Objective Recently, a cuffless blood pressure (BP) measurement device using pulse transit time (PTT) for beat-to-beat calculation of BP values has been validated over a short time period. However, it remains unknown how values obtained with this device compare with standard ambulatory measurements over a 24-hour period. We hypothesised that BP values measured by a cuffless PTT device (TestBP) are comparable with measurements by a standard upper arm cuff-based BP device (RefBP) in clinical practice over 24 hours.
Methods Between May and December 2017, 71 individuals were prospectively included. Cuffless using the Somnotouch-NIBP (Somnomedics GmbH, Randersacker, Germany) and cuff-based standard 24-hour BP measurements were performed simultaneously on the left and right arm, respectively. The first RefBP measurement was used as calibration measurement for the TestBP.
Results Mean (±SD) age was 49.3 (15.1) years, and 51% were male. Mean 24-hour BP for TestBP and RefBP were 140.8 (20.0) versus 134.0 (17.3) mm Hg for systolic (p<0.0001) and 85.8 (14.1)versus79.3 (11.7) mm Hg for diastolic (p<0.0001) measurements, respectively. Mean absolute systolic and diastolic disagreements between TestBP and RefBP were 10.2 (7.2) and 8.2 (5.5) mm Hg, respectively. The number (percentage) of absolute differences between the mean 24-hour BP values of the TestBP and RefBP within 5, 10 and 15 mm Hg were 23 (32.4), 43 (60.6) and 54 (74.6) for systolic and 24 (33.8), 51 (71.8) and 65 (91.6) for diastolic measurements, respectively.
Conclusion In clinical practice over 24 hours, there was a significant difference between the TestBP and RefBP with higher systolic and diastolic BP measured with the cuffless PTT device. Reasons for this difference need to be investigated.
Clinical trial registration NCT03054688; Results.
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Contributors Conception of the study: PK, ASV, AM, MM and TB. Data collection: PK, ASV, LK, AM and TB. Data analysis and interpretation: PK, ASV and TB. Drafting the article: PK, ASV and TB. Critical revision of the article: LK, AM and MM.
Funding The study was fully funded by the Medical Outpatient and Hypertension Clinic, ESH Hypertension Centre of Excellence, University Hospital Basel, Basel, Switzerland.
Competing interests None declared.
Patient consent Not required.
Ethics approval The study protocol complies with the Declaration of Helsinki, was approved by the local ethics committee (Ethikkommission Nordwest- und Zentralschweiz 2017–00323) and registered (NCT03054688) and externally monitored.
Provenance and peer review Not commissioned; externally peer reviewed.