With increasing experience among microsurgeons, established microsurgical techniques, and development of more reliable flaps, the failure rate of free-tissue transfer has been reduced significantly since its introduction almost three decades ago. Success rates, as reported in the medical literature, vary between 91 and 99 percent, with re-exploration rates between 6 and 25 percent. Regardless the improved flap survival rate, the consequence of a lost free flap is dramatic, medically, emotionally and economically. In order to lower the failure rates in microsurgical procedures, a close post operative monitoring is advocated in the early days after surgery.
Between 2001-2003, 84 cases of free tissue transfer were monitored using implantable ultrasonic doppler device (IUDD). 38%of the flaps were used for head and neck reconstruction, 33.3% for upper and lower extremity reconstruction, 15.5% breast reconstruction and in 10.7% for facial reanimation. In 22.6% the flap was buried and the implantable doppler was the only monitoring modality used. In 34.5% a skin island was used for additional monitoring. In 29.8% and 17.9% the flap was covered with a skin graft or placed intra-orally, respectively, making conventional monitoring difficult.
In six patients (7.1%) interruption of the blood flow was detected by the IUDD and a flap revision was performed. In two patients the flap was salvaged, in three patients (3.6%) the flap was lost and in a single patient (1.2%) the doppler indicated absent flow while in the revision the blood flow was found to be intact. In two of the lost flaps there was an early detection of the flow impairment by the IUDD but our surgical exploration was late by 3 – 4 hours due to uncertainty of the device accuracy.
Conclusions - comparing our success rates between the years 1998-2001 in the pre-implantable doppler era, to 2001-2003 there was a significant improvement from 90% to 94%. Although this can be partly attributed to the learning curve and improved surgical skills, we believe that the implantable ultrasonic doppler is an important adjunctive monitoring device that directly reflects the flow state in the blood vessel. It is particularly critical for buried flaps monitoring, where it serves as the sole monitoring option. It is also an important method in difficult locations for clinical assessment like intraoral flaps. It is sometimes hard to interpret the doppler sign, in our experience once the doppler sign is lost it should be considered as a true flow problem and a revision is indicated unless there is a clear other objective sign for flap vitality.
Another important application of the implantable dopper use is intraoperative monitoring of the microsurgical anastomoses during closure and inset of a free flap. Most of the early postoperative failures are due to failure of the flap on the operating table as a result from direct pressure or a kink to the vascular pedicle that becomes clinically apparent only several hours later, a situation that can be early detected and prevented by intraoperative monitoring.