Maternal oxygen administration and fetal cerebral oxygenation: Studies on near-term fetal lambs at both low and high altitude

2006 ◽  
Vol 195 (2) ◽  
pp. 535-541 ◽  
Author(s):  
Takuji Tomimatsu ◽  
Jorge Pereyra Peňa ◽  
Douglas P. Hatran ◽  
Lawrence D. Longo
Keyword(s):  
High Altitude ◽  
Cerebral Oxygenation ◽  
Oxygen Administration ◽  
Near Term

Near-Infrared Spectroscopy Monitoring of Cerebral Oxygenation and Influencing Factors in Neonates from High-Altitude Areas

Neonatology ◽  
2021 ◽  
pp. 1-6
Author(s):  
Bi Ze ◽  
Lili Liu ◽  
Ge Sang Yang Jin ◽  
Minna Shan ◽  
Yuehang Geng ◽  
...  
Keyword(s):  
Heart Disease ◽  
Infrared Spectroscopy ◽  
Brain Injury ◽  
Oxygen Saturation ◽  
High Altitude ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Low Altitude ◽  
Normal Neonates

<b><i>Background:</i></b> Accurate detection of cerebral oxygen saturation (rSO<sub>2</sub>) may be useful for neonatal brain injury prevention, and the normal range of rSO<sub>2</sub> of neonates at high altitude remained unclear. <b><i>Objective:</i></b> To compare cerebral rSO<sub>2</sub> and cerebral fractional tissue oxygen extraction (cFTOE) at high-altitude and low-altitude areas in healthy neonates and neonates with underlying diseases. <b><i>Methods:</i></b> 515 neonates from low-altitude areas and 151 from Tibet were enrolled. These neonates were assigned into the normal group, hypoxic-ischemic encephalopathy (HIE) group, and other diseases group. Near-infrared spectroscopy was used to measure rSO<sub>2</sub> in neonates within 24 h after admission. The differences of rSO<sub>2</sub>, pulse oxygen saturation (SpO<sub>2</sub>), and cFTOE levels were compared between neonates from low- and high-altitude areas. <b><i>Results:</i></b> (1) The mean rSO<sub>2</sub> and cFTOE levels in normal neonates from Tibet were 55.0 ± 6.4% and 32.6 ± 8.5%, significantly lower than those from low-altitude areas (<i>p</i> &#x3c; 0.05). (2) At high altitude, neonates with HIE, pneumonia (<i>p</i> &#x3c; 0.05), anemia, and congenital heart disease (<i>p</i> &#x3c; 0.05) have higher cFTOE than healthy neonates. (3) Compared with HIE neonates from plain areas, neonates with HIE at higher altitude had lower cFTOE (<i>p</i> &#x3c; 0.05), while neonates with heart disease in plateau areas had higher cFTOE than those in plain areas (<i>p</i> &#x3c; 0.05). <b><i>Conclusions:</i></b> The rSO<sub>2</sub> and cFTOE levels in normal neonates from high-altitude areas are lower than neonates from the low-altitude areas. Lower cFTOE is possibly because of an increase in blood flow to the brain, and this may be adversely affected by disease states which may increase the risk of brain injury.

High altitude-induced changes in alpha1-adrenergic receptors and Ins(1,4,5)P3 responses in cerebral arteries

1997 ◽  
Vol 272 (2) ◽  
pp. R669-R674 ◽  
Author(s):  
N. Ueno ◽  
Y. Zhao ◽  
L. Zhang ◽  
L. D. Longo
Keyword(s):  
High Altitude ◽  
Adrenergic Receptor ◽  
Cerebral Arteries ◽  
Control Value ◽  
Density Values ◽  
High Altitude Acclimatization ◽  
Normoxic Control ◽  
Near Term ◽  
Induced Changes

