How should the therapist achieve distribution of ventilation to nondependent lung regions in patients who are receiving mechanical ventilation? I. Increase the pressure limit setting on the ventilator. II. Deliver low tidal volumes to the patient. III. Provide the patient with a high inspiratory flow. IV. Apply high levels of PEEP

Question

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

Answer 1

?ANS: B
A. Incorrect response: See explanation B.
B. Correct response: Three conditions favor the delivery of ventilation preferentially to nondependent portions of the lung relative to the dependent lung regions. First, ventilation at low tidal volumes shifts the pressure-volume relationships between the dependent and the nondependent areas of the lung in such a manner as to favor alveoli in the nondependent lung.
Second, a high inspiratory flow or the use of accessory respiratory muscles preferentially distributes ventilation to nondependent regions. Third, in mechanically ventilated patients, especially those anesthetized or sedated, the abdominal contents restrict the dependent diaphragm, increasing the movement of the nondependent diaphragm and the nondependent portions of the lung.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.