Most of the controversy surrounding the utility of the implantable venous Doppler probe for free flap monitoring stems from false-positive losses of signal that prompt unnecessary flap re-explorations. However, there is a common conception among microsurgeons that a false-negative signal, meaning the presence of an audible venous Doppler tone despite a loss of perfusion, is impossible. Indeed, we could not find one report of a false-negative signal among all the reports that describe its accuracy.1–3 We report a case in which a deep inferior epigastric perforator (DIEP) flap developed significant hypoperfusion despite a normal implantable venous Doppler tone.
We raised a DIEP flap based on two contiguous perforating vessels to reconstruct a mastectomy defect in a 42-year-old woman. The distal of the two perforators had an arterial Doppler tone that was audible through the skin paddle before flap harvest. After dividing the deep inferior epigatric artery and vein, we performed our anastomosis to the right internal mammary artery and vein using 9-0 nylon interrupted suture on the artery and a 2.5-mm venous coupler device. The distal perforator was audible through the skin after the anastomosis was completed.
After the flap was inset, it became pale and the arterial tone on the skin paddle faded. On exploration, the arterial anastomosis appeared to be in spasm. We applied the Cook-Swartz Doppler probe (catalog no. G31631; Cook Vascular, Vandergrift, Pa.) proximal to the venous anastomosis and heard a satisfactory venous tone. We therefore applied papavarine to the anastomosis and closed the skin, satisfied that the flap had adequate perfusion and confident that the arterial tone and color would return after the spasm resolved.
Two hours postoperatively, the flap continued to be pale and had no arterial Doppler tone. The venous Doppler tone, however, was still audible and demonstrated appropriate augmentation and respiratory variation. Despite this, we returned the patient to the operating room based on the clinical appearance of the flap. The anastomosis appeared patent. On further examination, a tacking stitch was noted to be kinking the pedicle between the two perforators (Fig. 1). Removal of this stitch resulted in prompt return of the arterial tone on the skin paddle. The venous tone became somewhat louder as well. The incision was closed and the patient had an uneventful subsequent recovery, with total flap survival.
This case illustrates two important points. It reminds us that the presence of a venous tone does not necessarily imply adequate flap perfusion; it only implies microanastomotic patency. In our case, the distal perforator supplying the skin paddle became kinked. The proximal perforator supplied enough blood flow to create a venous Doppler tone, but it probably would have been insufficient to ensure flap survival. This case also underscores the notion that the implantable venous Doppler probe is but one tool in the flap monitoring armamentarium that must be interpreted in the context of the overall clinical picture.
Mark Sisco, M.D.
Gregory A. Dumanian, M.D.
Division of Plastic Surgery
Department of Surgery
Northwestern University Feinberg School of Medicine
1. Kind, G. M., Buntic, R. F., Buncke, G. M., Cooper, T. M., Siko, P. P., and Buncke, H. J., Jr. The effect of an implantable Doppler probe on the salvage of microvascular tissue transplants. Plast. Reconstr. Surg.
101: 1268, 1998.
2. de la Torre, J., Hedden, W., Grant, J. H., III, Gardner, P. M., Fix, R. J., and Vasconez, L. O. Retrospective review of the internal Doppler probe for intra- and postoperative microvascular surveillance. J. Reconstr. Microsurg.
19: 287, 2003.
3. Swartz, W. M., Izquierdo, R., and Miller, M. J. Implantable venous Doppler microvascular monitoring: Laboratory investigation and clinical results. Plast. Reconstr. Surg.
93: 152, 1994.
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