Free flap surgery: ischaemia time and anastomosis

anastamosis free flap ischaemia time microsurgery plastic surgery Sep 24, 2026

Free flap surgery is a careful balance of time, tissue and tiny vessels. Once the flap’s blood supply is divided, the tissue enters a period of ischaemia while it is transferred and the microvascular anastomoses are completed. For the scrub and scout team, understanding what is happening during this window helps make sense of why preparation and anticipation matter so much.

During ischaemia, the flap is temporarily without normal perfusion. Oxygen depletion drives anaerobic metabolism, with changes including lactate accumulation, acidosis and cellular electrolyte shifts. Reperfusion occurs once the vascular anastomoses are complete and blood flow is restored, but this can bring its own cellular stresses.

🔹 Ischaemia time matters. The aim is to minimise unnecessary interruption to flap perfusion while allowing meticulous microvascular work.

🔹 Anastomosis restores circulation. Donor vessels are connected to recipient vessels, creating the arterial inflow and venous outflow required for flap viability.

🔹 Repeated ischaemia may matter too. Research has found reduced flap blood flow following an early second ischaemic interval, highlighting that the pattern of interrupted perfusion can be important.

🔹 Preparation supports efficiency. Having microsurgical instruments, sutures, clamps and required equipment ready helps avoid preventable delays during this time-sensitive stage.

For scrub and scout nurses, the microvascular phase is a time for focused anticipation. Knowing where the team is within the flap transfer, anastomosis and reperfusion sequence helps us stay one step ahead.

The clinical takeaway? Every minute has context. Understanding ischaemia and anastomosis helps the scrub and scout team appreciate why smooth workflow during free flap surgery matters.

References

Ooms, M. et al. (2024). Free Flap Perfusion in Microvascular Head and Neck Reconstruction: Influence of the Number of Ischemia Intervals and Ischemia Duration: A Retrospective Study. Journal of Otolaryngology - Head & Neck Surgery.

Stephan, D. et al. (2023). The Impact of Transfer-Related Ischemia on Free Flap Metabolism and Electrolyte Homeostasis: A New In Vivo Experimental Approach in Pigs. Journal of Clinical Medicine.

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