A comparison of two sphygmomanometers that may replace the traditional mercury column in the healthcare workplace

OBJECTIVE: Alternatives to the traditional, but possibly toxic mercury sphygmomanometer are needed for accurate blood pressure measurements in the medical workplace. We compared the performance of two commercially available potential replacements for the mercury column; an anaeroid manometer (Baum & Co) and an automated oscillometric device (Omron HEM-907), using the mercury sphygmomanometer as a standard, in the same participants. METHODS: Two independent observers performed simultaneous triplicate blood pressure readings for 512 participants. The average difference and standard deviation of the difference comparing the mercury column vs. the anaeroid and automated devices were calculated for each of the three paired systolic and diastolic blood pressure readings. RESULTS: Both devices met the Association for the Advancement of Medical Instrumentation criteria for sphygmomanometers (< 5 mmHg average difference, < 8 mmHg standard deviation of the difference) for all three readings. Compared with the mercury standard, there were no significant differences (by paired t-test) with the anaeroid device (-0.83/0.73 mmHg, P=0.25/0.09), but the automated device slightly overestimated systolic blood pressure (by 2.12 mmHg, P=0.002) and underestimated diastolic blood pressure (by 2.36 mmHg, P=0.0002). The first reading was significantly higher and had a larger standard deviation than the second or third readings across all manometers. CONCLUSIONS: The automated device performed as well as an anaeroid manometer operated by well trained, experienced observers. The two alternative devices to the mercury sphygmomanometer examined in this study may be potential replacement devices for blood pressure measurement.