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

McClaine, Rebecca J.; Uemura, Kenichiro; Fuente, Sebastián G. de la; Manson, Roberto J.; Booth, John V.; White, William D.; Campbell, Kurtis A.; McClaine, Deborah J.; Benni, Paul B.; Eubanks, William S.; Reynolds, James D.

doi:10.1038/sj.jcbfm.9600094

Cited by 40 publications

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“…It should be noted that, in our study, the fetus remained well oxygenated. This fi nding is supported by a previous study, which showed that oxygenation remained constant even as fetal mean arterial pressure decreased signifi cantly in both near-term and preterm fetal sheep [33,34].…”

Section: Discussionsupporting

confidence: 86%

Comparison of the effects of sevoflurane and isoflurane anesthesia on the maternal-fetal unit in sheep

et al. 2009

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Section: Discussionsupporting

confidence: 86%

Comparison of the effects of sevoflurane and isoflurane anesthesia on the maternal-fetal unit in sheep

et al. 2009

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“…The effects of anesthesia on apoptosis in the developing fetal brain have been controversial, with inhibition (15), no effects (24) and promoting effects (14) all being reported. Similarly, the effects of anesthesia used during the development of fetal or newborn brains on long term memory and learning are also mixed with anesthesia being found to cause both transient improvement (15) and permanent impairment (9).…”

Section: Discussionmentioning

confidence: 99%

Anesthesia-Induced Neurodegeneration in Fetal Rat Brains

et al. 2009

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ABSTRACT:We investigated the extent of isoflurane-induced neurodegeneration on the fetuses of pregnant rats exposed in utero. Pregnant rats at gestational d 21 were divided into three experimental groups. Rats in the control group spontaneously breathed 100% oxygen for 1 h. Rats in the treatment groups breathed either 1.3 or 3% isoflurane in 100% oxygen through an endotracheal tube, with mechanical ventilation for 1 h. Rat pups were delivered by cesarian section 6 h after treatment, and fetal blood was sampled from the left ventricle of each fetal heart and evaluated for S100␤. Fetal brains were then evaluated for apoptosis, using caspase-3 immunohistochemistry in the CA1 region of the hippocampus and the retrosplenial cortex (RS). The 3% isoflurane treatment group showed significantly higher levels of S100␤ levels and significantly increased average densities of total caspase-3-positive cells in the CA1 hippocampus and RS cortex compared with the control and the 1.3% isoflurane groups. There were no differences in S100␤ levels or densities of caspase-3-positive cells between the control and 1.3% isoflurane groups. Isoflurane at a concentration of 3% for 1 h increased neurodegeneration in the hippocampal CA1 area and the retrosplenial cortex in the developing brain of fetal rats. Increasing evidence suggests that commonly used inhalational anesthetics, especially isoflurane, dose-and timedependently induce damage in various types of tissues and cells, including hippocampal slices (1), lymphocytes (2,3), neuroglioma (4), liver cells (5), gingival fibroblasts (6), neurosecretory PC12 cells (7,8), and primary cortical and striatal neurons (2,7,8). In animal studies, isoflurane, alone or in combination with midazolam or nitrous oxide, caused widespread neurodegeneration in the 7-d-old rodent brain and was associated with subsequent cognitive impairment (9,10). In the elderly rodent, isoflurane exposure also caused persistent memory impairment (11). Recent clinical studies suggest a greater incidence of learning disabilities in children exposed to anesthesia during surgery before the age of 3, especially in children over the course of multiple surgeries (12,13).Pregnant women sometimes require general anesthesia for various surgeries, such as cesarian sections and fetal surgeries.Because anesthetics easily cross the placenta, these interventions expose developing fetal brains to inhalational anesthetics as well. Because neurons in the developing brains are especially vulnerable to anesthesia-mediated neurodegeneration (9), it is possible that inhalational anesthetics administered to pregnant mothers can harm the developing fetal brains (14). We have previously shown that 1.3% isoflurane administered during late pregnancy did not produce detectable injury to the rat fetal brains (15). However, in the case of fetal surgery used to correct various congenital malformations during midgestation (18 -25 wk) (16), the fetal brain can be exposed to 2-3 times (2.5-3 minimal alveolar concentration [MAC]) the normally used clin...

