Reestablished circulation after free radial forearm flap transfer.

New circulation in the free flap reestablished at the recipient site is the key to successful microvascular reconstructive surgery. This study is the first evaluation of long-term circulatory changes in nine free radial forearm flap transfers. Postoperatively, color Doppler studies revealed that the flow volume through the arterial pedicle increased rapidly during the first 3 days, gradually increased until day 14 (exceeding flow volume through the facial artery of the unoperated contralateral side), then decreased slightly until the sixth month. The pulsatility index, representing vascular resistance downstream, decreased successively. Ohm's law explains that this flow increase is caused by reduced vascular resistance downstream, attributed to changes in the vascularity of the transferred flap and in the recipient bed. The authors believe the circulatory changes are determinants of the clinical properties of the flap. This study addresses the importance of clarifying the events that transpire at the macroscopic circulatory level in the transferred free flap.