ProHeMon - site visit 2

Proactive Health Monitoring, a joint project between the TampereUniversityHospital and the Tampere University of Technology.

Site visit in Tampere on 14 May 2004 

The project designs and implements methods for extending a normal-looking chair with the possibility to measure and analyse the ballistocardiogram (BCG) of a patient sitting in the chair for a relatively short time. The chair is provided with sensitive sensors that measure the BCG, and a wireless link for sending data to be analysed in a nearby PC.

A prototype chair has been wadded with thin EMFi foil, a plastic material that converts mechanical energy into an electrical signal and vice versa. The foil (or film) is a flexible material with electrically conductive layers that are permanently polarised. Changes in the pressure on the film generate a charge on the film's surfaces that can be measured as a current or a voltage signal. The signal is amplified with a battery-driven amplifier developed by the project team. The wireless connection has been implemented with the help of a new demonstration board kit by ChipCon. The amplifier is connected to a CircMon device for measuring cardiovascular parameters, which in turn is connected to a PC for storing and analysing data. 

Preliminary tests with the EMFi film have been performed with a mobile physiological signal measurement station built by the project team. The measurement station has three channels for measuring EMFi signals in addition to 12 channels for ECG signals and one for measuring heart beats. It works with batteries and a PC can be connected for storing data. In the tests, film was also taped directly to the skin of the test person. The signals were compared with ECG signals measured by two ECG electrodes. The results show that the EMFi film, both in the chair and taped on the test person, provided fairly good BCG-like signals. The EMFi film has thereby shown its potential for ballistocardiographic studies. All the equipement required have been (and must be) approved for hospital use.

Data acquisition software has also been developed for storing and analysing the data. The DaqSoft displays the measured data close to real-time and lets the user set both window lengths and amplitude magnitudes. Two versions are available, a standalone version and a client/server solution. The software uses EDF (European Data Format) for storing the data. 

By studying the acquired BCG data, the researchers hope to detect heart related problems. Also the respiration phase can be detected in the data and may be used for studying respiration related phenomena. A ballistocardiogram (BCG) is a record showing the body's recoil caused by cardiac contraction and by blood filling the veins. For example, the heart beat is clearly visible in a BCG for normal persons. Starr has classified BCGs into four classes (normal, slightly abnormal, markedly abnormal, and extremely abnormal) depending on how the BCG looks like.

The project team is now performing tests on several groups of persons to see if there is a correlation between BCGs of healthy persons and persons with heart related or respiratory problems. The test groups are divided as follows: 1) Healthy male and female subjects of age 20-30 years (as a reference group), 2) Healthy 50-70 year-old men, 3) Men aged 50-70 that have had an infarct of the heart, 4) Men aged 50-70 that have asthma, and 5) Men aged 50-70 that get dialysis treatment.

 About 20 persons are tested for each group. Uptil now groups 1 and 2 and half of group 3 have been tested. In general, the hypothesis that healthy persons have a normal BCG (and unhealthy persons do not) seem to hold, but preliminary results also show that there are non-normal BCGs of some "normal", healthy persons and that there are persons who have had an infarct that show normal BCGs. The challenge and the goal then are to recognise characteristic features of different diseases as well as possible and thereby perhaps detect persons that have the highest risk of an infarct.

Some publications related to the project are:

• Alametsä J., Värri A., Koivuluoma M., Barna L.: The Potential of EMFi Sensors in Heart Activity Monitoring, 2nd OpenECG Workshop Integration of the ECG into the EHR & Interoperability of ECG Device Systems, Berlin, Germany, 1.-3.4.2004
• Two more articles have been submitted about measuring BCGs using EMFi sensors.

More information

For more information, please contact the coordinator of the project, Docent Alpo Värri at the Tampere University of Technology or the other researchers involved.

Research consortium

• University of Tampere & TampereUniversityHospital, Department of Clinical Physiology:
• Professor Väinö Turjanmaa, Docent Tiit Kööbi, PhD students Teemu Koivistoinen
• TampereUniversity of Technology, Signal Processing Laboratory:
• Docent Alpo Värri, Dr.Tech. Eero Huupponen, PhD students Mikko Koivuluoma, Sakari Junnila, Jarmo Alametsä, Laurentiu Barna