During volume-assured pressure support (VAPS), how is the breath cycled if the pressure abruptly increases, and reaches the high-pressure limit setting?

A. flow cycled
B. volume cycled
C. pressure cycled
D. time cycled

?ANS: C
A. Incorrect response: During VAPS, when the delivered VT equals the set VT, the breath is flow cycled. In another situation, when the patient receiving VAPS demonstrates the need for a greater VT, the pressure limit is reached, and the inspiratory time lengthens. The result of these intrabreath adjustments is the delivery of a VT greater than the set VT.
B. Incorrect response: If the set VT appears to not be achieved, the set flow will continue until the set VT is delivered. This situation involves volume cycling.
C. Correct response: When the delivered VT does not equal the set VT during VAPS, the breath converts from a pressure control to volume control. Additional volume is then added to the breath to achieve the set VT. In the process, the high-pressure limit may be reached, thus activating the high-pressure alarm. This alarm condition causes inspiration to end. The breath then changes from flow cycled to pressure cycled.
D. Incorrect response: VAPS is either flow or volume cycled. Sometimes inspiration is prolonged. If the inspiratory time lasts longer than 3 seconds, the breath is automatically time cycled.