Meet the New ARDS: Expert panel announces new definition, severity classes ARDS and ALI, Critical Care, Free Full Text, JAMA, Mechanical Ventilation Add comments Dec302012 A consensus panel led by V. Marco Ranieri, Gordon Rubenfeld, Arthur Slutsky et al announced a new definition and severity classfication system for acute respiratory distress syndrome (ARDS) that aims to simplify the diagnosis and better prognosticate outcomes from the life-threatening pulmonary illness. The proposed “Berlin definition” predicted mortality ever-so-slightly better than the existing definition (created at the 1994 American-European Consensus Conference/AECC), when applied to a cohort of 4,400 patients from past randomized trials. The Berlin definition would include the following: • “Acute lung injury” no longer exists. Under the Berlin definition, patients with PaO2/FiO2 200-300 would now have “mild ARDS.” • Onset of ARDS (diagnosis) must be acute, as defined as within 7 days of some defined event, which may be sepsis, pneumonia, or simply a patient’s recognition of worsening respiratory symptoms. (Most cases of ARDS occur within 72 hours of recognition of the presumed trigger.) • Bilateral opacities consistent with pulmonary edema must be present but may be detected on CT or chest X-ray. • There is no need to exclude heart failure in the new ARDS definition; patients with high pulmonary capillary wedge pressures, or known congestive heart failure with left atrial hypertension can still have ARDS. The new criterion is that respiratory failure simply be “not fully explained by cardiac failure or fluid overload,” in the physician’s best estimation using available information. An “objective assessment“– meaning anechocardiogram in most cases — should be performed if there is no clear risk factor present like trauma or sepsis. The new Berlin definition for ARDS would also categorize ARDS as being mild, moderate, or severe: ARDS Severity PaO2/FiO2* Mortality** Mild 200 – 300 27% Moderate 100 – 200 32% Severe < 100 45% *on PEEP 5+; **observed in cohort There is no change in the underlying conceptual understanding of ARDS as an “acute diffuse, inflammatory lung injury, leading to increased pulmonary vascular permeability, increased lung weight, and loss of aerated lung tissue…[with] hypoxemia and bilateral radiographic opacities, associated with increased venous admixture, increased physiological dead space, and decreased lung compliance.” Although the authors emphasize the increased power of the new Berlin definition to predict mortality compared to the AECC definition, in truth it’s still poor, with an area under the curve of only 0.577, compared to 0.536 for the old definition. Clinical variables that are widely believed to be important and useful in the management of ARDS — static compliance of the respiratory system, radiographic severity, PEEP > 10, and corrected expired volume >10L/min — were not predictive of mortality or other clinical outcomes. After including these variables in the initial draft definition and testing them empirically in the cohort, they were all dropped from the final Berlin definition for ARDS. Authors did find a post-hoc “high risk profile” of patient with a 52% mortality from ARDS. These patients had severe ARDS (PaO2/FiO2 ratio < 100) and either a static compliance of = 13 L/min. What was wrong with the old definition of ARDS: 1) acute onset of hypoxemia with PaO2 / FiO2 ratio
Posted on: Tue, 22 Apr 2014 14:48:07 +0000
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