Symmetric Projection Attractor Reconstruction: Analysis of waveform morphology predicts COPD exacerbations

Research output: Chapter in Book/Report/Conference proceedingConference paper


Background: Respiratory pattern analysis is currently reduced to simplified biomarkers, such as rate. However, respiratory waveforms are complex and generally sampled with high fidelity. Our novel mathematical method, Symmetric Projection Attractor Reconstruction (SPAR) analyses the morphology and variability of such waveforms, without discarding any data.

Aims and objectives: To investigate whether SPAR can detect changes in respiratory waveforms that better predict impending COPD exacerbations.

Methods: Retrospective nasal pressure data, recorded during resting tidal breathing, were analysed from 10 COPD patients who were home monitored daily following hospital discharge, after an exacerbation.

Results: Over the 30 days of monitoring 4 patients re-exacerbated and 6 remained stable. SPAR transformations highlighted differences in waveform morphology between these two patient groups (Fig. 1). Statistically, SPAR measures outperformed respiratory rate in discriminating between groups at hospital discharge (ROC AUC 0.95 vs. 0.90) and throughout the monitoring period (ROC AUC 0.98 vs. 0.83).

Conclusions: SPAR provided supplementary, early evidence identifying patients who re-exacerbated. We predict that a combination of SPAR plus conventional measures may support clinical decision making at hospital discharge and during community monitoring, providing an earlier alert for patients, carers and clinical teams.
Original languageEnglish
Title of host publicationEuropean Respiratory Journal
Publication statusPublished - 2022


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