Low-stress determination of vital parameters based on flow measurement in the wrist artery

A novel RadialPeriOP system for non-invasive determination of blood pressure and other vital parameters is developed. The basis for this is the measurement of blood flow in the wrist artery using ultrasound Doppler measurement technology. Volumetric hemodynamic parameters are determined from the blood flow and the blood pressure is measured non-invasively via a control loop.

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Project description

Problem: Approximately 12 million surgeries are performed every year throughout Germany, of which 10-15 % are high-risk surgeries associated with increased morbidity and mortality. About 10 % of all patients develop serious complications after surgery. These data show that an optimal and individualized therapy is already necessary during the operation, so that the occurrence of complications can be counteracted at an early stage. As a useful measure, the determination of cardiac output and hemodynamic parameters and the associated optimized fluid delivery according to the principle of Goal-directed Therapy have been shown to be useful. From a physiological point of view, two parameters are decisive for hemodynamic optimization - blood pressure and blood flow.

Messprinzip von RadialisPeriOP: im Druckkissen über der Handgelenksarterie wird der Kissendruck so geregelt, dass ein kleiner Blutfluss erhalten bleibt. Bei dieser Regelung folgt der Kissendruck dem pulsatilen arteriellen Blutdruck.

The innovation of this approach is the use of the ultrasonic Doppler signal to determine pressure pulse and flow at the wrist.
In order to control the fluid balance, especially during an operation, the anaesthetist wants to know the state of the central circulatory system - is it necessary to add fluid or is it harmful? State-of-the-art technology is the bloody measurement of the pressure curve (pulse curve) in the radial artery or the bloodless measurement on the finger. This is used to determine the liquid distribution. This is associated with errors, because the pressure pulse propagates even in the case of poorly perfused peripherals and can be measured in the periphery.
This is the new approach of RadialisPeriOP: instead of the pressure measurement at the radial artery the flow measurement is performed because from a physiological point of view, blood flow is the decisive factor for organ perfusion. It allows a direct assessment of the peripheral blood flow or whether the blood volume is mainly in the circulatory centre. The pressure pulse is also measured - this means that all previous algorithms can still be used.
By means of error-tolerant intelligent signal analysis algorithms, further physiological parameters required for therapy control are estimated. In particular, an algorithm with a control recommendation of the fluid balance is to be developed. The peripheral measuring position allows a direct measurement of the peripheral resistance or the course of the peripheral perfusion, which decreases physiologically in case of a lack of volume. This is a previously unused additional control criterion for volume therapy and the recognition of a centering of the circulation.
RadialisPeriOP consists of several interlinked sensors (ultrasound sensors, pressure sensors and regulation) and is worn directly on the body. It is in direct interaction with the user - in this case the anaesthetist - and makes an essential contribution to the patient's health because it has a medical-diagnostic and therapeutic effect and makes a recommendation for fluid control to the user based on the measured data. The interaction of RadialisPeriOP with the anaesthetist optimizes hemodynamics and fluid therapy.
This enables better treatment of patients before, during and after surgery. However, it is also vital for patients in the intensive care unit that the treating physician can clearly and easily assess and correctly control the circulatory situation and the distribution of blood volume. In particular, the centering of the circulation is detected better than before by RadialisPeriOP.

Cooperation partners

  • GAMPT mbh
  • LB Engineering
  • TU Berlin – Fachgebiet Regelungssysteme
  • Universitätsklinikum Gießen-Marburg – Klinik für Anästhesiologie, Operative Intensivmedizin und Schmerztherapie
  • Deutsches Herzzentrum Berlin

Funding

The project is funded by the German Federal Ministry of Education and Research (promotional reference 13GW0190B).