Comparative Efficacy of Humidifiers for Noninvasive Infant Respiratory Support

Delivery of cold, dry air to infants while supporting their breathing can lead to hypothermia in addition to irritating and damaging their sensitive nares and negatively impacting outcomes with these therapies. In high resource settings, electric heated humidifiers are used to mitigate this problem. In many resource-constrained settings, passive nonelectric bubbling humidifiers are instead used. We here compare the efficacy of conventional electric heated humidification, custom-built low cost heated humidification, passive nonelectric bubbling humidification and a control of no humidification. In a hospital patient room (temperature 22 °C, humidity 50%), the temperature and humidity delivered to a simulated patient lung via a BC161-10 Fisher Paykel bubble continuous positive airway pressure (CPAP) system were measured with conventional electric heated humidification, low cost custom-built heated humidification, passive bubbling humidification and no humidification. (Delivered CPAP: 5 cm H2O; flowrate varied from 4 to 8 liters per minute (LPM) in 2 LPM increments.) As the flowrate was varied from 4 to 8 LPM, delivered relative humidity (standard deviation) with each humidifier was as follows: control 10% (3.6%), passive bubbler 44% (3.7%), custom-built humidifier 67% (1.7%), electric heated humidifier 91% (0.86%). Delivered temperature with the electric heated humidifier was 38 °C (0.21 °C) versus 33 °C for all other setups. Conventional electric heating humidification is more effective than passive bubbling humidification, and the custom-built low cost humidifier provides an intermediate degree of humidification. Through further improvement of this concept with a heated inspiratory circuit and sensor based control of the heating element, an effective yet low cost solution heating humidification could be developed.