A Biomedical Wireless Sensor Network for Hemodynamic Monitoring

In the Biomedical Wireless Sensor Network (BWSN) project a consortium of Scandinavian research institutions, technology startup companies, sensor producers, software companies and a hospital based clinical test facility collaborated for 36 months. A portfolio of multiple, experimental wireless sensor prototypes were implemented in sophisticated process control software modified for the project. The project objective was to facilitate real time and historical point-of-care sensor data for clinical decision support and monitoring in hemodynamic treatment. The wireless communication platform and results from clinical tests are presented in this paper. The radio frequency platform used in the project was operating in the 2.4 GHz ISM band based on the IEEE 802.15.4 Wireless Personal Area Network standard. Invasive sensors included a non-disposable blood pressure sensor, an epicardial 3- axis accelerometer and a digital pulmonary air leakage system. Non-invasive sensor signals came from an ECG sensor, a pulse oximeter, a medical radar and a temperature sensor. Point-to-point transmission of radio frequency signals from sensors to base stations and onwards in the biomedical wireless sensor network (BWSN) architecture was scrutinized during experimental surgery. A qualitative assessment of the sensor data presentation was made. Occurrence of shadowing effects influencing the radio frequency channel performance was quantified. The shadowing effects were caused by the dynamic work pattern of the clinical team in combination with stationary equipment in the operating room during surgery. The shadowing effects were not found to compromise the quality of the wireless sensor data. Shadowing parameters to reconstruct our measurements and model the communication links between individual sensors and two separate base stations are provided.