Final answer:
If a patient on assist-control ventilation develops a high ventilatory drive, it most likely results in respiratory alkalosis, due to the excessive removal of CO₂ from the blood.
Step-by-step explanation:
If a patient ventilated in the assist-control mode develops a high ventilatory drive, the most likely result is respiratory alkalosis. This condition is characterized by increased ventilation rate, leading to abnormally low blood carbon dioxide levels and a higher (alkaline) blood pH. The assist-control ventilation mode provides full ventilatory support with a set rate and additional breaths triggered by the patient's own effort. If the patient's drive to breathe increases, it can result in an increased respiratory rate, with more breaths being triggered, all of which are delivered at a preset volume. This can lead to excessive carbon dioxide being removed from the blood, causing respiratory alkalosis.