Definition Of ARDS Research Articles

Definition of ARDS in Qinghai Province: Verification of Berlin Definition Plateau Criteria

Definition of ARDS in Qinghai Province: Verification of Berlin Definition Plateau Criteria

Current Trends in Pediatric ARDS

Pediatric acute respiratory distress syndrome (PARDS) incidence is reported between 2.95 to 12.8 cases per 100,000 person years,1,2 which is lower than in adults but remains one of the most challenging form of lung diseases for a Pediatric Intensivist. Application of the adult ARDS definition is limited in pediatrics due to differences in risk factors, etiology, pathophysiology, hard to obtain PaO2 values, and lower levels and variation of PEEP utilization. To address these limitations, to promote early recognition and diagnosis of PARDS, and to improve prognostication and stratification of disease severity, the Pediatric Acute Lung Injury Consensus Conference (PALICC) published the first definition for PARDS in 2015.3 This definition (Table 1) kept the criteria of onset within seven days of a known clinical insult and the presence of respiratory failure not fully explained by cardiac failure or fluid overload. It eliminated the term acute lung injury, excluded bilateral infiltrate, and stratified severity of PARDS based on the oxygenation deficit as mild, moderate, and severe. Either oxygenation index or the oxygen saturation index (when arterial blood gas is not available) can be used to assess the degree of hypoxemia. Non-invasive ventilation is now included for continuous positive airway pressure of more than 5 cm H2O. Furthermore, PALICC included recommendations for defining PARDS in children with preexisting chronic lung disease, cyanotic congenital heart disease, and left ventricular dysfunction.The PARDS management guidelines are based on very limited pediatric data and are largely based on expert opinions.3 For ventilatory management, no mode of ventilation is found to be superior, patient-specific tidal volumes per ideal body weight according to disease severity are recommended (3–6 mL/kg for patients with reduced and 5–8 mL/kg for patients with better-preserved compliance). In the absence of transpulmonary pressure measurements, plateau pressure should be limited to 28 cm H2O and 29–32 cm H2O during increased chest wall elastance. Moderately elevated PEEP to 10–15 cm H2O should be titrated in severe PARDS to the observed oxygenation and hemodynamic response. The oxygenation goal for mild PARDS (PEEP < 10) is 92–97% and severe PARDS (PEEP >10) 88–92%, although in some patients, < 88% can be considered with oxygen delivery monitoring. Permissive hypercapnia with a pH of >7.15 is the goal except in severe pulmonary hypertension, intracranial hypertension, select congenital heart lesions, significant ventricular dysfunction with hemodynamic instability, and pregnancy. Recruitment maneuvers by slow incremental and decremental PEEP steps may be used for severe hypoxemia. High-frequency oscillatory ventilation remains as an alternative ventilatory mode for patients with moderate-to-severe PARDS. There is not enough evidence to support the routine use of inhaled nitric oxide, steroids, or prone positioning for PARDS at this time.3 Since the publication of the new definition, several studies comparing the previous definitions to PALICC suggest that the PALICC definition can not only identify more patients with PARDS but it is also better at risk stratification for mortality.4,5 Despite decades of research and experience of managing PARDS, there remains a lack of definitive clinical evidence in Pediatrics. Further pediatric research is needed to gain more insight and to improve outcome of PARDS.

Characteristics of Nonpulmonary Organ Dysfunction at Onset of ARDS Based on the Berlin Definition.

