Question

A 70-kg (154 lb) patient with emphysema is receiving mechanical ventilation. Current ventilator settings are as follows: VC, SIMV; VT 550 mL, respiratory rate 12/min, FIO₂ 0.30. The patient is awake and alert and does not appear to be in any distress. The total respiratory rate is 14/min. ABG results are as follows: pH 7.35, PaCO₂ 58 torr; PaO₂ 65 torr; HCO₃ 30 mEq/L. His SpO₂ is 94% and MIP is -30 cm H₂O. This patient is most likely

A. ready for a spontaneous breathing trial.
B. in an acute exacerbation.
C. oversedated.
D. in need of PEEP therapy.

Answer 1

The respiratory rate and tidal volume will adjust oppositely to changes in alveolar ventilation; they increase when ventilation is too low and decrease when it is too high to maintain proper gas exchange.

Step-by-step explanation:

The respiratory rate and volume of air per breath are critical elements in maintaining proper alveolar ventilation. When alveolar ventilation is too high, indicating hyperventilation, the respiratory rate may decrease and the volume of air per breath (tidal volume) may reduce to restrict the amount of air moving in and out of the alveoli. Conversely, when alveolar ventilation is too low, suggesting hypoventilation, the body compensates by increasing the respiratory rate and/or the tidal volume to enhance gas exchange and clear the accumulating carbon dioxide from the alveoli.