Final answer:
The primary compensatory mechanism for a patient with metabolic alkalosis is a decreased respiratory rate, which conserves CO₂ in an attempt to counteract the high pH level, but it is limited, and renal compensation may also be involved if needed.
Step-by-step explanation:
A nurse caring for a patient with metabolic alkalosis should assess for the primary compensatory mechanism, which is a decreased respiratory rate. This response is the normal reaction of the respiratory system to elevated pH levels. By decreasing the respiratory rate, the body attempts to conserve carbon dioxide (CO₂), thereby increasing the amount of CO₂ in the blood to counteract the alkalosis.
However, there is a limit to how much the respiratory rate can decrease, making this a less efficient compensatory mechanism compared to compensation for metabolic acidosis. Additionally, in case the respiratory system cannot fully compensate, renal compensation will occur, which involves adjustments to bicarbonate (HCO₃⁻) concentrations in the blood.