plethysmograph left hand
EKG
plethysmograph right hand

Photoplethysmograph

Photoplethysmograpy is a practicable method for monitoring of blood pressure and heart rate in real time. The method is based on the following: an LED illuminates the finger, and from the intensity of the light reflected a signal proportional to blood pressure is received. Though the measurement is very simple, heartbeats can be detected reliably. From this heart rate can be calculated, which has diagnostic significance as its fluctuation may point to a number of diseases.

Combined examination of EKG and blood pressure signal

By measuring the EKG and plethysmograph signal simultaneously we can pinpoint the delay between the pulse and heartbeat, which then gives information about the condition of the circulatory system. With our smartphone-connectible device the measurement can be performed in one’s home.

Valsalva maneuver tests

From blood pressure signals pulse pressure, a signal proportional to the blood volume discharged from the heart can be calculated. Its periodic fluctuation is in synchrony with respiration; the phase difference between them was tested along with Valsalva maneuvers. By reducing pressure on the lower body we simulated blood loss; pulse pressure followed respiration with a smaller phase difference than in normal circumstances.