Cerebral blood flow and oxygen consumption in the newborn dog

Hernández, M. J.; Brennan, Robert W.; Vannucci, Robert C.; Bowman, George

doi:10.1152/ajpregu.1978.234.5.r209

Cited by 31 publications

(26 citation statements)

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“…The baseline regional CBF results and the increased flow to infratentorial regions in our study concurs with previous data in newborn dogs (9,(12)(13)(14). During the acute recovery phase the cerebral hemispheric and the combined cerebellar-brainstem flows increased 250 + 39 and 536 k 29% above baseline, respectively, with the percentage increase to the brainstem-cerebellum being significantly greater than that to the hemispheres ( p < 0.005).…”

Section: Discussionsupporting

confidence: 92%

Cerebrovascular Hemodynamics during and after Recovery from Acute Asphyxia in the Newborn Dog

1985

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Section: Discussionsupporting

confidence: 92%

Cerebrovascular Hemodynamics during and after Recovery from Acute Asphyxia in the Newborn Dog

1985

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“…Our results agree with those of Hernandez, et at. (9) who have demonstrated that the newborn dog's cerebral vascular responsiveness to CO2 is lower than that reported for adult dogs. The lack of an additive effect of Paco2 on the reduction of brain blood flow during hypotension suggests that hypocapnea may not produce an adultlike effect on neonatal cerebral circulation.…”

Section: Summary Speculationmentioning

confidence: 89%

Brain Blood Flow and O2 Delivery during Hemorrhagic Hypotension in the Piglet

Laptook

Stonestreet

1983

Pediatr Res

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- MATERIALS AND METHODSand/or hypocapnea. The first objective of the current study is to demonstrate the effect of hypotension on brain blood flow by maintaining a constant Paco2 with controlled ventilation.In adult animals during hypotension regional blood flow responses reveal conflicting results. Using the microsphere technique in adult mongrel dogs (22) and cynomologus monkeys (6) after induced hypotension (via hemorrhage in the former and pharmacologic means in the latter) no differences in regional blood flow to the brain were detected. In contrast, during hemorrhagic hypotension in .adult dogs (18), blood flow (microspheres) was preferentially maintained to the medulla. In the piglet (15) we have shown that during hemorrhagic hypotension, regional differences in brain blood flow reduction did occur. The reduction was most pronounced in the cerebrum, less in the cerebellum, and least in the brainstem. The presence of hypotension and hypocapnea made it undertain as to which was responsible for the regional differences in reduced perfusion. Therefore, the second objective of the present study is to determine if regional differences in brain blood flow reduction and oxygen delivery exist when the mean arterial blood pressure is altered during hemorrhagic hypotension under conditions of controlled ventilation. Summary SpeculationNewborn piglets subjected to profound hypotension demonstrate regional differences in the reduction of brain blood flow. Cranial window studies of the microvasculature in adult cats clearly demonstrate that precapillary vessels in the brain do not respond in an identical manner to hypotension but rather react in a size dependent fashion. The observed differences in brain regional blood flow are possibly a manifestation of the relative composition (with respect to vessel size) of the regional parenchymal arterial beds.We have previously demonstrated regional differences in brain blood flow reduction when hemorrhagic hypotension was induced in spontaneously breathing newborn piglets. Both the mean arterial blood pressure and Paco2 correlated with the changes in brain blood flow. To determine if changes in brain blood flow during hypotension can be attributed to alterations of mean arterial blood pressure alone, eight newborn piglets were studied under conditions of controlled ventilation. Regional brain blood flow was measured by microspheres and the blood pressure was varied by phlebotomy. After baseline determinations, three measurements of blood flow were performed during hypotension. Hypotension produced a significant reduction in blood brain flow confirming the independent effect of mean arterial blood pressure in autoregulation of cerebral circulation. Significantly different regional blood flow responses occurred in response to hypotension (P < 0.05).The % reduction from control blood flow was greatest to the cerebrum, less to the cerebellum, and least to the brainstern. Furthermore, the blood flow was consistently decreased in the cerebral hemispheres during the entire exposure t...

