A Novel Prediction Of Simulated Fluid Responsiveness By Echocardiography Assessment Of Tricuspid Annulus Tissue Velocity With Passive Leg Raising

Background: Fluid responsiveness can be predicted by the effect of passive leg raising on cardiac output. Objectives: This research aimed to compare the changes in cardiac output and the peak systolic velocity values of Tricuspid annulus velocity at the free wall (S') before and after passive leg raising in healthy volunteers. Methods: The study was approved by ethical commission. The desired sample size was 28, and 57 volunteers were included after they signed informed consent. The first measurements, including vital signs, S', and cardiac output, were taken with the participants lying supine and were performed in the morning after 12 h fast. The participants were then asked to lie in a semirecumbent position for 3 min. After 3 min, the head of the bed was lowered to the supine position and the participants' legs were elevated at 45 degrees. Secondary measurements were repeated in this position. The differences between vital signs, cardiac output, and S' measurements before and after passive leg raising were statistically compared. The level of significance was set as p < 0.05. Results: The mean values of cardiac output and S' before passive leg raising was 9.59 L/min and 11.57 cm/s, respectively; however, those increased to 11.44 L/min and 13.72 cm/s after passive leg raising. The average increases were 16.17% for cardiac output and 15.67% for S'. The changes of cardiac output and S' were statistically significant. The changes of vital signs before and after passive leg raising were statistically insignificant. Conclusion: This study has demonstrated the concordance of rise in cardiac output with S' change by passive leg raising in healthy subjects. Further studies are needed to validate the use of S' values in critically ill subjects.