Early human development · 2007
Intracerebral regional distribution of blood flow in response to uterine contractions in growth-restricted human fetuses.
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Fu Jing, Olofsson Per
Аннотация
OBJECTIVE: To explore middle cerebral artery (MCA) and anterior cerebral artery (ACA) blood flow responses to superimposed acute hypoxemia in growth-restricted fetuses with and without established brain-sparing flow during basal conditions.
MATERIAL AND METHODS: 47 term fetuses suspected of growth restriction were exposed to an oxytocin challenge test with simultaneous cardiotocography and Doppler velocimetry in the umbilical artery, MCA and ACA. The MCA-to-ACA pulsatility index (PI) ratio was calculated during basal conditions, contractions and relaxations. Basal brain-sparing flow was defined as an MCA-to-umbilical artery PI ratio of<1.08, de novo brain-sparing flow in the MCA as an MCA PI decrease with> or =1 standard deviation during uterine contractions or relaxations compared with basal measurements, and de novo brain-sparing flow in the ACA as an ACA PI decrease with > or =1 standard deviation. Non-parametric statistical tests were used with P<0.05 considered significant.
RESULTS: MCA and ACA PI were both significantly lower in the brain-sparing flow group (N=8) during basal conditions (P< or =0.01). During the oxytocin challenge test, MCA and ACA PI both decreased in the non-brain-sparing flow group (N=39) (P< or =0.02) but not in the brain-sparing flow group (P> or =0.4). The MCA-to-ACA PI ratio remained unchanged in both groups. de novo brain-sparing flow calculations revealed no preferential flow to any cerebral artery.
CONCLUSION: Cerebral circulatory responses to acute hypoxemia are synchronized in the middle and anterior cerebral arteries without any preferential regional flow distribution.
MATERIAL AND METHODS: 47 term fetuses suspected of growth restriction were exposed to an oxytocin challenge test with simultaneous cardiotocography and Doppler velocimetry in the umbilical artery, MCA and ACA. The MCA-to-ACA pulsatility index (PI) ratio was calculated during basal conditions, contractions and relaxations. Basal brain-sparing flow was defined as an MCA-to-umbilical artery PI ratio of<1.08, de novo brain-sparing flow in the MCA as an MCA PI decrease with> or =1 standard deviation during uterine contractions or relaxations compared with basal measurements, and de novo brain-sparing flow in the ACA as an ACA PI decrease with > or =1 standard deviation. Non-parametric statistical tests were used with P<0.05 considered significant.
RESULTS: MCA and ACA PI were both significantly lower in the brain-sparing flow group (N=8) during basal conditions (P< or =0.01). During the oxytocin challenge test, MCA and ACA PI both decreased in the non-brain-sparing flow group (N=39) (P< or =0.02) but not in the brain-sparing flow group (P> or =0.4). The MCA-to-ACA PI ratio remained unchanged in both groups. de novo brain-sparing flow calculations revealed no preferential flow to any cerebral artery.
CONCLUSION: Cerebral circulatory responses to acute hypoxemia are synchronized in the middle and anterior cerebral arteries without any preferential regional flow distribution.