Fluid Assessment Scoring Tool (FAST): Development of a Novel Fluid Assessment Scoring Tool for Critically Ill Pediatric Patients—A Pilot Study

TL;DR

Researchers developed a new scoring tool called FAST to assess fluid overload in critically ill children, using clinical signs and lab values.

Contribution

The novel FAST scoring tool combines multiple clinical parameters to assess fluid status in pediatric ICU patients.

Findings

A FAST score of ≥3 showed 92% sensitivity and 68% specificity for detecting fluid overload.

Cross-validation confirmed FAST≥3 and FAST≥4 had similar performance with AUCs of 0.79 and 0.78, respectively.

FAST scores did not significantly correlate with PICU or hospital length of stay.

Abstract

Introduction

Monitoring fluid balance (FB) is important yet challenging in the pediatric intensive care unit (PICU). Currently used, conventional methods of fluid assessment are either not feasible or unreliable. Also, there is a lack of composite scores or clinical algorithms that use different parameters of fluid status. We aim to develop a fluid assessment scoring tool (FAST) to clinically assess the fluid status of children in the PICU.

Methods

In this pilot study, we included critically ill patients aged 0-21 years who presented to our PICU between December 2020 and March 2021 and required invasive or non-invasive mechanical ventilation, inotropes, diuretics, and renal replacement therapy. In our study, 32 patients contributed 118 encounters. We assigned scores 0-3 each for fontanelles, eyes, liver exam, daily weight changes, FB, urine output, blood urea nitrogen, creatinine, and chest X-ray findings. We also assigned a score of 0-3 for thoracic fluid content (TFC) as measured by the non-invasive ICON® monitor (Osypka Medical GmbH, Berlin, Germany). First, a non-parametric receiver operating curve (ROC) analysis was used to determine potential cut points for the FAST using the TFC as a “gold standard.” Cut points were selected based on a balanced sensitivity vs. specificity. Next, a 10-fold cross-validation area under the curve (AUC) for ROC analysis was performed to estimate the best-performing cut-point.

Results

The median (interquartile range, IQR) age was 78.7 (9.75-84) months, and 62.5% of patients were males. The median (IQR) FAST score was 4 (2-6). The median (IQR) TFC was 44.5 (29-57.25). Of the 118 encounters, 78 (66%) exhibited high TFC. The two potential FAST scores predicting a higher TFC that indicates fluid overload (FO) were ≥3 (sensitivity=92%; specificity=68%) and ≥4 (sensitivity=80%; specificity=80%). On cross-validation, FAST≥3 (AUC=0.79) and FAST≥4 (AUC=0.78) showed similar performance. When using our FAST cut points to evaluate outcomes, we do not observe significant differences in the median ventilator days, PICU days, or hospital stay days.

Conclusion

The FAST offers a practical approach to evaluating FO in critically ill pediatric patients. A FAST score ≥3 was associated with TFC-defined FO, suggesting clinical utility. Future multicenter studies are needed to validate its use and explore its impact on patient outcomes.

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