employment of these practitioners may be a safe and reasonable solution for staffing trauma centers.

Red blood cell transfusions and the risk of acute respiratory distress syndrome among the critically ill: a cohort study

INTRODUCTION

Recent data indicate that transfusion of packed red blood cells (pRBCs) may increase the risk for the development of acute respiratory distress syndrome (ARDS) in critically ill patients. Uncertainty remains regarding the strength of this relationship.

METHODS

To quantify the association between transfusions and intensive care unit (ICU)-onset ARDS, we performed a cohort study within Crit, a multicenter, prospective, observational study of transfusion practice in the ICU which enrolled 4,892 critically ill patients in 284 ICUs in the United States. Diagnostic criteria for ARDS were prospectively defined, and we focused on subjects without ARDS at admission. The development of ARDS in the ICU served as the primary endpoint.

RESULTS

Among the 4,730 patients without ARDS at admission, 246 (5.2%) developed ARDS in the ICU. At baseline, ARDS cases were younger, more likely to be in a surgical ICU, and more likely to be admitted with pneumonia or sepsis than controls without ARDS. Cases also were more likely to have a serum creatinine of greater than 2.0 mg/dl (23% versus 18%) and a serum albumin of less than or equal to 2.3 g/dl (54% versus 30%) and were more severely ill upon ICU admission as measured by either the APACHE II (Acute Physiology and Chronic Health Evaluation II) or SOFA (Sequential Organ Failure Assessment) score (p < 0.05 for all). Sixty-seven percent and 42% of cases and controls, respectively, had exposure to pRBC transfusions (p < 0.05), and the unadjusted odds ratio (OR) of developing ARDS in transfused patients was 2.74 (95% confidence interval [CI], 2.09 to 3.59; p < 0.0001) compared to those never transfused. After age, baseline severity of illness, admitting diagnosis, and process-of-care factors were adjusted for, the independent relationship between pRBC transfusions and ICU-onset ARDS remained significant (adjusted OR, 2.80; 95% CI, 1.90 to 4.12; p < 0.0001).

CONCLUSION

Development of ARDS after ICU admission is common, occurring in approximately 5% of critically ill patients. Transfusion of pRBCs is independently associated with the development of ARDS in the ICU.

Extravascular lung water in sepsis-associated acute respiratory distress syndrome: indexing with predicted body weight improves correlation with severity of illness and survival

OBJECTIVES

To determine whether extravascular lung water predicts survival in patients with early acute respiratory distress syndrome, to determine the relationship between extravascular lung water and other markers of lung injury, and to examine if indexing extravascular lung water with predicted body weight (EVLWp) strengthens its discriminative power.

DESIGN

Extravascular lung water and other markers of lung injury were measured prospectively in 19 patients with sepsis-induced acute respiratory distress syndrome for 3 days.

SETTING

The intensive care units of an academic tertiary referral hospital.

MEASUREMENTS AND MAIN RESULTS

Lung injury score, Sequential Organ Failure Assessment score, dead space-tidal volume fraction (Vd/Vt), and EVLWp were all significantly higher on day 1 in nonsurvivors compared with survivors (lung injury score, 2.8 +/- 0.34 vs. 1.9 +/- 0.50; p = .004) (Sequential Organ Failure Assessment score, 13 +/- 3.4 vs. 7.7 +/- 0.8; p = .006) (Vd/Vt, 0.68 +/- 0.07 vs. 0.58 +/- 0.07; p = .009) (EVLWp, 20.6 +/- 4.6 vs. 11.6 +/- 1.9 mL/kg; p = .002). EVLWp correlated with Sequential Organ Failure Assessment score, lung injury score, Vd/Vt, and PaO2/FIO2. The receiver operator characteristic curve analysis indicated that EVLWp, Vd/Vt, and extravascular lung water (p = .0005, .009, and .013, respectively) but not PaO2/FIO2 (p = .311) discriminate between survivors and nonsurvivors. Three-day average EVLWp >16 mL/kg predicted in-hospital mortality with 100% specificity and 86% sensitivity.

CONCLUSIONS

Increased extravascular lung water is a feature of early acute respiratory distress syndrome and predicts survival. Indexing extravascular lung water to predicted body weight, instead of actual body weight, improves the predictive value of extravascular lung water for survival and correlation with markers of disease severity.

External validation of a measurement tool to assess systematic reviews (AMSTAR)

BACKGROUND

Thousands of systematic reviews have been conducted in all areas of health care. However, the methodological quality of these reviews is variable and should routinely be appraised. AMSTAR is a measurement tool to assess systematic reviews.

