Abstract
The mini-fluid challenge (MFC) can guide individualised fluid therapy and prevent fluid overload and associated morbidity in adult intensive care patients. This ultrasound test is based on the Frank-Starling principles to assess dynamic fluid responsiveness, but limited MFC data exists for newborns. This brief report describes the feasibility of the MFC in 12 preterm infants with late onset sepsis and 5 newborns with other pathophysiology. Apical views were used to determine the changes in left ventricular stroke volume before and after a 3 ml/kg fluid bolus was given over 5 min. Four out of the 17 infants were fluid responsive, defined as a post-bolus increase in stroke volume of 15% or more.
Conclusion: The MFC was feasible and followed the physiological principles of stroke volume and extravascular lung water changes and 24% were fluid responsive. The MFC could enable future studies to examine whether adding fluid responsiveness to guide fluid therapy in newborns can reduce the risk of fluid overload.
Key Points
- Purpose of MFC: Designed to test fluid responsiveness in neonates, MFC evaluates changes in left ventricular stroke volume following a small fluid bolus (3 mL/kg over 5 minutes).
- Population: Included 12 preterm neonates with late-onset sepsis and 5 neonates with other conditions, demonstrating the method’s broad applicability.
- Findings on Fluid Responsiveness: 23% of neonates (4 out of 17) were fluid responders, defined by a stroke volume increase ≥15%.
- Pathophysiological Insights: In neonates with sepsis, MFC followed the principles of the Frank-Starling curve, linking preload to stroke volume changes.
- Respiratory Outcomes: Non-responders showed higher increases in oxygenation index post-MFC, suggesting an association between fluid overload and respiratory compromise.
- Ultrasound Use: Focused point-of-care ultrasound proved effective for monitoring stroke volume, although maintaining consistent insonation angles was critical for accuracy.
- Safety Considerations: Rapid fluid bolus administration (3 mL/kg) appears safe, but further study is required for very preterm infants with compromised cerebral autoregulation.
- Training Requirements: MFC implementation requires minimal but focused training for neonatal clinicians in point-of-care ultrasound.
- Comparison to Adults and Children: MFC methods adapted from adult and pediatric critical care may need modification due to neonatal physiological differences, such as higher cardiac output and vessel compliance.
- Future Directions: Larger, multicenter trials are necessary to validate findings and assess whether MFC-guided fluid therapy reduces neonatal fluid overload and improves clinical outcomes.
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