Change in cardiac index during Trendelenburg maneuver as a predictor of fluid responsiveness among patients under mechanical ventilation with spontaneous breathing activity: A protocol for prospective observational study

Background: Optimal fluid management in surgical intensive care units (SICUs) is challenging, with under or over-resuscitations linked to increased mortality and extended ICU stays. Dynamic parameters like stroke volume variation and pulse pressure variation are unreliable in intubated patients with spontaneous breathing activity. The passive leg raise (PLR), which relies on translocation of the patient’s intravascular volume, is effective in identifying fluid responsiveness, but it still has some limitations. Regarding limitations, another potential method, using the same principle, known as the Trendelenburg maneuver (TM), has been introduced. This study aims to assess the diagnostic performance of TM in mechanically ventilated patients with spontaneous breathing activity, focusing on changes in cardiac index in relation to fluid administration. Methods: In this single-center, prospective observational study conducted in a surgical ICU, we enrolled 68 patients with inadequate tissue perfusion who had spontaneous breathing while receiving mechanical ventilation to evaluate the diagnostic ability of TM in fluid responsiveness prediction. The patients were classified as fluid responders when the change in cardiac index, measured by the FloTrac™ sensor with the HemoSphere™ advanced monitoring platform, increased by more than 10% after fluid administration. Hypothesis: We hypothesize that TM has the ability to predict fluid responsiveness in mechanically ventilated patients with spontaneous breathing activity. Ethics and dissemination: This trial received approval from the Siriraj Institutional Review Board. We plan to present the result in peer-reviewed publications in critical care medicine. Trial registration: TCTR20230704005