Changes in Cardiac Index Induced by Unilateral Passive Leg Raising: a Novel Way for Assessing Fluid Responsiveness

Abstract

\n Background: To evaluate the fluid responsiveness of patients, we examined the change in cardiac index (CI) during a unilateral passive leg raising (PLR) test using the ProAQT/Pulsioflex. In addition, we compared the change of CI triggered by bilateral PLR test and unilateral PLR test, and the ability to estimate volume responsiveness in patients.Methods: This was a prospective, observational study, and we enrolled 40 individuals thought of volume expansion. The data of cardiac index, stroke variation in volume, stroke volume index, along with variation in pulse pressure were obtained with ProAQT/Pulsioflex at a semi-recumbent position, during unilateral PLR, bilateral PLR, as well as after expansion of volume (500 ml saline over 15 min). If CI improved more than 15% to the expansion of volume, patients were defined as responders.Results: We excluded three patients. We found that a unilateral PLR-triggered CI increment ≥7.455% forecasted a fluid-triggered CI increment ≥15% with 77.27% sensitivity and 83.33% specificity. Meanwhile, bilateral PLR-triggered increases in CI ≥9.8% forecasted a fluid-triggered CI increment ≥15% with 95.45% sensitivity and 77.78% specificity. The area under the ROC curves constructed for unilateral and bilateral PLR-triggered changes in CI was not significantly different (p=0.1544).Conclusions: The change of CI induced by unilateral PLR may estimate volume responsiveness in patients.Trial registration: Unilateral passive leg raising test to assess patient volume responsiveness: Single-Center Observational Clinical Study, ChiCTR2100046762. Registered 28 May 2021, https://www.chictr.org.cn/edit.aspx?pid=127104&htm=4