Acute Respiratory Distress Syndrome Flashcards Preview

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Flashcards in Acute Respiratory Distress Syndrome Deck (8):
1

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.

2

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

3

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.

4

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

5

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

6

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)

7

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

Plateau pressure

8

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