During volume-assured pressure support (VAPS), how is the breath ...

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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

Question 2

The therapist is preparing to ventilate a patient with the Hamilton Galileo using the adaptive support ventilation (ASV) mode. Which entry must the therapist provide before initiating ventilation on this patient?
 
  A. anatomic dead space
  B. physiologic dead space
  C. ideal body weight
  D. dead space-tidal volume ratio

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Answer to Question 1

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.

Answer to Question 2

ANS: C
A. Incorrect response: The patient's anatomic dead space is calculated from the ASV algorithm, which uses a formula involving the patient's ideal body weight.
B. Incorrect response: The patient's physiologic dead space is not determined.
C. Correct response: The patient's ideal body weight is entered in the ventilator for the determination of the patient's anatomic dead space.
D. Incorrect response: The patient's dead space-tidal volume ratio is not included as part of the ventilator's entry data before using ASV.