Regional Cerebral Blood Flow During Neonatal Asphyxia

Hernández, M. J.; Hawkins, R. A.

doi:10.1097/00000542-197909001-00295

Cited by 10 publications

(15 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%

“…Hypercarbia (13), hypoxia (7,16), and hypotension (17) are each known to lower cerebral vascular resistance under steady state conditions in the newborn dog. In our study, asphyxia is associated with significant hypotension, while studies by others in newborn dogs have shown marked hypercarbia and hypoxia during asphyxic insults of similar duration (9,10). Therefore the high flows seen in period I1 may be due to the marked acute increase in arterial pressure at a time when the vascular resistance is low due to the combined effects of the immediately preceding hypoxia, hypercarbia, and hypotension.…”

Section: Discussionsupporting

confidence: 50%

“…As mentioned earlier, technical difficulties precluded CBF measurements at the end of asphyxia in our study. However, previous work by Hernandez et al (9,10) and Hellman et al…”

Section: Discussionmentioning

confidence: 89%

“…These studies allow conclusions concerning CBF at the end of the asphyxic period in our study, and when combined with our results during the acute recovery phase, provide an estimate of the magnitude of the increase in CBF accompanying the recovery. Thus, Hernandez et al (9,10) measured regional CBF at 5 min of asphyxia using '4C-iodoantipyrine autoradiography and showed that blood flow was less than baseline for all areas except the pons, medulla, and spinal cord where it was 30, 80, and 83% above baseline, respectively. Recently, Hellman et al ( I 1) extended the asphyxic insult to 7-8 min duration and using the same autoradiographic technique showed that regional CBF was less than or equal to baseline for all areas studied.…”

Section: Discussionmentioning

confidence: 99%

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

1985

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 50%

“…As mentioned earlier, technical difficulties precluded CBF measurements at the end of asphyxia in our study. However, previous work by Hernandez et al (9,10) and Hellman et al…”

Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

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

1985

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“…An alternative explanation includes the sympathetic nervous system's control of the cerebral vasculature. Hernandez, et al (8) have documented a disproportionate increase in blood flow to the brainstem of newborn puppies during hypotension and asphyxia suggesting that differential innervation density of preparenchymal resistance vessels may be responsible for these frndings.…”

Section: Summary Speculationmentioning

confidence: 99%

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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Current Concepts of Pathophysiology of Perinatal Intraventricular Hemorrhage

Goddard‐Finegold¹

1985

Perinatal Neurology and Neurosurgery

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The term perinatal intracranial hemorrhage now evokes from most pediatricians, neonatologists, neurologists, and pathologists the thought of intracerebral, periventricular, intraventricular hemorrhage (PIVH). PIVH occurs most commonly in premature newborns of less than 32 weeks gestational age, most of whom have suffered the respiratory distress syndrome [1][2][3][4][5][6][7][8][9]. Most affected babies have sustained some degree of perinatal asphyxia [10]. The newborns who are symptomatic usually deteriorate, either suddenly or gradually, within the first three days after birth with bulging fontanelles, abnormalities on neurologic examination, bloody spinal fluid, a greater than 10% decrease in hematocrit, hypoglychorrachia, hyperglycemia, hypotension, and manifestations of seizure activity [6,7,9].These are the cardinal signs and symptoms of PIVH, but a significant proportion of affected infants exhibit only some of them, and a number of infants with hemorrhages are asymptomatic [6]. Two evaluations by computerized tomography (CT) of newborns of less than either 1500-or 1750-gm. birthweight revealed PIVH in 40 to 43% of the cases [1][2][3][4][5][6]. Twenty-five percent of the infants studied by Papile et al, who had PIVH on CT scans, were asymptomatic by Perinatal Neurology and Neurosurgery. Edited by

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Regional Cerebral Blood Flow During Neonatal Asphyxia

Cited by 10 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

Current Concepts of Pathophysiology of Perinatal Intraventricular Hemorrhage

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