Objective: 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).Methods: 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 (FiO 2 ) levels.Each condition was tested the following 3 times: baseline establishment, Aerogen, and H900.Results: Across all conditions, the H900 delivered significantly higher temperatures than the Aerogen, with an estimated marginal mean of 38.56C 0.34C (101.41F 2.61F) compared with 19.62C 0.34C (67.32F 2.61F) 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. 27.42mg/L for the H900).For both devices, RH decreased as FiO 2 and flow rate increased (P < .001).At the highest settings (FiO 2 100%, 60 liters per minute), RH declined to 71.3% 3.8% for the Aerogen and 42.3% 3.8% for the H900 (95% CI). Conclusion: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.
Karas et al. (Sun,) studied this question.