Mobile app tracks BP changes in pregnant women

Blood pressure (BP) estimates in pregnant women of the mobile app OptiBP meet the AAMI/ESH/ISO 81060-2:2018 criteria and are on a par with that of an oscillometric device, reports a study.

"[O]ur study shows that OptiBP meets AAMI/ESH/ISO 81060-2:2018 criteria and can reliably produce BP estimates in pregnant women that are comparable to standard oscillometric methods,” the researchers said. 

Forty-eight women participated in the study, of whom 32 completed the protocol. A total of 338 valid measurement pairs were assessed. [J Hypertens 2025;43:665-672]

The mean errors were –1.78 for systolic BP and 1.19 for diastolic BP. The patient-specific standard deviations of the mean error were 4.68 and 4.52, respectively. The overall success rate of OptiBP in capturing data was 79 percent across all visits.

The findings demonstrate a robust agreement between OptiBP-derived BP values and those obtained using the standard method, which are consistent with earlier publications. [Sci Rep 2020;10:17827; Blood Press 2022;31:288-296; J Clin Monit Comput 2022;36:1525-1533; BMC Anesth 2022;22:259]

“To the best of our knowledge, this is the first study evaluating a cuffless optical BP solution in the form of a smartphone embedded app in a dedicated cohort of women at various timepoints during their pregnancy,” the researchers said.

In a previous study assessing the performance of OptiBP in three emergent economies, the mobile app met the AAMI/ESH/ISO 81060-2:2018 criteria both overall and in subgroup analysis of 150 pregnant women from a tertiary hospital in South Africa. [NPJ Digit Med 2023;6:69]

The said study included a subset of women with gestational hypertension and pre-eclampsia, but it involved only a single set of measurements taken shortly after calibration.

BP variability

In general, BP decreases during the early stages of pregnancy. Systemic vasodilation begins as early as 5 weeks and peaks in the second trimester before returning to near pregravid levels at the end of the pregnancy. [Sci Rep 2017;7:6227]

On the other hand, cardiac output remains high and peripheral vascular resistance stays low into the second week of the postpartum period. Perioperative haemodynamic changes also frequently occur during caesarean section due to blood loss and the decreased sympathetic drive. [Circulation 2014;130:1003-1008; Obstet Gynecol 2017;130:e168-e186; Reg Anesth 1997;22:325-331]

"Despite these observations, the longitudinal data collected in [the current] study showed minimal BP variability,” the researchers said. 

“This may be explained by two factors: first, most women were enrolled in the tail end of their pregnancy where physiological changes in BP are less pronounced; second, the sympathetic blockade and intravascular volume depletion due to intraoperative bleeding were already resolved at the moment of assessment and did not translate into significant BP changes,” they added. 

This prospective, longitudinal, and monocentric study assessed the accuracy of the OptiBP algorithm against standard oscillometric BP measurements in pregnant women. Those scheduled for elective caesarean sections were enrolled during the preoperative anaesthesia consultations.

Researchers obtained paired BP measurements using OptiBP and the reference method at various timepoints in late pregnancy and the postpartum period. They assessed the agreement between these methods using the AAMI/ESH/ISO 81060-2:2018 standard thresholds of 5 mm Hg for mean standard deviation of the error and patient-specific standard deviation of the mean error.

“Future research should aim to include a diverse sample and focus on participants with diagnosed hypertensive disorders of pregnancy,” the researchers said.