In fact, think about it, a watch can measure the cardiac and blood pressure of the smart device is not very reliable , may be an approximate value, and the exact value is some deviation, for just want to understand these data can be used, but want to the exact value, it is still recommended to go to the hospital for examination.
Smart bracelets and smartwatches to measure blood pressure are relatively fewer products, because the difficulty of this test and the cost of testing will be greatly increased. Regardless of their measurement principle, I personally do not trust their measurement results. Because of our work, we often use electronic blood pressure monitors. I have found that even dedicated wrist electronic blood pressure monitors often produce unreliable results because there are so many factors that interfere with it.
Even if the blood pressure at the wrist can be measured accurately, it often doesn't necessarily reflect the true blood pressure within the patient's aorta. Because it's so far from the aorta, variations in the blood vessels, narrowed arteries, and blockages can affect the measured value, especially in the elderly. Detectives said that no matter which measurement principle is used, with the existing technology, the smart bracelet has not been able to do an accurate measurement of blood pressure. Medical sphygmomanometer as a medical device, our country has relevant regulations, the need for regular calibration to professional organizations, can be used. Home blood pressure monitors also need to be calibrated regularly to minimize the error. The smart bracelet this new thing, because it does not belong to the medical device, the country has not yet had the relevant testing standards, so the measurement results are for reference only, can never replace the sphygmomanometer, as the basis for diagnosis and treatment."
Summary: Smart bracelets are used to count the pulse and thus know the heart rate, basically still reliable. But if there's an arrhythmia, such as atrial fibrillation, that's not necessarily the case.
Smart bracelets can be used to measure blood pressure for fun. If you want to know your exact blood pressure, it's best to get a cuff-type electronic sphygmomanometer that measures the upper arm.