Long-term biosignals visualization and processing

• Autor(es): Gomes, Ricardo Rafael Baptista
• Data: 2011
• Identificador Persistente: http://hdl.handle.net/10362/7979
• Origem: Repositório Institucional da UNL
• Assunto(s): Biosignal; Signal processing; Long-term monitoring; Data structure
• Tipo de Documento: Dissertação de mestrado
• Idioma: Inglês
• Orientador(es): Gamboa, Hugo
• Contribuidor(es): RUN

Descrição

Thesis submitted in the fulfillment of the requirements for the Degree of Master in Biomedical Engineering

Long-term biosignals acquisitions are an important source of information about the patients’state and its evolution. However, long-term biosignals monitoring involves managing extremely large datasets, which makes signal visualization and processing a complex task. To overcome these problems, a new data structure to manage long-term biosignals was developed. Based on this new data structure, dedicated tools for long-term biosignals visualization and processing were implemented. A multilevel visualization tool for any type of biosignals, based on subsampling is presented, focused on four representative signal parameters (mean, maximum, minimum and standard deviation error). The visualization tool enables an overview of the entire signal and a more detailed visualization in specific parts which we want to highlight, allowing an user friendly interaction that leads to an easier signal exploring. The ”map” and ”reduce” concept is also exposed for long-term biosignal processing. A processing tool (ECG peak detection) was adapted for long-term biosignals. In order to test the developed algorithm, long-term biosignals acquisitions (approximately 8 hours each) were carried out. The visualization tool has proven to be faster than the standard methods, allowing a fast navigation over the different visualization levels of biosignals. Regarding the developed processing algorithm, it detected the peaks of long-term ECG signals with fewer time consuming than the nonparalell processing algorithm. The non-specific characteristics of the new data structure, visualization tool and the speed improvement in signal processing introduced by these algorithms makes them powerful tools for long-term biosignals visualization and processing.