If leak around the tube, use Pressure control mode, then SIMV Pressure control/ Pressure support once initiating breaths spontaneously
If no leak use Volume control mode (Pressure Regulated Volume Control or PRVC), then volume support once initiating breaths spontaneously
If normal underlying lungs, aim for tidal volumes of 6 - 8ml/kg.
Set trigger in the green (flow triggered) zone
Set Inspiratory time at 0.5 secs in infants, up to 1 sec in older children
Setting up - PRVC
1. Connect ventilator to air and oxygen supply.
2. Connect to power supply.
3. Ensure ventilator tubing is capped or attached to bellows.
4. Select the mode of ventilation - usually Pressure Regulated Volume Control (PRVC). This also turns the ventilator power on.
5. Turn alarm reset on.
6. Set pressures
a. UPPER PRESSURE LIMIT to > 5cm above desired peak pressure
b. PRESSURE CONTROL LEVEL ABOVE PEEP to desired peak pressure
c. PRESSURE SUPPORT LEVEL ABOVE PEEP - not necessary in PRVC, but set it to the same or slightly less than PC
d. PEEP set to desired level
e. Trigger level set in green zone (flow triggered).
7. Set respiratory pattern parameters
a. CMV RATE - usually to 20/min (30/min in infant)
b. INSPIRATORY PERIOD - dial gives a percentage, but the digital readout is in seconds - use it to achieve desired inspiratory time in seconds (usually 1.0s).
8. Set volume parameters
a. Set TIDAL VOLUME to achieve target. Remember that this ventilator is a 'minute volume divider' - i.e. you are actually setting the minute volume by adjusting rate and tidal volume controls. Thus if you change the rate, the ventilator will automatically change the tidal volume to maintain the same minute volume.
9. Set desired FiO2
10. Set alarm limits for minute volume
a. Set these to 20% above and below the desired set value.
11. Connect ventilator to patient and ensure adequate chest movement - 3 - 5 calibration breaths of increasing tidal volumes will be delivered initially.
SIMV PC + PS mode
1. As above in steps 1 - 7
2. Set SIMV rate around 2 - 4 breaths per minute less than the CMV rate
3. Typical starting pressures:
a. PEEP 5 cm
b. Pressure Control level above PEEP 15cm
c. Pressure Support level above PEEP 12cm
SIMV rate should always be lower than CMV rate.
Pressure support level should always be lower than pressure control level.