Continuous blood pressure measurement by using the pulse transit time: comparison to a cuff-based method

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology

Background:

• Pulse transit time (PTT) and pulse wave velocity (PWV) are established indirect measures correlated with systolic blood pressure (SBP).
• Non-invasive blood pressure monitoring remains a significant challenge in clinical practice.

Purpose of the Study:

• To develop and validate a non-linear function for determining absolute SBP from PWV using a single-point calibration.
• To assess the reliability of PTT-based SBP measurement against traditional cuff-based methods.

Main Methods:

• A non-linear algorithm was developed using PWV data from 13 volunteers to establish a SBP-PWV relationship.
• The derived function was applied to 50 volunteers, with individual offset correction, to calculate SBP.
• PTT was measured via ECG R-spike to finger plethysmography; reference SBP was obtained using a sphygmomanometric aneroid device.

Main Results:

• A significant correlation (r = 0.83) was observed between cuff-measured SBP and PTT-derived SBP across 276 measurements in 50 volunteers.
• Individual correlation coefficients ranged from r = 0.69 to r = 0.99.
• Bland-Altman analysis revealed limits of agreement of ±19.8 mmHg, indicating notable differences between methods.

Conclusions:

• PTT-based SBP measurement shows significant correlation with cuff-based SBP.
• Relevant differences exist between PTT and cuff methods, partly due to measurement variability during exercise.
• Absolute SBP can be measured using PTT with individual offset correction for the BP-PWV relationship.