Cerebral blood flow autoregulation during intracranial hypertension in hypoxic lambs

Journal Article · Tue Dec 01 04:00:00 EST 1987 · American Journal of Physiology; (USA)

OSTI ID:6994135

Borel, C O; Backofen, J E; Koehler, R C; Jones, Jr, M D; Traystman, R J ^[1]

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1. Johns Hopkins Medical Institutions, Baltimore, MD (USA)

The authors tested the hypothesis that hypoxic hypoxia interferes with cerebral blood flow (CBF) autoregulation when intracranial pressure (ICP) is elevated in pentobarbital-anesthetized lambs (3 to 9 days old). Cerebral perfusion pressure (CPP) was lowered stepwise from 73 to 23 mmHg in eight normoxic lambs and from 65 to 31 mmHg in eight other hypoxic lambs by ventricular infusion of artificial cerebrospinal fluid. In normoxic lambs, CBF measured by microspheres labeled with six different radioisotopes was not significantly changed over this range of CPP. In animals made hypoxic, base-line CBF was twice that of normoxic lambs. CBF was unchanged as CPP was reduced to 31 mmHg. Lower levels of CPP were not attained because a pressor response occurred with further elevations of ICP. No regional decrements in blood flow to cortical arterial watershed areas or to more caudal regions, such as cerebellum, brain stem, or thalamus, were detected with elevated ICP. Cerebral O{sub 2} uptake was similar in both groups and did not decrease when CPP was reduced. These results demonstrate that normoxic lambs have a considerable capacity for effective autoregulation of CBF when ICP is elevated. Moreover, cerebral vasodilation in response to a level of hypoxia approximating that normally seen prenatally does not abolish CBF autoregulation when ICP is elevated during the first postnatal week.

• OSTI ID: 6994135
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 253:6; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

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INTERMEDIATE MASS NUCLEI
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NERVOUS SYSTEM
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ORGANS
OXYGEN
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PHYSIOLOGY
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
RUMINANTS
RUTHENIUM 103
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SCANDIUM 46
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SCINTILLATION COUNTING
SECONDS LIVING RADIOISO
SHEEP
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TIN 113
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