Intraarterial Nitroglycerin Dosing for Lower Extremity Vasospasm

Administration Guidelines

The American Heart Association recommends that for severe, refractory lower extremity vasospasm, continuous intraarterial nitroglycerin infusion can be administered for 24 hours using standard intravenous dosing protocols, with a maximum concentration of 400 mcg/mL and typical maximum infusion rates of 200 mcg/min 1, 2.
The American College of Cardiology suggests that if no response occurs at 20 mcg/min, increase increments to 10 mcg/min, and subsequently to 20 mcg/min as needed, when using non-absorbing tubing 1, 2.

The American Heart Association mandates continuous blood pressure monitoring during intraarterial nitroglycerin administration, with systolic blood pressure not falling below 90 mmHg or decreasing more than 30 mmHg from baseline 1, 3.
In previously normotensive patients, do not reduce systolic BP below 110 mmHg; in hypertensive patients, do not reduce mean arterial pressure by more than 25% from baseline, as recommended by the American College of Cardiology 1, 3.

The American College of Cardiology states that absolute contraindication exists if the patient has used sildenafil within 24 hours or tadalafil/vardenafil within 48 hours due to risk of profound hypotension and death 1, 2.
Avoid in patients with initial systolic BP <90 mmHg or marked bradycardia (<50 bpm) or tachycardia (>100 bpm without heart failure), as cautioned by the American Heart Association 1, 4.

Tolerance to nitroglycerin develops within 7-8 hours and becomes clinically significant after 24 hours of continuous therapy, according to the American College of Cardiology 1, 2.
For continuous intraarterial infusions lasting beyond 24 hours, periodic increases in infusion rate may be necessary to maintain efficacy, as suggested by the American Heart Association 1, 2.