Heparin Reversal Protocol

Immediate Reversal Strategy

For patients requiring urgent heparin reversal, administer IV protamine sulfate at 1 mg for every 100 units of heparin given in the previous 2-3 hours, with a maximum single dose of 50 mg, delivered slowly over 10 minutes, as recommended by the American College of Critical Care Medicine 1, 2, 3

After 3-5 half-lives (>2-3 hours) of heparin administration, protamine is likely not needed, according to the American College of Critical Care Medicine 1

Administer protamine by slow IV injection over 10 minutes minimum to prevent severe hypotension, bradycardia, and anaphylactoid reactions, as recommended by the American College of Critical Care Medicine 1
Measure aPTT or ACT 5-10 minutes after protamine administration to confirm adequate reversal, as recommended by the American College of Critical Care Medicine and the American Heart Association 1, 2, 4

Do NOT routinely reverse prophylactic subcutaneous heparin, but consider reversal only if aPTT is significantly prolonged, as recommended by the American College of Critical Care Medicine 1, 2, 3
For cardiac surgery with cardiopulmonary bypass, use a fixed-dose ratio method (1.0-1.3 mg per 100 units) for operations with CPB duration <90 minutes, as recommended by the American Heart Association 4

If enoxaparin is given within 8 hours, administer 1 mg protamine per 1 mg enoxaparin (max 50 mg), as recommended by the American College of Critical Care Medicine 1, 2, 3

Do not calculate protamine based on total cumulative heparin dose, but rather only the dose given in the preceding 2-3 hours, as recommended by the American College of Critical Care Medicine 1
Do not routinely reverse prophylactic doses without clinical indication, as recommended by the American College of Critical Care Medicine 1, 2, 3

The American Heart Association recommends administering 1.0 to 1.3 mg of protamine for each 100 units of heparin administered, resulting in a dose of 30-39 mg protamine for 3000 units of heparin 5, 6, 7, 8
One milligram of protamine neutralizes approximately 85-100 units of heparin 9

For heparin administration within 30 minutes, use full calculated dose (30-39 mg for 3000 units) 10
For heparin administration 30-60 minutes prior, reduce to 0.5-0.75 mg per 100 units (15-22.5 mg for 3000 units) 10
For heparin administration 60-120 minutes prior, reduce to 0.375-0.5 mg per 100 units (11.25-15 mg for 3000 units) 10

Administer protamine by slow intravenous injection over 10 minutes to minimize risk of severe hypotension, bradycardia, and anaphylactoid reactions 10

Measure activated clotting time (ACT) or activated partial thromboplastin time (aPTT) 5-10 minutes after protamine administration to confirm adequate heparin reversal 9, 7, 8, 10
If ACT/aPTT remains elevated, administer additional protamine at 0.5 mg per 100 units of heparin 10

For cardiac surgery with cardiopulmonary bypass duration <90 minutes, the fixed-dose ratio method (1.0-1.3 mg per 100 units) is appropriate 5, 6, 7, 8

The American Society of Hematology (2018) conditionally recommends the administration of protamine for patients with unfractionated heparin (UFH) who experience life-threatening bleeding, despite very low certainty of evidence 11, 12
Protamine reduces the risk of major bleeding (RR 0.61, 95% CI 0.39-0.96) 11, 12
The American Heart Association/American Stroke Association (2011) recommends (Class I, Level B) the use of protamine sulfate to reverse heparin-associated intracranial hemorrhage, with dosage depending on the time since heparin cessation 13, 14, 15

The dosage of protamine should be adjusted based on the time since the last administration of heparin, considering heparin's half-life of approximately 30 minutes after intravenous administration
For life-threatening bleeding, protamine should be administered at a dose of 1 mg per 100 units of heparin given in the last 2-3 hours, with a maximum single dose of 50 mg, infused intravenously over at least 10 minutes 11, 12

The activated partial thromboplastin time (aPTT) or activated clotting time (ACT) should be measured 5-10 minutes after protamine administration to confirm adequate reversal 11, 12
If the aPTT/ACT remains elevated, additional protamine may be administered at a dose of 0.5 mg per 100 units of heparin 11, 12

In life‑threatening bleeding on therapeutic LMWH, protamine neutralizes approximately 60 % of anti‑Xa activity while fully reversing anti‑IIa activity, acknowledging that reversal is incomplete. 16, 17

The protamine dose should be calculated from the amount of UFH administered during the preceding 2 hours, not from the cumulative dose. 18, 19
< 30 min since last UFH dose: 1 mg protamine per 100 units of heparin. 18, 19
30–60 min: 0.5–0.75 mg protamine per 100 units of heparin. 18, 19
60–120 min: 0.375–0.5 mg protamine per 100 units of heparin. 18, 19
> 120 min: 0.25–0.375 mg protamine per 100 units of heparin. 18, 19
Maximum single dose: 50 mg administered over 10 minutes. 18, 19

If protamine is given within 8 hours of the last LMWH dose:
- First dose: 1 mg protamine per 1 mg enoxaparin (or per 100 anti‑Xa units), capped at 50 mg. 16, 17
- Second dose (if bleeding persists): 0.5 mg protamine per 100 anti‑Xa units. 16, 17
When the interval exceeds 8 hours, smaller protamine doses should be used. 16, 17

Protamine must be infused slowly intravenously over at least 10 minutes to reduce the risk of severe hypotension, bradycardia, and anaphylactoid reactions. 18, 19

Patients with a known fish allergy are at higher risk for protamine‑related reactions. 18
Infusion rates faster than 5 mg/min (i.e., > 50 mg in 10 minutes) markedly increase the likelihood of severe hypotension and anaphylaxis. 18, 19

Do not base protamine dosing on the total cumulative UFH dose; limit calculations to the heparin given in the preceding 2–3 hours. (Guideline derived from the same dosing recommendations above.)
Expect only partial reversal of LMWH‑associated anti‑Xa activity (~60 % neutralization) even when protamine is administered at the recommended doses. 16, 17
Avoid rapid protamine infusion (> 5 mg/min) because it significantly raises the risk of adverse hemodynamic events. 18, 19