How do you work-up the patient with suspected ARDS?

To Determine Diagnosis

Clinical Diagnosis (Berlin Criteria) - all 4 of:

  1. PaO2/FiO2 ratio ≤300
  2. Acute onset (within 1 week of known clinical insult)
  3. Bilateral opacities on CXR (not explained by effusions, collapse, or nodules)
  4. Respiratory failure not fully explained by heart failure or fluid overload (objective assessment such as echocardiogram recommended if no risk factors

Imaging to determine infiltrates:

  • CXR
  • Lung ultrasound
  • CT
To Determine Aetiology
Blood
  • Blood cultures
  • HIV serology
  • Herpes simplex IgG and PCR
  • CMB IgG and PCR
  • Pneumococcal PCR
  • Mycoplasma and chlamydia serology
Sputum / Bronchoalveolar Lavage
  • Routine culture
  • Fungal culture
  • Respiratory virus PCR
  • CMV, HSV, adenovirus PCR
  • Pneumocystis PCR
  • Galactomannan
  • Legionella culture and PCR
  • Mycoplasma pneumonia PCR
  • Smear and culture for M. tuberculosis
Nasal Swab
  • Respiratory virus PCR
Urine
  • Legionella antigen
  • Pneumococcal antigen
To Exclude Differentials
  • Vasculitis screen if suspicion of pulmonary haemorrhage
  • If diagnosis in doubt, consider open lung biopsy