From the Guidelines
Nitroglycerin should be avoided in patients with initial systolic blood pressure less than 90 mm Hg or 30 mm Hg or more below baseline, and systolic blood pressure generally should not be titrated to less than 110 mm Hg in previously normotensive patients or to greater than 25% below the starting mean arterial blood pressure if hypertension was present. When administering nitroglycerin, it is crucial to monitor blood pressure closely before each dose and maintain systolic blood pressure (SBP) above 90 mmHg to prevent hypotension 1. For intravenous nitroglycerin infusions, the dose can be initiated at a rate of 10 mcg per min through continuous infusion via nonabsorbing tubing and increased by 10 mcg per min every 3 to 5 min until some relief of symptoms or blood pressure response is noted 1.
Key considerations for nitroglycerin administration include:
- Starting dose: 10 mcg per min for IV infusions
- Titration: increase by 10 mcg per min every 3 to 5 min
- Monitoring: blood pressure should be monitored continuously or every 5-15 minutes
- Contraindications: initial systolic blood pressure less than 90 mm Hg, marked bradycardia or tachycardia
- Side effects: headache, hypotension
The most recent and highest quality study, from 2013, supports these guidelines for nitroglycerin administration in patients with unstable angina or non-ST-elevation myocardial infarction 1. It is essential to weigh the benefits of nitroglycerin against the potential risks, particularly hypotension, and to adjust the dose accordingly to maintain optimal blood pressure parameters.
From the FDA Drug Label
After the initial dosage titration, the concentration of the solution may be increased, if necessary, to limit fluids given to the patient. Once a partial blood pressure response is observed, the dose increase should be reduced and the interval between increases should be lengthened Adequate systemic blood pressure and coronary perfusion pressure must be maintained. Continuous monitoring of physiologic parameters (i.e., blood pressure and heart rate in all patients, other measurements such as pulmonary capillary wedge pressure, as appropriate) MUST be performed to achieve the correct dose.
The blood pressure parameters for nitroglycerin (IV) are not explicitly stated in terms of specific values, but it is mentioned that adequate systemic blood pressure and coronary perfusion pressure must be maintained.
- The dose should be titrated to achieve the desired level of hemodynamic function.
- Continuous monitoring of blood pressure and other physiologic parameters is necessary to achieve the correct dose 2.
From the Research
Blood Pressure Parameters for Nitro
- The administration of nitroglycerin can lead to a decrease in blood pressure, with a mean fall in systolic blood pressure of 14 mmHg for one dose and 8 mmHg for a second dose 3.
- The blood pressure drop is linearly correlated with initial systolic pressure, but not correlated with number of prior doses of nitroglycerin, initial heart rate, advanced life support time interval, age, or sex 3.
- Tachycardic patients are at a higher risk of hypotension after nitroglycerin administration, with an adjusted odds ratio of 1.60 for hypotension and 1.11 for a drop in blood pressure of 30mm Hg or greater 4.
- Pre-NTG blood pressure is a significant predictor of post-NTG hypotension, with a lower pre-NTG blood pressure increasing the risk of hypotension 4.
- Sublingual nitroglycerin can be used as a bridge to IV therapy in hypertensive emergencies, with a mean reduction of mean arterial blood pressure by 12.3% and 16.3% at 5 and 10 minutes after administration, respectively 5.
- The use of nitroglycerin in patients with inferior ST elevation myocardial infarction is not associated with a higher rate of hypotension compared to patients with STEMI in other territories 6.