Using photoplethysmographic signal for increasing the accuracy of indirect blood pressure measurement

Automatic and semi-automatic blood pressure meters are widespread in home health monitoring.However, their results are not accurate and reproducible enough, the reliability of selfassessment is not satisfactory and medical doctors have reservations about their results.The aim of this study was to increase the accuracy and reproducibility of the indirect, cuff-based blood pressure measurement with the help of the photoplethysmographic (PPG) signal.The additional information gained from the PPG signal during slow inflation provides more accurate results than conventional indirect methods and assures that the cuff pressure only slightly (by less than 10 mm Hg) exceeds the systolic pressure.Measuring the pulse wave transit time and its variation during slow inflation and deflation makes it possible to characterize the sympathetic control of the cardiovascular system and the rigidity of the brachial arteries.The PPG signal also indicates if the cuff is placed or inflated improperly.The method has been validated making 420 measurements on 51 subjects.