Review-based development of a protocol for intraoperative urokinase in free flap salvage

Background The intraoperative use of thrombolytic agents, such as urokinase, is an established adjunct technique in free flap salvage. However, choice of agent, technique of administration and dosage varies across reconstructive units, with no consensus on optimal protocol. Methods A retrospective review was performed of free flaps requiring operative exploration and salvage at our institution between July 2016 and June 2022. Flaps with persistent poor venous outflow despite standard salvage measures received urokinase thrombolytic therapy. A literature review was also performed to identify existing urokinase administration protocols, including indication and technique of administration. A search of PubMed and Embase databases was performed to identify relevant articles published between 1982 and 2022. Results 28 flaps required takeback to theatre for exploration and attempted salvage, with an overall salvage success rate of 71%. Urokinase was used in 8 cases when the flap did not respond intraoperatively to standard salvage procedures, with salvage success of 38%. For the literature review, 155 articles met our search criteria. 10 articles were suitable to be reviewed. Due to study heterogeneity and small case numbers, statistical analysis was not possible. A summative review of findings and outcomes was instead performed to compare with our own experience. Conclusions There is lack of uniformity in urokinase administration protocols across reconstructive units. We present a step-by step protocol for the use of intraoperative urokinase in free flap salvage that is easy to understand and follow. Standardisation of administration protocol and larger case series are required to determine the true efficacy and utility of urokinase. Level of evidence: Level IV, Therapeutic.