Cerebral blood flow velocity variability in very low birthweight infants

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dc.contributor.author Coughtrey, Heather en
dc.date.accessioned 2009-11-19T03:36:20Z en
dc.date.available 2009-11-19T03:36:20Z en
dc.date.issued 2002 en
dc.identifier.citation Thesis (MD)-- University of Auckland, 2002. en
dc.identifier.uri http://hdl.handle.net/2292/5502 en
dc.description.abstract Short-term variability in cerebral blood flow velocity (CBFV) in the VLBW infant largely relates to respiratory influence. Extreme variability may be a poor prognostic indicator. Few have studied cohorts of babies in this regard. I sequentially studied a consecutive cohort of unselected VLBW infants, to determine the frequency of respiratory influence on CBFVV and to identify factors associated with its occurrence. Doppler CBFV, arterial BP and respiratory signals were recorded simultaneously and spectral analysis was applied to identify a respiratory signal in BP and CBFV traces. Respiratory associated variability was present in the cerebral circulation at some time in more than half of the infants studied and was most likely in those of lowest gestational age who were hypotensive. Mortality, and cerebral morbidity as assessed by cerebral ultrasound were more common in those demonstrating a respiratory influence in CBFV. There was a strong correlation between the coefficient of variation(CV%) of BP and that of CBFV. Babies demonstrating hypotension had higher CV%s in CBFV; those who did not survive showed higher variability than survivors, but there was a wide spread of values in both groups. where the variability in CBFV was high, correlation between CBFV and BP was greater. However, no significant association was found between CV% of CBFV and brain injury, ductal patency, or sedation. Although exaggerated beat-to-beat variability in CBFV was an adverse prognostic indicator, absence of variability carried the worst prognosis. Slow variations of cerebral blood flow velocity at a frequency of 1-5 cycles per minute, previously described as a normal phenomenon, were also examined. Evolution of this variability was studied amongst those present for a month or more. Slow variations diminished with both increasing postnatal and postconceptional age, perhaps representing maturation of the balance between the two components of the autonomic nervous system. The cycle length of the slow variations was variable suggesting the presence of several low frequency components; longer recordings would be needed to resolve these. Addition of serial Doppler measurements of CBFV performed in the first week of life, did not improve prediction of an 18-month outcome obtained from ultrasound imaging alone. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA1156264 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title Cerebral blood flow velocity variability in very low birthweight infants en
dc.type Thesis en
thesis.degree.discipline Medicine en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Doctoral en
thesis.degree.name MD en
dc.subject.marsden Fields of Research::320000 Medical and Health Sciences::320100 Medicine-General en
dc.rights.holder Copyright: the author en
pubs.local.anzsrc 11 - Medical and Health Sciences en
pubs.org-id Faculty of Medical & Hlth Sci en

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