Volume 10 Issue 2
Classification of Tidal Breathing Airflow Profiles Using Statistical Hierarchal Cluster Analysis in Idiopathic Pulmonary Fibrosis
E. Mark Williams,Ricardo Colasanti,Kasope Wolffs,Paul Thomas andBen Hope-Gill
1Faculty of Life Sciences and Education, University of South Wales, Pontypridd CF37 1DL, UK
2Department of Computer Science, Swansea University, Swansea SA2 8PP, UK
3Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AT, UK
4Lung Function Laboratory, University Hospital Llandough, Llandough CF64 2XX, UK
5Department of Respiratory Medicine, University Hospital Llandough, Llandough CF64 2XX, UK
Author to whom correspondence should be addressed.
Abstract
In idiopathic pulmonary fibrosis (IPF) breathing pattern changes with disease progress. This study aims to determine if unsupervised hierarchal cluster analysis (HCA) can be used to define airflow profile differences in people with and without IPF. This was tested using 31 patients with IPF and 17 matched healthy controls, all of whom had their lung function assessed using spirometry and carbon monoxide CO transfer. A resting tidal breathing (RTB) trace of two minutes duration was collected at the same time. A Euclidian distance technique was used to perform HCA on the airflow data. Four distinct clusters were found, with the majority (18 of 21, 86%) of the severest IPF participants (Stage 2 and 3) being in two clusters. The participants in these clusters exhibited a distinct minute ventilation (p < 0.05), compared to the other two clusters. The respiratory drive was greatest in Cluster 1, which contained many of the IPF participants. Unstructured HCA was successful in recognising different airflow profiles, clustering according to differences in flow rather than time. HCA showed that there is an overlap in tidal airflow profiles between healthy RTB and those with IPF. The further application of HCA in recognising other respiratory disease is discussed.
Keywords: euclidian distance; minute ventilation; tidal volume; unstructured learning; lung function; inspiratory expiratory time
