Medication guide
Nitroglycerin.
Chest pain, CHF, and the questions every NREMT candidate misses.
Indications
- Suspected cardiac chest pain / ACS.
- Acute pulmonary edema / CHF exacerbation.
- Hypertensive emergency (in-hospital drip).
Dosing
- SL tablet or spray: 0.4 mg every 5 min ×3, SBP > 100 mmHg.
- Paste (Nitro-Bid): 1–2 inches to chest wall (in-hospital or extended transport).
- IV drip: 5–200 mcg/min, titrated (in-hospital).
Absolute contraindications
- Sildenafil (Viagra) or vardenafil in past 24 hours.
- Tadalafil (Cialis) in past 48 hours.
- SBP < 100 mmHg (some protocols use 90).
- Right-ventricular infarct (inferior MI with hypotension).
- Severe bradycardia or tachycardia.
- Increased intracranial pressure.
Right-sided MI test
With any inferior STEMI (II, III, aVF) — grab a right-sided 12-lead (V4R). ST elevation there = RV infarct = no nitro, give fluid instead.
EMS pearls
- Reassess BP before every dose.
- Have an IV before high-dose CHF nitro — you may need fluid.
- Tolerance builds fast — patient's own bottle may be inert.
- Warn the patient about headache — it's expected, not toxic.
Frequently asked
- What is the standard nitro dose?
- 0.4 mg SL every 5 minutes, up to 3 doses, as long as SBP > 100 mmHg. Paste and IV drips are used in-hospital for CHF and refractory ischemia.
- When is nitro absolutely contraindicated?
- PDE-5 inhibitor within 24–48 hours (sildenafil 24h, tadalafil 48h), SBP < 100 mmHg, and suspected right-ventricular MI (inferior MI with hypotension).
- Why is nitro dangerous in right-sided MI?
- The right ventricle is preload-dependent in RV infarct. Nitro drops preload and can cause profound hypotension.
- Should I give nitro in CHF?
- Yes — high-dose nitro is a first-line CHF treatment (as long as SBP is adequate). It drops preload and afterload, dramatically improving pulmonary edema.
Drill cardiac emergencies
Free practice test →Educational use only. Follow local protocols and medical direction.