Publication

Electrical bio-impedance (EBI) is defined as the opposition of biological tissue to the flow of electric current.  EBI is potential diagnostic and monitoring tool for occult traumatic injury. Bioimpedance technology is ideal for the pre-hospital setting because it is portable, quick, non-invasive and cost effective. The most common injury as a consequence of a traffic crash is chest blunt trauma and it is often occult. Thus there is a need of a tool for non-invasively detecting and monitoring it. Whether abnormal values of thoracic EBI would be found in thoracic trauma patients measuring EBI in the ambulance would uncover occult trauma. 

In this thesis thoracic EBI in healthy subjects was characterized in order to define what normal values are. As the biggest challenge to discriminate between healthy and thoracic trauma patients may lay in the inter-individual variability, the ratio between right and left sides of the thorax was also characterized. Different spectra of the bioimpedance values of different configurations of the body, such as total body, thoracic transversal, right lung, left lung and the ratio between the right side and the left side of the thorax, have been characterized in 16 healthy individuals at 50 kHz single frequency. The most promising parameter is the phase angle ratio between both sides of the thorax which value is 1.03±0.1 degrees. 
Using paired Student T-tests and Bland-Altman plots repeatability and reproducibility as dependency of the results on the operators has been determined. Thoracic as well as total body EBI proved been highly repeatable and reproducible. Finally measurements observed in the morning and in the evening were compared performing one sample Student T-test resulting in a non-statistically significant difference between morning and afternoon.