Related Experiment Video
Updated: Aug 25, 2026

Phase-Resolved Functional Lung MRI for Pulmonary Ventilation and Perfusion (V/Q) Assessment
Published on: August 9, 2024
Estimating respiratory pattern variability by symbolic dynamics
P Caminal1, J Mateu, M Vallverdú
1Dep. ESAII, C/ Pau Gargallo, 5, 08028 Barcelona, Spain. caminal@creb.upc.es
Objectives:
The traditional techniques of data analysis are often not sufficient to characterize the complex dynamics of respiration. In this study the respiratory pattern variability was analyzed using symbolic dynamics.
Methods:
A group of 20 patients on weaning trials from mechanical ventilation were studied at two different pressure support ventilation levels. Breath duration (T(TOT)) time series and the relation T(I)/T(TOT), that contains the influence of inspiratory time (T(I)), were considered. Length-3 words and 3 different symbols were proposed. The incidence of the overlapping tau and the parameter alpha were analyzed.
Results:
From the breath duration time series, the distribution of words with probability of occurrence higher than 6% was concentrated on one word for low respiratory variability, whereas high variability was characterized by 4 words, presenting a statistically significant difference (p = 0.0005). The probability occurrence of words "110" and "111" was also significantly different (p= 0.0005) when comparing both variabilities.
Conclusion:
The analysis carried out obtained discriminant functions able to correctly classify all the testing set series. These results permit the consideration of symbolic dynamics as a promising methodology to study the respiratory pattern variability.
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