Effect of flow rate, humidifier dome and water volume on maximising heated, humidified gas use for neonatal resuscitation

AimDry, cold gas is used for neonatal resuscitation, contributing to low admission temperatures and exacerbation of lung injury. Recently, a method of heating and humidifying neonatal resuscitation gases has become available. We aimed to determine the optimal flow rate, humidifier chamber and water volume needed to reach 36 °C, and near 100% humidity at the patient T-piece in the shortest possible time.MethodA T-piece resuscitator was connected via a heated patient circuit to a humidifier chamber. Trials were performed using different gas flow rates (6, 8 and 10 L/min), humidification chambers (MR290, MR225) and water volumes (30 g, 108 g). Temperature was recorded at the humidifier chamber (T1), distal temperature probe (T2) and the T-piece (T3) over a 20 min period at 30 s intervals. A test lung was added during one trial.ResultsNo significant difference existed between flow rates 8 L/min and 10 L/min (p = 0.091, p = 0.631). T3 reached 36 °C and remained stable at 360 s (8 L/min, MR225, 30 mL); near 100% RH was reached at 107 s (10 L/min, MR225, 30 mL). T3 and humidity reached and remained stable at 480 s (10 L/min, MR290, 30 mL). Target temperature and humidity was not reached with the test lung.ConclusionsIt is possible to deliver heated, humidified gases in neonatal resuscitation in a clinically acceptable timeframe. We suggest the set-up to achieve optimal temperature and humidity for resuscitation purposes is 10 L/min of gas flow, a MR290 humidification chamber, and 30 mL of water.