A smartphone app may not be an effective method of measuring blood pressure in pregnant women, a small experiment suggests.
Researchers tested an experimental smartphone app that uses the phone's camera to monitor blood flow in the index finger with each heartbeat. They compared results from the app to traditional blood pressure measurements taken on 96 occasions in 32 pregnant women.
The goal of the study was to see if the smartphone app could produce blood pressure readings close to those recorded with a traditional blood pressure cuff. But the app failed to meet this goal often enough to be considered an accurate test of blood pressure.
“Especially during pregnancy, a correct diagnosis of pregnancy related hypertension is crucial to tailor individual therapy,” said senior study author Dr Thilo Burkard of the University Hospital Basel in Switzerland.
The app in question was never released, Burkard is quick to point out. But these results suggest pregnant women should be cautious about relying on other apps they download that use a similar method to measure blood pressure.
“Relying on these apps may lead to the situation that women with high blood pressure may not seek advice by their physician since they may measure normal values with the app and women with normal blood pressure may be concerned by measuring elevated pressure with the app,” Burkard said by email.
High blood pressure is one of the leading causes of death among pregnant women worldwide, accounting for 14% of maternal mortality, researchers note in the journal Hypertension.
Because early diagnosis and treatment can reduce the risk of serious complications and deaths related to high blood pressure during pregnancy, reliable, simple and easily accessible tools are needed to help women detect high blood pressure at an early stage, the study authors say.
In adults, a blood pressure reading of 120/80 mmHg (millimeters of mercury) or lower is considered normal or healthy. Pressure readings that are consistently 140/90 mmHg or greater are considered high.
In the tests by Burkard's team, the app's readings deviated from those taken with the blood pressure cuff at least half of the time by at least 5 mmHg when measuring the top number, known as systolic blood pressure. In 64 out of 96 readings, the differences were within 15 mmHg, the study found.
Pregnant women typically get their blood pressure checked with a blood pressure cuff at each doctor's visit, and they may have more regular checkups if they're diagnosed with high blood pressure.
Since 2014, the number of available smartphone apps measuring blood pressure and pulse rate has surged, researchers note. Apps designed to use the smartphone camera to check blood pressure are very popular, and some of them have been downloaded by a million or more users.
But none of these apps have been validated with published clinical trials. One app was removed from the market after it failed to meet accuracy goals in a trial, the study authors also note.
While apps might one day deliver on their potential for giving consumers an easy way to monitor their blood pressure, there isn't enough evidence yet to recommend any apps to consumers, said Kumanan Wilson, a scientist at Ottawa Hospital Research Institute in Canada who wasn't involved in the study.
“There is substantial value in developing similar applications that are effective in determining blood pressure in pregnant women because of convenience and ease of access,” Wilson said by email.
Even though the app in the study failed to achieve this goal, the research is still critical to helping scientists eventually come up with an app that works, Wilson said.
“Evaluations such as the one conducted in this study are uncommon but are needed for consumers to have confidence in the information they are receiving as it can influence healthcare decisions,” Wilson said. “In the case of high risk populations, such as pregnant women with hypertension, this is particularly relevant.” — Reuters
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