Maternal “Oxygen and Fluids Therapy” to Correct Abnormalities in the Cardiotocograph (CTG): Scientific Principles vs Historical (Mal) Practices

Abstract

Some Guidelines on Cardiotocograph (CTG) trace continue to recommend the administration of oxygen and fluids to the mother to correct the abnormalities observed on the cardiotocograph. However, the fetus has a separate autonomic nervous system, blood volume, haemoglobin concentration, oxygen saturation and cardiovascular responses as compared to the mother. Therefore, administration of oxygen and fluids to the mother to correct observed “suspicious” CTG traces should be questioned in contemporary obstetric practice. This commentary examines the scientific principles and current scientific evidence on these historical practices, and all practising midwives and obstetricians should urgently review their individual clinical practice, based on the knowledge of anatomy, physiology and biochemistry as well as a critical review of current scientific evidence to prevent avoidable patient harm. Current evidence suggests that administration of oxygen to the mother, who has a normal oxygen saturation does not correct the observed abnormalities on the CTG trace, and it may in fact lead to harm. Similarly, administration of fluids (oral or intravenous) to a woman during labour who is not dehydrated or hypotensive may not only cause maternal dilutional hyponatremia and resultant complications, but also, it may cause neonatal convulsions. Women and babies expect every healthcare provider to practice evidence-based medicine during the intrapartum period, which is based on logic, common sense and robust scientific principles, irrespective of what is erroneously stated by some CTG guidelines.

Peripartum hyponatraemia: an overview of physiology, prevention and management

“…Labouring women have a higher risk of water intoxication when fluid balance becomes positive by more than 1500 ml. The traditional practice of bolus intravenous fluid administration to correct abnormal fetal cardiotocographic patterns has recently been challenged in view of both lack of evidence and risk of maternal and neonatal hyponatraemia 19 …”

“…The traditional practice of bolus intravenous fluid administration to correct abnormal fetal cardiotocographic patterns has recently been challenged in view of both lack of evidence and risk of maternal and neonatal hyponatraemia. 19 Neuraxial analgesia (combined spinal-epidural or epidural anaesthesia) minimises emotional stress and painful contractions. However, maternal hypotension (caused by blockade of the sympathetic nervous system, which results in vasodilatation and subsequent 'functional' hypovolaemia), can lead to a need for intravenous fluids to ensure adequate uteroplacental perfusion.…”