The Berlin definition of ARDS does not account for nonpulmonary organ failure, which is a major determinant of outcome. We examined whether an increasing severity of hypoxemia across the Berlin definition classifications also corresponded with evidence of multiple organ dysfunction on the day of ARDS onset. We also examined the representation of major etiologies for ARDS across the Berlin definition classifications. This single-center, retrospective study examined 15 years of data from a quality assurance program that monitored the use of lung-protective ventilation in ARDS. We analyzed 1,747 subjects without chronic kidney disease or severe chronic liver disease at ARDS onset. The most abnormal laboratory values at ARDS onset were analyzed as cutoff values to assess organ dysfunction. Data were analyzed by using non-parametric analysis of variance (Kruskall-Wallis test) and the Dunn post test. Categorical variables were compared by using the Fisher exact test. Alpha was set at 0.05. Factors independently associated with mortality were assessed by multivariate logistic regression modeling. Nonpulmonary organ dysfunction was present in at least 1 system at ARDS onset that increased with severity: 80% (mild), 83% (moderate), and 90% (severe). ARDS etiologies varied as severity increased: trauma-associated lung injury steadily decreased, whereas lung injury associated with aspiration and pneumonia steadily increased. Hospital mortality also increased significantly with the Berlin definition classifications: mild (22%), moderate (30%), and severe (47%). Multivariate logistic regression modeling revealed that the Berlin definition of severe ARDS was independently associated with mortality, as were cutoff values for renal and hepatic function as well as acidemia. Normal hematologic function and the absence of standard exclusion criteria used for therapeutic clinical trials in ARDS were protective. Nonpulmonary organ dysfunction was present at ARDS onset in most subjects and was more pronounced as ARDS severity increased. The Berlin definition classification of ARDS provided an elegant scheme for studying the syndrome because it coincided with increasing multiple organ dysfunction.

Lessons to learn from epidemiologic studies in ARDS.

Recent advances in our understanding of the epidemiology of ARDS has generated key insights into the incidence, risk factors, demographics, management and outcomes from this devastating clinical syndrome. ARDS occurs in 10% of all ICU patients, in 23% of all mechanically ventilated patients, with 5.5 cases per ICU bed each year. Although some regional variation exists regarding ARDS incidence, this may be less than previously thought. Subphenotypes are increasingly identified within the ARDS cohort, with studies identifying a 'hyperinflammatory' or 'reactive' subgroup that has a higher mortality, and may respond differently to therapeutic interventions. Demographic factors, such as race, may also affect the therapeutic response. Although mortality in ARDS is decreasing in clinical trials, it remains unchanged at approximately 40% in major observational studies. Modifiable ventilatory management factors, including PEEP, airway pressures, and respiratory rate are associated with mortality in ARDS. Hospital and ICU organizational factors play a role in outcome, whereas socioeconomic status is independently associated with survival in patients with ARDS. The Kigali adaptation of the Berlin ARDS definition may provide useful insights into the burden of ARDS in the developing world. ARDS exerts a substantial disease burden, with 40% of patients dying in hospital. Diverse factors, including patient-related factors such as age and illness severity, country level socioeconomic status, and ventilator management and ICU organizational factors each contribute to outcome from ARDS. Addressing these issues provides opportunities to improve outcome in patients with ARDS.

Interobserver Reliability of the Berlin ARDS Definition and Strategies to Improve the Reliability of ARDS Diagnosis

Failure to reliably diagnose ARDS may be a major driver of negative clinical trials and underrecognition and treatment in clinical practice. We sought to examine the interobserver reliability of the Berlin ARDS definition and examine strategies for improving the reliability of ARDS diagnosis. Two hundred five patients with hypoxic respiratory failure from four ICUs were reviewed independently by three clinicians, who evaluated whether patients had ARDS, the diagnostic confidence of the reviewers, whether patients met individual ARDS criteria, and the time when criteria were met. Interobserver reliability of an ARDS diagnosis was "moderate" (kappa= 0.50; 95%CI, 0.40-0.59). Sixty-seven percent of diagnostic disagreements between clinicians reviewing the same patient was explained by differences in how chest imaging studies were interpreted, with other ARDS criteria contributing less (identification of ARDS risk factor, 15%; cardiac edema/volume overload exclusion, 7%). Combining the independent reviews of three clinicians can increase reliability to "substantial" (kappa= 0.75; 95%CI, 0.68-0.80). When a clinician diagnosed ARDS with "high confidence," all other clinicians agreed with the diagnosis in 72%of reviews. There was close agreement between clinicians about the time when a patient metall ARDS criteria if ARDS developed within the first 48 hours of hospitalization (median difference, 5 hours). The reliability of the Berlin ARDS definition is moderate, driven primarily by differences in chest imaging interpretation. Combining independent reviews by multiple clinicians or improving methods to identify bilateral infiltrates on chest imaging are important strategies for improving the reliability of ARDS diagnosis.

