Comparison of central pressure estimates obtained from SphygmoCor, Omron HEM-9000AI and carotid applanation tonometry
Related Experiment Video
Updated: Jun 2, 2026
Measuring the Carotid to Femoral Pulse Wave Velocity (Cf-PWV) to Evaluate Arterial Stiffness
Published on: May 3, 2018
Jan G Kips1, Aletta E Schutte, Sebastian J Vermeersch
1Heymans Institute of Pharmacology, Belgium. Jan.Kips@UGent.be
Insights
The Omron HEM-9000AI overestimates central systolic blood pressure (cSBP) compared to SphygmoCor, with algorithm differences explaining the discrepancy. The Omron device shows a larger overestimation than SphygmoCor
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Medical Devices
Background:
- The Omron HEM-9000AI is the first automated tonometer estimating central systolic blood pressure (cSBP), a key cardiovascular risk predictor.
- Previous studies noted significant differences between Omron and SphygmoCor cSBP estimates without clear explanations.
Purpose of the Study:
- To investigate the sources of discrepancy between Omron HEM-9000AI and SphygmoCor cSBP estimates.
- To determine which device's cSBP estimate is more accurate.
Main Methods:
- Aortic cSBP, derived from calibrated carotid SBP, served as the reference standard.
- Applanation tonometry of radial, brachial, and carotid arteries was performed on 143 South African adults.
- Measurements were taken using both the Omron HEM-9000AI and SphygmoCor devices.
Main Results:
- Both devices showed strong correlation (r=0.99) in cSBP estimates.
- Omron's cSBP estimate was significantly higher (18.8 mmHg) than SphygmoCor's.
- Aortic SBP fell between the two estimates, indicating overestimation by Omron and underestimation by SphygmoCor.
Conclusions:
- Algorithm differences are the primary cause of the cSBP estimation discrepancies between Omron and SphygmoCor.
- The Omron HEM-9000AI demonstrates a larger overestimation of cSBP compared to the underestimation by SphygmoCor.
Background:
The Omron HEM-9000AI is the first automated tonometer to provide an estimate of central SBP (cSBP), which is considered to be more predictive of cardiovascular events than brachial pressure. However, considerable differences between the cSBP estimate of Omron and that of SphygmoCor have been reported, but not explained. This study assesses the sources of differences between both cSBP estimates and provides a handle on which estimate is closest to reality.
Method:
For this purpose, aortic cSBP derived from calibrated carotid SBP was used as device- and algorithm-independent reference. Radial, brachial and carotid applanation tonometry were performed in 143 black South Africans, aged 39-91 years. Each individual was measured with an Omron HEM-9000AI and a SphygmoCor.
Results:
When using both devices as advocated by their manufacturers, the corresponding cSBP estimates correlated strongly (r = 0.99, P < 0.001), but the Omron estimate was 18.8 (4.3) mmHg higher than the SphygmoCor estimate. Aortic SBP was in between both estimates: 11.7 (5.5) mmHg lower than cSBP-Omron and 7.1 (5.0) mmHg higher than cSBP-SphygmoCor. Alternative calibration of the radial SphygmoCor-curves with radial instead of brachial pressures yielded a cSBP that was 3.0 (4.2) mmHg lower than aortic SBP. The shape of the recorded pressure waves was similar in both devices: less than 5% of the observed cSBP difference was caused by differences in wave shape.
Conclusion:
The results from this study demonstrate that the considerable difference between the central pressure estimates of Omron HEM-9000AI and SphygmoCor is due to algorithm differences, and suggest that the overestimation by Omron HEM-9000AI is larger than the underestimation by SphygmoCor.
Related Concept Videos
01:21Sites for measuring blood pressure
The Brachial Artery: Primary Site for Blood Pressure Measurement
01:23Assessment of blood pressure in brachial artery(two-step method)
01:28Special considerations while measuring blood pressure
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
01:30Equipments Used To Measure Blood Pressure
This invasive approach involves cannulating a peripheral artery. During each cardiac contraction, pressure generates mechanical motion within the catheter, transmitted through rigid, fluid-filled tubing to a transducer. This transducer converts mechanical motion into electrical signals displayed as waveforms on a monitor. An automatic flushing system prevents blood backflow. Due to the potential risk of unexpected arterial blood loss, this method is primarily used in intensive...
01:17Measurement of Blood Pressure
01:15Assessment of blood pressure in brachial artery(one-step method)
Prepare for the Procedure: