Plethysmographic Variability Index as a Non-Invasive Predictor of Fluid Responsiveness in Ventilated Patients

Abstract

Introduction: The pleth variability index (PVi) is a non-invasive method derived from the plethysmographic signal obtained via pulse oximetry, measuring respiratory variations in pulse wave amplitude. Objective: To evaluate the utility of non-invasive predictors of fluid responsiveness to optimize fluid therapy in critically ill ventilated patients. Methodology: Qualitative evidence review study in Web of Science from 2020 to 2025. Fifteen articles were analyzed after applying three exclusion criteria. Results: In mechanically ventilated critically ill patients, fluid overload is significantly associated with increased mortality, reaching a relative risk of 19% (RR = 1.19) higher probability of death per additional liter of positive fluid balance. PVi is a dynamic, non-invasive parameter that allows identification of fluid responders, facilitating a more targeted resuscitation strategy with lower risk of complications. Discussion: Fluid overload in ventilated patients is linked to higher mortality and organ failure, especially in sepsis, ARDS, and AKI. Limitations of static parameters have prompted the use of dynamic predictors like PVi, which allows real-time, non-invasive assessment of fluid responsiveness. Conclusion: Fluid therapy in critically ill ventilated patients is essential, but excess fluids increase mortality, AKI, and prolonged ventilation. PVi provides dynamic, non-invasive monitoring to optimize fluid administration and improve outcomes. Further studies are needed to validate its clinical effectiveness.