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Existing fluid responsiveness studies using the mini-fluid challenge may be misleading: Methodological considerations
Johannes Enevoldsen1,2, Thomas W L Scheeren3, Jonas M Berg1,2
1Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
Acta Anaesthesiologica Scandinavica
|August 2, 2021
Summary
The mini-fluid challenge (MFC) may overestimate fluid responsiveness prediction. Current methods show poor accuracy for predicting response to the later fluid bolus, suggesting caution before clinical adoption.
Area of Science:
- Critical care medicine
- Hemodynamics
- Fluid responsiveness assessment
Background:
- The mini-fluid challenge (MFC) involves a small fluid infusion (100 ml) to predict response to a larger challenge (400 ml).
- Assessing hemodynamic effects of the MFC aims to guide subsequent fluid administration for improved stroke volume.
Purpose of the Study:
- To critically evaluate the methodology and statistical considerations of mini-fluid challenge (MFC) studies.
- To assess the predictive accuracy of the MFC for fluid responsiveness.
Main Methods:
- Secondary analysis of an existing study.
- Statistical simulations to evaluate MFC performance under various scenarios.
- Critical appraisal of MFC study designs.
Main Results:
- The MFC accurately predicted the total fluid response (MFC + 400 ml) with an AUROC of 0.92.
- However, MFC prediction for the response to the remaining 400 ml was worse than random (AUROC = 0.33).
- Simulations indicated that common analysis methods could yield an AUROC of 0.73 even without a true fluid response.
Conclusions:
- Existing mini-fluid challenge studies likely overestimate classification accuracy.
- Caution is advised before widespread clinical adoption of the MFC.
- Improved study designs require independent stroke volume measurement post-MFC to validate subsequent fluid response prediction.