PALICC definition of ARDS. Don’t remove that brick from the wall and keep it smart and simple

PALICC definition of ARDS. Don’t remove that brick from the wall and keep it smart and simple

The Presence of Diffuse Alveolar Damage on Open Lung Biopsy Is Associated With Mortality in Patients With Acute Respiratory Distress Syndrome

Diffuse alveolar damage (DAD) is considered the histologic hallmark of ARDS although DAD is absent in approximately half of patients with ARDS. The clinical implications of having the syndrome of ARDS with DAD vs other histologic patterns is unknown. To address this question, we conducted a meta-analysis of lung biopsy series for patients with ARDS.Studies were identified using MEDLINE, EMBASE, Cochrane Register of Controlled Trials, LILACS, and citation review from January 1, 1967, to September 1, 2015. Studies were included if they included all of the following: open lung biopsies (OLB) performed after ARDS diagnosis; a clear definition of ARDS and DAD; histologic results of the OLB indicated the presence or absence of DAD; and mortality reported for the DAD and non-DAD groups. We excluded studies conducted solely on a specific histology subgroup (eg, DAD) and studies with fewer than 5 patients. Two authors independently selected studies for inclusion, and there were no language restrictions.Of 8 included studies, 4 were high-quality (n = 228) and 4 were middle-quality trials (n = 122). The meta proportion of DAD between all the groups was 0.45 (95% CI, 0.35-0.56; Q test, 21.1; I(2), 66.8%; P ≤ .01). The pooled OR for mortality in ARDS with DAD compared with ARDS without DAD was 1.81 (95% CI, 1.14-2.80; Q test, 8.8; I(2), 20.2%; P = .269). Age, sex, and days elapsed between ARDS diagnosis and OLB as well as sequential organ failure assessment score and Pao2/Fio2 ratio on the day of OLB did not differ between DAD and non-DAD groups.This meta-analysis demonstrated that ARDS with DAD is associated with higher mortality than ARDS without DAD.

PALICC definition of ARDS. Don’t remove that brick from the wall and keep it smart and simple

PALICC definition of ARDS. Don’t remove that brick from the wall and keep it smart and simple

Nonlinear Imputation of Pao2/Fio2 From Spo2/Fio2 Among Patients With Acute Respiratory Distress Syndrome

ARDS is an important clinical problem. The definition of ARDS requires testing of arterial blood gas to define the ratio of Pao2 to Fio2 (Pao2/Fio2 ratio). However, many patients with ARDS do not undergo blood gas measurement, which may result in underdiagnosis of the condition. As a consequence, a method for estimating Pao2 on the basis of noninvasive measurements is desirable. Using data from three ARDS Network studies, we analyzed the enrollment arterial blood gas measurements to compare nonlinear with linear and log-linear imputation methods of estimating Pao2 from percent saturation of hemoglobin with oxygen as measured by pulse oximetry (Spo2). We compared mortality on the basis of various measured and imputed Pao2/Fio2 ratio cutoffs to ensure clinical equivalence. We studied 1,184 patients, in 707 of whom the Spo2≤ 96%. Nonlinear imputation from the Spo2/Fio2 ratio resulted in lower error than linear or log-linear imputation (P<.001) for patients with Spo2≤ 96%but was equivalent to log-linear imputation in all patients. Ninety-day hospital mortality was 26%to 30%, depending on the Pao2/Fio2 ratio, whether nonlinearly imputed or measured. On multivariate regression, the association between imputed and measured Pao2 varied by use of vasopressors and Spo2. A nonlinear equation more accurately imputes Pao2/Fio2 from Spo2/Fio2 than linear or log-linear equations, with similar observed hospital mortality depending on Spo2/Fio2 ratio vsmeasured Pao2/Fio2 ratios. While further refinement through prospective validation is indicated, a nonlinear imputation appears superior to prior approaches to imputation.

