Predicting the Timing and Cause of Microvascular Free Flap Failure: An Australian Study of 1569 Free Flaps.

Background: The aim of the study is to assess the possible predictors of microvascular free flap failure and determine the critical postoperative timing of flap failure, thereby minimizing this adverse outcome.

Methods: This is a retrospective single-institutional review of 1569 free flap operations. All free flaps with outcome status recorded were analyzed for possible predictors in the development of microvascular compromise. Compromised cases were then analyzed for differences in time to compromise and time to theater takeback between salvaged versus failed free flaps.

Results: Of the assessable 1569 free flaps, 31 developed microvascular compromise (2.0%); the salvage rate was 20.0%, and overall failure rate was 1.5%. Osteocutaneous free flaps in head and neck had increased risk of developing free flap failure compared to other flaps (odds ratio = 3.8, 95% confidence interval: 1.2-12.7). Among breast patients, previous radiotherapy had a significant association with flap failure ( P < 0.001). Free flap salvage rates dropped from 38.5% to 7.7% for compromises detected after 24 hours ( P = 0.160), and from 57.1% to 11.1% for free flaps taken back to theater greater than 3 hours after compromise detection ( P = 0.032).

Conclusions: Delays in compromise detection and flap takeback to theater resulted in reduced salvage rates, with the critical timing of takeback being under 3 hours. Standardized flap monitoring protocols and incorporation of newer technologies could see faster detection and improved salvage rates. Additional care is required when reconstructing: osteocutaneous head and neck free flaps and previously irradiated breast patients.