Entwicklung eines Meßsystems für die nichtinvasive und kontinuierliche Bestimmung der Compliance der Arteria Carotis

Objective: Development of a method for the continuous and non-invasive monitoring of the compliance of the carotid artery and of the flow through this artery. Method: For the measurement of the compliance it is necessary to determine simultaneously both the pressure and the volume change during at least one cardiac cycle. The impedance plethysmography is employed to indicate the volume change of a conductive liquid (blood) in a segment of the human body. This method is based on the measurement of the corresponding change of electrical impedance. The applanation tonometry is used for the monitoring of the blood pressure. Applanation tonometry requires that the extravascular pressure balances the intravascular pressure. The measurement of the applied extravascular pressure is performed by means of an appropriate sensor. Results: The method was evaluated of measurement in 11 healthy volunteers and in 1 patient (stenosis in the left carotid artery). The measured values of the compliance and the arterial blood flow were within the physiological range for the healthy volunteers. Conclusion: The method shown enables both continuous and non-invasive determination of the mechanical properties of the wall of the carotid artery and the arterial blood flow. Keywords: impedance plethysmography, applanation tonometry, vessel wall compliance