FETAL CARDIAC BYPASS ANALYSIS BY MEANS OF CORRELATION DIMENSIONS

During in vivo experiments of fetal cardiac surgery performed in sheep, physiological signals were recorded, and subsequently analyzed. In order to characterize their complexity, the fractal dimension was calculated. The adopted model of dimension estimation allowed for a possible multifractal nature of the signals, by considering two distinct fractal dimensions ν1, ν2 at different length scales. A comparison was also carried out with an alternative measure of system complexity, Approximate Entropy (ApEn). The results of the analysis suggest that fractal dimension may be a useful indicator of the cardiac stress and, ultimately, of the quality of the support delivered during the operation.