title: Thromboelastometry: A contribution to perioperative free-flap management.
abstract: BACKGROUND
  Microvascular tissue transfer is a fundamental part of reconstructive surgery. Different perioperative anticoagulation regimens exist, influencing hemostatic parameters. Since bleeding and thrombosis are major reasons for revision procedures and flap loss, current practice regarding anticoagulative treatment needs further refinement. Thromboelastometry has been demonstrated as worthwhile in the determination of alterations of the anticoagulation cascade. We evaluated this aspect of thromboelastometry for free flap surgery.
  
  
  METHODS
  Thirty-five patients undergoing free-flap surgery were enrolled in this study. Blood samples were obtained at three time points: at the beginning of surgery, at time of anastomosis and after 24 h. At each time point, thromboelastometry with special regard to clotting times for the intrinsic and extrinsic paths of coagulation was immediately performed. Global coagulation markers and clinical parameters were collected simultaneously.
  
  
  RESULTS
  Hemostatic changes were deducible using thromboelastometry perioperatively. Measured parameters differed significantly over time (p < 0.05). Heparin therapy showed a significant effect on the measured slope of INTEM-clotting times (p < 0.001). Altered values of thromboelastometry suggested non-inferiority to standard testing. Neither standard testing nor thromboelastometry were capable of predicting adverse events such as thrombosis, bleeding or flap loss (p > 0.05).
  
  
  CONCLUSIONS
  Thromboelastometry monitors hemostatic effects almost in real-time and could serve as a supplementary tool in microvascular tissue transfer once its use has been standardized. The utilization of thromboelastometry allows for assessment of the anticoagulation needs of individual patients undergoing free flap surgery, which is frequently accompanied by hemostatic changes in the perioperative setting. Our findings implicate further validation of thromboelastometry in free-flap surgery.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Germany. Electronic address: j.wikner@uke.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Wikner
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Benedicta E
authors.initials: BE
authors.lastname: Beck-Broichsitter
authors.affiliation: Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine, University Medical CenterHamburg-Eppendorf, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: Schlesinger
authors.affiliation: Medical Biometry and Epidemiology, University Medical Center Hamburg Eppendorf, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schön
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Heiland
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Alexandre Thomas
authors.initials: AT
authors.lastname: Assaf
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Rashad
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Riecke
authors.affiliation: Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine, University Medical CenterHamburg-Eppendorf, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Heckel
mesh_terms: D000368:Aged; D000714:Anastomosis, Surgical / Q000379:methods; D000925:Anticoagulants / Q000627:therapeutic use; D016063:Blood Loss, Surgical / Q000517:prevention & control; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D058752:Free Tissue Flaps / Q000098:blood supply / Q000637:transplantation*; D006085:Graft Survival; D006258:Head and Neck Neoplasms / Q000601:surgery; D006488:Hemostasis, Surgical / Q000379:methods; D006493:Heparin / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D019990:Perioperative Care; D010976:Platelet Count; D011446:Prospective Studies; D011517:Prothrombin Time; D019651:Plastic Surgery Procedures / Q000379:methods*; D013916:Thrombelastography / Q000379:methods*; D013918:Thrombin Time; D013927:Thrombosis / Q000517:prevention & control
chemical_list: D000925:Anticoagulants; D006493:Heparin
keywords: Anticoagulation; Free flap surgery; Heparin; Microsurgery; Thromboelastometry