Assessing fluid responsiveness with ultrasound in the neonatal intensive care setting: the mini-fluid challenge

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. What is Known: • Fluid overload is associated with morbidity and mortality. • The mini-fluid challenge (MFC) provides a personalised approach to fluid therapy. What is New: • The MFC is feasible in newborns. • The MFC followed the physiological principles of stroke volume and extravascular lung water changes.

Keywords: Fluid challenge; Newborn; Sepsis; Ultrasound.

Fig. 1

Example of a mini-fluid challenge (MFC) in a preterm infant. The apical long axis was used to visualise the aorta outflow tract. Pulse wave Doppler with minimal angle of insonation was added to capture stroke volume and determine the maximum velocity from 10 to 15 cardiac cycles at low sweep speed

Fig. 2

Average maximum doppler velocity in the aorta outflow tract before and after the mini-fluid challenge. Solid lines indicate a rise > 15% and thus fluid responsiveness