SRS316 - Assessing the effect of ischaemia time on free tissue transfer outcome: a systematic review and meta-analysis

Abstract Aims Free tissue transfer is a common plastic surgical procedure with a wide array of applications. There is limited consensus on how free flap ischaemia time impacts flap survival. This systematic review aims to evaluate the association between free flap ischaemia time and acute flap failure rate. Methods A systematic review and meta-analysis in compliance with PRISMA statement standards was conducted following registration on the PROSPERO Register (CRD420251052841). A search strategy was developed and the search conducted in September 2024. Studies eligible for inclusion reported length of ischaemia time for free flap surgery and acute flap failure rate. 78 articles were eligible for inclusion and were published between 1997 and 2024. Study populations ranged from 7 to 3926 patients, with a pooled total of 26 374 free flaps in 23 615 patients. The meta-analysis showed overall risk of flap failure was 3.5% (95% c.i. 3%–4.1%). Meta-regression using ischaemia time as a continuous variable showed an increasing risk of acute flap failure from 3% (2.3%–3.9%) at 30 min ischaemia time to 7.5% (4.4%–12.5%) at 240 min. The variables study type, flap type, indication and risk of bias did not account for between study heterogeneity which was substantial. Conclusions This study has systematically assessed existing literature to show a significant association between prolonged ischaemia time and acute free flap loss. This association can guide microsurgical training as carrying out microsurgery in a time efficient manner has a positive impact on free flap survival.