In response to high-altitude long-term hypoxemia, the cerebral arteries of fetal and adult sheep show decreased contractile responses to norepinephrine (NE) and other agonists. To test the hypothesis that hypoxia-induced developmental and vessel specific cerebral artery contractility changes are mediated, in part, by changes in alpha1-adrenergic receptor (alpha1-AR) density and/or NE-induced inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] responses, we performed the following study. In common carotid (Com) and main branch cerebral (MBC) arteries from normoxic adult ewes and near-term fetuses and those acclimatized to high altitude (3,820 m), we quantified alpha1-AR density (maximal binding in fmol/mg protein) and affinity (dissociation constant in nM) with the alpha1-AR antagonist [3H]prazosin. In addition, we quantified NE-induced Ins(1,4,5)P3 responses in these arteries. With long-term hypoxemia, alpha1-AR density in fetal and adult Com decreased 75% (from 113 +/- 18 to 28 +/- 5 fmol/mg protein) and 66% (from 54 +/- 3 to 18 +/- 4 fmol/mg protein), respectively, from normoxic control values. alpha1-AR density of the fetal and adult MBC decreased 76% (from 47 +/- 4 to 11 +/- 1 fmol/mg protein) and 61% (from 23 +/- 3 to 9 +/- 3 fmol/mg protein), respectively, from controls. In hypoxemic adult Com, the NE-induced Ins(1,4,5)P3 response decreased 51% (from 309 +/- 38 to 151 +/- 24%) from the control value. In fetal and adult MBC, long-term hypoxemia was associated with decreases of 35% (from 345 +/- 40 to 225 +/- 30%) and 44% (from 355 +/- 55 to 199 +/- 16%), respectively, from control values. We conclude that in the adult Com and MBC vessels, acclimatization to high-altitude, long-term hypoxemia was associated with significant decreases in both alpha1-AR density values and Ins(1,4,5)P3 responses to NE. Similarly, in the fetal MBC arteries, high-altitude hypoxemia was associated with marked attenuation of both alpha1-AR density and NE-induced Ins(1,4,5)P3 responses. The magnitude of decreases in NE-induced Ins(1,4,5)P3 responses in these vessels correlated fairly well with the decreases in alpha1-AR density. These findings suggest that changes in noradrenergic receptor-second messenger coupling may play a role in altered cerebrovascular tone in association with high-altitude acclimatization and other forms of long-term hypoxia in both fetus and adult.

scholarly journals Vitamin D status and metabolism in an ovine pregnancy model: effect of long-term, high-altitude hypoxia

2016 ◽  
Vol 310 (11) ◽  
pp. E1062-E1071 ◽  
Author(s):  
Ravi Goyal ◽  
Tara L. Billings ◽  
Trina Mansour ◽  
Courtney Martin ◽  
David J. Baylink ◽  
...  
Keyword(s):  
Vitamin D ◽  
High Altitude ◽  
Plasma Levels ◽  
Vitamin D Status ◽  
Molecular Determinants ◽  
Near Term ◽  
Specific Regulation ◽  
Circulating Levels

Vitamin D status increases during healthy mammalian pregnancy, but the molecular determinants remain uncharacterized. The first objective of this study was to determine the effects of pregnancy, and the second objective was to examine the role of chronic hypoxia on vitamin D status and metabolism in an ovine model. We analyzed the plasma levels of cholecalciferol, 25-OH-D, and 1α,25-(OH)2D in nonpregnant ewes, near-term pregnant ewes, and their fetuses exposed to normoxia (low altitude) or hypoxia (high-altitude) for 100 days. Hypoxic sheep had increased circulating levels of 25-OH-D and 1α,25-(OH)2D compared with normoxic sheep. Hypoxia increases in 25-OH-D were associated with increased expression of renal 25-hydroxylases CYP2R1 and CYP2J. Pregnancy did not increase further the plasma levels of 25-OH-D, but it significantly increased those of the active metabolite, 1α,25-(OH)2D, in both normoxic and hypoxic ewes. Increased bioactivation of vitamin D correlated with increased expression of the vitamin D-activating enzyme CYP27b1 and decreased expression of the inactivating enzyme CYP24a1 in maternal kidneys and placentas. Hypoxia increased parathyroid hormone levels and further increased renal CYP27b1. Pregnancy and hypoxia decreased the expression of vitamin D receptor (VDR) in maternal kidney and lung, with opposite effects on placental VDR. We conclude that ovine pregnancy is a model of increased vitamin D status, and long-term hypoxia further improves vitamin D status due to pregnancy- and hypoxia-specific regulation of VDR and metabolic enzymes.

Steroidogenesis in sheep pregnancy with intrauterine growth retardation by high-altitude hypoxia: effects of maternal altitudinal status and antioxidant treatment

2013 ◽  
Vol 25 (4) ◽  
pp. 639 ◽  
Author(s):  
Víctor H. Parraguez ◽  
Bessie Urquieta ◽  
Mónica De los Reyes ◽  
Antonio González-Bulnes ◽  
Susana Astiz ◽  
...  
Keyword(s):  
High Altitude ◽  
Growth Retardation ◽  
Intrauterine Growth Retardation ◽  
Plasma Concentrations ◽  
Antioxidant Vitamins ◽  
Vitamin Supplementation ◽  
Plasma Progesterone ◽  
Intrauterine Growth ◽  
Near Term ◽  
And Oxidative Stress

Sheep pregnancy in high-altitude environments frequently involves hypoxia and oxidative stress and causes intrauterine growth retardation. The adverse effects of altitude on fetal growth can be prevented by the administration of antioxidant vitamins, but the mechanisms responsible are not well known. The maintenance of a viable pregnancy depends largely on adequate placental steroidogenesis, especially in the last two-thirds of pregnancy. Thus, in the present study we evaluated the effect of antioxidant vitamins (C and E) on plasma concentrations of progesterone and 17β-oestradiol during the last two-thirds of high-altitude pregnancies in ewes both native and naïve to the high-altitude environment. In addition, pregnancy outcomes were evaluated by determining the bodyweight of newborn lambs. Sex steroid patterns differed between ewes with and without vitamin supplementation. Concentrations of plasma progesterone and 17β-oestradiol were significantly higher in the supplemented groups from approximately 40 days before parturition until near term. Newborn weights were significantly lower in animals not adapted to the higher altitude, and vitamin supplementation prevented this decrease. In conclusion, the administration of antioxidant vitamins in the present study enhanced placental steroidogenesis, thus favouring fetal development in pregnancies developing at high altitudes.

