A patient is receiving controlled, continuous mandatory ...

[lracut11]

A patient is receiving controlled, continuous mandatory ventilation, and suddenly experiences increased airway resistance. How will the patient's airway and alveolar pressures be affected by this condition?
 
  A. Neither of these two pressures will be influenced.
  B. These pressures will decrease in response to increased airway resistance.
  C. These pressures will increase in the presence of elevated airway resistance.
  D. Both pressures will fluctuate when this patient is confronted by increased airway resistance.

Question 2

A mechanically ventilated patient is receiving 6 ml/kg tidal volume. At the same time, the patient's Pplateau is 40 cm H2O. Which of the following ventilator adjustments should the therapist make at this time?
 
  A. Reduce the tidal volume to 5 ml/kg.
  B. Increase the inspiratory flow.
  C. Raise the upper pressure limit.
  D. Lengthen the expiratory time.

[amcvicar]

Answer to Question 1

ANS: C
A. Incorrect response: See explanation C.
B. Incorrect response: See explanation C.
C. Correct response: Choosing flow or volume versus pressure-controlled ventilation for CMV depends largely on the therapist's clinical experience because the two approaches are more similar than they are different. Clinical data are lacking in terms of one form of ventilation over the other. During volume-controlled ventilation, airway and alveolar pressures are dependent variables, and increase or decrease depending on changes in the patient's lung mechanics or patient effort. Thus worsening of airway resistance can cause abrupt increases in airway pressure to preserve minute ventilation.
D. Incorrect response: See explanation C.

Answer to Question 2

ANS: A
A. Correct response: No clinical trials of the magnitude of the ARDSnet study have been performed on patients with obstructive airways disease. Nonetheless, because of the presence of regional disparity in the degree of airflow obstruction, and because the concept behind lung protective strategies is to protect the more normal and healthier lung units from ventilator-induced lung injury (VILI), ventilating patients with respiratory failure from airflow obstruction in the same manner as patients in the ARDSnet trial seems reasonable. One particular adjustment is to decrease the delivered tidal volume from 6 ml/kg to 5 ml/kg because of the elevated Pplateau, which is 40 cm H2O.
B. Incorrect response: See explanation A.
C. Incorrect response: See explanation A.
D. Incorrect response: See explanation A.