Heated and Humidified Oxygen in Critical Care Transport: Evaluating the Use of Aerogen Pro-X Nebulizer as an...

Heated, humidified oxygen therapy is commonly used to support hypoxemic, nonintubated patients. Conventional high-flow nasal cannula (HFNC) systems are effective in hospital settings but are often large and less practical for use during critical care transport. Portable aerosol-generating devices offer a compact, transport-friendly alternative; however, a performance gap exists in their ability to maintain appropriate temperature and humidity under varying conditions compared with HFNC. We compared the effectiveness of a heated humidification device, Hamilton H900 (H900), with that of an aerosol-generating device, Aerogen Pro-X (Aerogen).

The Aerogen was tested with a Hamilton T1 ventilator set to "high-flow oxygen device mode," as used in emergency responses. Using a hygrometer, we measured humidity and temperature outputs at 3 different set flow rates and 6 different set fractions of inspired oxygen (FiO₂) levels. Each condition was tested the following 3 times: baseline establishment, Aerogen, and H900.

Across all conditions, the H900 delivered significantly higher temperatures than the Aerogen, with an estimated marginal mean of 38.56°C ± 0.34°C (101.41°F ± 2.61°F) compared with 19.62°C ± 0.34°C (67.32°F ± 2.61°F) for the Aerogen (95% confidence interval [CI]). In contrast, the Aerogen delivered significantly higher relative humidity (RH) than the H900 at 85.9% ± 0.9% compared with 57.7% ± 0.9% for the H900 (95% CI); however, its absolute humidity was lower than that of the H900 (14.53 mg/L vs. 27.42 mg/L for the H900). For both devices, RH decreased as FiO₂ and flow rate increased (P < .001). At the highest settings (FiO₂ 100%, 60 liters per minute), RH declined to 71.3% ± 3.8% for the Aerogen and 42.3% ± 3.8% for the H900 (95% CI).

The H900 maintained near-physiological temperatures, whereas the Aerogen demonstrated near-physiological RH. Although each device performed well within a specific domain, neither independently provided guideline-compliant humidification and temperature control across tested conditions. These findings support the development of a portable HFNC system that integrates efficient humidification with active temperature control for use in transport settings.