The Design of Korotkoff Sound Detection Using Amplitude Parameter and Oscillation Beat to Estimate Non-invasive Blood Pressure

Manual auscultation is still the standard for measuring non-invasive blood pressure. Much research has initiated the development of automated auscultation due to the measurement implications that manual measurement might have. Based on these investigations, one of the lightweight and simple-to-use algorithms, such as the amplitude approach, has yet to yield the best results. Therefore, the purpose of this study is to enhance Korotkoff sound detection with amplitude parameters to estimate blood pressure and to assess the suggested methods following relevant standards. The study involved 85 participants and 260 measurements. The steps of the method with the amplitude parameter used are filtering the sound signal with a frequency range of 28-171 Hz, filtering the pressure signal with a frequency range of 15-50 Hz to get pressure oscillations, filtering the sound signal at the amplitude threshold, and looking for a Korotkoff signal. The method findings are estimated and compared to manual measurements taken by specialists as a reference. The results reveal that an amplitude threshold of 2 x RMS (Root Mean Square) is preferable to a threshold of 1750. Meanwhile, Korotkoff beats in the minimum-maximum range of pressure oscillations (0.5-0.9 seconds) outperform the mean ± standard deviation pressure oscillations (0.6-0.8 seconds). In conclusion, method 3 produces the greatest results, with error values and percentages below 5, 10, and 15 mmHg, respectively, $4.5\pm 5.7$ mmHg, 73.5%, 90.0%, and 95.0% for systolic and $4.3\pm 5.5$ mmHg, 76.9%, 90.4%, and 95.4% for diastolic.