Maternal hyperoxygenation: A potential therapy for congenital heart disease in the fetuses? A systematic review of the current literature

Objectives: To assess efficacy, safety, outcomes, and intrauterine complications following maternal hyperoxygenation (MH) therapy in fetuses with congenital heart disease (CHD).

Methods: A systematic review was performed following an electronic search of databases. Articles were published before January 1, 2017, in an English-language and non-English-language journals (with English translations), and included human fetuses and expectant mothers with a fetal diagnosis of CHD who received MH.

Results: Ninety-six articles were identified; 72 were excluded and 24 full-text articles were reviewed. Only 9 articles met inclusion criteria and were analyzed. A total of 270 fetuses underwent MH therapy: 169 had CHD, and 101 had normal heart anatomies. Seven studies used fetal echocardiography, while 2 studies used cardiac magnetic resonance imaging (CMR). The mean gestational age at therapy was 33.4 weeks (26-38 weeks). Majority of MH protocols used 100% FiO₂ with non-rebreather face mask at 8 L of flow, achieving 60%-70% FiO₂ , or maternal PaO₂ goal of 250 mm Hg. No significant adverse events were reported. Four studies reported increased size of the hypoplastic cardiac structures after MH. Three studies utilized acute MH to risk stratify hypoplastic left heart syndrome fetuses. Two studies assessed acute MH in the setting of CMR.

Conclusion: The current evidence for MH therapy suggests an increase in pulmonary blood flow, and venous return, ductal flow, and heart dimensions in fetuses. MH has potential as a diagnostic and therapeutic tool in fetuses with CHD. Further randomized controlled trials are needed to ascertain whether MH therapy provides improved outcomes on fetuses with certain types of CHD.