Developmental changes in cerebral autoregulatory capacity in the fetal sheep parietal cortex
We validated laser Doppler flowmetry (LDF) for long-term monitoring and detection of acute changes of local cerebral blood flow (lCBF) in chronically instrumented fetal sheep. Using LDF, we estimated developmental changes of cerebral autoregulation. Single fibre laser probes (0.4 mm in diameter) wer...
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Published in | The Journal of physiology Vol. 539; no. 3; pp. 957 - 967 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
The Physiological Society
15.03.2002
Blackwell Publishing Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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Summary: | We validated laser Doppler flowmetry (LDF) for long-term monitoring and detection of acute changes of local cerebral blood
flow (lCBF) in chronically instrumented fetal sheep. Using LDF, we estimated developmental changes of cerebral autoregulation.
Single fibre laser probes (0.4 mm in diameter) were implanted in and surface probes were placed on the parietal cerebral cortex
at 105 ± 2 ( n = 7) and 120 ± 2 days gestational age (dGA, n = 7). Basal lCBF was monitored over 5 days followed by a hypercapnic challenge (fetal arterial partial pressure of CO 2 , P a,CO2 : 83 ± 3 mmHg) during which lCBF changes obtained by LDF were compared to those obtained with coloured microspheres (CMSs).
Mean arterial blood pressure (MABP) was increased and decreased using phenylephrine and sodium nitroprusside at 110 ± 2 and
128 ± 2 dGA. Intracortical and cortical surface laser probes gave stable measurements over 5 days. The lCBF increase during
hypercapnia obtained by LDF correlated well with flows obtained using CMS ( r = 0.89, P < 0.01). The signals of intracortical and surface laser probes also correlated well ( r = 0.91, P < 0.01). Gliosis of 0.35 ± 0.06 mm around the tip of intracortical probes did not affect the measurements. The range of MABP
over which cerebral autoregulation was observed increased from 20â48 mmHg at 110 dGA to 35 to > 95 mmHg at 128 dGA ( P < 0.05). Since MABP increased from 33 to 54 mmHg over this period ( P < 0.01), the range between the lower limit of cerebral autoregulation and the MABP increased from 13 mmHg at 110 dGA to 19
mmHg at 128 dGA ( P < 0.01). LDF is a reliable tool to assess dynamic changes in cerebral perfusion continuously in fetal sheep. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.2001.012590 |