Rapid response to intravenous vitamin K may obviate the need to transfuse prothrombin complex concentrates

Patients on warfarin who present with bleeding or who require an urgent procedure are commonly treated with intravenous (IV) vitamin K, which is supplemented with repletion of the vitamin K factors using either plasma or a prothrombin complex concentrate (PCC). In some such cases, use of vitamin K alone could be adequate to achieve acceptable hemostasis.

An algorithm emphasizing the use of vitamin K alone in patients presenting with non-life-threatening bleeding was encouraged, with repeat testing of the international normalized ratio (INR) within 5 hours. Depending on the INR result, patients received no factor repletion or plasma or PCC, as judged by the physician. Leftover samples from a separate cohort of patients with supratherapeutic INRs (INR > 4.0) were studied for clotting factor evaluation.

A total of 46 pre- and postinfusion INRs were evaluable from 41 patients. Median INR decreased from 5.8 to 2.5, with a median dose of 5 mg after a median time of 4.0 hours postinfusion. A total of 27 of 46 (59%) postinfusion samples showed an INR of 2.5 or less. Samples from patients with the highest INR showed the greatest decline in INR. Samples from supratherapeutic INR patients showed very high Factor VIII:C (200%) and a normal activated partial thromboplastin time in 23 of 50 (46%).

Use of IV vitamin K as sole therapy for urgent partial reversal of warfarin for non-life-threatening bleeding may provide adequate hemostasis within 5 hours, avoiding the need for clotting factor repletion.