what are the 4 primary variables during positive pressure ventilation - ANSWER 1. trig-
ger variable
2. control or target variable
3. limit variable
4. cycling variable
types of trigger variables - ANSWER 1. pressure-triggered
2. flow-triggered
3. volume-triggered
4. time-triggered
5. manual-triggered
pressure-triggered - ANSWER inspiration initiated by the patient causing *airway pres-
sure to drop*
flow-triggered - ANSWER inspiration initiated by the patient causing *inspiratory flow
to drop*
volume-triggered - ANSWER inspiration initiated by the patient *detecting a small
change in volume during exhalation*
time-triggered - ANSWER inspiration initiated by the ventilator
1
, manual-triggered - ANSWER therapist presses a button initiating inspiration
volume control (vc) or volume target - ANSWER sets a volume to be delivered
pressure control (pc) or pressure target - ANSWER sets a pressure to be delivered
limit variable - ANSWER establishes a maximum value that a variable (pressure, vol-
ume, time, flow) can reach during inspiration
inspiratory phase continues until terminated by control/target variable
does not end inspiration and results in a plateau
types of cycling variables - ANSWER 1. volume cycled
2. pressure cycled
3. time cycled
4. flow cycled
volume cycled - ANSWER pressure is applied to the airways until a preset volume is
delivered, minute volume will remain constant, but may result in baro or volutrauma
pressure cycled - ANSWER positive pressure is applied to the airways until a preset
pressure is reached, pressure will remain constant and the volume will change
time cycled - ANSWER used as the cycling variable during pressure control ventilation
flow cycled - ANSWER normal cycling mechanism in pressure support ventilation
spontaneous breath - ANSWER patient controls all
2
ger variable
2. control or target variable
3. limit variable
4. cycling variable
types of trigger variables - ANSWER 1. pressure-triggered
2. flow-triggered
3. volume-triggered
4. time-triggered
5. manual-triggered
pressure-triggered - ANSWER inspiration initiated by the patient causing *airway pres-
sure to drop*
flow-triggered - ANSWER inspiration initiated by the patient causing *inspiratory flow
to drop*
volume-triggered - ANSWER inspiration initiated by the patient *detecting a small
change in volume during exhalation*
time-triggered - ANSWER inspiration initiated by the ventilator
1
, manual-triggered - ANSWER therapist presses a button initiating inspiration
volume control (vc) or volume target - ANSWER sets a volume to be delivered
pressure control (pc) or pressure target - ANSWER sets a pressure to be delivered
limit variable - ANSWER establishes a maximum value that a variable (pressure, vol-
ume, time, flow) can reach during inspiration
inspiratory phase continues until terminated by control/target variable
does not end inspiration and results in a plateau
types of cycling variables - ANSWER 1. volume cycled
2. pressure cycled
3. time cycled
4. flow cycled
volume cycled - ANSWER pressure is applied to the airways until a preset volume is
delivered, minute volume will remain constant, but may result in baro or volutrauma
pressure cycled - ANSWER positive pressure is applied to the airways until a preset
pressure is reached, pressure will remain constant and the volume will change
time cycled - ANSWER used as the cycling variable during pressure control ventilation
flow cycled - ANSWER normal cycling mechanism in pressure support ventilation
spontaneous breath - ANSWER patient controls all
2
