Acute resp distress syndrome (ARDS)

Question 1

what is it?

Answer 1

increased permeability of alveolar capillaries leading to fluid accumulation in the alveoli i.e. non-cardiogenic pulmonary odema
- significant mortality and morbidity
in adults- can be subdivided into 2 stages-
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

Question 2

causes?

Answer 2

infection: sepsis, pneumonia
massive blood transfusion
trauma
smoke inhalation
acute pancreatitis
cardio-pulmonary bypass
Long bone fracture or multiple fractures (through fat embolism)
Head injury (causes sympathetic nervous stimulation which leads to acute pulmonary hypertension)

Question 3

typical presentation?

Answer 3

acute onset and severe-
SOB
elevated resp rate 
bilateral lung crackles 
low O2 stats

Question 4

investigations?

Answer 4

chest x-ray

arterial blood gas

Question 5

diagnostic criteria?

Answer 5

• acute onset (within 1 week of a known risk factor)
• pulmonary oedema: bilateral infiltrates on chest x-ray (‘not fully explained by effusions, lobar/lung collapse or nodules)
• non-cardiogenic (pulmonary artery wedge pressure needed if doubt)
• pO2/FiO2 < 40kPa (200 mmHg)

Question 6

management?

Answer 6

• ITU
• oxygenation/ventilation to treat hypoxaemia
• treatment of underlying cause ? AB for sepsis
• certain strategies such as prone positioning and muscle relaxation have been shown to improve outcome in ARDS
• general organ support e.g. vasopressors as needed