Blood Pressure Measuring Device Based on Korotkoff Sound's Tapping Period and Frequency Detection

The blood pressure level is a significant parameter in assessing a patient's cardiovascular health and even another physiological system condition. Nowadays, the gold standard for non-invasive blood pressure level measurement is utilizing stethoscope to listening Korotkoff sound that was produced when the pressure that applied on the patient's brachial artery are periodically declined. This method could lead the patient to be misdiagnosed because of the presence of subjectivity on deciding when the first and last tapping of Korotkoff sound occurred that were interpreted as the time when systolic and diastolic pressure occurred respectively. The automatic blood pressure measurements that frequently used today are employing the oscillometric method that could not replace the conventional one. This research explains how the tapping period of Korotkoff sound and the frequencies contained within it could enhance the automatic blood pressure measurement. By only using the period as a parameter, the error of 70% of both systolic and diastolic pressure measurement is less than 5 mmHg. By using both the period and frequency as parameters, the error of systolic and diastolic measurement is less than 5 mmHg for more than 72% of measurement. The period of Korotkoff sounds depends on the heart rate therefore it is necessary to develop an adaptive algorithm that involving heart rate level.