Clinical Characteristics and Outcomes Are Similar in ARDS Diagnosed by Oxygen Saturation/Fio2 Ratio Compared With Pao2/Fio2 Ratio

Oxygen saturation as measured by pulse oximetry/Fio2 (SF) ratio is highly correlated with the Pao2/Fio2 (PF) ratio in patients with ARDS. However, it remains uncertain whether SF ratio can be substituted for PF ratio for diagnosis of ARDS and whether SF ratio might identify patients who are systemically different from patients diagnosed by PF ratio. We conducted a secondary analysis of a large observational prospective cohort study. Patients were eligible if they were admitted to the medical ICU and fulfilled the Berlin definition of ARDS with hypoxemia criteria using either the standard PF threshold (PF ratio ≤ 300) or a previously published SF threshold (SF ratio ≤ 315). Of 362 patients with ARDS, 238 (66%) received a diagnosis by PF ratio and 124 (34%) by SF ratio. In a small group of patients who received diagnoses of ARDS by SF ratio who had arterial blood gas measurements on the same day (n = 10), the PF ratio did not meet ARDS criteria. There were no major differences in clinical characteristics or comorbidities between groups with the exception of APACHE (Acute Physiology and Chronic Health Evaluation) II scores, which were higher in the group diagnosed by PF ratio. However, this difference was no longer apparent when arterial blood gas-dependent variables (pH, Pao2) were removed from the APACHE II score. There were also no differences in clinical outcomes including duration of mechanical ventilation (mean, 7 days in both groups; P = .25), duration of ICU stay (mean, 10 days vs 9 days in PF ratio vs SF ratio; P = .26), or hospital mortality (36% in both groups, P = .9). Patients with ARDS diagnosed by SF ratio have very similar clinical characteristics and outcomes compared with patients diagnosed by PF ratio. These findings suggest that SF ratio could be considered as a diagnostic tool for early enrollment into clinical trials.

Genome-wide transcription profiling in neutrophils in acute respiratory distress syndrome

BackgroundAcute respiratory distress syndrome (ARDS) is characterised by diffuse neutrophil-mediated alveolar inflammation. Recently, we demonstrated that blood polymorphonuclear leucocytes (PMNs) in ARDS are basally activated, and exhibit aberrant oxidative burst and survival responses. The molecular mechanisms governing ARDS PMN function and longevity are incompletely understood. We aimed to use genome-wide transcriptional profiling of ARDS blood PMNs to explore underlying disease mechanisms and identify therapeutic targets aimed at manipulating PMN function and longevity. MethodsGeneChip Affymetrix oligonucleotide arrays were used to assess global transcriptional profiles in highly pure PMNs from ventilated patients fulfilling the Berlin ARDS definition (n=10), in freshly isolated PMNs from age-matched and sex-matched healthy volunteers (n=10), and in healthy volunteer PMNs exposed in vitro to recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) (1 ng/mL for 6 h). Ingenuity Pathway Analysis software was used to map probes identified as important onto specific pathways. FindingsTranscriptomic analysis showed that 1319 genes were altered in ARDS PMNs relative to healthy volunteer PMNs. Compared with well established reference databases, the gene expression profile in ARDS PMNs showed near-complete correlation to datasets derived from patients with sepsis and burns. Transcripts enriched in ARDS PMNs were differentially expressed in known functional network pathways associated with cancer, cellular compromise, apoptotic mechanisms, and chemotaxis. Of the observed gene changes, only 292 (22%) were seen in healthy volunteer PMNs after exposure to rhGM-CSF, of which 216 showed the same directional change as ARDS PMNs. InterpretationExisting genome-wide studies in ARDS use total blood leucocytes; our study is the first, to our knowledge, to use unbiased global genomic profiling of highly pure ARDS blood PMNs in parallel with age-matched and gender-matched healthy volunteer PMNs treated with rhGM-CSF. Collectively our results show that ARDS PMNs display important de-novo transcriptional activity. The global transcriptomic changes were consistent with the observed aberrant ARDS PMN survival and functional phenotype that we have previously reported, and show near-complete correlation to existing sepsis and burns datasets, but only limited transcriptomic overlap with healthy volunteer PMNs treated with rhGM-CSF. FundingNational Institute for Health Research, GlaxoSmithKline.

Pulse oximetry vs. PaO2 metrics in mechanically ventilated children: Berlin definition of ARDS and mortality risk.

