Nitroglycerin should be withheld if SBP is below which threshold?

Nitroglycerin should be withheld if SBP is below which threshold?

• A. Below 60 mmHg
• B. Below 80 mmHg
• C. Below 90 mmHg
• D. Below 100 mmHg

Answer: (C)

This question tests knowing the blood pressure level at which nitroglycerin should be withheld to avoid dangerous drops in perfusion. Nitroglycerin dilates veins and reduces preload, which lowers blood pressure and cardiac output. If the systolic blood pressure is already below 90 mmHg, giving nitroglycerin can cause a significant or rapid drop in BP, risking inadequate perfusion to the heart and brain and potentially leading to fainting, shock, or worsened myocardial ischemia. For that reason, nitroglycerin is withheld when SBP is under 90 mmHg. In contrast, higher thresholds (like 100 mmHg) would expose patients to unnecessary hypotension, and very low cutoffs (like below 60 or 80) could overly restrict therapy in someone who could safely tolerate it, so 90 mmHg is the balance point used in guidelines.

This question tests knowing the blood pressure level at which nitroglycerin should be withheld to avoid dangerous drops in perfusion. Nitroglycerin dilates veins and reduces preload, which lowers blood pressure and cardiac output. If the systolic blood pressure is already below 90 mmHg, giving nitroglycerin can cause a significant or rapid drop in BP, risking inadequate perfusion to the heart and brain and potentially leading to fainting, shock, or worsened myocardial ischemia. For that reason, nitroglycerin is withheld when SBP is under 90 mmHg.

In contrast, higher thresholds (like 100 mmHg) would expose patients to unnecessary hypotension, and very low cutoffs (like below 60 or 80) could overly restrict therapy in someone who could safely tolerate it, so 90 mmHg is the balance point used in guidelines.