ABILITY OF A CUFFLESS 24 HOUR AMBULATORY BLOOD PRESSURE MEASUREMENT DEVICE TO TRACK BLOOD PRESSURE CHANGES COMPARED TO A CUFF-BASED DEVICE

Abstract

Objective: There is an increasing number of cuffless blood pressure (BP) measurement devices on the market. Beneath the absence of generally accepted validation protocols for these devices, the ability of these devices to track changes in BP levels over 24h in relation to an initial calibration BP is unknown. Aim of this study was to analyse this ability in a cuffless 24h BP device using pulse transit time. Design and method: We prospectively enrolled 166 participants for simultaneously performed cuffless (TestBP, Somnotouch NIBP) and cuff-based (RefBP, Spacelabs 90217A or IEM Mobil-o-graph) 24h BD measurements. Main exclusion criteria were atrial fibrillation or an inter-arm difference of >10 mmHg. TestBP calibration was based on initial RefBP measurement (CalibBP). As surrogate parameters for tracking individual changes in BP levels after the CalibBP, we used the difference between CalibBP and mean 24h, awake and asleep BP measured by RefBP and TestBP. Additionally, we analysed the relationship between the difference of CalibBP and RefBP vs the difference between RefBP and TestBP. Results: Mean (±SD) age was 51.2 (15.1) years and 53% were male. Mean (±SD) difference between CalibBP and mean 24h BP by RefBP / TestBP were 7.4 (13.2) versus 1.8 (8.3) mmHg for systolic (p < 0.0001) and 6.6 (6.8) versus 1.6 (5.8) mmHg for diastolic (p < 0.0001). Corresponding ranges for CalibBP-RefBP were -35 – 55 mmHg vs. -14 – 34 for CalibBP-Test BP. Figure 1 shows a near linear relationship between the difference between CalibBP and RefBP and the difference between RefBP and TestBP for systolic and diastolic BP values. Red line indicates the theoretical situation that TestBP follows CalibBP without tracking changes in BP levels, green line an ideal agreement of RefBP and TestBP. Conclusions: This is the first study to show the lower ability of the cuffless BP device to track changes of BP levels after an initial calibration measurement compared to a standard cuff-based device over 24h. Additionally, the difference between the RefBP and the TestBP was nearly linearly associated with the difference between a CalibBP and the changes of the BP level.