METHODOLOGY

AMSTAR was used to appraise 42 reviews focusing on therapies to treat gastro-esophageal reflux disease, peptic ulcer disease, and other acid-related diseases. Two assessors applied the AMSTAR to each review. Two other assessors, plus a clinician and/or methodologist applied a global assessment to each review independently.

CONCLUSIONS

The sample of 42 reviews covered a wide range of methodological quality. The overall scores on AMSTAR ranged from 0 to 10 (out of a maximum of 11) with a mean of 4.6 (95% CI: 3.7 to 5.6) and median 4.0 (range 2.0 to 6.0). The inter-observer agreement of the individual items ranged from moderate to almost perfect agreement. Nine items scored a kappa of >0.75 (95% CI: 0.55 to 0.96). The reliability of the total AMSTAR score was excellent: kappa 0.84 (95% CI: 0.67 to 1.00) and Pearson's R 0.96 (95% CI: 0.92 to 0.98). The overall scores for the global assessment ranged from 2 to 7 (out of a maximum score of 7) with a mean of 4.43 (95% CI: 3.6 to 5.3) and median 4.0 (range 2.25 to 5.75). The agreement was lower with a kappa of 0.63 (95% CI: 0.40 to 0.88). Construct validity was shown by AMSTAR convergence with the results of the global assessment: Pearson's R 0.72 (95% CI: 0.53 to 0.84). For the AMSTAR total score, the limits of agreement were -0.19+/-1.38. This translates to a minimum detectable difference between reviews of 0.64 'AMSTAR points'. Further validation of AMSTAR is needed to assess its validity, reliability and perceived utility by appraisers and end users of reviews across a broader range of systematic reviews.

High tidal volume is associated with the development of acute lung injury after severe brain injury: an international observational study

OBJECTIVE

Although a significant number of patients with severe brain injury develop acute lung injury, only intracranial risk factors have previously been studied. We investigated the role of extracranial predisposing factors, including hemodynamic and ventilatory management, as independent predictors of acute lung injury in brain-injured patients.

DESIGN

Prospective multicenter observational study.

SETTING

Four European intensive care units in university-affiliated hospitals.

PATIENTS

Eighty-six severely brain-injured patients enrolled in 13 months.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients with severe brain injury (Glasgow Coma Scale score <9) were studied for 8 days from admission. Ventilatory pattern, respiratory system compliance, blood gas analysis, and hemodynamic profile were recorded and entered in a stepwise regression model. Length of stay in the intensive care unit, ventilator-free days, and mortality were collected. Eighteen patients (22%) developed acute lung injury on day 2.8 +/- 1. They were initially ventilated with significantly higher tidal volume per predicted body weight (9.5 +/- 1 vs. 10.4 +/- 1.1), respiratory rate, and minute ventilation and more often required vasoactive drugs (p < .05). In addition to a lower Pao2/Fio2 (odds ratio 0.98, 95% confidence interval 0.98-0.99), the use of high tidal volume (odds ratio 5.4, 95% confidence interval 1.54-19.24) and relatively high respiratory rate (odds ratio 1.8, 95% confidence interval 1.13-2.86) were independent predictors of acute lung injury (p < .01). After the onset of acute lung injury, patients remained ventilated with similar tidal volumes to maintain mild hypocapnia and had a longer length of stay in the intensive care unit and fewer ventilator-free days (p < .05).

CONCLUSIONS

In addition to a lower Pao2/Fio2, the use of high tidal volume and high respiratory rate are independent predictors of acute lung injury in patients with severe brain injury. In this patient population, alternative ventilator strategies should be considered to protect the lung and guarantee a tight CO2 control.

Comparison of the SpO2/FIO2 ratio and the PaO2/FIO2 ratio in patients with acute lung injury or ARDS

BACKGROUND

The diagnostic criteria for acute lung injury (ALI) and ARDS utilize the Pao(2)/fraction of inspired oxygen (Fio(2)) [P/F] ratio measured by arterial blood gas analysis to assess the degree of hypoxemia. We hypothesized that the pulse oximetric saturation (Spo(2))/Fio(2) (S/F) ratio can be substituted for the P/F ratio in assessing the oxygenation criterion of ALI.

METHODS

Corresponding measurements of Spo(2) (values </= 97%) and Pao(2) from patients enrolled in the ARDS Network trial of a lower tidal volume ventilator strategy (n = 672) were compared to determine the relationship between S/F and P/F. S/F threshold values correlating with P/F ratios of 200 (ARDS) and 300 (ALI) were determined. Similar measurements from patients enrolled in the ARDS Network trial of lower vs higher positive end-expiratory pressure (n = 402) were utilized for validation.

