Those with blood impediment have consumed excessive alcohol, accumulated excessive heat, or suffered from cold obstructing the meridians and collaterals, or dampness invading the nutrient and defensive systems, leading to blood stagnation and thus forming the ailment. Consequently, the blood cannot nourish the exterior, and the qi cannot sustain the interior. When both the interior and exterior are compromised, gradual emaciation occurs.

If the left side withers first, the right side cannot lift; if the right side withers first, the left side cannot extend; if the upper part withers first, it cannot control the lower part; if the lower part withers first, it cannot overcome the upper part; if the middle part withers first, it cannot facilitate smooth flow. Hundreds of symptoms and thousands of manifestations all stem from the loss of blood. The pulse at the left cun position is knotted and not smooth, or appears as if it is severed.