High frequency oscillation ventilation

Background

• High Frequency Oscillation Ventilation (HFOV) is an alternative method for mechanical ventilation in difficult to oxygenate in critically ill ARDS patients.
• Studied in patients with PaO2/FiO2 < 200
• Goal is to maintain alveolar recruitment for adequate gas exchange and decrease lung injury/atelectrauma
• See Oscillate trial

Procedure

Ventilator protocol from the Oscillate trial

• Recruitment maneuver of 40 cmH2O PEEP for 40 seconds
• Initiate high frequency ventilation -> 3-15Hz
  • I:E time of 1:2
• VT minimized to keep pH >7.25
  • Goal of 1-4 ml/Kg
• Maitain mean airway pressure of 30 cmH2O with pressure adjusted to maintain a PaO2 of 55-80 mmHg
• Reversion to standard ventilation of mean airway pressure was ≤24 cmH2O for 12 hours or anytime when ≤20 cmH2O
• Re-initiation of HFOV if FIO2 >0.4 or PEEP >14 cmH2O for >1 hour in the subsequent 48 hours

Mechanism

• Low tidal volumes
• Delivered at high frequency
• Maintains lung recruitment
  • Reduces Ventilator Induced Lung Injury (VILI) from recruitment and de-recruitment

Pros and Cons

• Pros
  • Limits VILI

• Cons
  • No difference or likely to cause harm in adult ARDS patients