An orally intubated patient is receiving PC-CMV. The therapist ...

[elizabeth18]

An orally intubated patient is receiving PC-CMV. The therapist suddenly notices that the patient's exhaled tidal volume has fallen significantly. Which of the following occurrences is the likely cause of this loss of volume?
 
  A. The cuff on the endotracheal tube is overinflated.
  B. The patient's static compliance has increased.
  C. An oversized endotracheal tube has been used.
  D. The endotracheal tube has migrated into the right mainstem bronchus.

Question 2

The diagram show below depicts an end-expiratory valve used to generate PEEP during mechanical ventilation. Which of the following statements describes the function of this valve?
 
  A. A decreased flow through this apparatus causes an increased PEEP.
  B. An increased flow through this device produces an increased PEEP.
  C. When the flow through this apparatus remains constant, the PEEP level generated fluctuates.
  D. The PEEP level produced by this device is proportional to the level of flow.

[sarah_brady415]

Answer to Question 1

ANS: D
A. Incorrect response: An overinflated endotracheal tube cuff will not affect the patient's tidal volume.
B. Incorrect response: If static compliance increases, tidal volume will increase in PC-CMV. Tidal volume will decrease when Raw increases in PC-CMV.
C. Incorrect response: Using an oversized endotracheal tube will not cause the patient's tidal volume to drop suddenly.
D. Correct response: Commonly, distal migration of the endotracheal tube is detected by an increase in airway resistance during volume control ventilation, and a decrease in the tidal volume during pressure control ventilation.

Answer to Question 2

ANS: D
A. Incorrect response: See explanation D.
B. Incorrect response: See explanation D.
C. Incorrect response: See explanation D.
D. Correct response: The device pictured in response D is an end-expiratory valve called a flow resistor used for generating PEEP. A flow resistor requires a constant flow to maintain a constant pressure. Therefore, if the flow through a flow resistor is low, the PEEP level developed will be low. Conversely, when the flow through this device is high, the level of PEEP will be high. Another type of end-expiratory valve is the threshold resistor, which maintains a steady level of PEEP regardless of the flow moving through the device.