Clinical Research Papers

Todd J. Brinton, E. Daniel Walls, Alay K. Yajnik and Shiu-Shin Chio

Background Both the mercury sphygmomanometer and oscillometric measurement methods are widely in use for pediatric, adult, and geriatric patients. However, inherent differences between the methods of measurement may create varying degrees of sensitivity to age and potentially result in differences between measurements for these two techniques.

Design Measurements of systolic and diastolic blood pressures in 154 subjects were obtained using the mercury sphygmomanometer and pulse dynamic oscillometric methods in accordance with the 1987 Association for the Advancement of Medical Instrumentation guidelines. Subjects were separated into three age groups and their data analyzed for differences between measurements for these two techniques.

Methods Two qualified nurses derived systolic and diastolic blood pressures using phase I and phase IV Korotkoff sounds, respectively, during simultaneous monitoring with the pulse dynamic oscillometric method.

Results Inter-nurse variabilities for measurements derived by mercury sphygmomanometer were 1.8 ± 4.1 for systolic and 0.9 ± 3.9 for diastolic blood pressure. Mean differences (reference - device) of -5 ± 5 mmHg (pulse dynamic value higher) for systolic and 1 ± 5 mmHg (pulse dynamic value lower) for diastolic blood pressure between pulse dynamic and mercury sphygmomanometer values were found for all subjects. However, pulse dynamic systolic blood pressure was significantly higher than mercury sphygmomanometer systolic blood pressure for group 1 (n = 51, aged 11-22 years, mean difference -5.6 mmHg, P= 0.03). A similar trend was observed with group 2 (n = 51, aged 23-54 years, mean difference -4.3 mmHg, P=0.06). We observed no significant difference for systolic blood pressure with group 3 (n =52, aged 55-85 years, mean difference -3.8 mmHg, P > 0.1). For all three groups we found no significant difference for diastolic blood pressure.

Conclusion The variation in the agreement of systolic blood pressure measurements can be attributed to the differing effects of age-dependent arterial changes on the measurement methods. The findings indicate that, although the pulse dynamic oscillometric method and mercury sphygmomanometer correlate well when agreement between measurements of systolic blood pressure is dependent on age and the method of measurement employed. Blood Press Monit 3:125-129 © 1998 Lippincott-Raven Publishers.

Blood Pressure Monitoring 1998, 3:125-129.