ORIGINAL ARTICLE Quantifying temperature and relative humidity of medical gases used for newborn resuscitation Jennifer A Dawson, 1,2,3 Louise S Owen, 1,2,3 Robin Middleburgh 4 and Peter G Davis 1,2,3 1 The Royal Women’s Hospital, 2 Murdoch Childrens Research Institute, and 3 The University of Melbourne, Melbourne, Victoria, Australia and 4 University of Newcastle, Newcastle, England 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. Key words: humidification; medical air; oxygen. What is already known on this topic? 1 Most infants are resuscitated with gases described as ‘cold’ and ‘dry’. 2 Gases used for ongoing ventilation are usually heated and humidified. 3 Unconditioned gases can damage respiratory mucosa. What this paper adds? 1 Piped gases used for delivery room resuscitation are extremely dry. 2 The temperature of piped gases is similar to ambient temperature. 3 The relative humidity of piped oxygen is significantly drier than piped air. Background Newborn resuscitation guidelines have undergone significant changes over the past decade. The introduction of saturation targeting, the provision of blended air and oxygen, the use of positive end expiratory pressure and improved measures for thermoregulation have all been introduced 1 with the aim of improving neonatal outcomes. The use of heated, humidified gases in the delivery room may also improve outcomes by reducing hypothermia, 2 preserving mucosal function 3 and reducing respiratory complications. 4 However, the gases used to stabilise infants during resuscitation are usually unconditioned air and oxygen, often described as ‘cold and dry’, in comparison to the heated humidified gases used for ongoing ventilation in neonatal intensive care units (NICU). The aim of this study was to determine exactly how ‘cold and dry’ these unconditioned gases are. Method This observational study took place at The Royal Women’s Hos- pital (RWH), Melbourne, Australia. The RWH supplies piped air and oxygen to sites throughout the hospital including delivery rooms, operating theatres and the NICU. Piped gas outlets are fitted with flow meters and blenders (Bird Low Flow Air/O2 MicroBlender, Care Fusion, Dublin, OH, USA). We connected gas tubing and a t-connector to these flow meters and set gas flow to 10 L/min. A calibrated thermo- hygrometer and probe (Testo 635 and 9769, Testo AG, Lenzkirch, Germany) was inserted into the t-connector, such Correspondence: Dr Jennifer Dawson, Neonatal Services, The Royal Women’s Hospital, Corner Grattan Street and Flemington Road, Parkville, Vic. 3052, Australia. Fax: 0308345 3789; email: jennifer.dawson@ thewomens.org.au Conflict of interest: None declared. Author Contributions JAD: Conceived and designed the study, collected, analysed and inter- preted data, drafted the manuscript. LSO: Contributed to study design, collected, analysed and interpreted data, drafted the manuscript. RM: Contributed to data collection and editing of manuscript. PGD: Contributed to study design, data interpretation, drafting the manu- script, supervision of all aspects of the study. All authors approved the final version of the manuscript. Accepted for publication 29 May 2013. doi:10.1111/jpc.12393 Journal of Paediatrics and Child Health 50 (2014) 24–26 © 2013 The Authors Journal of Paediatrics and Child Health © 2013 Paediatrics and Child Health Division (Royal Australasian College of Physicians) 24