Análisis de la efectividad antihipertensiva mediante el monitoreo ambulatorio de presión arterial. Utilidad del modelo de Transformada de Fourier Discreta. / [Analysis of antihypertensive effectiveness by means of ambulatory blood pressure monitoring. Usefulness of the Discrete Fourier Transform Model]

ABSTRACT

In order to assess the usefulness of the Discrete Fourier Transform Model (DFT) to evaluate time-course drug effects on hypertensive patients studied with Ambulatory Blood Pressure Monitoring (ABPM) a number of experiments were carried out. A total of 10 mild to moderate hypertensive patients were evaluated under placebo and after 8 weeks of active treatment with Enalapril 20 mg per day using ABPM. Systolic and Diastolic blood pressure (SBP and DBP) were registered every 15 minutes during daytime and every 30 minutes at night. Pressure profiles of each patient were initially smoothed by hourly means. DFT was then applied to these profiles. The minimum number of harmonics necessary to generate a statistically significant fitting of the blood pressure profile, were obtained by residuals analysis (run test and analysis of variance of the mean sum of residual squares with each new harmonic incorporated to the model). A profile of the blood pressure differences (treatment-placebo) with the rough data of each patient was smoothed by hourly means. DFT was applied again on these substraction profiles. To estimate peak and trough drug effects for the blood pressure decrease function, maximum, minimum and inflexion points were calculated defining the following parameters T peak time from drug administration to maximum pressure decrease; T late response time from drug administration to the inflexion point following the last minimum previous to the next dose; BP peak the maximum blood pressure decrease amplitude; and the slope BP peak/T peak. The stability of the individual circadian rhythm was confirmed for both ABPM controls comparing times of maximum and minimum on the DFT smoothed profiles.(ABSTRACT TRUNCATED AT 250 WORDS)