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Does the Position or Contact Pressure of the Stethoscope Make Any Difference to Clinical Blood Pressure Measurements: An Observational Study

Lookup NU author(s): Fan Pan, Dr Ding Chang Zheng, Emeritus Professor Alan MurrayORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

This study aimed to investigate the effect of stethoscope position and contact pressure on auscultatory blood pressure (BP) measurement.Thirty healthy subjects were studied. Two identical stethoscopes (one under the cuff, the other outside the cuff) were used to simultaneously and digitally record 2 channels of Korotkoff sounds during linear cuff pressure deflation. For each subject, 3 measurements with different contact pressures (0, 50, and 100 mm Hg) on the stethoscope outside the cuff were each recorded at 3 repeat sessions. The Korotkoff sounds were replayed twice on separate days to each of 2 experienced listeners to determine systolic and diastolic BPs (SBP and DBP). Variance analysis was performed to study the measurement repeatability and the effect of stethoscope position and contact pressure on BPs.There was no significant BP difference between the 3 repeat sessions, between the 2 determinations from each listener, between the 2 listeners and between the 3 stethoscope contact pressures (all P > 0.06). There was no significant SBP difference between the 2 stethoscope positions at the 2 lower stethoscope pressures (P = 0.23 and 0.45), but there was a small (0.4 mm Hg, clinically unimportant) significant difference (P = 0.005) at the highest stethoscope pressure. The key result was that, DBP from the stethoscope under the cuff was significantly lower than that from outside the cuff by 2.8 mm Hg (P < 0.001, 95% confidence interval =3.5 to =2.1mmHg).Since it is known that the traditional Korotkoff sound method, with the stethoscope outside the cuff, tends to give a higher DBP than the true intraarterial pressure, this study could suggest that the stethoscope position under the cuff, and closer to the arterial occlusion, might yield measurements closer to the actual invasive DBP.


Publication metadata

Author(s): Pan F, Zheng DC, He PY, Murray A

Publication type: Article

Publication status: Published

Journal: Medicine

Year: 2014

Volume: 93

Issue: 29

Print publication date: 01/12/2014

Date deposited: 05/08/2015

ISSN (print): 0025-7974

ISSN (electronic): 1536-5964

Publisher: Lippincott Williams & Wilkins

URL: http://dx.doi.org/10.1097/MD.0000000000000301

DOI: 10.1097/MD.0000000000000301


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Funding

Funder referenceFunder name
2013GZ1043Sichuan Province Science and Technology Support Program
2011SZ0123Sichuan Province Science and Technology Support Program
EP/F012764/1EPSRC
EP/I027270/1Engineering and Physical Sciences Research Council (EPSRC)

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