The Effect of Tracheal Intubation-Induced Autonomic Response on Photoplethysmography

Figure 1

Illustration of photoplethysmogram DC and AC components. The DC value corresponds to the smallest blood volume in the finger (end diastole), which corresponds to the highest light transmission value of each pulse through the finger. The AC values correspond to the difference between the highest (end diastole) and lowest (end systole) light transmission values of each pulse representing the pulse added volume of blood in the finger. Units for the photoplethysmogram DC and AC components are analog-to-digital converter counts that are proportional to the light transmission in Watts.