Adult respiratory distress syndrome

Question 1

Adult respiratory distress syndrome?

Answer 1

Defined as an acute condition characterized by bilateral pulmonary infiltrates and severe hypoxemia (PaO2/FiO2 ratio < 200) in the absence of evidence for cardiogenic pulmonary oedema (clinically or pulmonary capillary wedge pressure of less than 18 mm Hg).

Question 2

How is it subdivided?

Answer 2

1. Early stages consist of an exudative phase of injury with associated oedema.
2. The later stage is one of repair and consists of fibroproliferative changes. Subsequent scarring may result in poor lung function.

Question 3

What causes ARDS?

Answer 3

1. Sepsis
2. Direct lung injury
3. Trauma
4. Acute pancreatitis
5. Long bone fracture or multiple fractures (through fat embolism)
6. Head injury (causes sympathetic nervous stimulation which leads to acute pulmonary hypertension)

Question 4

Clinical features?

Answer 4

1. Treat the underlying cause
2. Antibiotics (if signs of sepsis)
3. Negative fluid balance i.e. 4. Diuretics
4. Recruitment manoeuvres such as prone ventilation, use of positive end expiratory pressure
5. Mechanical ventilation strategy using low tidal volumes, as conventional tidal volumes may cause lung injury (only treatment found to improve survival rates)