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Exploring the Effect of Movement on the SureBP® Algorithm in a Connex® Spot Monitor


Acquiring an accurate blood pressure reading can be challenging for clinicians that work with certain patient populations. For pediatric and geriatric patients, along with those in pain or discomfort, sitting still in the recommended position may not always be feasible. And while testing standards are being developed for transport-induced motion artifacts in blood pressure readings,1 no studies have focused on how to confidently measure blood pressure in these patients.

Research Objectives

Researchers developed a study to assess the accuracy of an automated vital signs device—the Welch Allyn Connex Spot Monitor—when it encountered patient-simulated movement that can be common in a clinic or hospital setting. To calculate blood pressure readings, the Connex Spot Monitor utilizes a unique, inflation-based SureBP algorithm.2, 3 Researchers were interested in determining if the Connex Spot Monitor with the SureBP algorithm could still provide precise, consistent and reliable blood pressure readings under those conditions. 

Study Parameters: Over the period of two months, 40 participants volunteered to take part in the study. Researchers collected data for readings taken while the patient moved and compared that to measurements taken in stillness. Readings taken with patient-induced motion required study participants to simulate serial pronation and supination of the left arm every five seconds throughout the reading.4 For comparison, manual auscultatory measurements were taken without patient movements before and after the readings where movement was present.


Bruce S. Alpert, David Quinn, Matthew Kinsley, Tyson Whitaker and Thomas T. John.

Key Research Goals

Voluntary and involuntary patient-induced movement can impact the acquisition and accuracy of blood pressure readings. Therefore, researchers designed and implemented a study to determine if the Welch Allyn SureBP algorithm in the Connex Spot Monitor could reliably complete successful and accurate blood pressure readings under these challenging conditions.


Can’t Stop the Beat: 93% Success Rate in Obtaining a Reading on the First Attempt

The Welch Allyn Connex Spot Monitor with the SureBP algorithm generated a blood pressure value for 93% of patients (37 volunteers) on the first measurement attempt.5 When a second attempt was performed, the device recorded a value in 100% of patients (the remaining three volunteers).6 The automated Welch Allyn device required little to no repeat readings. Beyond reducing the frequency of repeat measurements, this level of successful first-time readings can also help improve the overall patient experience. With fewer measurements to retake, clinicians can instead focus their time on important patient interactions.

93% Single Read Success Rate

Performance Under Pressure: Accuracy in Relation to Movement 

In addition to determining the percentage of successful blood pressure readings, researchers also analyzed the accuracy of readings acquired by the automated Welch Allyn device. During this study, the Connex Spot Monitor demonstrated consistency with movement, producing 85-87.5% of readings in a range of +/- 10 mmHg as compared to the manual device for the systolic and diastolic.7,9


Percentage of Readings Falling within ±10 mmHg of Manual Control Readings7, 9
Connex Spot Monitor Percentage of Readings Falling within ±10 mmHg of Manual Control Readings
Connex Spot Monitor Performance in the Presence of Motion7, 9

Difference of Test Reading to Control Reading

Connex Spot Monitor Performance in the Presence of Motion Whisker Chart


An automatic vital signs device, one that can consistently provide accurate readings on various patient populations, has beneficial implications for movement-prone patients. Any motion during measurement can cause repeat readings and data inaccuracies, which consume precious clinician time and may affect clinical decision-making. Therefore, standardizing your practice with an automated vital signs device—specifically one shown to withstand the challenges of patient movement—can help provide efficiencies and improve the quality of patient data. The automated Welch Allyn Connex Spot Monitor with SureBP technology meets these criteria, having performed favorably on difficult-to-measure patients, providing a high rate of first-time readings with strong clinical accuracy.

Regardless of a patient’s ability to remain still, clinicians need to feel confident in the data they collect and the tools they use. That is why a robust, motion-tolerant vital signs solution is an important tool across care settings. Just because your patients move, that does not mean they cannot be measured.


1, 5-6. Alpert, Bruce S., David Quinn, Matthew Kinsley, Tyson Whitaker, and Thomas T. John. “Accurate Blood Pressure during Patient Arm Movement.” Blood Pressure Monitoring 24, no. 1 (February 2019): 42-44.

2. Alpert BS. Validation of the Welch Allyn Pro BP 2000, a professional-grade inflation-based automated sphygmomanometer with arrhythmia detection in a combined pediatric and adult population by ANSI/AAMI/ISO standard testing. Blood Press Monit. 2018 Dec;23(6):315-317. doi: 10.1097/MBP.0000000000000350. PubMed PMID: 30312180; PubMed Central PMCID: PMC6250254

3. Alpert BS. Validation of the Welch Allyn SureBP (inflation) and StepBP (deflation) algorithms by AAMI standard testing and BHS data analysis. Blood Press Monit. 2011 Apr;16(2):96-8. doi: 10.1097/MBP.0b013e328345232f. PubMed PMID: 21412074.

4. Methodology: The arm movements selected for the motion-induced measurement criteria consisted of patients simulating serial pronation/supination of the left forearm. These motions were chosen because researchers found that they caused pressure disturbances with similar characteristics to those found in clinics. Therefore, these repeatable motions were determined to accurately represent movements that would affect blood pressure readings. 

7, 9. “Precision, Consistency and Reliability in Blood Pressure Readings.” Case study. Welch Allyn, 2018. 1-5.

8. The readings from the automatic Welch Allyn device fell within ±10 mmHg of the control reading in instances where motion was and was not present.