Author Question: The therapist notices that the tidal volume of a mechanically ventilated patient is greater during ... (Read 86 times)

ericka1 · **on:** Jul 16, 2018

The therapist notices that the tidal volume of a mechanically ventilated patient is greater during inspiration than during exhalation. Which of the following conditions is likely the cause of this situation? I. The patient has a bronchopleural fistula. II. The patient has developed retained secretions. III. The ventilator's in-line nebulizer has been turned on. IV. The ventilator's humidifier has been overfilled with sterile water.

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

Question 2

Which of the following measurements correlates well with a patient's end-tidal CO2 value?

A. HCOB. Paco2C. Sao2
D. Pvco2

Mollythedog · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: A
A. Correct response: A bronchopleural fistula is a communication between the pleural space and the tracheobronchial tree. This condition can cause the disparity between the inspired and expired tidal volume to be of the magnitude of 100 ml or more, depending on the size of the fistula.
B. Incorrect response: Retained secretion will cause increased airway resistance. During VC ventilation, the tidal volume will be constant, and the PIP will increase. During PC ventilation, the tidal volume will vary and the PIP will remain constant.
C. Incorrect response: If the ventilator's in-line nebulizer is operating, a separate gas source often drives the device. That additional gas combines with the delivered tidal volume and causes the tidal volume to increase.
D. Incorrect response: Overfilling the humidifier of a mechanical ventilator will not cause a disparity between the delivered tidal volume and the exhaled tidal volume.

Answer to Question 2

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: A common gas concentration measurement is the exhaled CO2 concentration using infrared absorption technology. The CO2 at end-expiration (end-tidal CO2) correlates with the arterial CO2, and can be used to trend ventilation effectiveness when the tidal volume and the expiratory time are held nearly constant.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.