Acute Respiratory Distress Syndrome Flashcards Preview

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Flashcards in Acute Respiratory Distress Syndrome Deck (8):

What is acute respiratory distress syndrome?

  • A form of lung insult or injury that happens acutely.
  • There are a variety of etiologies with all of them causing a diffuse inflammatory response
  • The condition has a high mortality without prompt recognition and treatment.


How do you determine the severity of ARDS?

The severity of ARDS can be stratified upon this ratio using PEEP as a constant as an increase in PEEP can alter the value.

  1. Mild: > 200 - < 300 on PEEP > 5 cmH2O
  2. Moderate > 100 - < 200 on PEEP > 5cmH2O
  3. Severe     < 100 on PEEP > 5cmH2O


What are the clinical features associated with ARDS?

Patients present with both symptoms of ARDS and the underlying inciting event. The ARDS Definition Task Force redefined ARDS as:

  1. Onset within 1 week of a known clinical insult or new or worsening respiratory symptoms
  2. Bilateral opacities not fully explained by effusions, lobar/lung collapse, or nodules
  3. Respiratory failure that is not explained by cardiac failure or volume overload
  4. Impaired oxygenation with a low PaO2 to fraction of inspired oxygen (FIO2) < 300 mmHg. The ratio is calculated as PaO2/FIO2. For example, if a patient has a PaO2 on their blood gas of 65 and on 85% oxygen, has a ratio of 112.


What diagnostic tests are used to diagnose ARDS?

  • CXR – abnormal findings are essential to support the diagnosis and help determine the underlying cause. Are there lobar consolidations, infiltrates or bronchograms consistent with PNA? Do you see Kerley B lines and/or cardiomegaly to suggest CHF?
  • Chest CT – is not essential unless the CXR findings are not clear or if you are looking for cavitation due to TB. If pancreatitis is the suspected cause, an abdominal CT is done
  • EKG – look for cardiac dysfunction including MI, arrhythmias
  • BNP – will not diagnose ARDS but helps distinguish the presence of edema
  • Echocardiogram – either TTE or TEE depending on the suspicion of valvular heart disease
  • Cultures – Bacterial, fungal, viral cultures if an infectious process is suspected


What are the most common causes of ARDS?

  • Sepsis
  • Infectious or aspiration pneumonia
  • Trauma and burns
  • Pancreatitis
  • Smoke inhalation
  • Shock
  • Transfusion related lung injury
  • Complications of cardiothoracic surgery
  • Complications of hematopoietic stem cell transplant
  • Drug toxicity


How do you treat patients with ARDS?

  • Ventilatory support – with low tidal volumes 6 ml/kg of ideal body weight. Adjust PEEP to maintain saturations
  • Oxygenation – maintain oxygen saturations > 88%
  • Treatment of underlying cause
  • Nutrition- monitor serum protein, albumin and pre albumin levels. Initiate feedings if no contraindication
  • Fluid management – After resolution of shock, effort should be made to attempt diuresis CVP used as guide, goal <4
    • Shortens time on vent and ICU length of stay (13 days vs 11 days)


What indicator is the most predictive of lung injury in ARDS?

Plateau pressure


What is the goal plateau pressure in ARDS?

  • Goal plateau pressure < 30, the lower the better
    • Decreases alveolar over-distention and reduces risk of lung strain
  • Adjust tidal volume to ensure plateau pressure at goal
  • It may be permissible to have plateau pressure > 30 in some cases
    • Obesity
    • Pregnancy
    • Ascites