Objective and methods: As the result of vigorous bubbling, infants receiving continuous positive airway pressure (CPAP) by an underwater seal (bubble CPAP) were observed to have vibrations of their chests at frequencies similar to high-frequency ventilation (HFV). We performed a randomized crossover study in 10 premature infants ready for extubation to test whether bubble CPAP contributes to gas exchange compared to conventional ventilator-derived CPAP. Measurements of tidal volume and minute volume were made using the Bear Cub neonatal volume monitor, and gas exchange was measured using an oxygen saturation monitor and a transcutaneous carbon dioxide (tcpCO2) monitor.
Results: There was a 39% reduction in minute volume (p < 0.001) and a 7% reduction in respiratory rate (p = 0.004) with no change in tcpCO2 or O2 saturation for infants supported with bubble versus ventilator-derived CPAP.
Conclusions: The lack of difference in blood gas parameters associated with a decrease in the infant's minute volume and respiratory rate with bubble CPAP compared with ventilator-derived CPAP suggests that the chest vibrations produced with bubble CPAP may have contributed to gas exchange. Bubble CPAP may offer an effective and inexpensive option for providing respiratory support to premature infants.