Point-of-care ultrasonography to predict fluid responsiveness in children
A systematic review and meta-analysis
March 2023 by Dr Justin Skowno
All anaesthetists have given many fluid boluses, mostly to try and help their patients. Unfortunately, knowing whether that bolus actually achieved the goal you had hoped for is rather harder than it seems. This study assesses the current literature and focuses on POCUS to determine fluid responsiveness. It is a technically thorough paper, following current guidelines (PRISMA-DTA), and finds 25 papers on the topic with assessable, relevant data. They find that POCUS, specifically delta-Aortic Velocity peak and somewhat less so delta-IVC diameter, are valuable in diagnosing fluid responsiveness BUT they are operator dependent in terms of skills required to get the measurements and have high heterogeneity.
Fluid responsiveness is such a core diagnostic concept in paediatric anaesthesia and critical care that we almost forget that, despite not having a nice gold standard device to help us, we are actively assessing this in our patients most of the time. We use our clinical skills and mental models influenced by Guyton, and supplement these with whichever devices we have at hand and are familiar with.
This field has steadily developed over the past 25-30yrs, and broadly follows findings in the adult world. However, the physiological variations present within our paediatric space are substantially larger than encountered in adults. The studies presented here investigate patients post cardiac surgery, neonates, adolescents, etc. with a very wide range of physiologies. As a result, it is harder to demonstrate consistent benefit or lack of benefit for a diagnostic test in this area in any one study. Dynamic indicators of fluid responsiveness in highly controlled situations (animal models with flow probes) are exceptionally accurate at picking it up – our challenge is the heterogeneity of practice noted.
This paper adds to the field and is a good read for those interested in the detail. It is specifically useful for anyone interested in cardiovascular physiology and POCUS.