Acute Respiratory Distress Syndrome (ARDS)

Question 1

Acute Respiratory Distress Syndrome: Define

Answer 1

ARDS may be caused by direct lung injury or it can occur secondary to severe systemic illness. There is increased permeability of alveolar capillaries leading to fluid accumulation in the alveoli - i.e. non-cardiogenic oedema. It is a serious condition that has a mortality of around 40% and is associated with significant morbidity in those who survive.

Question 2

Acute Respiratory Distress Syndrome: Aetiology

Answer 2

Pneumonia 
Pancreatitis
Vasculitis
Haemorrhage 
Trauma

Question 3

Acute Respiratory Distress Syndrome: Prognosis

Answer 3

50-75% Mortality
However, this varies with:
Age
Number of organs affected
Cause of ARDS 
- Pneumonia mortality = 86%
- Trauma mortality = 38%

Question 4

Acute Respiratory Distress Syndrome: Symptoms/Signs

Answer 4

Breathlessness
Inspiratory Crackles - Bilateral 
Tachycardia
Tachypnoea
Cyanosis 
Peripheral Vasodilation

Question 5

Acute Respiratory Distress Syndrome: Investigation

Answer 5

Bloods: FBC, U&E, LFT, Blood Culture, ABGs
CXR: Bilateral pulmonary infiltrates
Pulmonary Artery Catheter - to measure pulmonary capillary wedge pressure PCWP.

Question 6

Acute Respiratory Distress Syndrome: Diagnostic Criteria

Answer 6

The following four have to exist for it to be ARDS:

1. Acute onset
2. CXR shows bilateral infiltrates
3. PCWP < 19 mmHg or lack of clinical congestive heart failure
4. Refractory Hypoxamia with FiO2 < 200

Question 7

Acute Respiratory Distress Syndrome: Management

Answer 7

Admit to ITU
Treat Underlying cause
Supportive Therapy:
- Respiratory support = CPAP
- Circulatory support = Arterial line & Swan-Ganz catheter
- Nutritional support = High fat, antioxidant formulations