Requiring PaO2/FiO2 ratio (PF) to define ARDS may bias towards children with cardiovascular dysfunction and hypoxemia. We sought to evaluate (1) the Berlin definition of ARDS in children using PF; (2) the effect of substituting SpO2/FiO2(SF) ratio; (3) differences between patients with and without arterial blood gases; and (4) the ability of SpO2 and PaO2 indices to discriminate ICU mortality. Single center retrospective review (3/2009-4/2013) of mechanically ventilated (MV) children. Initial values for PF, SF, oxygenation index (OI), and oxygen saturation index (OSI) after intubation and average values on day 1 of MV were analyzed against ICU mortality, subgrouped by Berlin severity categories. Of the 1,833 children included, 129 met Berlin PF ARDS criteria (33 % mortality); 312 met Berlin SF ARDS criteria (22 % mortality). Children with a PaO2 on day 1 of MV had higher mortality and severity of illness, were older, and had more vasoactive-inotropic infusions (p < 0.001). SF could be calculated for 1,201 children (AUC for ICU mortality 0.821), OSI for 1,034 (0.793), PF for 695 (0.706), and OI for 673 (0.739). Average SF on day 1 discriminated mortality better than PF (p = 0.003). Berlin PF criteria for ARDS identified less than half of the children with ARDS, favoring those with cardiovascular dysfunction. SF or OSI discriminate ICU mortality as well as PF and OI, double the number of children available for risk stratification, and should be considered for severity of illness scores and included in a pediatric-specific definition of ARDS. Multicenter validation is required.

ABSTRACT 45

Background: The anatomical feature of ARDS is to diffuse alveolar damage (DAD) but the correlation between the American European Consensus Conference (AECC) definition of ARDS and DAD has not been studied in Pediatrics. Aim: To compare the AECC definition of ARDS to autopsy findings. Methods: Retrospective matching study of autopsies conducted at Hospital La Misericordia between 2000 - 2010 (n 355). The findings of the histopathological and clinical history was processed by calculating sensitivity, specificity and likelihood ratio considering the pulmonary and extrapulmonary risk factors. Results: The sensitivity of clinical criteria is 64.4 (95 % CI) and specificity 71 (95 % CI), with (LR)+=2.2 and LR (-) 0.5 . With intrapulmonary risk factors, the sensitivity is 80 (95 % CI) and specificity 50 (95 %) with an LR (+) of 1.6 and an LR (-) of 0.4. With extrapulmonary risk factors, the sensitivity is 55 (95 % CI) and specificity 84 (95 %) with LR + of 3.43 and LR- of 0.53. Conclusions: The clinical AECC criteria adequately discriminate patients with DAD and extrapulmonary risk factors, but not in the case where the factor is pulmonary. An adequate contribution of this study is that stratification is done based on the risk factors. Despite the limitations of the AECC definition, they are still valuable since patients will benefit from the proposed treatments even if they do not have DAD.

Is there still a role for the lung injury score in the era of the Berlin definition ARDS?

BackgroundThe Lung Injury Score (LIS) remains a commonly utilized measure of lung injury severity though the additive value of LIS to predict ARDS outcomes over the recent Berlin definition of ARDS, which incorporates severity, is not known.MethodsWe tested the association of LIS (in which scores range from 0 to 4, with higher scores indicating more severe lung injury) and its four components calculated on the day of ARDS diagnosis with ARDS morbidity and mortality in a large, multi-ICU cohort of patients with Berlin-defined ARDS. Receiver Operator Characteristic (ROC) curves were generated to compare the predictive validity of LIS for mortality to Berlin stages of severity (mild, moderate and severe).ResultsIn 550 ARDS patients, a one-point increase in LIS was associated with 58% increased odds of in-hospital death (95% CI 14 to 219%, P = 0.006), a 7% reduction in ventilator-free days (95% CI 2 to 13%, P = 0.01), and, among patients surviving hospitalization, a 25% increase in days of mechanical ventilation (95% CI 9 to 43%, P = 0.001) and a 16% increase (95% CI 2 to 31%, P = 0.02) in the number of ICU days. However, the mean LIS was only 0.2 points higher (95% CI 0.1 to 0.3) among those who died compared to those who lived. Berlin stages of severity were highly correlated with LIS (Spearman’s rho 0.72, P < 0.0001) and were also significantly associated with ARDS mortality and similar morbidity measures. The predictive validity of LIS for mortality was similar to Berlin stages of severity with an area under the curve of 0.58 compared to 0.60, respectively (P-value 0.49).ConclusionsIn a large, multi-ICU cohort of patients with ARDS, both LIS and the Berlin definition severity stages were associated with increased in-hospital morbidity and mortality. However, predictive validity of both scores was marginal, and there was no additive value of LIS over Berlin. Although neither LIS nor the Berlin definition were designed to prognosticate outcomes, these findings suggest that the role of LIS in characterizing lung injury severity in the era of the Berlin definition ARDS may be limited.

