Staggered passive leg raising test for predicting several degrees of fluid responsiveness in mechanical ventilated patients: an observational study

Abstract

Introduction: Fluid therapy is one of the cornerstones of resuscitation, although only 50% of critically ill patients are fluid responders. In recent years, the most traditionally used techniques to understand patient’s fluid status, such as central venous pressure (CVP) or mean arterial pressure (MAP), have shown to be unreliable in predicting fluid responsiveness. Consequently, new techniques have been developed as improved predictors, such as, stroke volume variation (SVV) or continuous cardiac output (CO) monitoring systems. FloTrac/Vigileo system calculates continuous CO and SVV by analyzing the arterial pulse waveform though semi-invasive arterial catheterization. Passive leg raising (PLR) test is an alternative preload-modifying maneuver: when inferior limbs are raised an amount of blood is autotransfused to the central circulation. PLR has been included in several guidelines in critically ill patient’s resuscitation. Combined with a SVV and CO monitoring system, PLR may help predict fluid responsiveness in critically ill patients. However, none of these techniques have been proved to predict several degrees of fluid responsiveness, which could lead to a better and more individualized fluid therapy, where patients would receive the amount of fluid that their heart can manage. Objectives: The aim of this study is to evaluate if Staggered Passive Leg Raising (SPLR) test can trigger significant changes on SVV, CO and MAP assessed by Vigileo/FloTrac device in mechanical ventilated patients in order to establish several degrees of fluid responsiveness. Design: This is an observational, cross-sectional study performed in The department of Anesthesiology in a third level teaching facility, Hospital Universitari Josep Trueta. The study will be performed in 2017. Participants and methods: Patients (n=32) attending the operating room between April and May 2017 for a major surgery who will need monitoring with Vigileo/FloTrac device, CVP and mechanical ventilation. Measurements of SVV, CO and MAP will be obtained with Vigileo/FloTrac in baseline status, during SPLR test and after a fluid bolus. ANOVA analysis for repeated measures will be used for analyzing mean SVV, CO and MAP