New Insight into an Old Paradigm: Wrapping and Dangling with Lower-Extremity Free Flaps

Abstract

Flap edema can often compromise an otherwise successful lower-extremity microsurgical reconstruction. To train a flap toward maturity, various wrapping and dangling protocols have been described. Mixed tissue oxygenation of a myocutaneous free flap for lower-extremity reconstruction is examined as measured by ViOptix with wrapping and unwrapping during dangling at different postoperative time points. The results are compared with the nonaffected lower extremity and additional healthy controls. Upon dangling a reconstructed lower extremity, the tissue oximetry recording of a free flap descended rapidly until the leg was reelevated and then continued at this low level with a gradual return to the predangling baseline. The extent of this drop in tissue oxygenation depended upon positioning, and the length of time to reach its baseline upon reelevation decreased as flap matured postoperatively. In addition, wrapping of a reconstructed lower extremity also decreased the overall drop in tissue oxygenation level and the time to recovery while having no effect on the control. Results of this prospective study can lead to an increased understanding of free flap physiology in lower-extremity reconstruction and can further validate and refine our postoperative management strategies regarding dependency and edema control.

Changes of Oxygenation and Hemoglobin-Concentration in Lower Extremity Free Flaps during Dangling

“…This pattern was modified by the type of flap and duration of training, but it remained fairly constant in its behavior and was well consistent with the findings of Ridgway et al 8 Immediately after the beginning of dependency, an initial increase in StO 2 was noticed in the flap (►Fig. 1).…”

“…This state is improved over time as the flaps become independent of the pedicle by vessel ingrowth from the surrounding tissue (randomization) and regain basic innervation. 8,16 However, these effects take place over a longer span of time, while the short-term changes described in this work are more likely attributable to the vascular changes discussed in the following.…”

“…The published studies are either solely based on clinical examination or include only a very limited number of patients. 7,8 Therefore, the aim of our study was to assess the microcirculatory changes in lower extremity free flaps during dangling to gain further insight into flap physiology.…”

Early Mobilization after Free-flap Transfer to the Lower Extremities

“…Cutaneous, subcutaneous, and muscular vascular resistances increase within a limb when venous pressure is greater than 25 mm Hg and decrease blood flow by up to 40%. 8,9 This response to elevated venous pressure is termed the venoarteriolar response. The venoarteriolar response mechanism reportedly continues within tissues even after free-flap transfer.…”

“…The venoarteriolar response mechanism reportedly continues within tissues even after free-flap transfer. 6,8,9 Ridgway et al 8 have demonstrated that after dangling for 5 minutes on the seventh postoperative day, tissue oxygenation in a lower-extremity free flap decreases significantly and does not return to the baseline value for as long as 44 minutes. These findings support the common perception of many surgeons, who, therefore, start postoperative mobilization between 1 and 3 weeks after the transfer of free flaps to the lower extremity.…”