Acute Respiratory Distress Syndrome

Question 1

Define Acute Respiratory Distress Syndrome

Answer 1

Non-cardiogenic pulmonary oedema and diffuse lung inflammation with increased vascular permeability

Question 2

Criteria for diagnosis of Acute Respiratory Distress Syndrome

Answer 2

Acute onset
Bilateral opacities on CXR
PaO2/FiO2 ratio <300 on positive end-respiratory pressure
PCWP < 19mmHg or lack of clinical congestive HF

Question 3

Aetiology of Acute Respiratory Distress Syndrome

Answer 3

Direct lung injury or secondary to systemic illness.
Damage -> inflammatory mediator release -> increased capillary permeability and pulmonary oedema

Most common: pneumonia, pancreatitis, burns, sepsis, aspiration, drug overdose etc.

Question 4

Epidemiology of Acute Respiratory Distress Syndrome

Answer 4

10-15% of those admitted to ICU meet the criteria
Increase in incidence in mechanically ventilated patients
Mortality 30-50%

Question 5

Presenting symptoms of Acute Respiratory Distress Syndrome

Answer 5

Rapid deterioration in respiratory function
Dyspnoea
Cough 
Fever
Pleuritic chest pain

Question 6

Signs of Acute Respiratory Distress Syndrome on examination

Answer 6

Cyanosis
Tachypnoea
Tachycardia
Peripheral vasodilation
Bilateral fine inspiratory crackles
Low sats

Question 7

Investigations for Acute Respiratory Distress Syndrome

Answer 7

CXR - bilateral alveolar and interstitial shadowing
Bloods - amylase high, cultures positive for underlying cause
ABG - low partial pressure oxygen, PaO2/FiO2 <300 on PEEP
Pulmonary artery catheter - pulmonary capillary wedge pressure (PCWP) <19
Sputum cultures
BNP and echo - rule out heart failure