Is there a specific INR cut-off value that would prompt you to consider administering vitamin K for patients with mechanical valves requiring urgent non-cardiac surgery and if so, what would be your starting dose?   

For urgent surgery that could result in significant bleeding, I would give vitamin K if the INR was 1.6 or higher. I would avoid high doses of vitamin K so as to allow more rapid anticoagulation post-op. Usually one dose of 5mg is enough. I would start low molecular weight heparin post op until INR ...