The effect of hematocrit on photoelectric plethysmogram

In order to study the effect of hematocrit (Ht) on the photoelectric plethysmograms of fingers and toes, an experimental model study and a clinical study were carried out. Experimentally, it was found that the height of the plethysmograms increased when the values of Ht were lowered. In the clinical study, 3 groups of patients with different HT values ranging from 27 to 55% were examined. A reverse relationship was found between the Ht value and pulse height of the plethysmogram. The physical effects of the blood flow and contents upon the plethysmograms were discussed.