Novel Adaptive High-Flow Oxygen Therapy

Abstract Rationale: High-flow oxygen therapy (HFOT) enhances oxygenation and patient comfort but may be limited by its linear flow. We investigated a novel adaptive high-flow mode, Manual Positive Airway Pressure (Manual PAP), designed to increase flow during inspiration and decrease it during expiration. This study evaluates the efficacy of Manual PAP across five pressure settings.Methods: Using a Bellavista 1000e ventilator (Zoll, MA, USA) connected to an ASL 5000 lung simulator, we modeled an adult male patient with an ideal body weight of 66 kg, compliance of 40 mL/cmH₂O, and resistance of 10 cmH₂O/L/s. The respiratory rate was set to 20 breaths per minute with a 1-second inspiratory time. Muscle pressure (Pmus) was varied in 5 cmH₂O increments, from 5 to 30 cmH₂O. Manual PAP was applied through a nasal cannula. Maximum and minimum flow across pressure settings (1-5 cmH₂O) were recorded at each pressure level and used to calculate r values. Generative AI was also used in writing abstract and figure.Results: Pearson correlation analysis demonstrated strong relationships between Pmus and both maximum and minimum flow across pressure settings, with most R values achieving statistical significance (P < 0.05). R values for each setting were as follows: Max Flow: Pressure 1cmH₂O (R = 0.986), Pressure 2cmH₂O (R = 0.948), Pressure 3 cmH₂O(R = 0.985), Pressure 4cmH₂O (R = 0.918), Pressure 5cmH₂O (R = 0.947)Min Flow: Pressure 1cmH₂O (R = -0.859), Pressure 2cmH₂O (R = -0.851), Pressure 3cmH₂O (R = -0.735), Pressure 4cmH₂O (R = -0.786), Pressure 5cmH₂O (R = 0.923) All R values were statistically significant (P < 0.05) except for min flow at pressures 3 and 4. Although min flow correlations for pressures 3 and 5 were not statistically significant or not negative. The mean flow remained relatively constant with delta flow between P mus 5 and pmus 30 being < 5L/min for each pressure settingConclusion: The results demonstrate a strong positive correlation between maximum flow and Pmus, and a negative correlation with minimum flow except for pressure setting 3,4 and 5, indicating increased flow in response to patient inspiratory effort while potentially keeping mean flow stable by reducing flow during expiration. This increased flow during inspiration and reduced flow during expiration should improve oxygenation and CO2 washout. These effects are more pronounced with deeper breaths, reflected by increasing Pmus. Further studies in-vivo are needed to confirm clinical significance of these results.