406

Introduction: There is increased interest in using noninvasive respiratory support modalities for treatment of pediatric patients with acute hypoxemic respiratory failure. The PaO2/FiO2 (PF) ratio is required to identify patients with ARDS by the Berlin definition. Although the Berlin definition of ARDS includes patients treated with CPAP ≥ 5 cm H2O there may be disparity between the preset fraction of inhaled oxygen (FiO2) and the fraction of delivered oxygen (FDO2) in patients treated with nasal modes of positive pressure support. There have been no published reports that have described the FDO2 across a range of patient minute ventilation and disease states during nasal noninvasive support. In order to determine the incidence of ARDS, we must be able to accurately and reliably predict oxygen delivery during noninvasive support. Methods: Neonatal, infant, and child face/nasal airway models were constructed with a 3D printer using data from a newborn, 7 month old, and 5 year old, respectively. All had simulated oral leaks and were affixed to a spontaneously breathing test lung model (ASL 5000; Ingmar, PA) configured for healthy, restrictive, and obstructive lung mechanics. Simulated conditions were programmed as resistance, compliance, pleural pressure and respiratory rate to achieve appropriate minute ventilation. The lung model was supported at 0.40 FiO2, using high flow nasal cannula (HFNC; non-occlusive prong), continuous positive airway pressure (CPAP; occlusive prong), and noninvasive ventilation (NIV; occlusive prong). FDO2 was measured distal to the oral leak with an oxygen analyzer during HFNC (0.5–32 L/min), nasal CPAP (4–8 cm H20), and NIV. We instituted a priori acceptable FDO2 measurements within a 0.5% margin to account for any error related to the accuracy of the oxygen analyzer. After a 2 minute stabilization of the analyzer, FDO2 measurements were obtained sequentially (N=10) for each model. Results: FDO2/FiO2 approximates 1 in neonates with healthy and obstructive disease at flow ≥ 4L/min, and in restrictive disease at ≥ 2L/min. The FDO2/FiO2 approximates 1 in all disease conditions at 8L/min and 24L/min in infants and children, respectively. Linear relationships with R2 >95% (neonate), >89% (infant) and >84% (child) were evident at lower flows where FDO2/FiO2 did not yet approach 1. In all disease states for the infant model, FDO2/FiO2 decreased linearly during HFNC between flows of 8L/min and 24L/min. Measured FDO2/FiO2 was 1 in Neonatal NIV, infant and child BiPAP during all levels of support tested. FDO2/FiO2 = 1 with all CPAP conditions, with the exception of the infant healthy model at CPAP 4. Conclusions: The major finding of this study is that there is a linear relationship between FDO2/FiO2 with HFNC until a critical point at which the delivered flow exceeds the minute ventilation and leak, resulting in less air entrainment. At this point, the preset FiO2 and FDO2 equilibrate, effectively providing FDO2 = FiO2. In respiratory devices that are intended to deliver pressure, there appears to be no loss of oxygen from the preset value to what is delivered, regardless of nasal/oral leak, pressure and disease state. This may be due, in part, to the occlusive nature of the nasal airway interface and airway pressurization at the level of the oral leak. These data suggest that FiO2 delivery can be reliably predicted in children treated with nasal modes of noninvasive support. This has clinical and research implications to identify patients with and at risk for ARDS.

