Noninvasive tracking of systolic arterial blood pressure using pulse transit time measured with ECG and carotid doppler signals with intermittent calibrationNoninvasive tracking of systolic arterial blood pressure using pulse transit time measured with ECG and carotid doppler signals with intermittent calibrationAN00232251
We have developed a non-invasive blood pressure measurement system using pulse transit time (PTT) from the heart to the common carotid artery, measured by using an electrocardiogram (ECG) R-wave and carotid arterial Doppler signals at the anterior neck. In this study, we examined the validity of our system by comparing PTT derived systolic blood pressure (Dopp_SBP) with invasive radial systolic arterial pressure (Inv_SBP) with calibration every 15 min in the ICU setting.Methods: 17 patients under invasive mechanical ventilation in the ICU were studied. Carotid arterial flow via an 8-MHz Doppler flow probe, ECG, and radial arterial pressure signals were transferred to a personal computer at a rate of 1 kHz and processed to calculate Dopp_SBP from PTT using our own calibration formula.Results: We recorded 3,770 pairs of Inv_SBP and Dopp_SBP in 17 patients. Inv_SBP ranged from 213 to 82 mmHg, and Dopp_SBP from 185 to 71 mmHg. The Bland-Altman plot of the comparison between Inv_SBP and Dopp_SBP revealed limits of agreement of ?20.1 to 17.7 mmHg (mean difference, -1.2 mmHg). There was a statistically significant close linear correlation between Inv_SBP and Dopp_SBP (y = 0.9494x + 7.5171, R2 = 0.8471, p < 0.0001).Conclusions: The results of the present study show that our system using Doppler ultrasound flow and ECG signals, is feasible for systolic blood pressure tracking over a longer interval if it is combined with intermittent calibration. This work was supported by JSPS Kaken Grant Number 24592367.