An inaccurate automated device negatively impacts the diagnosis and treatment of gestational hypertension

Abstract

Objectives: Automated blood pressure devices are frequently introduced in maternity care without prior validation for their accuracy in pregnancy. Our objectives were to, firstly, establish the accuracy in pregnancy of a locally used device (Welch Allyn 300) and, secondly, to audit its impact on the diagnosis and treatment of hypertension.

Study design: Validation study: The device was evaluated using the grading criteria of the European Society of Hypertension International Protocol (ESH-IP) (2010). Two observers took nine same-arm measurements alternating between the Welch Allyn and the mercury sphygmomanometer. Thirty-three women of any gestation were included. Clinical audit: One observer took three same-arm measurements alternating between the Welch Allyn and the mercury sphygmomanometer. One hundred women of any gestation referred with suspected hypertension were included. The main outcome measures were the proportion diagnosed with hypertension or commenced on anti-hypertensive treatment on the presenting visit when using either the manual or the automated device.

Main outcome measures: Grading criteria of the ESH-IP (2010) and proportion of women diagnosed with hypertension or commenced on antihypertensive therapy at the presenting visit when using either manual sphygmomanometry or the Welch Allyn device.

Results: The Welch Allyn 300 series failed to meet the criteria of the ESH-IP (2010) for pregnancy. Compared to the mercury device, it under diagnosed hypertension by 48% and need for treatment by 80%.

Conclusions: The Welch Allyn 300 cannot be recommended for the measurement of blood pressure in pregnancy. Its use leads to the under-diagnosis and under-treatment of gestational hypertension.

Keywords: Blood pressure; Hypertension; Oscillometric; Preeclampsia; Pregnancy; Validation; Welch-Allyn Vital Signs.