Ventilator associated lung injury

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Background

Terminology
  • An acute lung injury that is suspected to have developed during mechanical ventilation is termed ventilator-associated lung injury (VALI).
  • If it can be proven that the mechanical ventilation caused the acute lung injury it is termed ventilator-induced lung injury (VILI).
  • VALI is the appropriate term in most clinical situations because it is virtually impossible to prove causation outside of the research laboratory.
Epidemiology
Pathogenesis
  • VALI is alveolar injury caused by overexpansion of alveoli (volutrauma), repeated alveolar collapse and expansion (RACE), and cyclic atelectasis.
  • Eventually, in serve VALI/ARDS alveoli edema/bleeding and loss of surfactant can cause complete alveoli collapse. [2]


Clinical Features

  • Indistinguishable from ARDS.
Clinical signs
  • Hypoxemic - or requiring a greater fraction of inspired oxygen (FiO2) to maintain the same arterial oxygen tension.
  • Tachypneic
  • Tachycardic
  • VALI may also be associated with multiple organ dysfunction syndrome (MODS).[3]
Imagining
  • CXR - increased bilateral interstitial or alveolar opacities of any severity.
  • Computed tomography (CT) - heterogeneous consolidation and atelectasis, as well as focal hyperlucent areas that represent overdistended lung.[4]

Differential Diagnosis


Evaluation

Check for Deterioration after intubation (DOPE)
  • D - Displacement of tube → Attach end-tidal CO2 to verify and check depth (cm at lip)
  • O - Obstruction of tube/circuit → Use suction catheter to remove mucus plug, or make sure patient not biting down
  • P - Pneumothorax → Verify via ultrasound, CXR, or needle thoracostomy (high suspicion)
  • E - Equipment failure → Connect to BVM
  • S - Stacked breaths → Auto-PEEP especially in COPD/Asthma → Disconnect from ventilator

VALI does NOT need to be distinguished from Acute respiratory distress syndrome because evaluation and management are the same.[5]

  • CXR
  • CBC
  • Chem 10
  • UA
  • LFT
  • Lipase
  • PT/PTT
  • Influenza (seasonal)
  • Blood cultures
  • Lactate
  • Consider bedside echo
  • Consider ABG/VBG
  • Consider BNP


Management

Prevention is key with ventilator lung protective settings.

Management is the same as ARDS:

  • Continue mechanical ventilation.
  • Apply lung protective settings.
  • Treat underlying causes.
  • Supportive care
Ventilator Lung Protective Settings
  • Mode: AC (Assist Control). - Fully supported mode (rather than partially supported) on either volume (better studied) or pressure control (both acceptable).
  • Tidal volume: 6ml/kg of predicted body weight (PBW)
  • RR: 12-14bpm
  • PEEP - cm H2O
  • I:E - 2
  • Plateau pressure: ≤30 cm H2O


Also see Ventilator Management

Disposition

  • Admit to ICU


See Also

Mechanical ventilation (main)


External Links

LITFL - VALI

References

  1. Gajic O, Dara SI, Mendez JL, et al. Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation. Crit Care Med 2004; 32:1817.
  2. Rouby JJ, Brochard L (2007). "Tidal recruitment and overinflation in acute respiratory distress syndrome: yin and yang.". Am J Respir Crit Care Med 175 (2): 104–6. doi:10.1164/rccm.200610-1564ED. PMID 17200505.
  3. Plötz FB, Slutsky AS, van Vught AJ, Heijnen CJ. Ventilator-induced lung injury and multiple system organ failure: a critical review of facts and hypotheses. Intensive Care Med 2004; 30:1865.
  4. International consensus conferences in intensive care medicine: Ventilator-associated Lung Injury in ARDS. This official conference report was cosponsored by the American Thoracic Society, The European Society of Intensive Care Medicine, and The Societé de Réanimation de Langue Française, and was approved by the ATS Board of Directors, July 1999. Am J Respir Crit Care Med 1999; 160:2118.
  5. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. The Acute Respiratory Distress Syndrome Network. N Engl J Med 2000; 342:1301.