Acute respiratory distress syndrome

Background

Non-cardiogenic pulmonary edema due to lung capillary endothelial injury
- Proteinaceous material accumulate in alveoli in a heterogeneous manner
Symptom of an underlying disease

 PaO2/FIO2 ratio
 *200-300 Mild
 *100-200 Moderate
 *< 100 Severe

Presentation
- Severe dyspnea
- Hypoxemia
- Diffuse crackles
Imaging
- Diffuse patchy pulmonary infiltrates
Causes
- Sepsis
- Pancreatitis
- Burns
- Aspiration
- Trauma
- Near drowning
- Fat embolism
- Amniotic fluid embolism

Treat underlying cause
- Cover for sepsis
  - Pneumonia in addition to other identified source
- Tamiflu 75mg BID oral or NGT if influenza season ^[2]
Supplemental O2
Noninvasive ventilation
- Limited role as patients require prolonged ventilation
Ventilator Settings
- Permissive hypercapnia
- Tidal volume 6-8cc/kg of ideal body weight^[3]
  - Limit barotrauma to healthy area of lung
  - Increase PEEP to improve oxygenation
- Maintain plateau pressures < 30 ^[4]
- Ensure adequate sedation
  - Better synchrony with vent
  - Decreased oxygen consumption
  - Less delirium
  - Increased patient comfort

↑ Ferguson ND et. al. The Berlin definition of ARDS: an expanded rationale, justification, and supplementary material. Intensive Care Med. 2012 Oct;38(10):1573-82.
↑ http://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm
↑ Brower RG, et al. "Ventilation With Lower Tidal Volumes As Compared With Traditional Tidal Volumes For Acute Lung Injury And The Acute Respiratory Distress Syndrome". The New England Journal of Medicine. 2000. 342(18):1301-1308.
↑ Hansen-Flaschen et al. Acute respiratory distress syndrome: Clinical features and diagnosis.UpToDate accessed 3/26/14

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