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ABSTRACT The effects of HH on cerebral O2 delivery and on the ratio between O2 delivery and cerebral O2 consumption, i.e. the cerebral fractional O2 extraction, has been studied in 20

unanesthetized fetal sheep in utero and 7 newborn lambs. Cerebral O2 delivery was calculated as the product of cerebral blood flow (CBF), measured with the radioactive microsphere technique,

and arterial O2 content (CaO2). Fetuses were studied as PO2 varied from 12 to 35mmHg; lambs, as PaO2 varied from 30 to 150mmHg. All data were corrected to a constant arterial PCO2. Neither

cerebral O2 delivery nor fractional O2 extraction varied with PaO2 (unless hypoxia was extreme) in either fetuses or lambs, despite wide differences in their physiologic circumstances. This

suggests that the regulated variable during HH is (CBFX CaO2), not CBF. Since PaO2 and CaO2 are not linearly related, CBF must respond to changes in CaO2 rather than PaO2. This indicates

regulation of cerebral blood flow at the tissue level. Cerebral fractional O2 extraction is relatively constant between fetuses and lambs despite considerable differences in cerebral O2

consumption and delivery. Thus, the most important determinant of cerebral O2 delivery is not developmental stage, but O2 need. ARTICLE PDF AUTHOR INFORMATION AUTHORS AND AFFILIATIONS *

Departments of Pediatrics and Anesthesia/Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland M Douglas Jones Jr., Adam A Rosenberg, Raymond Koehler, 

Richard J Traystman, Michael A Simmons & Richard A Molteni Authors * M Douglas Jones Jr. View author publications You can also search for this author inPubMed Google Scholar * Adam A

Rosenberg View author publications You can also search for this author inPubMed Google Scholar * Raymond Koehler View author publications You can also search for this author inPubMed Google

Scholar * Richard J Traystman View author publications You can also search for this author inPubMed Google Scholar * Michael A Simmons View author publications You can also search for this

author inPubMed Google Scholar * Richard A Molteni View author publications You can also search for this author inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT

THIS ARTICLE CITE THIS ARTICLE Jones, M., Rosenberg, A., Koehler, R. _et al._ 256 HYPOXIC HYBOXIA (HH) AND CEREBRAL O2 DELIVERY IN THE FETAL AND NEWBORN SHEEP. _Pediatr Res_ 15 (Suppl 4),

482 (1981). https://doi.org/10.1203/00006450-198104001-00267 Download citation * Issue Date: 01 April 1981 * DOI: https://doi.org/10.1203/00006450-198104001-00267 SHARE THIS ARTICLE Anyone

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