Which of the following statements apply to the use of extrinsic PEEP for the purpose of minimizing auto-PEEP? I. Adding extrinsic PEEP requires less effort on behalf of the patient to trigger a breath. II. The addition of extrinsic PEEP only affects breathing circuit pressure and pressure in the airways. III. The use of extrinsic PEEP increases pulmonary compliance throughout the lungs

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

ANS: A
A. Correct response: Judicious amounts of extrinsic PEEP in the airway help equilibrate trapped pressure (auto-PEEP) with pressure throughout the ventilatory circuitry. The application of extrinsic PEEP requires less pressure by the patient to trigger inspiration. Extrinsic PEEP only compensates for 70% to 80% of the auto-PEEP. Up to this level, the extrinsic PEEP only affects the breathing circuit and the pressure in the patient's airways. Auto-PEEP in the alveoli is not balanced by the application of extrinsic PEEP. Instead, the use of extrinsic PEEP greater than that in the circuit and the patient's airways appears to begin elevating alveolar pressures and thus becomes counterproductive because regional overdistention develops in less obstructed regions.
B. Incorrect response: See explanation A.
C. Incorrect response: See explanation A.
D. Incorrect response: See explanation A.?