Presentation and applications of approximate entropy in medicine
Journal Title: Αρχεία Ελληνικής Ιατρικής - Year 2004, Vol 21, Issue 2
Abstract
Approximate entropy (ApEn) is a real positive number which compares the regularity of different time-series of numbers under specific circumstances. Such time-series can be, for example, the beats of an electrocardiogram (ECG) or the daily secretion of hormones. Τhe algorithm of ApEn was invented in 1991 by the American Steve Pincus and has been used for the comparison between physiological and non-physiological conditions. This article presents concisely the most important applications of ApEn according to the international bibliography along with two relevant studies from our laboratory. The applications concern the evaluation of “suspicious” electroencephalogram and ECG recordings, the study of pulsatile hormone secretion and other scientific fields such as the movements of the muscles of respiration. From the mathematical point of view, ApEn states the possibility that the values of time-series are, and stay within, certain limits. These limits are the so-called filter of the algorithm (r). In practice the algorithm checks the differences between the values, not the values themselves, because the target of ApEn is the check of regularity (complexity) of a system. The number of differences in each value which will be compared with the filter of the algorithm comprises the so-called “window” of the method (m). The appropriate computerization of ApEn demands at least 60 values (N). Higher ApEn means wide disorder, in which case the values of time-series differ greatly between each other. Conversely, lower ApEn means regularity. Whenever we want to compare two or more values of ApEn, all ApEn calculations must use the same r, m and N, N being the total number of values of the time-series. For this reason the ApEn values are symbolized as ApEn (m, r, N). The sensitivity of the ApEn algorithm is specified by the researcher by choosing the parameters N, m and r. For N
Authors and Affiliations
P. KARKALOUSOS, E. DELICHA
Keywords
Related Articles
- EP ID EP128886
- DOI -
- Views 87
- Downloads 0
Work related stress in health care professionals in the economic crisis
OBJECTIVE Evaluation of work related stress in those employed in health care occupations in Korinthia. METHOD The study was conducted in the primary and secondary health care services in Korinthia. The response rate a...
Acute myelomonocytic leukemia initially presenting asdiffuse gingival swelling
No abstract available
Fluoroquinolones in the treatment of community-acquired pneumonia: <br /> Rates of prescription versus emerging resistance of pneumococci
Community-acquired pneumonia (CAP) is the most severe respiratory infection caused by Streptococcus pneumoniae (S. pneumoniae). The empirical treatment of CAP includes the administration of a β-lactam or/and a macrolide...
Επάρκεια εμβολιαστικής κάλυψης κατά την εγγραφή στο σχολείο.<br /> Έρευνα χρονικής στιγμής σε μαθητές αστικού πληθυσμού
ΣΚΟΠΟΣ Η έγκυρη και ακριβής εκτίμηση του επιπέδου εμβολιασμών των παιδιών που εγγράφονται στην Α΄ δημοτικού, καθώς και αξιολόγηση της ολοκλήρωσης του υποχρεωτικού σχήματος εμβολίων της προσχολικής ηλικίας. ΥΛΙΚΟ-ΜΕΘΟ...
Τhe role of exercise in the prevention and treatment of osteoporosis in postmenopausal women
Osteoporosis is the most common metabolic bone disease and postmenopausal women comprise the group at highest risk. During the first five to ten years after the beginning of menopause, rapid loss of bone density amountin...