Brain oxygen tension, oxygen supply, and oxygen consumption during arterial hyperoxia in a model of progressive cerebral ischemia

S. Rossi, N. Stocchetti, L. Longhi, M. Balestreri, D. Spagnoli, E. Roncati Zanier, G. Bellinzona

Research output: Contribution to journalArticle

Abstract

We investigated the changes in brain oxygen tension (ptiO2) after ventilation with pure O2 in order to (1) clarify the pathophysiology of O2 exchange in the cerebral microcirculation; and (2) investigate the relationship between brain O2 tension, O2 delivery, and consumption in steady-state conditions during stepwise cerebral blood flow (CBF) reductions. A swine model was developed to reduce CBF in three stable steps: (1) baseline (CBF 100%), (2) CBF of 50-60% of baseline, and (3) CBF of 2 reflected the CBF reductions, since it was respectively 27.95 (±10.15), 14.77 (±3.58), and 3.45 (±2.89) mm Hg during the three CBF steps. Hyperoxia was followed by an increase in ptiO2, although the increase was significantly lower when hyperoxia was applied during progressive ischemia. O2 supply to the brain did not change during hyperoxia. Arteriovenous oxygen difference (AVDO2) decreased during the phases of intact CBF and moderate impairment, but not during the phase of severe CBF reduction. In conclusion, ptiO2 reductions closely reflect the imbalance between oxygen delivery and demand; this implies a link between low ptiO2 and defective O2 supply due to impaired CBF. However, this relation is not necessarily reciprocal, since manipulating brain oxygen tension does not always influence brain oxygen delivery, as in the case of ventilation with pure oxygen.

Original languageEnglish
Pages (from-to)163-174
Number of pages12
JournalJournal of Neurotrauma
Volume18
Issue number2
Publication statusPublished - 2001

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Keywords

  • AVDO
  • Brain oxygenation
  • Cerebral ischemia
  • Hyperoxia
  • PtiO

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

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