Accurate Blood Pressure Measurement at Home

Automatic and semi-automatic bloodpressure meters are simple-to-use thus widespread in home health monitoring. However, their results are not accurate and reproducible enough, the reliability of self-assessment is not satisfactory, medical doctors have reservations for the results. The occlusion by the cuff – applied in the majority of indirect bloodpressure meters changes the biomechanical properties of the arteries resulting in a change in the systolic and diastolic values. Presently available devices neglect the variation caused by breathing. This can be as high as 10 Hgmm in the systolic pressure. The aim of the research work has been to increase the accuracy and reproducibility of the indirect, cuffbased blood pressure measurement with the help of the photoplethysmographic (PPG) signal. The PPG signal helps to measure the systolic pressure directly unlike the oscillometric method that measures the mean pressure and gives only an estimate for the systolic and diastolic pressures. The additional information gained by monitoring the PPG signal before and during slow inflation provides more accurate results than conventional indirect methods and assures that the cuff pressure only slightly (by less than 10 Hgmm) exceed the systolic pressure. The PPG signal also indicates if the cuff is placed or inflated improp-