Effect of Humidification on Fraction of Inspired Oxygen with Nasal Oxygen Therapy

We incorporated the Michigan Dual Adult Training & Test Lung (TTL), Laerdal Airway Management Trainer, and two mechanical ventilators in a model to imitate spontaneous breathing. Then we monitored and compared the FIO2 in the TTL bellows as oxygen therapy with or without a bubble-type humidifier through a nasal cannula with different flow rates on the Laerdal Airway Trainer, with an open or closed mouth states. We use the paired t-test, two-tailed, α=0.05, to compare FIO2 data between using and not using a humidifier. The research data shows, in open or closed mouth breathing states, using the humidifier always resulted in lower FIO2 than not using the humidifier, with statistical significance. As with humidifier use or non-use, open mouth breathing always resulted in higher FIO2 than closed mouth breathing, with statistical significance. In conclusion, bubble-type humidification with nasal cannula oxygen therapy resulted in a lower FIO2 than dry nasal oxygen therapy. Nasal oxygen therapy in open mouth breathing produces a higher FIO2 than in closed mouth breathing. Bubble-type humidifier should be used with caution clinically. The inappropriate use of the oxygen therapy device may cause inadvertent hypoxia. Besides, open mouth breathing can elevate FIO2 during nasal cannula oxygen therapy.