Ability of Passive Leg Raising Test in Predicting Positive Fluid Response in Paediatric Patients with Shock: A Prospective Observational Study

Introduction: Shock is an acute syndrome in which the circulatory system is unable to provide adequate oxygen and nutrients to meet the metabolic demands of vital organs. Fluid replacement is often necessary to optimise the cardiovascular function by maintaining adequate cardiac preload and output. It’s a reversible manoeuvre that simulates a rapid fluid bolus by shifting blood from the lower extremities and abdominal compartment into the central circulation. Aim: To evaluate the Passive Leg Raising (PLR) test as a simple bedside tool to assess volume responsiveness in children with shock aged less than eight years. Materials and Methods: The present prospective observational study was conducted in Paediatric Ward and Paediatric Intensive Care Unit of a tertiary level teaching hospital between November 2020 to October 2022. Total 42 children between one month to eight years of age diagnosed with shock were included in the study. Bedside echocardiography was done to calculate stroke volume combining Velocity Time Integral (VTI) at aortic root with the Cross-sectional Area (CSA) of the aortic root. VTI was measured at baseline, after PLR and after giving a fluid bolus of 10 mL/kg of crystalloid fluid. Change in VTI was compared between PLR and fluid bolus interventions. Cut-off for positive test was kept as ≥12% increase in VTI from baseline for both PLR and fluid bolus. Results: Mean age of study population was 55 months (SD50), out of which 27 (64.3%) were below four years of age. A total of 29 (69%) of patients were male. Overall sensitivity of passive leg raise test was 76.7%, specificity of 85.7% when cut-off value was taken as >12% for change in VTI post-PLR. Negative predictive value of PLR was 37.5% and positive predictive value of 97.1%. The Area Under the Receiver Operating Characteristic (AUROC) curve was 0.855 with significance of 0.021. Conclusion: The study found that the PLR test is a reasonably accurate tool for predicting fluid responsiveness in children younger than eight-year-old. When an increase in cardiac index of more than 12% is used as the indicator of a positive test, the PLR manoeuvre correctly identifies about 77% of fluidresponsive children and correctly identifies about 86% of children who are not fluid responsive.