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.

Although clinical observation is the gold standard, the ideal free flap monitoring device has not been identified. The purpose of the present study was to review the first 14 months of experience using an implantable 20-MHz ultrasonic Doppler probe to monitor the microvascular anastamoses of free tissue transfers. Twenty-five flaps in 23 patients, with an average age of 51 years (age range 18 to 81 years), were performed. Probes were secured downstream of the venous anastamosis using a silicone-poly fluorotetraethylene sleeve. Doppler sounds were transduced before the flap was inset. Monitoring by nursing staff included conventional techniques (temperature, colour, capillary refill) and continuous Doppler flow monitoring. Dynamic diagnostic testing for anastomotic patency was facilitated by applying manual pressure on the flap to increase venous flow (the audible ‘whoosh’ sign) and valsalva manoeuvre to impede venous return momentarily (the ‘heave’ sign). Intraoperative vessel kinking, hematoma formation occluding venous outflow, and venous thrombosis were detected in four cases before concluding the procedure and corrected. Rapid, immediate cessation of audible flow was detected postoperatively in three of 25 flaps. Re-exploration (re-exploration rate 12%) led to salvage of all three flaps (salvage rate 100%). It was concluded from this study that flap re-exploration was prevented in four cases (16%) because of intraoperative use of the implantable Doppler probe. Earlier detection of flap compromise perioperatively is thought to have contributed to the 100% salvage rate and to the 100% flap survival rate in the first 25 cases in which the implantable Doppler probe was used.

Although clinical observation is the gold standard, the ideal free flap monitoring device has not been identified. The purpose of the present study was to review the first 14 months of experience using an implantable 20-MHz ultrasonic Doppler probe to monitor the microvascular anastamoses of free tissue transfers. Twenty-five flaps in 23 patients, with an average age of 51 years (age range 18 to 81 years), were performed. Probes were secured downstream of the venous anastamosis using a silicone-polyfluorotetraethylene sleeve. Doppler sounds were transduced before the flap was inset. Monitoring by nursing staff included conventional techniques (temperature, colour, capillary refill) and continuous Doppler flow monitoring. Dynamic diagnostic testing for anastomotic patency was facilitated by applying manual pressure on the flap to increase venous flow (the audible 'whoosh' sign) and valsalva manoeuvre to impede venous return momentarily (the 'heave' sign). Intraoperative vessel kinking, hematoma formation occluding venous outflow, and venous thrombosis were detected in four cases before concluding the procedure and corrected. Rapid, immediate cessation of audible flow was detected postoperatively in three of 25 flaps. Re-exploration (re-exploration rate 12%) led to salvage of all three flaps (salvage rate 100%). It was concluded from this study that flap re-exploration was prevented in four cases (16%) because of intraoperative use of the implantable Doppler probe. Earlier detection of flap compromise perioperatively is thought to have contributed to the 100% salvage rate and to the 100% flap survival rate in the first 25 cases in which the implantable Doppler probe was used.