Hans van den Heuvel

METHODS In this prospective observational study the revised 2010 International Protocol of the European Hypertension Society was used for the validation of two different devices. This study was exempted from approval of the Medical Research Ethics Committee of the University Medical Center in Utrecht (reference number 16-637), as the Committee confirmed that the Dutch Medical Research Involving Human Subjects Act (WMO) did not apply to this study. Device details The iHealth Track is a fully automated oscillometric BP monitor by Andon Health Co, China. The accessory cuff can be used, according to the manual, for arm circumferences of 22- 42 cm. Its Bluetooth functionality allows data synchronization with different health apps on smartphone and tablet. This monitor is previously validated in a general population according to the American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060-2:2013 standard. The Omron HEM-9210T (Omron Healthcare Co. Ltd., Kyoto, Japan) is an automated oscillometric device for BP measurement on the upper arm. The wide-range cuff is used for arms 22–42 cm in circumference. Data can also be transferred to a database using Bluetooth connection. This device is validated in a general population using 85 subjects according to the ANSI/AAMI/ISO criteria. 12 Recruitment The EHS protocol requires 33 subjects within one specific group. Pregnant women with age over 21 years old were recruited on the maternal ward of an academic teaching hospital (Utrecht University Medical Center). All subjects were at least 25 weeks pregnant and were hospitalized for different reasons (e.g. preeclampsia, preterm rupture of membranes, need for i.v. medication) but without discomfort or contractions, as this could possibly alter blood pressure. Exclusion criteria for the validation were unclear Korotkoff sounds, arrhythmia, or arm circumference above or below the device prescription (22-42cm). A subgroup of the recruited patients was diagnosed with preeclampsia. Preeclampsia was defined as de-novo hypertension in pregnancy (a blood pressure equal to >140 and/or >90 mmHg on two separate measurements) with proteinuria or new-onset thrombocytopenia, renal insufficiency, neurological complications, liver involvement or fetal growth restriction. 13 Procedures Overseen by an independent supervisor [JH], measurements were performed and recorded by two observers blinded from both each other’s readings and from the device readings, CHAPTER 3 42