Name a key contraindication to nitroglycerin administration in ICEMA standing orders.

• A. Systolic blood pressure below the threshold (hypotension) or recent use of phosphodiesterase inhibitors.
• B. Allergy to aspirin.
• C. History of asthma.
• D. Hypoglycemia.

Answer: (A)

Nitroglycerin works by dilating veins and arteries, which lowers preload and blood pressure while reducing myocardial oxygen demand. Because of this, two situations make its use unsafe under standing orders: low systolic blood pressure and recent use of phosphodiesterase inhibitors. If the blood pressure is already too low, additional vasodilation can cause dangerous drops in perfusion. PDE-5 inhibitors (such as sildenafil, tadalafil, or similar drugs) markedly amplify nitroglycerin’s effect, risking life-threatening hypotension. The other options don’t pose the same direct safety risk with nitroglycerin: an aspirin allergy doesn’t stop nitroglycerin, asthma history isn’t a contraindication, and hypoglycemia isn’t a contraindication to nitroglycerin itself (though hypoglycemia would be treated first if present).