While mechanically ventilating a patient for respiratory failure from airflow obstruction, when is increasing the delivered tidal volume up to 8 ml/kg appropriate?

A. when the patient has difficulty triggering a breath
B. when the patient demonstrates a severe respiratory acidosis
C. when the Pao2 falls below 70 mm Hg
D. when the inspiratory flow is inadequate

ANS: B
A. Incorrect response: Increasing the tidal volume when a patient is experiencing difficulty triggering a breath is inappropriate. The sensitivity setting may need to be adjusted, or the presence of auto-PEEP needs to be determined. If auto-PEEP is present, the following methods can be employed to reduce it: (1) increasing the inspiratory flow, (2) lengthening Te, (3) reducing the Vt, (4) reducing the respiratory rate, (5) using low resistance exhalation valves, (6) using a larger ETT, and (7) instituting applied PEEP.
B. Correct response: Increasing the Vt to 8 ml/kg may be appropriate when mechanically ventilating a patient for respiratory failure from airflow obstruction when the patient experiences severe patient-ventilator dyssynchrony or severe respiratory acidosis.
C. Incorrect response: Generally, the Fio2 is increased, or PEEP is added to elevate a patient's Pao2.
D. Incorrect response: Increasing the tidal volume when the inspiratory flow is inadequate is counterproductive. If the inspiratory flow is determined to be too low, the therapist should then increase that setting.?