Is the absence of an intravenous line (IV) a contraindication to administering nitroglycerin (nitro) in a patient with chest pain?

From the Guidelines

The lack of an IV access is not a reason to withhold nitroglycerin in a patient with chest pain. Sublingual nitroglycerin (0.4 mg tablet or spray) can and should be administered without delay when a patient presents with chest pain suspicious for angina or myocardial infarction, as recommended by the 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes 1. The medication can be given every 5 minutes for up to three doses, as long as the patient's systolic blood pressure remains above 90 mmHg. However, establishing IV access is still important when treating chest pain patients, as it allows for administration of additional medications if needed and provides a route for emergency interventions if the patient's condition deteriorates. The primary concern with nitroglycerin administration is hypotension, not the route of administration, as noted in the 2014 AHA/ACC guideline 1 and further supported by the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. Nitroglycerin works by dilating blood vessels, which reduces cardiac workload and improves blood flow to the heart muscle, as explained in the 2007 ACC/AHA guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction 1. This vasodilation effect can cause blood pressure to drop, which is why monitoring vital signs before and after administration is essential, regardless of whether an IV is in place. Key considerations for nitroglycerin administration include:

• Monitoring blood pressure and adjusting dosage accordingly
• Avoiding administration in patients with hypotension or recent use of phosphodiesterase inhibitors
• Using sublingual or topical forms for patients without IV access
• Establishing IV access for potential emergency interventions and additional medication administration. Overall, the benefits of nitroglycerin in reducing myocardial oxygen demand and improving blood flow to the heart muscle outweigh the risks, and its administration should not be delayed due to lack of IV access, as supported by the 2013 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction 1.

From the Research

Administration of Nitroglycerin

• The absence of an intravenous line (IV) is not a contraindication to administering nitroglycerin (nitro) in a patient with chest pain, as nitroglycerin can be administered sublingually or via other routes 2, 3.
• Intravenous administration of nitroglycerin is often used in the emergency department to enable titration to effect with predictable pharmacokinetics 3.
• Studies have shown that intravenous nitroglycerin can be effective in treating ischemic chest pain, even in patients who are refractory to sublingual nitroglycerin 2, 4.

Alternative Routes of Administration

• Sublingual nitroglycerin is a common alternative route of administration, especially in patients without an IV line 3, 4.
• Other routes of administration, such as oral or topical, may also be considered, although they may not be as effective for acute chest pain 3.

Safety and Efficacy

• The safety and efficacy of intravenous nitroglycerin have been demonstrated in several studies, including a prospective case series that showed significant decrease in chest discomfort after 1 to 2 boluses 4.
• However, the use of intravenous nitroglycerin requires careful monitoring of blood pressure and other vital signs to avoid hypotension and other adverse effects 3, 4.