ARDS Flashcards
Definition?
Acute, diffuse, inflammatory form of lung injury (acute respiratory
failure) Characterized by:
1. Hypoxemia
2. Decreased lung compliance
3. Diffuse pulmonary infiltrates on CXR
4. Normal PAWP (< 18 mmHg)
5. PaO2/ FiO2 < 26.6
Pathophysiology of ARDS?
Two phases are recognized in ALI / ARDS:
• An acute phase, characterized by
1) Widespread destruction of the capillary endothelium, extravasation of protein-rich fluid and interstitial
edema
2) Migration of neutrophils and extensive release of cytokines
3) The alveolar basement membrane is also damaged, and fluid seeps into the airspaces, stiffening the
lungs and causing ventilation/perfusion mismatch.
• A later reparative phase, characterized by
4) Fibroproliferation, and organization of lung tissue.
5) If resolution does not occur, disordered collagen deposition occurs leading to extensive lung scarring.
Causes / Conditions associated with development of Acute Respiratory Distress Syndrome?
On notes
What is Berlin criteria?
Mild PaO2/FiO2: 200 - 300, mortality rate: 27%
Moderate 100 - 200 32%
Severe < 100 45
Management of ARDS?
(Ventilation, Steroids, Fluids, Nutrition)
Admit to ITU, give supportive therapy and treat the underlying cause.
• Respiratory support:
o Positive end-expiratory pressure (PEEP) of 5-15 cm H2O to prevent premature alveolar closure.
Although PEEP helps with oxygenation, it does so at the expense of cardiac output.
o Prone positioning: This has been found to significantly improve oxygenation (up to 65%).
• Steroids:
o Low dose steroids are associated with improved mortality and morbidity outcomes
• Sepsis
o Identify organism(s) and treat accordingly. If clinically septic, but no organisms cultured, use empirical
broad-spectrum antibiotics, but avoid nephrotoxic antibiotics.
• Hemodynamic management
o Fluids should be replaced, but with care not to overload. Assessment may be made by measuring blood
pressure and urine output. Finer assessment may be necessary using a Swan Ganz catheter to measure
the pulmonary capillary wedge pressure.
o If there is evidence of circulatory failure despite adequate hydration - such as fall in cardiac or urine
output - then consider low dose dopamine as a renal arterial dilator, and dobutamine for its positive
inotropic action. If there is fluid overload, consider frusemide 40-120 mg per 24 hours IV
• Other supportive care
o Nutritional support - enteral feeding is better than parenteral feeding.
o Venous thromboembolism prevention with low molecular weight heparin.
o Gastric ulcer prevention with prophylactic medications.
What are the long-term sequelae of ARDS?
• Impaired gas exchange with refractor hypoxemia
o V/Q mismatch
o Physiological shunting
• Decreased lung compliance
o Stiff, poorly or non-aerated regions of lung
• Pulmonary hypertension
