Modeling of Peripheral Resistance in the Microvasculature for Diabetic Patients with Ultrasound Doppler Technique

Abstract

Diabetes is a growing health problem worldwide and involves long-term complications. Microangiopathy is one of the main issues associated with diabetes and is a condition that is difficult to detect. The aim of this project is to evaluate two different blood flow models based on the three-element Windkessel model and compare these results with velocity curves from ultrasound measurements.

A recently developed ultrasound Doppler instrument, EarlyBird, was used to measure blood velocities during three different tests. The experiment consisted of healthy volunteers and diabetic patients, and the tests were designed to induce changes in peripheral resistance with stimuli. In one of the tests, simultaneous blood pressure measurements and ECG were also recorded. These data were then used in simulations and calculations. In this thesis, two models have been developed with one consisting of a pressure-dependent peripheral resistance and the other with a pressure-independent resistance. The model performance has been verified through the three different tests and modelled in Simscape, Matlab. Blood pressure measurements were used as input to the models, and the simulated flow curves were compared with the velocity from the ultrasound instrument. Relative changes from the simulated flow were calculated and compared with the reference velocity. The results indicated that the model with pressure-dependent peripheral resistance could accomplish better model adaption than the other model. The results might also indicate the potential of estimating peripheral resistance with velocity measurements alone. In order to verify this finding, more research and experiments are needed.