Quantifying temperature and relative humidity of medical gases used for newborn resuscitation

Aim: The gases used to stabilise infants during resuscitation are usually unconditioned air and oxygen, often described as 'cold and dry', in comparison with the heated, humidified gases used for ongoing ventilation in neonatal intensive care units. The aim of this study was to determine exactly how 'cold and dry' these unconditioned gases are.

Method: Multiple measurements of temperature and relative humidity (RH) of piped gases were recorded at different sites, and at different times of day, across The Royal Women's Hospital, Melbourne. Ambient temperature and relative humidities were also recorded.

Results: Eighty paired air and oxygen measurements of temperature and RH were recorded. Mean temperatures of piped oxygen and air were 23.3 (0.9) and 23.4 (0.9) °C respectively. Mean RH of piped air was 5.4 (0.7) %; piped oxygen was significantly drier, mean RH 2.1 (1.1) %.

Conclusion: Piped gases were delivered at room temperature and were extremely dry. This highlights the importance of research assessing the practicality of heating and humidifying resuscitation gases, and assessing the impact of their use on clinically important neonatal outcomes.