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Charles Gomersall

  • knowledge based system which controls the Evita XL in CPAP/ASB mode only
  • developed to aid weaning
  • 3 main functions
    • automatic adjustment of assistance
    • automatic weaning
    • automatic weaning trial

Automatic adjustment of assistance

Level of ΔPASB is automatically adjusted in steps of 2-4 mbar to keep parameters within following ranges:

Spontaneous breathing rate >15 bpm
<30 bpm (<34 bpm for patients with respiratory failure due to neurological disorders)
Expired tidal volume >250 ml (ideal body weight <55 kg)
>300 ml (ideal body weight >55 kg)
End tidal CO2 <55 mmHg (<65 mmHg for patients with COPD


Automatic weaning & weaning trial

  • ventilator automatically attempts to reduce ΔPASB in steps of 2-4 mbar while keeping parameters within the ranges shown above
  • when the level of ΔPASB reaches a predefined level (ΔPASB goal) the ventilator starts an observation period. If the patient's parameters remain within the ranges shown above for the observation period the ventilator recommends that the patient can be separated from the ventilator


  • patient body weight 35-200 kg
  • ventilator in adult mode
  • CPAP/ASB mode
  • automatic tube compensation deactivated
  • invasive ventilation via ETT or tracheostomy
  • apnoea ventilation on and properly set
  • end tidal CO2 monitoring through the ventilator
  • flow monitoring activated
  • ΔPASB should be set between ΔPASB goal+5 mbar and 35 mbar
  • PEEP 0-20
  ΔPASB goal
Tracheostomy and active humidification 5 mbar
Endotracheal tube and active humidification 7 mbar
Tracheostomy and HME/filter 9 mbar
Endotracheal tube and HME/filter 12 mbar


  • Set alarms appropriately
  • In CPAP/ASB mode select the SmartCare tab

  • Select patient weight, airway access, medical history and night rest in turn and make the appropriate settings
    •  if night rest is turned on no weaning will take place during the specific period
  • After making all the appropriate settings select patient session and turn SmartCare on


©Charles Gomersall, April, 2014 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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