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“…Nonetheless, despite the critical importance of these issues, and knowledge that cerebrovascular PaCO 2 reactivity differs dramatically between the immature and mature organism (11), the role of CO 2 in cerebral tissue oxygenation has received relatively little attention, especially in the immature brain. (12)(13)(14). …”

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confidence: 99%

Fetal Hypercapnia and Cerebral Tissue Oxygenation: Studies in Near-Term Sheep

2006

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The precise role of CO 2 in cerebral oxygenation is not as well defined as O 2 , especially in the immature brain. In the ovine fetus, we tested the hypotheses that arterial PCO 2 (PaCO 2 ) plays a critical role not only in the regulation of cerebral blood flow but also in the regulation of cerebral tissue oxygenation. I n the developing fetus and newborn infant, as well as the adult, the maintenance of optimal cerebral oxygenation is of critical importance, as the brain is highly dependent on a continuous and adequate O 2 supply to maintain structural and functional integrity. Cerebral tissue oxygenation is maintained and carefully regulated by the balance of several factors. These include CBF, arterial O 2 partial pressure (PaO 2 ) and content, cerebral metabolic rate for O 2 (CMRO 2 ), and the relative position of the Hb-oxygen dissociation curve (1,2). Arterial CO 2 tension (PaCO 2 ) long has been recognized as playing a major role in CBF regulation of the fetus (3) as well as the adult (4,5). Thus, it is reasonable to anticipate that CO 2 , as well as O 2 , plays a significant role in cerebral tissue oxygenation.Variation of PaCO 2 commonly occurs in the management of the fetus and newborn during the perinatal period. During labor, fetal hypercapnia with respiratory acidosis, in part resulting from transient compression of the umbilical cord, is not uncommonly seen (6). In addition, vaginal delivery itself may be associated with respiratory acidosis and hypoxia (7). Alternatively, with moderate to severe maternal hyperventilation, particularly during the later stages of labor, fetal hypocapnia with respiratory alkalosis may develop (8,9). In addition, among critically ill newborn infants, significant changes in PaCO 2 can present problems. Under some circumstances, hypocapnia is believed to be of value to prevent an excessive increase in CBF. In other instances, "permissive" hypercapnia is practiced to optimize CBF, to reduce the risk of periventricular leukomalacia, and to minimize ventilator-associated lung injury (10). Nonetheless, despite the critical importance of these issues, and knowledge that cerebrovascular PaCO 2 reactivity differs dramatically between the immature and mature organism (11), the role of CO 2 in cerebral tissue oxygenation has received relatively little attention, especially in the immature brain. (12)(13)(14). MATERIALS AND METHODSExperimental animals and instrumentation. For these studies, we used six pregnant Western ewes and their singleton fetuses obtained from Nebeker Ranch (Lancaster, CA). All surgical and experimental procedures were performed within the regulations of the Animal Welfare Act, the National Institutes of Health Guide for the Care and Use of Laboratory Animals, "The Guiding Principles in the Care and Use of Animals" approved by the Council of the American Physiologic Society, and the Animal Care and Use Committee of Loma Linda University.Pregnant ewes and their fetuses were instrumented at 122 Ϯ 3 d of gestation (term 145 d), as we have described in...

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

Cited by 40 publications

References 40 publications

Comparison of the effects of sevoflurane and isoflurane anesthesia on the maternal-fetal unit in sheep

Comparison of the effects of sevoflurane and isoflurane anesthesia on the maternal-fetal unit in sheep

Anesthesia-Induced Neurodegeneration in Fetal Rat Brains

Fetal Hypercapnia and Cerebral Tissue Oxygenation: Studies in Near-Term Sheep

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