Makindo Medical Notes

⚠️ Key Point: There is a 10-fold variability in patient response to UFH. 👉 With full-dose therapy, always monitor APTT ratio daily and adjust dose to stay within the therapeutic range (1.5–2.5). This minimises both bleeding and thrombosis risk.

📖 About

Always check the BNF link here.

• 💉 Naturally occurring glycosaminoglycan (porcine/bovine derived).
• 🩺 Used in treatment and prevention of thrombosis.
• ⚡ Indirect thrombin inhibitor via potentiation of antithrombin III.

⚡ Properties

• ⏱️ Short half-life: 30–120 minutes.
• 🔄 Action quickly reversible with protamine.
• MW 5,000–35,000 Da (mean ~12–14,000).
• Binds antithrombin → enhances inactivation of factor Xa + thrombin.
• 🎯 Prolongs activated partial thromboplastin time (APTT).
• ⚠️ Heparin-induced thrombocytopenia (HIT) may develop after 5–10 days.

🩺 Indications

• Acute thrombosis where close control is required.
• Cardiopulmonary bypass / renal dialysis circuits.
• IV perioperatively (e.g. carotid endarterectomy).
• Acute coronary syndrome post-thrombolysis.
• VTE prophylaxis (now usually LMWH preferred).
• Low-dose flush for vascular catheters.

⚠️ Cautions

• ❌ Do not take blood for APTT from the same arm as UFH infusion.
• Bleeding disorders (haemophilia), thrombocytopenia, liver/renal failure.
• Uncontrolled hypertension (SBP >200 or DBP >120 mmHg).
• Active peptic ulcer, oesophageal varices, aneurysm, proliferative retinopathy.
• Recent head/spinal/eye surgery, trauma, or recent stroke.
• History of HIT or HITT (thrombosis + thrombocytopenia).

📊 Monitoring

• APTT ratio target: 1.5–2.5.
• Plasma anti-Xa assays may be used in special cases.
• Check platelets regularly to detect HIT.

💥 Side Effects

• 🩸 Bleeding (manage with protamine, blood products if needed).
• ⚠️ HIT: ~5% incidence, more common with prolonged use – stop all heparins, urgent haematology advice.
• ⬆️ Hyperkalaemia (via aldosterone suppression).
• 🦴 Osteoporosis with long-term therapy.

💊 Dosing (UFH)

• VTE prophylaxis (medical): 5,000 units SC every 8–12h (largely replaced by LMWH).
• VTE prophylaxis (surgical): 5,000 units SC 2h pre-op, then every 8–12h.
• Acute thrombosis (e.g. DVT/PE): Loading dose 5,000 units IV (10,000 if severe PE), then infusion at 18 U/kg/h.
• Typical maintenance: 1,000–2,000 units/hour IV, adjusted to APTT.
• 🧪 Infusion prep: 25,000 units UFH in 50 mL saline (1 mL = 500 U). Adjust according to APTT nomogram.
• APTT check: every 4–6h until stable, then daily.

📉 Dose Adjustment (APTT-based)