A short session of maternal hyperoxygenation ameliorates the cerebral oxygenation difference between fetuses with and without congenital heart defects

Abstract

Objectives: To assess if a 10 min session of maternal hyperoxygenation increases cerebral tissue oxygenation as measured by magnetic resonance imaging (MRI) T2* in fetuses with and without congenital heart defects (CHDs). Study design: At mean gestational ages of 32 (early) and 37 (late), we measured fetal cerebral T2* before and during the last minutes of a 10 min maternal hyperoxygenation (oxygen 10 l/min, Hudson non-rebreathing mask) in 22 fetuses without CHDs and 11 fetuses with CHDs using a 1.5 Tesla Philips scanner with a breath-hold, multi-echo, gradient-echo sequence. Results: During maternal hyperoxygenation equilibrium, the mean fetal cerebral T2* values in CHD fetuses seemingly normalized and were comparable to those in fetuses without CHD breathing ambient air. Hyperoxygenation T2* was 160 ms (CI 149–170) early and 123 ms (CI 112–134) late in fetuses with CHD and ambient air T2* was 158 ms (CI 152 to 164) early and 126 ms (CI 120–131) late in fetuses without CHD, (p=0.97). Lower ambient air cerebral T2* z-score at the late-stage scan was correlated with lower head circumference z-scores at birth. Conclusion: Our findings suggest that fetal cerebral oxygenation in CHD fetuses can reach normal values during a short session of maternal hyperoxygenation. This supports the hypothesis that tissue hypoxia can influence brain development in fetuses with CHD. However, since side effects of fetal hyperoxygenation have been described, it remains to be determined if chronic maternal hyperoxygenation has a positive impact on the fetal brain in CHDs.

Keywords

• Congenital heart defect
• Fetal development
• Outcome
• Magnetic resonance imaging
• Brain imaging
• Hyperoxygenation