OBJECTIVETo study the change rule of the hemodynamics of expanded skins and research the transplant time of random-pattern flaps that are made of the expanded skin.

METHODS72 ears of 64 rabbits were used as a subject of experiment. Four items of the contrasted skin (n = 8) and expanded skin (n = 8 x 8), Which include the microvessel diameter, the microvessel density, the blood velocity and the blood volume, were observed and measured by the microcirculatory imaging computer analysis system, the enzyme histochemical dyeing and the more functions colored pathological imaging computer analysis system. The length -width proportion and the largest area of the flaps that had made of the expansive skin and survived were measured.

RESULTS(1) The four items of expanded skin, that the microvessel diameter, the microvessel density, the blood velocity and the blood volume are 13.43 +/- 0.98 micrometer, 0.0472 +/- 0.0022, 1012.70 +/- 65.51 micrometer/s, 14.71 +/- 0.74 micrometer(3)/s respectively, are much bigger or quicker than those of contrasted skin [(7.22 +/- 0.71) micrometer, 0.0108 +/- 0.0002, (327.01 +/- 65.51) micrometer/s, (1.46 +/- 0.41) micrometer(3)/s] and there is the significant difference between both (6.49 < t < 49.49, P < 0.01). (2) The blood velocity increases in the expanding phases and always keeps on higher level. The other items all change periodically. Span of the period is four weeks. The microvessel diameter and the blood volume have a peak value at third weekend of every period and in the later period enhance more on the basis of the former period. The microvessel density changes in definite range in every period. (3) The surviving area of the random skin flaps is the largest which were made of the expanded skin in third weekend of every period, it changes more than those of other weekends in same period and later period is superior to the former period. There is a significant difference compared with contrasted random skin flaps (q = 3.7215, P < 0.05; q = 5.5026, P < 0.01).

CONCLUSIONThe hemodynamics of the expanded skin changes periodically in expansive course. The time of peak value of the blood volume is the best opportunity that random-pattern skin flaps are made of the expanded skin in every period.