Yesterday I was surprised by a newly published paper in the American Journal of Obstetrics and Gynaecology by Raghuraman et al, which investigated the effect of giving oxygen to women during labour when they had abnormal fetal heart rate patterns recorded by CTG monitoring. Here is what they said about the outcome:
Intrapartum maternal O2 administration for Category II EFM did not resolve high risk Category II features or hasten the resolution of recurrent decelerations. These results suggest that O2 administration has no impact on improving Category II EFM patterns.Raghuraman, et al., 2020.
It wasn’t the findings that surprised me. What surprised me was discovering that in other parts of the world, oxygen use during labour is still common place.
If your practice continues to involve applying oxygen when the CTG is abnormal but the woman is well oxygenated, please desist forthwith. It doesn’t modify the heart rate pattern (and these researchers are far from the first to report this). Fussing about with oxygen masks draws clinician’s attention away from doing something that might be more appropriate, like identifying whether this is an appropriate physiological response to the eustress of labour, or whether something pathological is happening, for instance.
It is also potentially harmful – as Chandraharan recently pointed out:
In fact, the Cochrane Systematic Review on maternal oxygen therapy to treat fetal heart rate abnormalities has concluded that not only there was no evidence that this intervention would help improve perinatal outcomes, abnormal cord blood pH values (less than 7.2) were recorded significantly more frequently in the oxygenation group than the control group (RR 3.51, 95% CI 1.34 to 9.19). This finding should not be surprising to any obstetrician or midwife who understands human physiology because excessive oxygen administration to the mother (i.e. hyperbaric oxygen) may lead to vasospasm of the spiral arterioles supplying the placental bed, leading to increased risk of hypoxia and acidosis in the fetus. Moreover, excessive oxygen may also lead to the production of oxygen-free radicals which may increase the risk of fetal neurological injury.Chandraharan, 2020, p. 13.
What this paper highlighted to me was the way that clinical practice standards around the world continue to be far from evidence-based. This is particularly the case when it comes to all things related to intrapartum fetal heart rate monitoring. Don’t assume that because something is standard practice in your part of the world that it is based in sound evidence.
Chandraharan, E. (2020). Maternal “Oxygen and Fluids Therapy” to Correct Abnormalities in the Cardiotocograph (CTG): Scientific Principles vs Historical (Mal) Practices. Journal of Advances in Medicine and Medical Research, 10-16. https://doi.org/10.9734/jammr/2020/v32i830460
Raghuraman, N., Lopez, J., Carter, E., Macones, G., Tuuli, M., & Cahill, A. (2020). The effect of intrapartum oxygen supplementation on Category II fetal monitoring. American Journal of Obstetrics and Gynecology, in press. https://doi.org/10.1016/j.ajog.2020.06.037