Which ventilator setting is most likely to contribute to respiratory alkalosis in a patient?

A high respiratory rate is most likely to contribute to respiratory alkalosis in a patient because it increases the amount of carbon dioxide (CO2) that is exhaled. When a patient breathes rapidly, they hyperventilate, leading to a decrease in arterial CO2 levels (hypocapnia). This drop in CO2 causes a shift in the acid-base balance, resulting in respiratory alkalosis, which is characterized by an increase in blood pH.

Under normal circumstances, the respiratory rate is adjusted to maintain adequate CO2 levels in the body. However, when the respiratory rate is high due to mechanical ventilation or patient condition, it can cause the lungs to remove CO2 at a rate faster than the body produces it. This imbalance leads to the condition known as respiratory alkalosis.

In contrast, high tidal volume would generally be associated with adequate ventilation and may not necessarily lead to a decrease in CO2 levels unless coupled with increased respiratory effort. A low respiratory rate is likely to cause CO2 retention, potentially leading to respiratory acidosis, while excessive PEEP primarily affects lung mechanics and oxygenation, and is not directly related to the development of respiratory alkalosis.