title: Joint symbolic dynamic analysis of cardiorespiratory interactions in patients on weaning trials.
abstract: Assessing autonomic control provides information about patho-physiological imbalances. Measures of variability of the cardiac interbeat duration RR(n) and the variability of the breath duration T<inf>Tot</inf>(n) are sensitive to those changes. The interactions between RR(n) and T<inf>Tot</inf>(n) are complex and strongly non-linear. A study of joint symbolic dynamics is presented as a new short-term non-linear analysis method to investigate these interactions in patients on weaning trials. 78 patients from mechanical ventilation are studied: Group A (patients that failed to maintain spontaneous breathing and were reconnected) and Group B (patients with successful trials). Using the concept of joint symbolic dynamics, cardiac and respiratory changes were transformed into a word series, and the probability of occurrence of each word type was calculated and compared between both groups. Significant differences were found in 13 words, and the most significant p<inf>n</inf>(W<inf>c010, r010</inf>): 0.0041 &#177; 0.0036 (group A) against 0.0012 &#177; 0.0024 (group B), p-value = 0.00001. The number of seldom occurring word types (forbidden words) also presents significant differences fw<inf>cr</inf>: 6.9 &#177; 6.6 against 13.5 &#177; 5.3, p-value = 0.00004. Joint symbolic dynamics provides an efficient non-linear representation of cardiorespiratory interactions that offers simple physiological interpretations.
authors.affiliation: Biomedical Engineering Research Centre (CREB), Dep. ESAII, Technical University of Catalonia, Barcelona, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Caminal
authors.forename: B
authors.initials: B
authors.lastname: Giraldo
authors.forename: H
authors.initials: H
authors.lastname: Zabaleta
authors.forename: M
authors.initials: M
authors.lastname: Vallverdu
authors.forename: S
authors.initials: S
authors.lastname: Benito
authors.forename: D
authors.initials: D
authors.lastname: Ballesteros
authors.forename: L
authors.initials: L
authors.lastname: Lopez-Rodriguez
authors.forename: A
authors.initials: A
authors.lastname: Esteban
authors.forename: M
authors.initials: M
authors.lastname: Baumert
authors.forename: A
authors.initials: A
authors.lastname: Voss