Quantitative Assessment of Blood Pressure Measurement Accuracy and Variability from Visual Auscultation Method by Observers without Receiving Medical Training

Figures

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  Figure 1. Blood pressure determination procedure by 10 observers using two measurement methods: traditional manual auscultatory method of listening for Korotkoff sounds and visual auscultation method by visualizing the Korotkoff sound waveform. The data analysis procedure is also given.

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  Figure 2. Illustration of converted Korotkoff sound waveform with some examples of video frames, and demonstration of SBP and DBP determination by visualizing the appearance and disappearance of Korotkoff sounds, respectively.

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  Figure 3. Within-observer measurement variabilities (SD of three repeated measurements on each Korotkoff recording) of SBP (a) and DBP (b) from the two measurement techniques: traditional manual auscultatory method of listening for Korotkoff sounds and visual auscultation method by visualizing the Korotkoff sound waveform. The average measurement variability across the 30 Korotkoff recordings is plotted individually for each observer.

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  Figure 4. Mean and SD of SBP and DBP measured by each individual observer using the two measurement methods: traditional manual method (a) and visual auscultation method (b). The reference answers of SBP and DBP provided by the British Hypertension Society are also given.

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  Figure 5. Histograms of measurement errors of SBP and DBP from each individual observer using the two measurement methods: traditional manual method and visual auscultation method. There are a total of 900 comparisons for each measurement method (from 30 Korotkoff recordings, 10 observers, and 3 repeated determinations).

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  Figure 6. Mean and SEM of BP measurement errors of SBP and DBP from each individual observer using the two measurement methods: traditional manual method and visual auscultation method. Asterisk indicates that there is a significant difference between the measured BP values in this study and those reference answers provided by the BHS training database. “NS” indicates that there is no significant difference.

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  Figure 7. Waveform examples of Korotkoff sounds to illustrate the uncertainties of determining BPs from visual auscultation method, leading to BP measurement errors. The SBP and DBP were determined from one beat below and one beat above the actual audible Korotkoff sounds at systole and diastole, respectively.