Cerebral oxygenation at high altitude and the response to carbon dioxide, hyperventilation and oxygen

2000 ◽  
Vol 98 (2) ◽  
pp. 159-164 ◽  
Author(s):  
C. H. E. IMRAY ◽  
S. BREAREY ◽  
T. CLARKE ◽  
D. HALE ◽  
J. MORGAN ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
High Altitude ◽  
Cerebral Oxygenation

scholarly journals General Anesthesia Improves Fetal Cerebral Oxygenation without Evidence of Subsequent Neuronal Injury

2005 ◽  
Vol 25 (8) ◽  
pp. 1060-1069 ◽  
Author(s):  
Rebecca J McClaine ◽  
Kenichiro Uemura ◽  
Sebastian G de la Fuente ◽  
Roberto J Manson ◽  
John V Booth ◽  
...  
Keyword(s):  
General Anesthesia ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Fetal Brain ◽  
Drug Regimen ◽  
Initial Increase ◽  
Anesthetic Agents ◽  
Pregnant Sheep ◽  
Near Term ◽  
Anesthetic Exposure

Anesthetic exposure during pregnancy is viewed as a relatively routine medical practice. However, recent rodent studies have suggested that common anesthetic agents can damage the developing brain. Here we assessed this claim in a higher order species by exposing previously instrumented near-term pregnant sheep at gestational day 122 (±1) to a combination of midazolam, sodium thiopental, and isoflurane at clinically relevant doses and means of anesthetic delivery (i.e., active ventilation). Four hours of maternal general anesthesia produced an initial increase in fetal systemic oxygenation and a sustained increase in fetal cerebral oxygenation, as determined by in utero near-infrared spectroscopy. Postexposure monitoring failed to identify changes in physiologic status that could be injurious to the fetal brain. Finally, through the histologic assessment of noninstrumented sheep at the same gestational time point, we found no evidence for a direct fetal neuro-toxic effect of our triple-drug regimen. Collectively, these results appear to corroborate the presumed safety of inhalational anesthetic use during pregnancy.

scholarly journals Effects of Desflurane Versus Propofol Anesthesia on Regional Cerebral Oxygenation during Spinal Surgery in the Prone Position

2021 ◽  
pp. 1-6
Author(s):  
Stachtari Chrysoula ◽  
Koraki Eleni ◽  
Stachtari Chrysoula ◽  
Bagntasarian Stella ◽  
Gkiouliava Anna ◽  
...  
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Spinal Surgery ◽  
Cerebral Oxygenation ◽  
Demographic Data ◽  
Prone Positioning ◽  
Anaesthetic Agents ◽  
Oxygen Administration ◽  
Hemodynamic Variables ◽  
Significant Difference

Context: Postural change during anaesthesia has a complex effect on systemic and cerebral circulations. Aim: The goal of the study was to evaluate the effects of desflurane and propofol on cerebral oxygenation during spinal surgery in the prone position. Settings and Design: A prospective randomized double-blinded trial. Methods and Materials: Fifty-two patients scheduled for spinal surgery were randomly allocated to propofol (n=25) and desflurane (n=27) groups. Anaesthetic agents were maintained to obtain a bispectral index of 50-55. SAP, DAP, HR, SPO2, ETCO2 and right and left rSO2 were assessed at seven-time points: supine position without oxygen administration (T1), supine position with oxygen administration (T2-baseline), intubation in the supine position (T3), just after prone positioning (T4), 10 minutes after prone positioning (T5), at the end of surgery in the prone position (T6) and at the end of anaesthesia in the supine position (T7). PCO2, PO2 and Hb partial were also recorded at T3 and T7. Results: Demographic data, pre-oxygenation hemodynamic variables and rSO2 were comparable between the groups. There was no significant difference between groups in SAP, DAP, HR, SPO2, and ETCO2 (p=0.095, p=0.061, p=0.357, p=0.088, p=0.328 respectively). PCO2, PO2 and Hb were not significant different between groups (p=0.542, p=0.394, p=0.768 respectively). rSO2 values were not significantly different between groups. In the propofol group, right rSO2 was significantly higher at T3 (p=0.017) and significantly lower at T5 (p=0,019) and at T6 (p=0,028) compared to baseline. Left rSO2 decreased significantly from baseline at T5 (p=0.026) in the propofol group. Left and right rSO2 in the desflurane group decreased significantly from baseline at T5 (p=0.0004 and p=0.0115). Conclusion: In the prone position, desflurane and propofol were associated with a significant decrease in rSO2 without differences between these anaesthetics.

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