Plastic Surgery Research Council

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Free Flap Bleeding Complications Related To Intravenous Heparin Infusion Administration
Andrew Lewandowski1, Lisa Scupham2, Paul Bullen1, Michael Wagels1
Department of Plastic and Reconstructive Surgery, Princess Alexandra Hospital School of Medicine, University of Queensland

Reconstructive free flap surgery incorporates prolonged operative times, microvascular trauma and large flap donor sites. These patients require complex reconstructions of traumatic or oncologic defects, and require a complex balance between risk of bleeding and thrombotic catastrophe. Subsequently, anticoagulation regimens vary greatly between Plastic and Reconstructive Surgeons, and remain largely subject to anecdotal evidence, This is due to a lack of sufficient evidence in the literature to guide appropriate anticoagulation. This study will provide retrospective data on the rates of complications relating to heparin infusions in free flap patients, and guide prospective studies to appropriately alter management in the future.

METHODS:
We retrospectively reviewed 1078 free flaps or tissue reimplantations performed at a major tertiary referral centre over a 10-year period. Indication for surgery, anticoagulation data and complication rates were collated from previous unit audits and chart review. 59 patients with 60 flaps were placed on heparin and evaluated for complications, defined as thrombosis/haematoma requiring reoperation. aPTT was recorded and evaluated, comparing area under the curve for variations from the desired therapeutic range. Complications were recorded in relation to the aPTT and related to flap and patient outcomes.

RESULTS:
1078 patients underwent surgery in a 10-year period. 5.56% (60) of these were free flaps or replants that received perioperative IV Heparin infusions. The rate of haematoma was 36.7% (22) and thrombosis was 16.7% (10) whilst on heparin. Flaps had a higher risk of partial/complete flap loss if a complication occurred (p=0.004). Flaps with thrombosis had a significantly greater subtherapeutic aPTT area under curve (p=0.02).

CONCLUSIONS:
Patients undergoing free flap surgery that require intravenous heparin are at a significantly increased risk of post-operative bleeding events, however the risk of subtherapeutic dosing puts flaps at significantly increased risk of partial or complete loss. This study provides sufficient evidence to start prospectively analyzing the 'safe' APTT range for these patients, as well as the role of LMWH or Novel Oral Anticoagulants (NOACs).


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