The therapist is providing mechanical ventilation to a patient, and in the process sets ventilator inflation to extend into neural expiration. What is the potential problem with this situation?

A. The delivered tidal volume will decrease.
B. The inspiratory flow will be inadequate to meet the patient's inspiratory demands.
C. The trigger sensitivity will be altered.
D. Dynamic hyperinflation may develop.

?ANS: D
A. Incorrect response: When ventilator inflation extends into neural expiration, the delivered VT actually increases.
B. Incorrect response: Extending ventilator inspiration into neural expiration does not influence the inspiratory flow.
C. Incorrect response: Extending ventilator inspiration into neural expiration does not influence the ventilator's trigger sensitivity.
D. Correct response: When ventilator inflation extends into neural expiration, the time available for expiratory flow, before the next inspiratory effort, is reduced. If passive FRC is not reached during this abbreviated expiratory phase, dynamic hyperinflation, or auto-PEEP occurs.