Effects of tilt on cerebral hemodynamics measured by NeoDoppler in healthy neonates

Anders Hagen Jarmund,Siri Ann Nyrnes,Hans Torp,Siv Steinsmo Ødegård

doi:10.1038/s41390-020-01354-w

Anders Hagen Jarmund, Siri Ann Nyrnes + Show 2 more

Open Access

https://doi.org/10.1038/s41390-020-01354-w

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Abstract

BackgroundToday, there are conflicting descriptions of how neonates respond to tilt. Examining physiologic responses of cerebral blood flow velocities (BFVs) in challenging situations like a tilt requires equipment that can cope with positional changes. We aimed to characterize how healthy term neonates respond to mild cerebral hemodynamic stress induced by a 90° tilt test using the recently developed NeoDoppler ultrasound system.MethodsA small ultrasound probe was fixated to the neonatal fontanel by a cap, and measured cerebral BFV in healthy neonates during and after a 90° head-up tilt test, five min in total, at their first and second day of life. Unsupervised k-means cluster analysis was used to characterize common responses.ResultsFifty-six ultrasound recordings from 36 healthy term neonates were analyzed. We identified five distinct, immediate responses that were related to specific outcomes in BFV, heart rate, and pulsatility index the next two min. Among 20 neonates with two recordings, 13 presented with different responses in the two tests.ConclusionsInstant changes in cerebral BFV were detected during the head-up tilt tests, and the cluster analysis identified five different hemodynamic responses. Continuous recordings revealed that the differences between groups persisted two min after tilt.ImpactNeoDoppler is a pulsed-wave Doppler ultrasound system with a probe fixated to the neonatal fontanel by a cap that can measure continuous cerebral blood flow velocity.Healthy neonates present with a range of normal immediate cerebral hemodynamic responses to a 90° head-up tilt, categorized in five groups by cluster analysis.This paper adds new knowledge about connection between immediate responses and prolonged responses to tilt.We demonstrate that the NeoDoppler ultrasound system can detect minute changes in cerebral blood flow velocity during a 90° head-up tilt.

Highlights

Neonates are subject to tremendous stress during birth, and the subsequent transition to extrauterine life involves extensive changes in hemodynamics.[1]
Two recordings were identified as outliers and excluded during cluster analysis as described below
In this study, the NeoDoppler ultrasound system was used to record instant and prolonged changes in blood flow velocities (BFVs) and related parameters to 90° tilt in healthy neonates born at term

Summary

Introduction

Neonates are subject to tremendous stress during birth, and the subsequent transition to extrauterine life involves extensive changes in hemodynamics.[1]. Examining physiologic responses of cerebral blood flow velocities (BFVs) in challenging situations like a tilt requires equipment that can cope with positional changes. We aimed to characterize how healthy term neonates respond to mild cerebral hemodynamic stress induced by a 90° tilt test using the recently developed NeoDoppler ultrasound system. METHODS: A small ultrasound probe was fixated to the neonatal fontanel by a cap, and measured cerebral BFV in healthy neonates during and after a 90° head-up tilt test, five min in total, at their first and second day of life. CONCLUSIONS: Instant changes in cerebral BFV were detected during the head-up tilt tests, and the cluster analysis identified five different hemodynamic responses. Continuous recordings revealed that the differences between groups persisted two min after tilt

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