Why Do Free Flap Vessels Thrombose? Lessons Learned From Implantable Doppler Monitoring

Abstract

Background: Before implantable venous Doppler monitoring, by the time the failing flap was explored, thrombosis had often occurred and therefore the cause of flap flow cessation was often difficult to determine. The Doppler allowed the detection of flow cessation in failing flaps before thrombosis occurred in every case since the authors started using it in 1999. Objectives: To review the authors’ experiences with the implantable venous Doppler. Methods: The authors reviewed 43 free flaps in 40 consecutive patients (1999 to 2002) in which the implantable venous Doppler was used. All cases were performed at the Saint John Regional Hospital, Saint John, New Brunswick, by the senior author. Data were collected from the hospital and office charts. Results: The Doppler detected inadequate blood flow in nine free flaps. In five of the cases, the cause was a kink in the vein. Repositioning the vein to get rid of the kink salvaged all five flaps. In the sixth case, compression of the vein after insetting was detected and successfully corrected. Flow cessation in the seventh case was attributable to arterial vasospasm, which was also salvaged. In the last two cases, the cause was low flow in the flap from the time the vessel clamps were let go. In spite of patent anastomoses, these two flaps were lost because there was not enough flow to sustain them. Conclusion: The implantable venous Doppler has allowed intraoperative detection of free flap vessel flow cessation, identification of the reasons for, and the correction of these prethrombotic states.

Pedicle streaking: A novel and simple aid in pedicle positioning in free tissue transfer

“…Free flap success rates have increased from 94% to 98.8%. [ 1 ] Williams et al . identified kinking as the most common cause of occlusion.…”

“…Virchow's triad states three conditions for thrombosis-hypercoagulability, stasis and endothelial damage. A twist in the pedicle causes mechanical obstruction of flow creating stasis[ 1 ] and thus predisposing to thrombosis.…”

“…The common causes of flap failure are anastomotic failures, pedicle positioning and hypercoagulable states. [ 1 ]…”

Implantable Doppler monitoring of buried free flaps during vascularized lymph node transfer

“…The implantable Doppler system is the most commonly used invasive monitor and is reliable across a wide range of reconstructive procedures. 7,9,[17][18][19] Specifically, it is associated with Left ankle 1 (1) increased flap salvage rates and low complication rates. 20 An analysis that examined its efficacy in 547 consecutive, non-buried free flaps concluded that there is a strong trend toward improved salvage rates with implantable Doppler monitoring compared to clinical monitoring (80% vs 66%, P = 0.48) without increasing the rate of false-positive operative re-explorations.…”

Color Doppler Ultrasonography for Monitoring a Free Flap Anastomosis During a Head and Neck Surgical Camp

“…Although handheld external Doppler was available to the surgical team, the loss of a Doppler signal can often be a late finding after vascular flow for a free flap has already been compromised. 1 Our team utilized a portable ultrasound device to interrogate the free flap anastomosis in effort to overcome some of the limitations imposed by working in this resource-limited setting. The use of ultrasound to visualize free flap anastomoses is rarely described in the Head and Neck literature 2,3 and is seldom used given the reliability of external Doppler or implantable Doppler technology.…”