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Updated: May 21, 2026
A Methodological Approach to Non-invasive Assessments of Vascular Function and Morphology
Published on: February 7, 2015
Determination of central blood pressure by a noninvasive method (brachial BP and QKD interval)
Antoine Cremer1, Mark Butlin, Léopold Codjo
1Cardiology/Arterial Hypertension Unit, Hôpital Saint André, University Hospital, Bordeaux, France. antoine.cremer@voila.fr
Insights
A new method estimates central systolic blood pressure (SBPc) noninvasively using brachial blood pressure (BPb) and the QKD interval. This arterial stiffness marker allows for potential ambulatory monitoring of BPc.
Area of Science:
- Cardiovascular Research
- Biomedical Engineering
- Hypertension Management
Background:
- Central blood pressure (BPc) measurement is crucial for understanding cardiovascular risk.
- Therapeutic trials show varied effects of antihypertensives on cardiovascular outcomes despite similar brachial BP (BPb) changes.
- Differences in BPc response to treatment may explain varying clinical outcomes.
Purpose of the Study:
- To develop and validate a noninvasive method for automatic measurement of central systolic blood pressure (SBPc).
- To utilize the QKD interval, an indicator of arterial stiffness, for BPc estimation.
- To establish a reliable algorithm for estimating SBPc from noninvasive measurements.
Main Methods:
- Simultaneous invasive measurement of SBPc (pigtail probe) and noninvasive BPb with QKD interval recording.
- Development of an SBPc estimation algorithm using a cohort of 65 patients (136 measurements).
- Validation of the developed algorithm in a separate cohort of 80 patients.
Main Results:
- A regression equation was derived: SBPc = 105 + 1.29 × mBPb - 0.39 × HR - 0.30 × height - 0.11 × QKD.
- The algorithm explained 81% of the variance in invasive SBPc (± 13 mmHg) in the development cohort.
- The validated algorithm showed a small difference of 2 ± 14 mmHg between measured and estimated SBPc in the validation cohort.
Conclusions:
- It is feasible to estimate central systolic blood pressure (SBPc) noninvasively by measuring brachial blood pressure (BPb) and the QKD interval.
- The developed algorithm demonstrates good accuracy in estimating SBPc.
- Further research may lead to a noninvasive ambulatory method for monitoring SBPc in clinical practice.
Background:
The measurement of central blood pressure (BPc) has become a matter of importance. Several therapeutic trials have noted a different protective effect against cardiovascular complications with different antihypertensive strategies, but an identical decrease in brachial BP (BPb). A possible explanation lies in the different effects of the treatments on BPc. We propose a new noninvasive method for the automatic measurement of BPc based on the QKD interval, an arterial stiffness marker.
Materials And Methods:
This study was carried out on patients referred for cardiac catheterization. We simultaneously measured the central SBP (SBPc) invasively with a pigtail probe, and the BPb by a cuff coupled with recording of the QKD interval. Two cohorts were studied, one to define an algorithm of SBPc estimation and one to validate this algorithm.
Results:
The first cohort included 65 patients. We performed 136 simultaneous measurements. In the multivariate analysis, four variables were significantly correlated with SBPc: mean BPb (mBPb), QKD, height and heart rate (HR) with the following regression equation: SBP = 105 + 1.29 × mBPb - 0.39 × HR - 0.30 × height - 0.11 × QKD. This equation estimated 81% of the variance of the invasive SBPc ± 13 mmHg. This algorithm was then tested in another cohort of 80 patients. Difference between measured and estimated SBPc was 2 ± 14 mmHg.
Conclusion:
This study showed that it is possible to estimate SBPc by simultaneous measurement of QKD and BPb. If further studies confirm these results, a noninvasive ambulatory method of monitoring of SBPc could be employed in clinical practice.
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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...
01:21Sites for measuring blood pressure
The Brachial Artery: Primary Site for Blood Pressure Measurement
01:15Assessment of blood pressure in brachial artery(one-step method)
Prepare for the Procedure:
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.
01:17Measurement of Blood Pressure