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.