Acute respiratory distress syndrome (ARDS)

Question 1

Define acute respiratory distress syndrome.

Answer 1

Acute respiratory distress syndrome (ARDS) is a NON-CARDIOGENIC PULMONARY OEDEMA and DIFFUSE LUNG INFLAMMATION SYSTEM that often complicates critical illness.

Question 2

Explain the aetiology/risk factors of acute respiratory distress syndrome.

Answer 2

Many different conditions can lead to ARDS, although sepsis is the most common cause, usually with a pulmonary origin (e.g., pneumonia). Other conditions associated with ARDS include aspiration, inhalation injury, acute pancreatitis, trauma, burns, pulmonary contusion, transfusion-related lung injury, cardiopulmonary bypass, fat embolism, disseminated intravascular coagulation, and drug overdose.

Critical illness, cigarette smoking, and alcohol use are predisposing factors for ARDS. Sex, ethnicity, and race have not been associated with the incidence of ARDS.

Question 3

Summarise the epidemiology of acute respiratory distress syndrome.

Answer 3

Overall, 10% to 15% of patients admitted to the intensive care unit meet the criteria for ARDS, with an increased incidence among mechanically ventilated patients meeting the criteria for ARDS.
Mortality is between 40% and 50%.

Question 4

Recognise the presenting symptoms of acute respiratory distress syndrome.

Answer 4

SOB
Fatigue
Discolouration of nails
Rapid resp rate
Tachycardia
Fever

Question 5

Recognise the signs of acute respiratory distress syndrome on physical examination.

Answer 5

Low oxygen saturation
Acute respiratory failure
Dyspnoea
Increased respiratory rate
Pulmonary crepitations
Low lung compliance
Fever, cough, pleuritic chest pain
(Frothy sputum)

Question 6

Identify appropriate investigations for acute respiratory distress syndrome and interpret the results.

Answer 6

CXR - New onset of bilateral opacities that is not fully explained by effusions, lobar/lung collapse.
ABG - A PaO₂/FiO₂ (inspired oxygen) ratio of ≤300 on positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) ≥5 cm H₂O is part of the diagnostic criteria for ARDS.
Sputum culture
Blood culture
Urine culture
Amylase and lipase