[Blood supply of free skin flaps]

This article discusses the factors which determine the blood supply of free skin flaps. The method of free transfer consists of three steps, namely, the elevation of the flap, its transfer to the target area with microvascular anastomosis, and the healing of the flap on the recipient site. During the first two steps the flaps meet with a diminished blood supply and, in addition, their tissues undergo a period of ischemia. The flaps are usually able - within certain limits - to tolerate these disturbances of blood circulation. The healing of the flap begins with the proliferation of capillaries in the recipient site, which is stimulated by the relative hypoxia of the transferred tissues. The first capillary links between the recipient site and the flap can usually be observed on the third day after the transfer. On the sixth day after the operation, the anastomoses are quite numerous and can take over the blood supply to the flap. The progress of this dynamic process depends on the functional ability of the anastomosed vascular pedicle. The development of a new blood supply to the flap leads to profound remodelling of its original vascular system and the axial character of the flap is usually lost.