A Study on Estimating the Blood Pressure by Using the Pulse Wave Transit Time in Shock Patients Who Received Vasopressor Drugs

Background: Blood pressure is clinically used for monitoring shock patients and as a therapeutic indicator for them. Non-invasive blood pressure measurement has weak points such as the use of a cuff and it is a discontinuous measurement. A method of measuring the blood pressure by using the PWTT (pulse wave transit time) has been studied to make up for those weak points. If blood pressure monitoring can be done by using the difference of the PWTT between different points in the body, then this method wil l be a quite useful to monitor the BP of seriously ill patients. This study aimed to verify whether or not the PWTT has a significant correlation with the blood pressure of shock patients who received vasopressor infusion and whether this method is clinically applicable. Methods: The study subjects were 20 shock patients who were hospitalized in intensive care units and they had received vasopressor, and we measured the PWTT and we analyzed its correlation with the SBP (systolic blood pressure) and DBP (diastolic blood pressure), as measured by non-invasive monitoring. We then determined the effects of the PWTT on the SBP and DBP. Results: From the results of correlation analysis between the PWTT and the SBP and DBP, the SBP displayed a statistically significant negative correlation with the PWTT of 18 patients, while no significant correlation between the PWTT and DBP was observed. At the same time, from the results of the regression analysis of the blood pressures and the PWTT of each patient, it was found that the PWTT had a negative effect on the SBP of all the patients, except two. Conclusions: The PWTT has a negative correlation with the SBP of the patien ts who received vasopressor infusion.