Accurate blood pressure during patient arm movement: the Welch Allyn Connex Spot Monitor's SureBP algorithm

Background Current blood pressure (BP) measurement guidelines specify patient requirements, including being still. Some populations of patients cannot comply. A new International Organization for Standards is being developed to test devices that claim tolerance to transport-induced motion artifacts. This study proposes the first protocol to assess BP device accuracy in the presence of patient-induced motion. Participants and methods Forty healthy volunteers (23 males) participated. The device tested was the Welch Allyn Connex Spot Monitor (CSM) using the SureBP algorithm. A reusable cuff was placed on the left arm. During inflation/deflation cycles the participant performed pronation/supination movements of the left forearm every 5 s. The CSM readings during motion were compared to the average of manual resting auscultatory estimations immediately before and after each motion cycle (bracketing). Results The CSM recorded a BP reading on the first cycle in 37 participants. It displayed a reading in all 40 participants with one repeat cycle in the other three. The mean +/- SD for the device minus the manual BP values was 0.9 +/- 7.3 mmHg for systolic BP and -3.4 +/- 7.9 mmHg for diastolic BP. Conclusion This study represents a proposal for an automated BP device assessment in the presence of patient-induced motion. The CSM device, which uses an inflation-based algorithm, routinely produced BP values that closely matched auscultatory values bracketed immediately before and after the motion-associated cycle. The CSM should be of significant clinical value in populations in whom resting 'still' readings are not usually feasible, such as pediatric and geriatric patients, and patients in pain from injury or illness.