Birthing women denied nitrous oxide(N20) to relieve labour pain as a result of the COVID pandemic received opioids instead, without any adverse outcomes for mother or child, according to a new study published in the Australian and New Zealand Journal of Obstetrics and Gynaecology. Some anaesthetists have also argued for reducing N20 use as it is a greenhouse gas.
The study, conducted at Lyell McEwin Hospital in Australia, looked at the impact of withholding nitrous oxide (N20), a decision adopted by many hospitals worldwide over fears of virus transmission from the aerosol-generating procedure.
Anaesthetist Professor Bernd Froessler and colleagues compared patient notes for all 243 women birthing at Lyell McEwin over a seven week period in March/April 2020, half of whom did not have access to N20.
They found that although opioid use “significantly increased” when N20 was withheld, there was no increase in epidural use and no change in labour duration, Caesarean section rates, birthing complications or newborn alertness.
Nitrous oxide is used by more than 50% of Australian women to relieve pain in labour, followed by epidurals (40%) and opioids (12%), according to the Australian Institute of Health and Welfare.
However, N20 represents 6% of global greenhouse gas emissions, with 1% due to medical use (ie, around 0.06% of total global warming is due to medical N20). This has led to a debate in medical circles whether it should be replaced with other methods of pain relief.
Many obstetricians argue that effective pain relief in childbirth should be the priority, particularly given the low percentage of emissions, but the Australian and New Zealand College of Anaesthetists has advocated for a reduction in N20 use in a bid to improve environmental sustainability in anaesthesia.
“Obviously no-one wants to deprive labouring women of adequate and easy pain relief but given there are other analgesic options, including epidurals and opioids, perhaps these could be considered,” said Prof Froessler.
UniSA statistician and researcher Dr Lan Kelly said that the findings should reassure women that pain relief besides N20 does not compromise their health or their baby’s.
However, in a recent Sydney Morning Herald article, principal midwifery officer at the Australian College of Midwives, Kellie Wilton, said mothers should not be made to feel guilty about their pain relief choices and suggested hospitals could introduce nitrous oxide destruction systems to allow for its ongoing use.
When nitrous oxide destruction systems were introduced in Swedish hospitals, the carbon footprint from the gas was halved.
Source: University of South Australia
