ARDS

Question 1

What is it?

Answer 1

Acute respiratory distress syndrome (ARDS) is caused by the increased permeability of alveolar capillaries leading to fluid accumulation in the alveoli, i.e. non-cardiogenic pulmonary 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

Causes?

Answer 2

infection: sepsis, pneumonia
massive blood transfusion
trauma
smoke inhalation
acute pancreatitis
Covid-19
cardio-pulmonary bypass

Question 3

Clinical features are typically of an acute onset and severe:

Answer 3

dyspnoea
elevated respiratory rate
bilateral lung crackles
low oxygen saturations

Question 4

Key investigations?

Answer 4

A chest x-ray and arterial blood gases are the key investigations.

Criteria (American-European Consensus Conference)
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 (300 mmHg)

Question 5

Management?

Answer 5

due to the severity of the condition patients are generally managed in ITU
oxygenation/ventilation to treat the hypoxaemia
general organ support e.g. vasopressors as needed
treatment of the underlying cause e.g. antibiotics for sepsis
certain strategies such as prone positioning and muscle relaxation have been shown to improve outcome in ARDS