Hypercoagulability in free flaps post-COVID-19
Research type
Research Study
Full title
The hypercoagulable state in COVID-19 and implications for free flap surgery in the lower limb: A retrospective multi-centre study
IRAS ID
319718
Contact name
George Wheble
Contact email
Sponsor organisation
North Bristol NHS Trust
Clinicaltrials.gov Identifier
not applicable, not applicable
Duration of Study in the UK
0 years, 6 months, 2 days
Research summary
The principal aim of this research is to compare the rate of thrombotic complications in lower limb free flap surgery in a pre- and post-COVID-19 cohort.
Free flap surgery is undertaken where there is no alternative to repair a defect (whether following injury, infection, or cancer) other than limb amputation. ‘Free flaps’ are autotransplants of the patient’s own tissue, and can be composed of skin, fat, fascia, muscle and/or bone. In the initial post-operative period, the free flap relies on usually a single microvascular arterial supply and a single microvascular venous drainage, and therefore is vulnerable to thrombosis (blood clots) in the recipient vessels, at the anastomosis site and within the microvasculature of the flap. Thrombosis can lead to flap death and, in some cases, delayed amputation of the limb.
Anecdotally, some units that perform high volumes of this type of surgery have noticed an increased rate of thrombotic complications in the post-COVID-19 era. The hypercoagulable state associated with severe COVID-19 infection and COVID-19 Vaccine-Induced Thrombotic Thrombocytopaenia (VITT) have been widely documented, although existing evidence focuses on macrovascular thrombosis, where patients present with symptoms of such an event, including deep vein thrombosis and pulmonary embolism (blood clots in the legs or lungs). Little is known about the impact of the hypercoaguable state associated with COVID-19 infection on microvascular thrombosis in the context of free tissue transfer to the lower limb.
This study aims to assess whether previous COVID-19 infection (including mild and asymptomatic infection) or vaccination appears to increase the thrombotic complication rate in these patients.Knowledge of an increased rate of thrombosis in such patients, if it does exist, will pave the way for future studies aimed at delineating appropriate pre-operative screening and thromboprophylaxis.
REC name
Wales REC 4
REC reference
23/WA/0072
Date of REC Opinion
28 Feb 2023
REC opinion
Further Information Favourable Opinion