The therapist is about to establish ventilator settings for a patient who is to receive pressure-controlled ventilation (PC-CMV). Which of the following control panel adjustments must the therapist make to institute this form of ventilation? I. pressure support above PEEP II. inspiratory pressure above PEEP III. inspiratory time IV. mandatory rate

A. I, II only
B. II, III, IV only
C. I, II, III only
D. I, III, IV only

?ANS: B
A. Incorrect response: Pressure support ventilation involves the delivery of some level of pressure to be delivered during each spontaneous breath to overcome the work of breathing imposed on the patient by an artificial airway. Pressure support ventilation (PSV) differs from pressure-controlled ventilation (PCV) in that PSV is used only for patients who are breathing spontaneously, whereas PCV is for breaths that are patient triggered (pressure or flow) or time triggered. With PCV, the pressure remains constant throughout inspiration, and the pressure is unaffected by changes in lung compliance and airway resistance.
B. Correct response: With pressure control ventilation (PCV), the peak inspiratory pressure, mandatory rate, inspiratory time, or I:E ratio are set. An advantage of PCV is that alveolar pressure cannot exceed the set pressure. One of the goals of PCV is to avoid permitting the PIP from exceeding 30 cm H2O, thus minimizing the potential for alveolar overdistention. Inspiratory time is set during PCV. The mandatory rate is set during PCV.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.