Monday, 14 March 2016

Lung injury after one-lung ventilation: a review of the pathophysiologic mechanisms affecting the ventilated and the collapsed lung. AA August 2015.

This article provides an overview of the mechanisms of lung injury after one-lung ventilation (OLV), and suggests strategies to prevent this from occurring. Postthoracoctomy acute lung injury (ALI) occurs in 4% to 15% of patients. ALI and ARDS are leading cause of death after thoracic surgery and significantly reduce 1-year survival (56% vs 92%). Mechanisms of lung injury in the ventilated lung include volutrauma, atelectrauma, hyperperfusion, biotrauma and oxidative injury. Mechanisms of lung injury in the collapsed lung include atelectasis, ischaemia-reperfusion injury, biotrauma and surgical trauma. This article recommends the following strategies to prevent lung injury after OLV:

Before OLV:

  • Ventilation with volatile agents may reduce risk of ALI
  • Avoid overhydration
  • Routine recruitment maneuvers after GA induction and endotracheal intubation – provides sustained oxygenation benefit for OLV and improves lung compliance and CO2 elimination
  • Lung isolation should only be established when necessary to minimise its duration
During OLV (collapsed lung):
  • CPAP to be considered to avoid dense atelectasis and minimise the shunt fraction
  • Minimise suctioning to avoid negative pressure trauma
  • Slow airway pressure increases and cycling maneuvers and using lower FiO2 during lung recruitment at the end of OLV
During OLV (ventilated lung):
  • Low Vt of 4 – 5 ml/kg predicted boy weight
  • PEEP of 5 – 10 cmH2O
  • Respiratory rate and minute ventilation targets to be relaxed to allow mild hypercapnia (PaCO2 40-60)
  • High FiO2 may be necessary at the onset of OLV but should be reduced after approximately 20 to 30 minutes of OLV
After OLV
  • Avoid hyperoxia
  • Protective 2-lung ventilation
  • Post extubation NIV may be considered

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