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Cerebral blood flow autoregulation after moderate hypoxemia in the newborn piglet.

Authors
  • Odden, J P1
  • Farstad, T
  • Roll, E B
  • Hall, C
  • Bratlid, D
  • 1 Department of Pediatric Research, Rikshospitalet, University of Oslo, Norway. , (Norway)
Type
Published Article
Journal
Biology of the neonate
Publication Date
Jan 01, 1994
Volume
65
Issue
6
Pages
367–377
Identifiers
PMID: 8043698
Source
Medline
Language
English
License
Unknown

Abstract

The isotope-labelled microsphere method was used to study blood flow autoregulation in the brainstem (BS), cerebellum (CBL), cerebrum (CBR) and choroid plexus (ChPl) in 21 newborn piglets exposed to hypoxemia and/or hypovolemia. One group of piglets (n = 7) was made hypoxemic by breathing 10% O2 for 10 min, a second group (n = 8) was studied during hypoxemia (10% O2, 10 min), followed by hypovolemia (bleeding 20% of estimated blood volume). A third group of piglets (n = 6) was made hypovolemic by bleeding 20%. Hypoxemia significantly impaired the autoregulatory capacity in CBL and CBR resulting in a pressure-passive flow pattern. Hypovolemia alone did not produce any significant cerebral vascular response in BS, CBL and CBR, not even when hypovolemia was preceded by hypoxemia, indicating a rapid restoration of the autoregulatory capacity of the cerebral vasculature after hypoxemia of moderate duration. The hypotension seen both during hypoxemia and hypovolemia was gradually compensated for and normalized within 60 min. However, animals exposed to both hypoxemia and hypovolemia were still hypotensive 60 min after the hypoxemic insult. Cardiac output (CO) was not affected by hypoxemia, but was consistently reduced in hypovolemia. We therefore speculate that in the newborn a reduced CO might be a more specific parameter for hypovolemia than a low blood pressure.

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