Classification of Respiratory Distress Syndrome (ARDS)

Definition and Classification

• The Berlin Definition categorizes ARDS as mild (200 < PaO₂/FiO₂ ≤ 300 mmHg), moderate (100 < PaO₂/FiO₂ ≤ 200 mmHg), or severe (PaO₂/FiO₂ ≤ 100 mmHg), with all categories requiring a minimum PEEP of 5 cmH₂O, as recommended by the European Society of Intensive Care Medicine 1
• The Berlin Definition established the current classification system for ARDS with required elements including timing, imaging, origin of edema, and oxygenation, as published by the Society of Critical Care Medicine 1

Severity Classification and Treatment

• Prone positioning is recommended for severe ARDS (PaO₂/FiO₂ < 100 mmHg) by the American Thoracic Society 2

Clinical Application and Pitfalls

• PaO₂/FiO₂ ratio should be calculated with patients on at least 5 cmH₂O of PEEP, as suggested by the European Respiratory Society 1
• Misattribution of pulmonary edema can lead to misclassification, highlighting the importance of ruling out cardiogenic causes, as emphasized by the American College of Chest Physicians 1

Acute Respiratory Distress Syndrome Classification

Introduction to SDRA Classification

• The European Respiratory Review notes that the current classification based on oxygenation does not fully capture the heterogeneity of SDRA at three distinct levels: etiological, physiological, and biological 3

Severity Classification

• The Berlin Definition classifies SDRA into three categories based on the degree of hypoxemia, with the American Thoracic Society and other guideline societies implicitly supporting this classification through their recommendations for its use in clinical practice 3

Heterogeneity and Treatment

• The European Respiratory Review highlights that the inherent heterogeneity of SDRA explains why multiple treatments targeting specific pathophysiological mechanisms have failed in clinical trials, emphasizing the need for more personalized approaches 3