Featured ubpulse H3

Heart beat and blood volume

  1. The heart pumps blood around the all of the body.
  2. The blood volume at finger is synchronized with heart beat (fig. a).
  3. At each heart beat, the blood volume is increased and then decreased ( fig.b).
  4. If we can measure the blood volume changes, the heart beat can be measured.

 

Optical measuring heart beat

  1. The light from the light source (fig.a) is absorbed by tissue, bone, venous blood and arterial blood.
  2. The light absorption is in proportion to arterial blood volume (fig.b).
  3. The output of the light detector shows the blood volume changes synchronized with heart beats (fig.c).
  4. Usually, the measured AC component is named by pulse wave or PPG (Photo Plethysmo Gram).