IS IT THE END OF A LONG AND PRODUCTIVE ERA?: THE FUTURE OF THE MERCURY SPHYGMOMANOMETER AND THE STETHOSCOPE

Abstract

Arterial pulsation which had long been studied for estimation of blood pressure or mean blood pressure was replaced by the measurement of systolic and diastolic blood pressure using Korotkoff sound detected by stethoscope in the beginning of the previous century. In the meantime, vast of modern knowledge of human hypertension from epidemiology to randomized clinical trial had been built on the Korotkoff sound and stethoscope methodology. Hypertension is very special clinical entity in terms of the diagnosis is solely dependent on the manual blood pressure measurement by a physician or nurse. The observer related error was mentioned frequently but the source of the error is numerous and the noncompliance with the standard measurement protocol is not only confined to the observer related factor but also, practically more important, to the other factors such as resting period, environment, exposure to drugs, behavioral factors, and etc. After emerging of automated device using oscillometric algorithm, gradually auscultation methods has been replaced by automated device. Even with the environmental hazard issue by mercury manometer, the reason to be replaced does not seem to be accuracy issue but feasibility issue because, in general, standardization of the auscultation method costs more. Fortunately, since 1990 s, most randomized clinical trial has been using automated device to measure blood pressure even though validation data for each trial were scarce. Moreover clinician should have attention on the blood pressure measurement protocol for each trial before applying the result to practice. Mercury seems be replaced at any time because the accuracy of electronic manometer is very high. Stethoscope as another part of the conventional technique seems to be useful to measure blood pressure in special situation such as arrhythmia, pregnancy, or patient driven needs. As reported in several studies, in some patient group, the error of automated device can be unacceptable for clinical use, about 5 mmHg difference. So conventional technique could survive in the form of stethoscope and digital manometer in the future. In case automated device using auscultation technique would be available, the stethoscope for the purpose of blood pressure measurement will be disappeared for good. The technical issues in 1990 s in developing auscultation device could be tackled if applying current information processing technology. Otherwise it is not the time for the stethoscope to retire.