The quest for accurate wearable blood pressure monitors.

The automated cuff-oscillometric blood pressure (BP) measurement currently is the standard method for evaluating hypertension using office, home and ambulatory measurements. It eliminated observer-related issues of the auscultatory method and made out-of-office BP monitoring feasible. But there are issues with this method, mainly due to the limited BP information they provide, the use of an inflatable cuff, and because measurements are provided only in static conditions. Cuffless wearable devices can provide complete information of the individual's BP profile and behavior, for days, weeks, months, unobtrusively, during all routine daily activities and during sleep. However, at the present time there is no convincing evidence that any cuffless BP technology has adequate accuracy as required for clinical use, and scientific societies do not recommend them. Novel tools implemented in smartwatches, such as the Apple 'Hypertension Notification Feature', can be useful in detecting undiagnosed hypertension in the general population, but require confirmation by cuff BP measurement and are not intended for monitoring treated hypertensives. Novel smartwatch-type cuff-oscillometric (not cuffless) BP monitors can be used for self-measurement at home, at work and other settings, and also for ambulatory monitoring including nighttime sleep. Some successful validation studies, mainly on static validation, have been reported, but more research is needed in ambulatory conditions involving motion and position and in clinical use. While continuing to pursue cuffless wearable BP technologies, smartwatch-type cuff-oscillometric devices deserve our close attention for establishing their optimal use.