RESULTS

In the derivation data set (2,613 measurements), the relationship between S/F and P/F was described by the following equation: S/F = 64 + 0.84 x (P/F) [p < 0.0001; r = 0.89). An S/F ratio of 235 corresponded with a P/F ratio of 200, while an S/F ratio of 315 corresponded with a P/F ratio of 300. The validation database (2,031 measurements) produced a similar linear relationship. The S/F ratio threshold values of 235 and 315 resulted in 85% sensitivity with 85% specificity and 91% sensitivity with 56% specificity, respectively, for P/F ratios of 200 and 300.

CONCLUSION

S/F ratios correlate with P/F ratios. S/F ratios of 235 and 315 correlate with P/F ratios of 200 and 300, respectively, for diagnosing and following up patients with ALI and ARDS.

Bedside assessment of extravascular lung water by dilution methods: temptations and pitfalls

OBJECTIVES

To review the advantages and limitations of dilution methods to assess extravascular lung water (EVLW) at the bedside and to discuss the clinical value of EVLW measurements.

DATA SOURCE

Experimental and clinical studies were searched in PUBMED by using "extravascular lung water" and "dilution method" as keywords and further selected as studies investigating either the reliability or the clinical usefulness of dilution methods to assess EVLW. Related articles and the reference lists of selected studies were scanned for additional relevant references.

CONCLUSIONS

Both the double-indicator (thermo-dye) dilution and the single-indicator (cold saline) dilution methods showed close agreement with gravimetric measurement of EVLW (the reference ex vivo method) and have the advantage of being available at the bedside. Most limitations of dilution methods have been described in experimental conditions and lead to an underestimation of EVLW. These limitations include large pulmonary vascular obstruction, focal lung injury, and lung resection. Dilution methods provide an easy and clinically acceptable estimation of EVLW in most critically ill patients, including those with acute respiratory distress syndrome (ARDS). Assessing EVLW may be useful to predict outcome, to diagnose pulmonary edema, to better characterize patients with ARDS, to guide fluid therapy, and to assess the value of new treatments or ventilatory strategies in patients with pulmonary edema.

Potential Refinements of The International Society for Heart And Lung Transplantation Primary Graft Dysfunction Grading System

Primary graft dysfunction (PGD) is responsible for significant morbidity and mortality after lung transplantation and The International Society for Heart and Lung Transplantation (ISHLT) Working Group on PGD has recently reported standardized consensus criteria, based on the recipient arterial blood-gas analysis and chest X-ray findings, to define PGD and determine its severity (grade range, 0-3). The grading system has been shown to predict post-transplant outcomes; however, further evaluation and refinement of the validity of the grading system is an important next step to enhance its utility. In this review, we describe advantage and disadvantages of the current PGD grading system based on series of analyses we have conducted and possible options for its potential refinement. The suggested revisions are (1) additional assessment time points at 6 and 12 hours should be included, (2) only bilateral infiltrates on chest X-ray (not unilateral infiltrates) should be considered as an infiltrate in bilateral lung transplants, (3) information from the chest X-ray is useful within 6 hours of final lung reperfusion (T0) but is not necessary to classify grade 3 at 12 to 72 hours, (4) apply PGD grade to single and bilateral lung transplant separately, (5) all extubated patients should be considered as grade 0 to 1, (6) note if PGD grade is being defined by specific inclusion and exclusion criteria, including extubation, with clear chest X-ray, on nitric oxide or extracorporeal membrane oxygenation. Although, further evaluations of the PGD definition and grading system are needed, the suggested refinements in this review may further enhance the reliability and validity of the PGD grading system as an important new lung transplant study instrument.

