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Mechanical ventilation

Initial settings



Spontaneous or controlled mode

Pressure or volume controlled

Peak and plateau pressure

Tidal volume

I:E ratio

Initial settings

Initial settings that would be reasonable for most patients are:

  • FiO2 1.0
  • PEEP 5-10cm H2O
  • SIMV or P-SIMV
  • Inspiratory pressure 25 cm H20 or tidal volume 400-450ml
  • I:E ratio 1:2
  • RR 15/min

These settings should then be adjusted to the following important end points:

Airway pressure: the plateau pressure should be less than 30 cmH2O, except in exceptional circumstances. This avoids ‘barotrauma’.

Tidal volume: when lung compliance is low (e.g. ARDS), the tidal volume should be limited to 6-8 ml/kg. This avoids ‘volutrauma’. The tidal volume is slightly less important when breathing spontaneously, or when compliance is good, as long as airway pressures are controlled.

Respiratory rate should be adjusted to control the CO2. Initial upper limit of 20/min.
Often the rate will have to be high (e.g. 30/min) but this should be discussed with a senior clinician, as it can be dangerous.

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