Free flap monitoring in plastic and reconstructive surgery.

Free flaps are regularly used in plastic and reconstructive surgery but have a significant failure rate due to vessel thrombosis in the re-established arterial or venous circulation. A monitor of flap perfusion and oxygenation would allow the early detection of progressing flap ischaemia, hastening the required intervention and maximising the chances of salvaging the flap. A dual wavelength spectrophotometer has been designed and constructed which can monitor haemodynamic events in flaps during surgery and postoperatively. Eleven patients undergoing free flap surgery were studied. Measurements were made during surgery before division of the vessels and during and after microvascular anastomosis. Significant changes in all parameters were observed on reperfusion of the flaps after anastomosis or tourniquet ischaemia. Abnormal reperfusion in one flap and subsequent ischaemic events in two others were identified.