The machines used to administer gas in hospitals today, now mix nitrous oxide gas with pure oxygen (instead of room air). The levels of the mix can usually be adjusted to ranges from 100% pure Oxygen up to Nitrous Oxide 70% with Oxygen 30% (or 70:30). These are 'safety ranges', ensuring that the woman never receives less than the equivalent of room air oxygen (about 21%) and allowing the caregiver to provide pure oxygen to the woman if needed.
Nitrous oxide can also come in a pre-mixed, blue cylinder (called 'Entonox' or 'Equinox') with a set ratio of 50% Nitrous Oxide and 50% Oxygen (or 50:50). The woman needs at least 50% Nitrous oxide to provide a level of pain relief for labour. Higher concentrations (such as 70:30) are normally reserved for when the gas is used for medical interventions.
Last revised: Wednesday, 5 December 2012
This article contains general information only and is not intended to replace advice from a qualified health professional.