Final answer:
The nurse should prioritize monitoring blood pressure and the risk for falls after administering the ACE inhibitor lisinopril because of its hypotensive effects and potential to cause hypotension-related complications such as falls.
Step-by-step explanation:
After administering the ACE inhibitor lisinopril, it is most important for the nurse to monitor for blood pressure and risk for falls. ACE inhibitors like lisinopril are prescribed to lower high blood pressure by blocking the action of angiotensin-converting enzyme (ACE), which in turn reduces the production of angiotensin II, leading to vasodilation and decreased blood pressure. These medications can therefore potentially cause hypotension, especially after the initial dose, increasing the risk of falls. Additionally, ACE inhibitors can affect kidney function and lead to an increase in serum potassium levels, known as hyperkalemia, although this is a secondary concern following blood pressure evaluation.