Sequence of colour changes observed in Raynaud's disease.

Triphasic Color Response Include Three Stages Blanching (stage of local syncope) With exposure to cold, digital aerioles goes into spasm Decreased flow is evidenced by pallor or blanching Digits may appear white Cyanosis (stage of local asphyxia) Capillaries and venules dilate Red Engorgement (stage of recovery) With rewarming or passing of attack, the digital vasospasm resolves Blood flow into dilated aeries and capillaries increases dramatically Reactive hyperemia impas bright red color to the digits