Early sinusoidal heart rate patterns and heart rate variability to assess hypoxia-ischaemia in near-term fetal sheep.

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dc.contributor.author Kasai, Michi en
dc.contributor.author Lear, Christopher en
dc.contributor.author Davidson, Joanne en
dc.contributor.author Beacom, Michael J en
dc.contributor.author Drury, Paul en
dc.contributor.author Maeda, Yoshiki en
dc.contributor.author Miyagi, Etsuko en
dc.contributor.author Ikeda, Tomoaki en
dc.contributor.author Bennet, Laura en
dc.contributor.author Gunn, Alistair en
dc.date.accessioned 2020-02-11T22:48:01Z en
dc.date.issued 2019-12 en
dc.identifier.citation Journal of physiology 597(23):5535-5548 Dec 2019 en
dc.identifier.issn 0022-3751 en
dc.identifier.uri http://hdl.handle.net/2292/49913 en
dc.description.abstract KEY POINTS:•Therapeutic hypothermia needs to be started as early as possible in the first 6 h after acute injury caused by hypoxia-ischaemia (HI), but the severity and timing of HI are often unclear. In this study we evaluated whether measures of heart rate variability (HRV) might provide early biomarkers of HI. •The duration but not magnitude of suppression of HRV power and conversely increased sample entropy of the heart rate were associated with severity of HI, such that changes in the first 3 h did not discriminate between groups. •Relative changes in HRV power bands showed different patterns between groups and therefore may have the potential to evaluate the severity of HI. •Aberrant fetal heart rate patterns and increased arginine vasopressin levels in the first hour after moderate and severe HI were correlated with loss of EEG power after 3 days' recovery, suggesting potential utility as early biomarkers of outcome. ABSTRACT:Therapeutic hypothermia is partially neuroprotective after acute injury caused by hypoxia-ischaemia (HI), likely because the timing and severity of HI are often unclear, making timely recruitment for treatment challenging. We evaluated the utility of changes in heart rate variability (HRV) after HI as biomarkers of the timing and severity of acute HI. Chronically instrumented fetal sheep at 0.85 gestational age were exposed to different durations of umbilical cord occlusion to produce mild (n = 6), moderate (n = 8) or severe HI (n = 8) or to sham occlusion (n = 5). Heart rate (HR) and HRV indices were assessed until 72 h after HI. All HI groups showed suppressed very low frequency HRV power and elevated sample entropy for the first 3 h; more prolonged changes were associated with greater severity of HI. Analysis of relative changes in spectral power showed that the moderate and severe groups showed a shift towards higher HRV frequencies, which was most marked after severe HI. This shift was associated with abnormal rhythmic HR patterns including sinusoidal patterns in the first hour after HI, and with elevated plasma levels of arginine vasopressin, which were correlated with subsequent loss of EEG power by day 3. In conclusion, absolute changes in HRV power in the first 3 h after acute HI were not significantly related to the severity of HI. The intriguing relative shift in spectral power towards higher frequencies likely reflects greater autonomic dysfunction after severe HI. However, sinusoidal HR patterns and elevated vasopressin levels may have utility as biomarkers of severe HI. en
dc.format.medium Print-Electronic en
dc.language eng en
dc.relation.ispartofseries The Journal of physiology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights This is the peer reviewed version of the following article: Journal of physiology 597(23):5535-5548 Dec 2019, which has been published in final form at http://dx.doi.org/10.1113/jp278523. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri https://authorservices.wiley.com/author-resources/Journal-Authors/licensing-and-open-access/open-access/self-archiving.html en
dc.title Early sinusoidal heart rate patterns and heart rate variability to assess hypoxia-ischaemia in near-term fetal sheep. en
dc.type Journal Article en
dc.identifier.doi 10.1113/jp278523 en
pubs.issue 23 en
pubs.begin-page 5535 en
pubs.volume 597 en
dc.rights.holder Copyright: Wiley en
pubs.end-page 5548 en
pubs.publication-status Published en
dc.rights.accessrights http://purl.org/eprint/accessRights/RestrictedAccess en
pubs.subtype Research Support, Non-U.S. Gov't en
pubs.subtype Journal Article en
pubs.elements-id 783346 en
pubs.org-id Medical and Health Sciences en
pubs.org-id Medical Sciences en
pubs.org-id Physiology Division en
dc.identifier.eissn 1469-7793 en
pubs.record-created-at-source-date 2019-09-19 en
pubs.dimensions-id 31529698 en

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