Acute Respiratory Distress Syndrome Flashcards
def
acute & persistant lung inflammation with increased vascular permeability
- acute onset
- bilateral pulmonary oedema
- hypoxaemia
- ARDS is the severe end of the spectrum of ‘acute lung injury’
what is a pulmonary infiltrate
substance denser than air, such as pus, blood, protein which is found in the parenchyma of the lungs
aetiology
damage to the lungs causes release of inflammatory mediators, increased capillary permeability, pulmonary oedema, impaired gas exchange and decreased lung compliance
- sepsis
- aspiration
- pneumonia
- pancreatitis
- trauma
what are the three stages of ARDS
exudative
proliferative
fibrotic
epi
1/6000PA in UK
history
cyanosis
tachypnoea & tachycardia
diffuse inspiratory crepitations
investigations
1 CXR
-bilateral alveolar & interstitial shadowing
2 bloods
-FBC, UEs, LFTs, ESR/CRP, amylase, ABG
-plasma BNP <100pg/ml may distinguish ARDS/ALI from heart failure
3 echo
-aortic/mitral valve dysfunction or decreased LVEF favours haemodynamic oedema over ARDS
4 bronchoscopy
-if cause cannot be ascertained from the history
management
1 respiratory support
-intubation & mechanical ventilation
-O2 (fiO2 50-60%)
-involves low tidal volume ventilation to prevent alveolar overdistension and ventilator-associated lung injury
2 sedation and analgesia
-to improve tolerance of mechanical ventilation and reduce o2 consumption
-neuromuscular blockade used only when sedation is inadequate
3 fluid management
-conservative strategy to avoid pulmonary oedema IF hypotension and organ hypoperfusion can be avoided
4 nutritional support
5 treat cause
6 prophylaxis/treat complications
-nosocomial pneumonia
-DVT
complications
respiratory failure
death
complications related to mechanical ventilation (pneumothorax) or intensive care (nosocomial pneumonia)
prognosis
dependent on cause but generally poor
60% mortality from sepsis
increased mortality with increased age, sepsis, steroid treatment prior to onset of ARDS
