A patient is receiving mechanical ventilation in the ...

[ETearle]

A patient is receiving mechanical ventilation in the pressure-regulated volume control (PRVC) mode and suddenly has an increase in airway resistance. How will this increase in airway resistance influence the delivered tidal volume?
 
  A. The delivered tidal volume will remain relatively constant.
  B. The increased airway resistance will cause the delivered tidal volume to decrease.
  C. The increased airway resistance will result in an increased delivered tidal volume.
  D. An unpredictable tidal volume will be delivered because of the increased airway resistance.

Question 2

Which of the following methods enables the therapist to evaluate the presence of auto-PEEP? I. performing an inspiratory hold maneuver II. noting the presence of expiratory flow at the end of exhalation III. periodically measuring a smaller tidal volume during pressure-controlled ventilation IV. using an esophageal balloon
 
  A. I, III only
  B. II, IV only
  C. I, III, IV only
  D. II, III, IV only

[Sierray]

Answer to Question 1

ANS: A
A. Correct response: Pressure-regulated volume control (PRVC) is a pressure-control mode with a volume target. It is also classified as a dual control mode. The therapist selects a tidal volume, and the ventilator delivers a test breath. During the test breath, the ventilator calculates the system compliance and airway resistance to determine the pressure needed to deliver the set tidal volume. The ventilator may adjust the pressure delivery every breath in increments of 1 to 3 cm H2O up to the maximum pressure that equals the upper pressure limit minus 5 cm H2O. Therefore the delivered tidal volume will remain relatively constant as either or both lung compliance and airway resistance change.
B. Incorrect response: See explanation A.
C. Incorrect response: See explanation A.
D. Incorrect response: See explanation A.

Answer to Question 2

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: The presence of auto-PEEP can be evaluated via the following methods: (1) observing the persistence of expiratory flow at the end of the allotted expiratory time, which suggests incomplete lung emptying, and the presence of auto-PEEP, (2) observing from a flow-time scalar the failure of the expiratory flow to return to baseline and the initiation of an inspiration before expiratory flow ceases, (3) performing an end-expiratory hold following a mandatory breath devoid of any patient effort, and (4) using an esophageal balloon to detect the inspiratory triggering load imposed by any auto-PEEP. Esophageal pressure will be higher in the presence of auto-PEEP than in the absence of auto-PEEP.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.

[ETearle]

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TYSM