ARDS is characterized by pulmonary inflammation leading to increased vascular permeability and loss of aerating lung tissues. ARDS is common in many critically ill patients, affecting nearly 175 000 patients/year in Europe alone. This brings with it a substantial fiscal burden for our health care system but also a burden of mortality: some 35-40% fail to survive. Meanwhile, survivors face a substantial and sustained morbidity, with evidence of impaired functional capacity and increased healthcare costs extending up to 5 years or more after hospital discharge. Current ARDS treatments, however, are mostly supportive and no specific pharmacotherapies have been shown to impact to the outcome of the ARDS patients.
The Conceptual Model of ARDS
ARDS Risk Factors
The common risk factors for ARDS can be divided into direct and indirect causes.
Direct risk factors:
Indirect risk factors:
ARDS: The “Berlin Definition”
Recently, the ARDS definition has been revised with a special focus on feasibility, reliability, validity and objective evaluation of its performance resulting in The “Berlin Definition”. The Berlin Definition was published in 2012 by The ARDS Definition Task Force (JAMA, 2012;307(23):2526-2533. The ARDS severity is defined by PaO2/FiO2 ratio (P:F ratio: the partial pressure of arterial oxygen, in kPa, divided by the inspired fraction of oxygen, as a measure of impaired oxygenation): a P/F 300-201 mmHg defines mild ARDS, 200-101 mmHg moderate ARDS and ≤100 mmHg severe ARDS. The ARDS “Berlin Definition” is summarized in a Figure below.