Comparative Efficacy of Humidifiers in Noninvasive Infant Respiratory Support
Introduction: Infant respiratory distress is a significant problem worldwide and there is considerable need for affordable respiratory support devices in low-resource settings. We compare the efficacy of three humidifier setups and a control with no humidification device.
Methods: In a hospital patient room (22ºC, 50% humidity), the temperature and humidity delivered to a balloon-simulated patient lung (38ºC) via a BC161-10 Fisher Paykel bubble CPAP system was measured with the following devices: Fisher Paykel heated humidifier, custom-built low-cost heated humidifier, standard passive non-electric Salter Labs bubbling humidifier, and a control with no humidifier. Delivered CPAP set at 5cm H2O and flow rate varied from 4-8L/min in 2L/min increments.
Results: As the flow rate was varied from 4-8 LPM, the 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%), heated humidifier 91% (0.86%). The delivered temperature with the F&P humidifier was 38-39ºC, the temperature for the heated device was 34ºC, and the temperature for the bubble cup and control was 33ºC.
Discussion: There is a significant difference in relative humidity generated by each device. The F&P humidifier provides the highest humidity, the passive bubbler provides considerably more humidity than the control, and the custom-built device 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 inexpensive solution for heat and humidification could be developed.