Patients who present to the ED with an elevated INR due to vitamin K antagonists many times do not need to be reversed.  Simply holding a dose is all that is usually necessary for patients with an INR < 9.  Fortunately, guidelines published in CHEST are available to help guide management.
 

• INR: >Therapeutic to 5.0 with no bleeding - Lower warfarin dose, or omit a dose and resume warfarin at a lower dose when INR is in therapeutic range
• INR: >5.0 to 9.0 with no bleeding - Omit the next 1 to 2 doses of warfarin, monitor INR more frequently, and resume treatment at a lower dose when INR is in therapeutic range, or omit a dose and administer 1 to 2.5 mg oral vitamin K.* [*This option is preferred in patients at increased risk for bleeding (eg, history of bleeding, stroke, renal insufficiency, anemia, hypertension.]
• INR: >9.0 with no bleeding - Hold warfarin and administer 5 to 10 mg oral vitamin K. Monitor INR more frequently and administer more vitamin K as needed.
• Any INR with serious or life-threatening bleeding - Hold warfarin and administer 10 mg vitamin K by slow IV infusion; supplement with prothrombin complex concentrate, fresh frozen plasma, or recombinant human factor VIIa, depending on clinical urgency. Monitor and repeat as needed.
   

Reference:

Ansell, J, Hirsh, J, Hylek, E, et al. Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; (6 Suppl):160s.

References

Ansell, J, Hirsh, J, Hylek, E, et al. Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; (6 Suppl):160s.