Variability in Blood Pressure Measurements from Recorded Auscultation Sounds

Blood pressure measurement is clinically important. The manual auscultation method is retained as the current "gold standard". This study was designed to evaluate the variability of repeat measurements by the same operator, and between operators, when evaluating the same data.Ten young volunteer subjects with no known cardiovascular disease were studied. Korotkoff sounds were recorded from a standard stethoscope head connected to an acoustic microphone, and the audio sounds recorded during blood pressure measurements with cuff deflation, while subjects sat quietly on a chair. All recordings were replayed blindly and independently, to two trained operators. The operators identified systolic and diastolic blood pressure (SBP and DBP) without knowledge of the subject. After all recordings had been analysed once, the analysis was repeated.SBP rangedfrom 95 to 112 mmHg, and DBP from 58 to 78 mmHg. The difference in repeat listening measurements for each observer was -0.8 ±3.3 and -0.5 ±2.1 mmHg for SBP, and -0.4 ±2.3 and 0.4 ± 1.7 mmHg for DBP. The difference between the two operators for each measurement was 0.7 ± 1.6 and 0.9 ± 3.6 mmHg for SBP, and -1.7 ± 2.3 and -1.0 ± 2.0 mmHg for DBP. We have shown similar variability between operators as between repeat measurements on identical recordings.