Coagulation and Vitamin K in Head and Neck Microvascular Free Flap Surgery

Plain-language summary

For patients with large head and neck tumors the recommended treatment, in many cases, is a combination of extensive surgery and postoperative radiotherapy. The surgical procedure involves resection of the tumor and reconstruction with a so called microvascular free flap, i.e. tissue transferred from for instance the arm or leg to the resection site. Complications of this complex procedure include, but are not limited to, bleeding and blood cloths (thrombosis) in the transferred tissue (free flap), which can cause very serious complications including need for further surgery and loss of the flap. Routine blood tests can measure parts of the system that regulates bleeding and the forming of blood clots, the so called coagulation system, but these tests don't cover the whole system. There are however more advanced instruments, such as ROTEM, rotational thromboelastometry, which provide a more global view of the hemostatic potential of whole blood. ROTEM is one of few more advanced assays that can be analyzed in emergency situations in major hospitals. Other more advanced coagulation assays are thrombin generation and measurements of specific coagulation factors, several of which are vitamin K dependent. Vitamin K is essential in the coagulation system and also involved in many other physiological processes. Deficiency of this vitamin is common, but not well studied in patients undergoing head an neck free flap surgery. The investigators plan to study ROTEM and other above mentioned coagulation parameters in patients undergoing major head and neck surgery including microvascular free flap reconstruction to assess if these parameters can help predict patients at risk for bleeding or flap thrombosis. Further on this could hopefully enable prevention of complications and improve treatment of coagulation complications that still occur.

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