Resumen de Development of a technology to estimate haemodynamic parameters during haemodialysis
Introduction Haemodialysis (HD) is an effective therapy for patients with end-state renal disease. However patients can suffer from adverse side effects during haemodialysis such as hypotension, headache and vomiting, related to the unbalanced shift of fluids between the extracellular (ECW) and intracellular(ICW) spaces. Bioimpedance spectroscopy has been used as a non-invasive method for measuring total body water (TBW), and the distribution of ECW and ICW fluid volumes and their variations during HD. Different approaches have been used, such as whole-body or segmental impedance measurements. These approaches can not give information about regional fluid shifts; they are sensitive to body position; and the measured impedance is mainly that of the limbs. They also require the use of relatively long cables which compromises the accuracy of the measurements at high frequencies. Research Objectives __The new method developed in this thesis allow us to estimate fluid shifts in different body regions during HD. The understanding of these shifts is essential in determining the efficacy of the HD process. This PhD thesis was done as a part of the Haemoscan project (6th FP) with the objective of solving a clinically relevant problem: haemodynamic instability, that affects about 25% of HD patients. We propose a method based on local, multifrequency bioimpedance measurements that allow us to develop estimators for the fluid distribution and variations during HD. These estimators will be used to develop an indicator for the hypovulemic crisis; thus increasing the quality of the HD treatment. This will be achieved by analyzing the results obtained during the clinical measurements on stable and hypotensive patients. The general objectives of the thesis are:
1) Performance assessment of the prototype of the local impedance spectroscopy analyzer sensor.
2) Developing the experimental protocol and software for the clinical measurements on patients using the developed impedance.