Transfusion-related acute lung injury in patients with burns

Transfusion-related acute lung injury (TRALI) has not been systematically described in patients with burn injury, and the characterization of TRALI in patients with pre-existing acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) also is lacking. Our aim was to identify TRALI in burn patients and to attempt to characterize transfusion (TXN)-related pulmonary deterioration in burn patients with pre-existing ALI or ARDS. We undertook a retrospective review of mechanically ventilated and transfused burn patients at an adult regional burn center between January 1, 2003, and January 5, 2005. A blinded intensivist independently rated pre- and post-TXN chest radiographs (CXRs). There were 25 patients (age 51 +/- 19 years, %TBSA burns 30 +/- 19, full thickness %BSA 17 +/- 19, with a 24% incidence of smoke inhalation) who received 124 TXNs. New ALI developed within 6 hours after four TXNs. In one TXN, there were no other precipitating causes (eg, infection, inhalation injury), suggesting possible TRALI (incidence 0.8%). Existing ALI or ARDS was present before 63 (51%) of the TXNs. Definite worsening of the CXR and deterioration in the PaO2/FiO2 ratio (18% +/- 4%) within 6 hours of TXN occurred after six transfusions. In two of the TXNs, there were no other precipitating causes, suggesting possible TXN-related pulmonary deterioration (incidence 3.2%). Vigilance must be maintained for TRALI in burn patients. For patients with existing ALI or ARDS, we suggest that worsening of the CXR and reduction in the PaO2/FiO2 ratio by 20% or more within 6 hours of transfusion should be investigated for possible TRALI with appropriate donor investigations.

Polymorphisms in the mannose binding lectin-2 gene and acute respiratory distress syndrome

OBJECTIVE

The variant alleles in the mannose binding lectin-2 (MBL-2) gene have been associated with MBL deficiency and increased susceptibility to sepsis. We postulate that the variant MBL-2 genotypes are associated with increased susceptibility to and mortality in acute respiratory distress syndrome (ARDS).

DESIGN

Nested case-control study.

SETTING

Tertiary academic medical center.

PATIENTS

Two hundred and twelve Caucasians with ARDS and 442 controls genotyped for the variant X, D, B, and C alleles of codon -221, 52, 54, and 57, respectively.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients homozygous for the variant codon 54B allele (54BB) had worse severity of illness on admission (p = .007), greater likelihood of septic shock (p = .04), and increased odds of ARDS (adjusted odds ratio, 6.7; 95% confidence interval, 1.5-31) when compared with heterozygotes and homozygotes for the wild-type allele. This association with ARDS was especially strong among the 311 patients with septic shock (adjusted odds ratio, 12.0; 95% confidence interval, 1.9-74). Among the patients with ARDS, the 54BB genotype was associated with more daily organ dysfunction (p = .01) and higher mortality (adjusted hazard rate, 4.0; 95% confidence interval, 1.6-10). Development of ARDS and outcomes in ARDS did not vary significantly with variant alleles of codon -221, 52, and 57, but the power to detect an effect was limited secondary to the low allele frequencies.

CONCLUSIONS

The MBL-2 codon 54BB genotype may be important in ARDS susceptibility and outcome. Additional studies are needed to confirm these findings in other populations.

Reproducibility of physiological track-and-trigger warning systems for identifying at-risk patients on the ward

OBJECTIVE

Physiological track-and-trigger warning systems are used to identify patients on acute wards at risk of deterioration, as early as possible. The objective of this study was to assess the inter-rater and intra-rater reliability of the physiological measurements, aggregate scores and triggering events of three such systems.

DESIGN

Prospective cohort study.

SETTING

General medical and surgical wards in one non-university acute hospital.

PATIENTS AND PARTICIPANTS

Unselected ward patients: 114 patients in the inter-rater study and 45 patients in the intra-rater study were examined by four raters.

MEASUREMENTS AND RESULTS

Physiological observations obtained at the bedside were evaluated using three systems: the medical emergency team call-out criteria (MET); the modified early warning score (MEWS); and the assessment score of sick-patient identification and step-up in treatment (ASSIST). Inter-rater and intra-rater reliability were assessed by intra-class correlation coefficients, kappa statistics and percentage agreement. There was fair to moderate agreement on most physiological parameters, and fair agreement on the scores, but better levels of agreement on triggers. Reliability was partially a function of simplicity: MET achieved a higher percentage of agreement than ASSIST, and ASSIST higher than MEWS. Intra-rater reliability was better then inter-rater reliability. Using corrected calculations improved the level of inter-rater agreement but not intra-rater agreement.

CONCLUSION

There was significant variation in the reproducibility of different track-and-trigger warning systems. The systems examined showed better levels of agreement on triggers than on aggregate scores. Simpler systems had better reliability. Inter-rater agreement might improve by using electronic calculations of scores.

Clinical epidemiology of acute lung injury and acute respiratory distress syndrome: incidence, diagnosis, and outcomes

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are clinical syndromes characterized by the sudden onset of severe hypoxemia and diffuse bilateral pulmonary infiltrates in the absence of left atrial hypertension. Although advances have been made in the understanding of the etiology, pathophysiology, and epidemiology of both entities, many questions remain regarding their incidence, diagnosis, and outcomes. This article reviews the currently used definition of ARDS and ALI, different studies that have advanced the understanding of the epidemiology and outcomes of these entities, and several diagnostic issues that are important for both clinicians and researchers.

