What is meant by stating that flow and volume are dependent variables during pressure-targeted ventilation with time or flow as the cycling variable?

A. that flow and volume will remain constant despite respiratory mechanics
B. that flow and volume will vary with lung mechanics and patient effort
C. that they will facilitate patient triggering
D. that they will influence inspiratory time

?ANS: B
A. Incorrect response: See explanation B.
B. Correct response: With pressure-targeted ventilation, the therapist sets an inspiratory pressure target (with either time or flow as the cycling criterion) such that flow and volume are dependent variables. Being dependent variables means that flow and volume will vary according to how lung compliance and airway resistance change, and how patient effort fluctuates. Flow and volume will change according to these situations in an attempt to maintain the target pressure.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.