The influence of arterial inflow and venous outflow on the survival of reversed-flow island flaps: an experimental study.

Reversed-flow flaps are currently used for reconstruction of the distal portion of the upper and lower extremities. However, detailed experimental studies on the reversed-flow flap are lacking, and there have been many clinical reports concerning its postoperative complications. In the present study, the effects of blood inflow and outflow on flap viability were investigated. Six groups of island flaps, which differed in whether arterial inflow and venous outflow were retrograde or antegrade, were prepared on the rat's abdomen. The venous pressure of the vascular pedicle (n = 5), the blood flow (n = 10), and the survival rates of flaps (n = 10) were measured in each group. When arterial inflow was retrograde, the viable flap area diminished in proportion to the decrease in blood flow. The correlation coefficient between blood flow and survival rates of the flaps was 0.885, which indicates that blood inflow to the flap is closely related to the area of flap viability. The relationship between the venous outflow and the viable flap area was "all or nothing". When venous outflow was retrograde, there was either no effect on flap area at all or complete congestive necrosis.