A study of the agreement between patient self-assessment and study personnel assessment of bleeding symptoms

BACKGROUND

Clinical trials investigating new platelet transfusion therapies frequently require the assessment of bleeding for the study outcome. These assessments are commonly performed by study personnel and can be time-consuming. The purpose of this study was to assess whether patients were able to reliably assess their bleeding status on a daily basis.

STUDY DESIGN AND METHODS

Patients admitted to hospital to receive chemotherapy for acute leukemia or to undergo allogeneic peripheral blood progenitor cell transplant were included. Patients were given an introduction to a form for documenting the occurrence of 16 bleeding symptoms. Patients completed this form and were examined daily by a study assessor. A weekly health record review was also performed by a study assessor. The agreement between raters was determined by calculating the raw agreement, chance-corrected agreement, and chance-independent agreement.

RESULTS

Thirty-five patients completed 458 assessment forms that were paired with 559 forms completed by a study assessor with 450 matched forms available for analysis (mean, 12.86 per patient). Agreement for most individual bleeding symptoms was high. Thirteen items had agreement greater than 90 percent and all items had agreement greater than 77 percent. The lowest agreement was seen for skin symptoms: petechiae (89.2%), purpura (80.9%), and ecchymosis (77.6%). The negative predictive value of patient self-assessment was high (range, 71.1%-100%) whereas the positive predictive value was lower (range, 0%-86.5%).

CONCLUSION

The reliability was very good between patients and study assessors with the patients reporting excellent negative predictive value and variable positive predictive value.

The Role of CT-scan Studies for the Diagnosis and Therapy of Acute Respiratory Distress Syndrome

CT has provided new insights on the pathophysiology of acute respiratory distress syndrome (ARDS), demonstrating that ARDS does not affect the lung parenchyma homogeneously. These findings suggest that lung edema, as assessed by CT scan, should be included in the definition. Lung CT findings may provide a firm rationale for tailoring tidal volume during mechanical ventilation. Ideally, tidal volume should be proportional to the portion of the lung open to ventilation, as assessed by CT scan, rather than to the body weight. CT assessment of lung recruitability seems to be a prerequisite for a rational setting of positive end-expiratory pressure.

Conceptos actuales en la fisiopatología, monitorización y resolución del edema pulmonar

Pulmonary edema, both in its lesional as well as hydrostatic version, is a frequent cause of acute respiratory failure. From the pathophysiological point of view, the most important advance is undoubtedly the knowledge that the reabsorption process of pulmonary edema is an active process with energy consumption. This concept has revolutionized this field due to the possibility of finding substances or factors that stimulate or inhibit this reabsorption. Furthermore, in the monitoring field, significant advances have also been experimented due to the possibility of quantifying the edema in a simple and reliable way with transpulmonary thermodilution.

Limitations of clinical trials in acute lung injury and acute respiratory distress syndrome

PURPOSE OF REVIEW

To review the challenges and limitations of randomized clinical trials in acute respiratory distress syndrome, with special emphasis on those pertaining to ventilatory management.

RECENT FINDINGS

Superbly executed randomized trials of ventilatory strategy have garnered deserved attention from the critical care community and yet have illustrated the limitations of our current approach to clinical research in this area. Inexact definitions, incomplete mechanistic understanding of complex pathophysiology, inappropriate outcome variables, diverse therapeutic environments, lengthy data acquisition time and ethical constraints on trial design limit the applicability of randomized control trial methodology to acute respiratory distress syndrome and acute lung injury. As yet, clinical practice does not seem to have been greatly impacted by the implications of completed randomized controlled trials per se. Recent issues, both ethical and interpretive, regarding control group participants have raised troubling and theoretically important issues that are yet to be fully resolved.

SUMMARY

Without tighter definitions of the condition under treatment, more specific targets for interventions to act upon, stratification that recognizes key interactive elements, and cointerventions based on better mechanistic understanding, randomized controlled trials of new drugs, ventilatory strategy, and other management approaches in acute respiratory distress syndrome are likely to remain a blunt instrument for investigation. As valuable as they are for calling important therapeutic principles to attention and for helping to suggest general guidelines for care, the limitations of randomized controlled trials for treating the individual with acute respiratory distress syndrome must be acknowledged.