科研之友
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摘要
ObjectiveMagnetic resonance imaging allows the noninvasive observation of Po-2 changes between air breathing and oxygen breathing through quantification of the magnetic longitudinal relaxation time T-1. Changes in Po-2 are proportional to changes in the longitudinal relaxation rate R-1 (where R-1=1/T-1oxygen-1/T-1air). Knowledge of this response could inform clinical interventions using maternal oxygen administration antenatally to treat fetal growth restriction. We present in vivo measurements of the response of the fetal-placental unit to maternal hyperoxia. DesignProspective cohort. SettingLarge tertiary maternity hospital. SampleNine women undergoing low-risk pregnancy (21-33weeks of gestation) and five nonpregnant adults. MethodsDuring imaging the air supply to mothers was changed from medical air (21% oxygen) to medical oxygen (100% oxygen) and T-1 was monitored over time in both the placenta and fetal brain using a periodically repeated magnetic resonance imaging sequence. To demonstrate that the method could detect a brain response, brain responses from five normal adult volunteers were measured using a similar imaging protocol. Main outcome measureChanges in T-1 following oxygen challenge. ResultsNo significant R-1 (P=0.42, paired t-test) was observed in fetal brains. A significant placental R-1 (P=0.0002, paired t-test) of 0.020.01/s (mean +/- SD) was simultaneously observed in the same participants. In the brains of the nonpregnant adults, a significant R-1 (P=0.01, paired t-test) of 0.005 +/- 0.002/s was observed. ConclusionShort-term maternal oxygen administration does not improve fetal brain oxygenation, in contrast to the response observed in the adult brain.
- 出版日期2014-12
