Glyceryl trinitrate (GTN) infusion

Dilution guide

Indication

Acute pulmonary oedema, unstable angina, hypertensive emergency (with LV failure).

Preparation

50 mg in 250 mL D5W or NS via polyethylene set (avoid PVC — adsorbs GTN).

Dilution

200 mcg/mL

Rate

Start 5–10 mcg/min IV; titrate by 5–10 mcg/min q3–5 min to symptom relief (max 200 mcg/min).

Monitoring

  • Continuous BP (arterial line preferred at high doses)
  • HR, symptoms of chest pain
  • SpO2

Common errors

  • PVC tubing → 40–80% drug loss
  • Hypotension with RV MI or hypovolaemia
  • Concomitant PDE5 inhibitor (24–48 h) → catastrophic hypotension

Pearls

  • Tolerance in 24–48 h — plan for early transition
  • Preload > afterload reduction at low doses
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