Should I start the patient on nitroglycerin (NTG) prior to cardiology consultation?

Nitroglycerin Management Prior to Cardiology Consultation

Patients with continuing ischemic chest pain should receive sublingual nitroglycerin (0.3-0.4 mg) every 5 minutes for up to 3 doses, after which an assessment should be made about the need for intravenous nitroglycerin if not contraindicated. 1

Initial Management Algorithm

Step 1: Assess for Contraindications

• Do not administer nitroglycerin if:
  • Patient has taken PDE-5 inhibitors within 24-48 hours (sildenafil, vardenafil) or 48 hours (tadalafil) 1, 2, 3
  • Systolic blood pressure < 90 mmHg or 30 mmHg below baseline 2
  • Suspected right ventricular infarction 2
  • Severe anemia or increased intracranial pressure 3

Step 2: Initial Nitroglycerin Administration

• For patients with continuing ischemic pain:
  • Administer sublingual nitroglycerin 0.3-0.4 mg 1
  • Patient should be seated during administration to prevent falls from potential lightheadedness 3
  • One tablet should be dissolved under the tongue (not chewed or swallowed) 3
  • May repeat every 5 minutes up to 3 doses total 1

Step 3: Evaluate Response

• If pain resolves: Continue monitoring and proceed with cardiology consultation
• If pain persists after 3 doses within 15 minutes:
  • Consider IV nitroglycerin for persistent ischemia 1
  • Seek immediate cardiology consultation 1
  • Consider IV morphine for continued ischemic pain despite maximally tolerated anti-ischemic medications 1

Special Considerations

Risk of Hypotension

• Establish IV access before nitroglycerin administration in patients with inferior MI 2
• Have IV fluids ready (500-1000 mL normal saline) in case of hypotension 2
• Position patient supine with legs elevated if hypotension occurs 2
• Monitor blood pressure closely during administration 3

Important Caveats

1. Response to nitroglycerin is not diagnostic: Studies show that relief of chest pain with nitroglycerin does not reliably distinguish between cardiac and non-cardiac chest pain 4, 5. The positive likelihood ratio for having coronary artery disease if nitroglycerin relieves chest pain is only 1.1 4.

2. Intravenous nitroglycerin may be effective when sublingual fails: In patients with refractory angina who don't respond to sublingual nitroglycerin, IV administration may still provide relief 6. This should be considered while awaiting cardiology consultation.

3. Prophylactic use: For patients with known angina, nitroglycerin can be used 5-10 minutes prior to activities that might precipitate chest pain 3.

Documentation and Handoff

When consulting cardiology, document:

• Timing and dose of nitroglycerin administration
• Patient's response to treatment
• Blood pressure measurements before and after administration
• Any adverse effects observed
• ECG findings before and after nitroglycerin

Remember that while nitroglycerin is an important first-line treatment for suspected acute coronary syndrome, it should not delay definitive evaluation and management by cardiology, especially in patients with persistent symptoms.