Implantable Doppler Ultrasound Monitoring in Head and Neck Free Flaps: Balancing the Pros and Cons

Abstract

Objectives/Hypothesis: Free flap transfer offers a versatile option for reconstruction in head and neck surgery, with success rates over 95%. There remains a substantial re-exploration rate of roughly 5% to 15%, with early recognition of compromise essential to flap survival. Monitoring techniques are highly desirable, with the gold standard being clinical monitoring. The Cook-Swartz Doppler (CSD) probe utilizes Doppler technology to inform clinicians about real-time flow. We aim to describe our adoption of this technology in 100 consecutive free flaps.Study Design: Prospective case series. Methods: Prospective data were collected from July 2014 to June 2015 on 100 consecutive free flaps performed at a head and neck unit in London, Ontario. All patients had a CSD inserted for arterial and venous monitoring.Results: A total of 100 free flaps were performed on 99 patients. Sensitivity was 87.1% and specificity was 85.7%. Positive predictive value was 98.8% and negative predictive value was 33.3%. False-negative and false-positive rate were 1.0% and 12.0%, respectively. The exploration rate was 12%, with no flap loss and two partial debridements. The CSD was helpful in management in 9% of cases and was clinically unhelpful in 11% of cases, with 10 of 11 abnormal signals ignored. There were three unique CSD complications; one retained wire, one pedicle laceration during extraction, and one clot around the probe interrupting signal.Conclusions: The CSD is a helpful adjunct to clinical monitoring but has unique complications, which were not previously described. Pros and cons must be considered for new centers adopting this technology.

Comparison of Hyperspectral Imaging and Microvascular Doppler for Perfusion Monitoring of Free Flaps in an In Vivo Rodent Model

“…It is considered to be simple to use and to interpret, safe, examiner-independent, efficient, and can also be used successfully with buried flaps. The invasiveness, a possible focus of infection, and the risk of injury when removing the sample are regarded as disadvantages [ 50 , 54 , 55 ]. In addition, it also seems that complete MFF necrosis can occur despite an adequate MDS signal and thus despite adequate blood flow through the anastomosis [ 55 ].…”

Implantable Doppler Removal After Free Flap Monitoring Among Head and Neck Microvascular Surgeons

“…With only three reported cases of anastomotic disruption due to wire removal failure in the FDA MAUDE database and an estimated incidence of 1 in 5,333 free flap cases in this series, pulling the implantable Doppler wire remains safe with judicious placement of the cuff and wires intraoperatively and careful extrication; however, microvascular surgeons must be aware that there is a rare risk of injury to the vascular pedicle. There should be a low threshold for operative re‐exploration if there are concerns of vascular anastomotic injury after wire removal which may present itself even 6 hours after wire removal 18 …”

“…In our study, two respondents reported pulling the wire now due to concerns with the MRI compatibility on postoperative imaging. Hayler et al reported one case of the wire snapping during removal on postoperative day 10 18 . X‐ray showed a small segment of the wire in the surgical site, and after informing the patient, the wire was left in place.…”

“…Hayler et al evaluated their experience with 100 consecutive free flaps monitored with an implantable Doppler. 18 They reported on a patient who experienced neck swelling 6 hours after removal of the Doppler wire, underwent immediate exploration in the operating room, and was found to have a laceration of the venous pedicle. The authors postulated that a loop of wire may have been caught behind the pedicle, and upon removal, may have caused a laceration.…”

“…There should be a low threshold for operative re-exploration if there are concerns of vascular anastomotic injury after wire removal which may present itself even 6 hours after wire removal. 18 The alternative to pulling the implantable Doppler wire is to cut the wire and leave the proximal portion of wire in situ. In this study, two respondents stated only cutting the wire in their practice.…”