Automated blood pressure self-measurement station compared to office blood pressure measurement for first trimester screening of pre-eclampsia

Abstract

Background: Preeclampsia is a serious medical disorder affecting pregnancy. Screening in early pregnancy can identify women at risk and enable effective prophylactic treatment. Accurate blood pressure (BP) measurement is an important element of the screening algorithm. Automated self-screening, while attending the first trimester ultra sound scan, using a BP self-measurement (BPSM) station, could be a low-cost alternative to office BP measurements (OBPM) on both arms performed by clinical staff, if the measurement quality can be ensured. Objectives: The aim of this study was to compare automated BPSM using a self-measurement station on one arm, with OBPM performed by clinical staff on both arms. Primary outcome was the difference in mean arterial pressure (MAP) between the two methods and secondary outcomes were safety and practicality issues. Methods: Pregnant women attending ultrasound-examination at 12 weeks gestational age were recruited and randomized to start with having two OBPMs taken on both arms by staff, using two standard validated automatic upper arm BP devices, or self-measuring using an automated BPSM station following a crossover study design. The BPSM station consists of a validated blood pressure device, and an add-on sensor system capable of registering blood pressure values, rest-time, back-supported, legs-crossed, and ambient noise-levels respectively, and providing interactive guidance during the measurement process, for supporting the self-measurement process. Results: A total of 80 complete BP measurement sets were obtained, for a total of 240 BPSM measurements and 320 OBPM measurements. We found no significant difference between the OBPM and BPSM methods (p=0.86) for mean arterial pressure (MAP). However, erroneous measurements were observed frequently during the experiment, mainly during the first of the 3 BPSM measurements (6%), secondary during the second BPSM measurement (3%). Only one data set (1%) was excluded due to OBPM errors. Conclusion: No significant difference in MAP between the two methods was found. Means for detecting and repeating erroneous BP measurements should be implemented. Measurement errors was found in 9 % of the measurement sets which is not acceptable for clinical use. Thus, several measures have been identified in order to properly identify and recover from such measurement errors in the future.