Evaluation of the Implantable Doppler Probe for Free Flap Monitoring in Lower Limb Reconstruction

Timely reexploration and reanastomoses can salvage failing free flaps. The use of the implantable Doppler probe provides direct evidence of vascular impairment of the microvascular anastomoses and allows for postoperative NPWT. The aim of this retrospective study was to compare the Doppler probe to conventional monitoring techniques for free flap monitoring in lower limb reconstruction and to identify risk factors for perfusion disturbance and reexploration.

All patients receiving free muscle flap reconstruction for lower limb soft tissue defects at our department from 2000 to 2013 were included, and all adverse events, timely detection of perfusion problems, and outcome of revision surgery were assessed by chart analysis.

For lower limb reconstruction, 110 free muscle transfers were performed of which 41 muscle flaps were conventionally monitored and 69 flaps were monitored using the implantable Doppler probe. In 18 cases, the free muscle flaps needed revision because of perfusion disturbances. The salvage rate was 80% with monitoring by the implantable Doppler probe compared with 62.5% using conventional monitoring methods resulting in success rates of 95.7 and 92.7%, respectively.

The use of the implantable Cook-Swartz Doppler probe represents a safe monitoring method for lower limb reconstruction, which allows for the additional use of NPWT. Higher salvage and revision success rates can be attributed to an earlier detection of perfusion impairment. However, a larger patient cohort is necessary to verify superiority over conventional postoperative monitoring.