Towards symbolization using data-driven extraction of local trends for ICU monitoring
ABSTRACT We propose a methodology for the extraction of local trends from a stream of data. It has been designed to suit the needs of interpretation-oriented visualization and symbolization from ICU monitoring data. After giving implementation details for efficient computation of local trends, we propose the use of a characteristic analysis span for each variable. This characteristic span is obtained from a set of criteria that we compare and evaluate in regard of analysis of ICU monitoring data gathered within the Aiddaig project. The processing results in a rich visual representation and a framework for the local symbolization of the data stream based on its dynamics.
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- "Our own research is similar in that we are concerned with the applications of results from machine learning processes to data streams in order to detect adverse clinical condi- tions. Shashar et al.  utilise the work of Calvelo et al.  for decomposing the data stream into trend and stability for each data point. The maximum length of each segment, which gives the best approximation according to the overall piece-wise accuracy and also localised linear accuracy is called the characteristic span. "
ABSTRACT: Intelligent clinical data analysis systems require precise qualitative descriptions of data to enable effective and context sensitive interpretation to take place. Temporal abstraction (TA) provides the means to achieve such descriptions, which can then be used as input to a reasoning engine where they are evaluated against a knowledge base to arrive at possible clinical hypotheses. This paper surveys previous research into the development of intelligent clinical data analysis systems that incorporate TA mechanisms and presents research synergies and trends across the research reviewed, especially those associated with the multi-dimensional nature of real-time patient data streams. The motivation for this survey is case study based research into the development of an intelligent real-time, high-frequency patient monitoring system to provide detection of temporal patterns within multiple patient data streams. The survey was based on factors that are of importance to broaden research into temporal abstraction and on characteristics we believe will assume an increasing level of importance for future clinical IDA systems. These factors were: aspects of the data that is abstracted such as source domain and sample frequency, complexity available within abstracted patterns, dimensionality of the TA and data environment and the knowledge and reasoning underpinning TA processes. It is evident from the review that for intelligent clinical data analysis systems to progress into the future where clinical environments are becoming increasingly data-intensive, the ability for managing multi-dimensional aspects of data at high observation and sample frequencies must be provided. Also, the detection of complex patterns within patient data requires higher levels of TA than are presently available. The conflicting matters of computational tractability and temporal reasoning within a real-time environment present a non-trivial problem for investigation in regard to these matters. Finally, to be able to fully exploit the value of learning new knowledge from stored clinical data through data mining and enable its application to data abstraction, the fusion of data mining and TA processes becomes a necessity.Artificial Intelligence in Medicine 02/2007; 39(1):1-24. DOI:10.1016/j.artmed.2006.08.002 · 2.02 Impact Factor
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- "A patient record is a long, high frequency, multivariate time series data. Classical monitoring improvement techniques are focused on algorithms at a numerical level (Tsien et al., 2000; Calvelo et al., 2000). On the contrary, we propose that symbolic abstraction could bring useful information to data, providing a better understanding of these still poorly formalized data but also, and more deeply, a new approach for monitoring based on dynamic anomaly detection. "
ABSTRACT: We work on the design of computerized systems that support experts during their complex and poorly formalized data interpretation process. We consider interpretation as the process by which high level abstracted information is attached to data. We assume that a computer could efficiently helps an expert in such a process via a structural coupling (Maturana and Varela, 1994) based on their interactions. Enaction appears as a stimulating source of inspiration for the design of such systems. Our approach is applied to the exploration of physiological time series acquired from patients in intensive care unit (ICU). Time series interpretation for ICU monitoring systems
- "Ordinarily the learning of ontologies is usually associated with discovering taxonomic relationships from such fields as knowledge acquisition and sharing, knowledge representation or distributed knowledge-based systems   . Others have developed methods to symbolise and classify various modalities in trends or time series data  . However, in this paper we explore the use of an ontology-based analysis of a single numeric performance indicator over a number of years. "
Conference Paper: Ontology trend analysis of dynamic signals[Show abstract] [Hide abstract]
ABSTRACT: This paper describes a novel approach to analysing trends of a performance signal indicator from an industrial metallurgical reactor over a number of years of operation. Using a minimum message length algorithm, a detailed ontology of the signal behaviours or modalities was established. An abstraction of these yielded a number of related super states that in turn provided an insightful correspondence for the domain experts. Further detailed identification of the likely composition and causal influences contributing to each mode was subsequently induced with supervised learning.Intelligent Sensors, Sensor Networks and Information Processing Conference, 2004. Proceedings of the 2004; 01/2005