Clinical Utility of High Resolution Ultrasonography in the Postoperative Monitoring of Free Tissue Transfers

Introduction: Early recognition and rapid reexploration of free flaps with signs of vascular compromise are associated with better outcomes; however, the best method for monitoring tissue perfusion has yet to be established. The purpose of this study was to report the clinical utility of high resolution ultrasonography (US) for monitoring vascular compromise after free tissue transfers.

Methodology and Material: Twenty-two patients (men 20, women 2, mean age 39.5) with tissue defects in extremities, reconstructed by 15 free fasciocutaneous, 5 free osteocutaneous, 1 free musculocutaneous, and 1 buried muscle flaps were included in this study. The status of anastomosis pedicle and subcutaneous blood flow in grafted flap was monitored by power Doppler US at the time of surgery and 1, 3, 7 and 14 days after surgery. This ultrasonography examination was also added whenever conventional bedside monitoring showed abnormality.

Results: In eighteen of twenty-two patients, no flap failure occurred when the power Doppler signal was present. In two of twenty-two patients, power Doppler US detected thrombosis of anastomosis pedicle when conventional bedside monitoring showed abnormality. One patient had arterial thrombosis with complete loss of subcutaneous blood flow in flap. The other patient showed obstruction of venous flow of anastomosis pedicle with decreased subcutaneous blood flow in flap. Emergent surgical reexploration showed same findings as US. We were able to salvage these two failing flaps by thrombectomy with vein graft. On the other hand, there were 2 patients with partial flap losses. In one patient, there was already no subcutaneous blood circulation in the affected part of flap at the time of surgery, but blood flow of anastomosis pedicle was present. This revealed that anastomosis vascular system did not cover whole part of flap and we could not salvage this partial necrosis.

The other partial necrosis occurred due to infection. We could not help performing irrigation and debridement of infected tissue. Power Doppler US detected all vascular compromises with no false positive or negative.

Conclusions: The use of high resolution US provided the optimal assessment of perfusion in not only anastomosis pedicles, but also subcutaneous capillaries in grafted flaps. This devise was a useful adjunct in monitoring the perfusion of free tissue transfer during the postoperative period. However, we have to investigate the recommended frequency of flap monitoring by this technique to help decrease flap loss by detecting impending vascular compromise before it becomes clinically evident