Estimating arterial wall impedance using a plethysmogram

This paper proposes a new method to estimate the mechanical impedance of arterial walls with biological signals, such as electrocardiogram, arterial pressure, and pulse oximetric plethysmogram that reflects arterial pulsation. A mathematical model of the fingertip arterial wall is developed on the basis of the relationship between the arterial pressure and the plethysmogram. The validity of the proposed method is then discussed by applying to monitor the arterial wall impedance properties during surgical operations. It has been demonstrated that the changes of the measured impedance parameters correspond to events during operations.