Comparisons of auscultatory hybrid and automated sphygmomanometers with mercury sphygmomanometry in hypertensive and normotensive pregnant women: parallel validation studies.

OBJECTIVE: To find a suitable replacement for mercury sphygmomanometry to measure blood pressure (BP) accurately in normal and hypertensive pregnancy.

METHODS: Two parallel validation studies were carried out in 340 pregnant women, 170 with a hypertensive disorder and 170 normotensive women. An auscultatory hybrid sphygmomanometer, A&D UM-101, and a professional automated oscillometric device for office and clinic use, Omron HEM-907, were tested. Using a modified British Hypertension Society (BHS) Protocol, nine sequential BP recordings were taken alternating between the mercury sphygmomanometer and the study device. The first readings for each device were discarded, and three differences between mercury and study device were calculated for each woman for SBP and DBP. Main outcome measures were the percentages of BP readings that were within 5, 10 and 15 mmHg absolute difference from mercury sphygmomanometry.

RESULTS: Women in both studies were an average of 34 weeks' gestation and of similar ethnicity, age and BMI. In hypertensive women, 29% had preeclampsia and 73% were receiving antihypertensives. Amongst hypertensive women, SBP was within 5 mmHg of mercury BP in 94% of readings with the auscultatory device and 75% with the automated device (P = 0.021); DBP was within 5 mmHg in 97 and 61% readings, respectively (P = 0.001). Results were similar amongst normotensive pregnant women. Both devices achieved an A/A rating according to the BHS protocol.

CONCLUSION: The auscultatory hybrid sphygmomanometer is more accurate than the automated oscillometric device in pregnancy, specifically in hypertensive pregnancies. It is an acceptable replacement for mercury sphygmomanometry in pregnancy.