Effects of subanesthetic dose of nitrous oxide on cerebral blood flow and metabolism: a multimodal magnetic resonance imaging study in healthy volunteers.
Anesthesiology
; 118(3): 577-86, 2013 Mar.
Article
em En
| MEDLINE
| ID: mdl-23324809
ABSTRACT
BACKGROUND:
Nitrous oxide, in a concentration of 50% or more, is a known cerebral vasodilator. This study investigated whether a lower dose (30%) of nitrous oxide would also increase cerebral blood flow. In addition, the authors wished to study whether the increase in cerebral blood flow was accompanied by an increase in cerebral metabolism.METHODS:
Multimodal Magnetic Resonance Imaging at 3T was performed, and data were obtained in 17 healthy volunteers during three inhalation conditions medical air, oxygen-enriched medical air (40% oxygen), and 30% nitrous oxide with oxygen-enriched medical air (40% oxygen). Arterial spin labeling was used to derive the primary tissue specific hemodynamicoutcomes:
cerebral blood flow, arterial blood volume and arterial transit times. Magnetic Resonance Susceptometry and proton Magnetic Resonance Spectroscopy were used for secondary metabolicoutcomes:
venous oxygenation, oxygen extraction fraction, cerebral metabolic oxygen rate and prefrontal metabolites.RESULTS:
Nitrous oxide in 40% oxygen, but not 40% oxygen alone, significantly increased gray matter cerebral blood flow (22%; P < 0.05) and arterial blood volume (41%; P < 0.05). Venous oxygenation increased in both oxygen and nitrous oxide conditions. Compared with medical air inhalation, nitrous oxide condition caused a significantly larger decrease in oxygen extraction fraction than 40% oxygen alone (mean [SD] 11.3 [5.6]% vs. 8.3 [5.9]% P < 0.05), while global cerebral metabolic rate and prefrontal metabolites remained unchanged.CONCLUSIONS:
This study demonstrates that 30% nitrous oxide in oxygen-enriched air (40% oxygen) significantly increases cerebral perfusion, and reduces oxygen extraction fraction, reflecting a strong arterial vasodilatory effect without associated increases in metabolism.
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Base de dados:
MEDLINE
Assunto principal:
Encéfalo
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Imageamento por Ressonância Magnética
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Circulação Cerebrovascular
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Anestésicos Inalatórios
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Óxido Nitroso
Limite:
Adult
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Female
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Humans
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Male
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article