Table 3.

Ventilator management for acute severe asthma and COPD.

Ventilator setting	Initial setting	Adjustment
Mode	Assist-control volume-control mode	Avoid assist-control pressure-control mode as the volume delivered can vary with changes in airway resistance
FIO2	50%	Target SpO2 88%-92%, and not higher than 98%, given the risk of hypercapnia
Rate	10 breaths/min	Target pH 7.25-7.45. To lower PaCO2, increase the rate. Do not increase the rate if incomplete exhalation occurs (flow–time curve does not return to baseline at end expiration)
Tidal volume	6 ml/kg PBW	Target pH 7.25-7.45. To lower PaCO2, increase the tidal volume up to 8 ml/kg PBW. Do not increase the tidal volume if incomplete exhalation occurs (flow–time curve does not return to baseline at end expiration)
Inspiratory flow	60 L/min	In the presence of incomplete exhalation, increase the inspiratory flow to decrease inspiratory time and to increase expiratory time
PEEP	5 cmH2O	To avoid aggravating air trapping and to avoid increasing auto-PEEP, the PEEP can be kept at 5 cmH2O
Trigger sensitivity	Flow trigger, 2 L/min (the lower the value, the more sensitive is the trigger)	To avoid ineffective triggering, keep the triggering threshold low (i.e. keep the absolute flow trigger value low). Avoid an absolute trigger value <2 L/min, as this may lead to auto-triggering (ventilator triggering without patient’s initiation of a breath)

For men, PBW (kg) = 50 + (0.91 × [height (cm) − 152.4]). For women, PBW (kg) = 45.5 + (0.91 × [height (cm) − 152.4]). FIO₂: inspired oxygen fraction, PaCO₂: partial pressure of arterial carbon dioxide, PBW: predicted body weight, PEEP: positive end-expiratory pressure, SpO₂: peripheral oxygen saturation.