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“…This may explain the higher control flow values to this area, and the flow increase during hypoxia. Because mild and moderate hypoxia do not decrease O2 consumption (13,14,40,41), the brainstem should require higher levels of oxygen delivery and blood flow than the cortex and subcortex. However, we know of no studies of the regional differences in oxygen consumption during hypoxia in the fetus, newborn, or adult (1 1).…”

Section: Cardiac Output (Mlomin-'kg Body-')mentioning

confidence: 99%

“…Glucose recycling through lactate is an active mechanism in the primate fetus as well as in the young of other species. (Pediatr Res 118: 1984) or inferential data derived from infusion studies, tolerance tests (6,14), and stable isotope methodology (15). Previous investigations using the newly born baboon as a model for the study of neonatal energy metabolism suggest that this animal resembles the small-for-gestational-age human infant in terms of response to fasting and diminished body fat (19,20).…”

Section: Cardiac Output (Mlomin-'kg Body-')mentioning

confidence: 99%

Regional Cerebral Blood Flow: Studies in the Fetal Lamb during Hypoxia, Hypercapnia, Addosis, and Hypotension

1984

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ABSTRACT. In order to determine the relative roles of O2 tension and content, C 0 2 tension, hydrogen ion concentration, arterial blood pressure, and cardiac output in the regulation of fetal cerebral blood flow (CBF), we used radioactively labeled microspheres to measure flow to 20 major brain regions in 24 chronically catheterized fetal lambs. We continually monitored fetal heart rate and blood pressure, and periodically measured arterial Po2, Pco2, pH, and hematocrit. In addition to CBF measurements during control periods, we measured CBF during: 1) hypoxia ( 0 2 content < 6 ml-dl-'; O2 tension c 15 torr) induced by having the ewe breathe a gas mixture with low 0 2 concentration, 2) hypercapnia (Pcoz > 50 torr) induced by increasing the maternal inspired COz, 3) acidosis and alkalosis (7.60 > pH > 6.60) induced by infusing lactic acid or bicarbonate into the fetus, and 4) hypotension (blood pressure < 35 mm Hg) and hypertension (blood pressure > 55 mm Hg) induced by rapidly phlebotomizing or transfusing the fetus. We used multiple regression analysis and analysis of covariance to examine the dependence of total cerebral blood flow on arterial O2 tension and content, COz tension, pH, blood pressure, and cardiac output. The results demonstrated that 1) fetal CBF increased linearly as oxygen tension or content decreased and a hierarchy of responsivity occurred (brainstem > subcortex and cortex), 2) fetal CBF increased as carbon dioxide tension increased with a different hierarchy of responsivity (brainstem > subcortex > cortex), and 3) autoregulation of fetal CBF over a wide range of blood pressure or cardiac output was maintained for both total CBF and the various brain regions examined. (Pediatr Res 18:1309-1316,1984 Abbreviations CBF, cerebral blood flow During the past several years, numerous investigators have used the radioactive microsphere technique to measure newborn and fetal cerebral blood flow in different species (1,19,24,25,36,40). In these studies, which have examined changes in flow as a function of changes in blood gas tensions, pH, and blood

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Cerebral blood flow and oxygen consumption in the newborn dog

Cited by 31 publications

References 0 publications

Cerebrovascular Hemodynamics during and after Recovery from Acute Asphyxia in the Newborn Dog

Cerebrovascular Hemodynamics during and after Recovery from Acute Asphyxia in the Newborn Dog

Brain Blood Flow and O2 Delivery during Hemorrhagic Hypotension in the Piglet

Regional Cerebral Blood Flow: Studies in the Fetal Lamb during Hypoxia, Hypercapnia, Addosis, and Hypotension

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