Algorithm for identifying and separating beats from arterial pulse records

BACKGROUND: This project was designed as an epidemiological aid-selecting tool for a small country health center with the general objective of screening out possible coronary patients. Peripheral artery function can be non-invasively evaluated by impedance plethysmography. Changes in these vessels appear as good predictors of future coronary behavior. Impedance plethysmography detects volume variations after simple occlusive maneuvers that may show indicative modifications in arterial/venous responses. Averaging of a series of pulses is needed and this, in turn, requires proper determination of the beginning and end of each beat. Thus, the objective here is to describe an algorithm to identify and separate out beats from a plethysmographic record. A secondary objective was to compare the output given by human operators against the algorithm. METHODS: The identification algorithm detected the beat's onset and end on the basis of the maximum rising phase, the choice of possible ventricular systolic starting points considering cardiac frequency, and the adjustment of some tolerance values to optimize the behavior. Out of 800 patients in the study, 40 occlusive records (supradiastolic- subsystolic) were randomly selected without any preliminary diagnosis. Radial impedance plethysmographic pulse and standard ECG were recorded digitizing and storing the data. Cardiac frequency was estimated with the Power Density Function and, thereafter, the signal was derived twice, followed by binarization of the first derivative and rectification of the second derivative. The product of the two latter results led to a weighing signal from which the cycles' onsets and ends were established. Weighed and frequency filters are needed along with the pre-establishment of their respective tolerances. Out of the 40 records, 30 seconds strands were randomly chosen to be analyzed by the algorithm and by two operators. Sensitivity and accuracy were calculated by means of the true/false and positive/negative criteria. Synchronization ability was measured through the coefficient of variation and the median value of correlation for each patient. These parameters were assessed by means of Friedman's ANOVA and Kendall Concordance test. RESULTS: Sensitivity was 97% and 91% for the two operators, respectively, while accuracy was cero for both of them. The synchronism variability analysis was significant (p < 0.01) for the two statistics, showing that the algorithm produced the best result. CONCLUSION: The proposed algorithm showed good performance as expressed by its high sensitivity. The correlation analysis demonstrated that, from the synchronism point of view, the algorithm performed the best detection. Patients with marked arrhythmic processes are not good candidates for this kind of analysis. At most, they would be singled out by the algorithm and, thereafter, to be checked by an operator

Dostoyevsky and epilepsy: between science and mystique Dostoiévski e a epilepsia: entre a ciência e a mística

This article, the result of a research project presented as a Master's degree dissertation in the graduate program of "Teaching of Health Education" at UNIFESP, seeks to highlight the pertinence of analyzing epilepsy and especially, the paradoxical experience of the epileptic individual through literary narrative. Using as its object the novel, The Idiot, by Fyodor Dostoyevsky, it seeks to discuss the relationship between epilepsy and the mystic experience, bearing in mind the context of the scientific and humanistic perspectives of the 19th century and today.<br>Este artigo, fruto de uma pesquisa apresentada como dissertação de mestrado junto ao programa de pós-graduação "Ensino em Ciências da Saúde" da UNIFESP, procura apontar a pertinência de se analisar a epilepsia e, principalmente, a paradoxal experiência do epiléptico através da narrativa literária. Tomando como objeto o romance O Idiota, de Fiódor Dostoiévski, procura-se discutir a relação entre epilepsia e experiência mística, considerando o contexto das perspectivas científicas e humanísticas do século XIX e de hoje

Management of hyperthyroidism due to Graves' disease: frequently asked questions and answers (if any)

Graves\u2019 disease is the most common cause of hyperthyroidism in iodine-replete areas. Although progress has been made in our understanding of the pathogenesis of the disease, no treatment targeting pathogenic mechanisms of the disease is presently available. Therapies for Graves\u2019 hyperthyroidism are largely imperfect because they are bound to either a high rate of relapsing hyperthyroidism (antithyroid drugs) or lifelong hypothyroidism (radioiodine treatment or thyroidectomy). Aim of the present article is to offer a practical guidance to the reader by providing evidence-based answers to frequently asked questions in clinical practice