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

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Microvascular reconstructive free flap surgery is an important part of the recommended treatment for extensive head and neck tumors. However, the procedure includes risks of perioperative coagulation related complications, such as bleeding, but also thrombosis in the flap blood vessels. In about 10%...

Microvascular reconstructive free flap surgery is an important part of the recommended treatment for extensive head and neck tumors. However, the procedure includes risks of perioperative coagulation related complications, such as bleeding, but also thrombosis in the flap blood vessels. In about 10% of cases this requires reoperation, but, in spite of intense efforts, about 5% of all patients suffer from flap failure, i.e. necrosis of the free flap. This results in significant suffering for the patients who must undergo further surgery and oftentimes considerable prolonged hospital stay etc. This in turn leads to increased health care costs. There are several indications that tendency towards thrombosis can increase the risk of flap failure. Previous studies have indicated that increased levels of fibrinogen and inherited thrombophilia, such as APC resistance, are associated with thrombotic free flap complications, but more conventional coagulation parameters, such as PK/INR and aPTT have not shown the same connection. Low fibrinogen levels have also been associated with bleeding complications. Most patients undergoing the above mentioned surgery receive anticoagulant therapy. However, there is no international consensus on any specific pharmacological regime. Many different prophylactic therapies are used, including low molecular weight heparin, dextran and acetylsalicylic acid. Still coagulation-related complications are difficult to prevent. Defective coagulation apparently seems to be associated with bleeding and thrombotic perioperative complications. It would therefore be desirable to increase the knowledge about factors influencing the development of these complications, and the patients at risk for them. ROTEM, rotational thromboelastometry, is a viscoelastic essay that provides a more global view of the hemostatic potential in whole blood, and it is also one of few more advanced assays that can be analyzed around the clock in many Swedish hospitals. The aim of this project is to study perioperative coagulation and vitamin K status, and thereby further on hopefully be able to prevent, and improve the treatment of, bleeding and thrombosis related complications in patients undergoing head and neck microvascular free flap surgery.

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