Quantitative Comparison of Korotkoff Sound Waveform Characteristics: Effects of Static Cuff Pressures and Stethoscope Positions

• Published in: Annals of biomedical engineering 2018-11, Vol.46 (11), p.1736-1744
• Main Authors: Pan, Fan, Chen, Fei, Liu, Chen, Yang, Zhipeng, Liu, Zhihong, Zheng, Dingchang
• Format: Article
• Language: English
• Subjects: Adult; Amplitudes; Biochemistry; Biological and Medical Physics; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Biophysics; Blood pressure; Blood Pressure Determination - instrumentation; Blood Pressure Determination - methods; Circumferences; Classical Mechanics; Female; Heart Sounds; Humans; Interpolation; Levels; Male; Medical instruments; Middle Aged; Models, Cardiovascular; Position measurement; Pressure effects; Pressure measurement; Stethoscopes; Variance analysis
• ISSN: 0090-6964; 1573-9686
• DOI: 10.1007/s10439-018-2080-0

The underlying principles of Korotkoff sound (KorS) during blood pressure measurement and its waveform characteristic changes with cuff pressure and stethoscope position have not been fully understood. This study aimed to quantify the effects of cuff pressure and stethoscope position on the measured KorS waveform characteristics. Thirty healthy subjects were recruited in this study. Four stethoscopes were placed on the circumferential direction around the arm (m1, m2, m3 and m4; m1 was above the artery, and equal distance between each other), and then sequentially at three different longitudinal positions (‘upper’, ‘middle’ and ‘low’ part under the cuff). At each longitudinal position, three levels of static cuff pressure (high: SBP + 10 mmHg, low: DBP-10 mmHg, and medium: DBP + (SBP-DBP)/3) were applied during the recording of KorS waveform. The averaged KorS waveform was firstly computed by using an interpolation method, separately for measurements from different stethoscope locations and cuff pressures. Two quantitative indices were derived to characterize the recorded KorS waveform: intensity amplitude and high-level duration of KorS waveform. Post-hoc pairwise comparisons after analysis of variance were used to compare the waveform characteristic differences between different stethoscope locations and between cuff pressures. Variance analysis demonstrated that the effects of stethoscope circumferential and longitudinal positions and cuff pressure on the two KorS waveform indices were significant ( all p