English

Conclusion We need a more individualised approach of hypoxic respiratory failure and ARDS. It is questionable that the new Berlin ARDS definition was the most required change to our approach of ARDS. One could argue that our patients could be better off, if we had moved away from trying to find commonality between very different conditions as the old and new ARDS definitions do. The ‘one size fits all’ approach tried for many years has not led to substantial progress. It may be high time for a different strategy and during the mean time, it may also be wise to use physiology as a compass to avoid the obvious mistakes associated with a cookbook approach.

Corrigendum

Ajay Dharia and Carolyn S. Calfee, Updates in the Management of Acute Lung Injury, 2012; 3 (6), 287-292 original doi ( 10.1177/1944451612466107 ). In the November 2012 issue of ICU Director, for the article listed above, the authors wish to correct an error in the references for Tables 1 and 2. The incorrect citations are found in the table legend. For Table 1 the legend should read ‘Adapted from Bernard et al.’ (ref # 6) and in Table 2 should read ‘Adapted from ARDS Definition Task Force et al.’ (ref # 7).

Acute respiratory distress syndrome - the Berlin definition: impact on an ICU of a university hospital

The current definition of ARDS was established in 1994 by the AECC. In 2011 emerged the Berlin definition. The aim of this study was to find a new approach from the impact of ARDS in an ICU and to analyze APACHE II score, days of mechanical ventilation (MV), duration of ARDS and mortality.

424

Introduction: The hallmark of severe ARDS, defined as PaO2/FiO2 ratio (P/F)? 100, is severe hypoxemia, which is associated with high mortality rates (45-83% in recent studies). In the Berlin ARDS definition validation, mortality increased in both clinical & physiologic databases between mild (P/F 201-300: 27%, 20%), moderate (P/F 101-200: 32%, 41%), & severe ARDS (P/F? 100: 45%, 52%). Hypothesis: An evidence-based ARDS treatment algorithm, including rescue strategies, is associated with reduced mortality. Methods: Prospective cohort study (6 years, 7/2005-6/2011). ARDS patients (n=240) treated with an evidence-based algorithm combining low tidal volume lung protective ventilation & rescue strategies [inhaled nitric oxide, prone positioning, high frequency oscillatory ventilation (HFOV), & ECMO]. Data were collected prospectively by a single APACHE Data Coordinator & analyzed by Berlin definition ARDS severity. Results: Hypoxemia severity was associated with increased mortality: mild (mean P/F=251.6 ± 28.4, n=7; 1 death, 14%), moderate (mean P/F=137.1 ± 30.0, n=50; 10 deaths, 20%), & severe (mean P/F=67.5 ± 15.7, n=183; 58 deaths, 32%). Severe group mortality was less than in the Berlin validation data (32% vs. 45%/52%, p=0.0011/0.02). Mortality etiology was multi-system organ failure (mild: 1, moderate: 8, severe: 48) & hypoxemia (moderate: 2, severe: 10). ICU LOS increased with ARDS severity (mild: 7.6d±8.5, moderate: 15.9d±17.8, severe: 21.1d±25.4). HFOV & ECMO were used more in the severe (67, 47) than in moderate group (4, 2).SAPS II & APACHE III scores were 54.1 ± 30.4/60.7 ± 28.0 (mild), 67.5 ± 20.8/71.8 ± 22.4 (moderate), & 66.0 ± 23.1/68.8 ± 23.7 (severe). Lower scores in severe ARDS document underestimation of illness severity by not accounting for PEEP & rescue therapies. Standardized mortality ratios (SMR, actual vs. APACHE national predicted, based on primary ICU diagnoses which were not uniform) were 0.74 in mild, 0.60 in moderate, & 0.99 in severe ARDS. Conclusions: In this largest single-center study of 183 severe ARDS patients, mortality was significantly reduced with use of an evidence-based treatment algorithm compared to national multicenter data. Critical care of severe ARDS patients should be regionalized.

Erratum to: The Berlin definition of ARDS: an expanded rationale, justification, and supplementary material

Erratum to: The Berlin definition of ARDS: an expanded rationale, justification, and supplementary material