Accurately measuring night-time blood pressure in individuals in a way that delivers meaningful results has been a long-standing challenge for physicians.
While blood pressure can be monitored around the clock via ambulatory blood pressure monitoring, the recording still requires a person to wear a cuff on their arm throughout the night, which inflates at regular intervals. This has little impact on a patient’s normal activities during the day, but can disrupt a person’s sleep pattern at night, and as a consequence it is likely to have an impact on the accuracy of the data and readings acquired.
With growing evidence pointing to nocturnal, or night-time, blood pressure as indicative of an increasing risk of cardiovascular events, such as stroke or coronary heart disease, accurately measuring nocturnal blood pressure (BP) is an important aspect of hypertension management. It can offer physicians a clearer insight into a patient’s hypertension, which can determine the severity of the condition and in turn influence treatment options. With experts suggesting that night-time blood pressure readings are a more accurate measurement of a person’s circulatory health, there are benefits to measuring blood pressure at night as well as during the day. Advantages are that it can rule out white coat hypertension, so that people are not given unnecessary prescriptions for BP-lowering drugs. It can also detect masked hypertension, so that people receive the medications they need for high blood pressure. But gathering readings during the night interferes with sleep, with the frequent cuff inflations that occur to capture the readings at regular intervals.
Sleep disturbance and deprivation caused by night-time BP measurement can lead to inaccurate BP assessment, meaning the reading may be higher than the usual night-time BP value. In addition, patients may get so fed up with the night-time monitoring that it could lead to reduced adherence and see them fail to correctly follow hypertension treatment or to monitor night-time BP over multiple nights. Therefore, reducing sleep disturbance caused by night-time BP measurement is indispensable for appropriate hypertension management. One simple approach to help offset sleep disturbance is to reduce the frequency of BP measurements and the number of cuff inflations per night. However, this will lead to a decrease in the accuracy of nocturnal hypertension diagnoses. That has underlined the need for more discreet home blood pressure monitoring where there is only minimal sleep disturbance.
Smart ring solution
One approach to measuring blood pressure 24/7 that has significantly less impact on a patient’s sleep is with smart rings. The hope is that such devices that have a significantly reduced impact on a patient’s sleep could provide more accurate nocturnal blood pressure measurements. Sky Labs’ CART-I plus smart ring, which is capable of round-the-clock blood pressure monitoring, uses photoplethysmography (PPG) signals to measure the bloodstream through a wearer’s finger. It has already been shown as effective and highly-accurate in helping continuously monitor heart rhythm and support diagnosis of Atrial Fibrillation. A new feature of CART-I is its ability to monitor hypertension without user intervention, and overcoming the sleep-depriving limitations of existing methods. Sky Labs is currently running a clinical study on the use of the smart ring for BP monitoring, with results due to be published early next year for continuous blood pressure monitoring.