Sister hospitals in Bosnia.

Abstract

<h3>Background</h3> High-flow nasal cannula (HFNC) is an emerging therapy for respiratory failure but the extent of exhaled air dispersion during treatment is unknown. We examined exhaled air dispersion during HFNC therapy <i>versus</i> continuous positive airway pressure (CPAP) on a human patient simulator (HPS) in an isolation room with 16 air changes·h⁻¹. <h3>Methods</h3> The HPS was programmed to represent different severity of lung injury. CPAP was delivered at 5–20 cmH₂O <i>via</i> nasal pillows (Respironics Nuance Pro Gel or ResMed Swift FX) or an oronasal mask (ResMed Quattro Air). HFNC, humidified to 37°C, was delivered at 10–60 L·min⁻¹ to the HPS. Exhaled airflow was marked with intrapulmonary smoke for visualisation and revealed by laser light-sheet. Normalised exhaled air concentration was estimated from the light scattered by the smoke particles. Significant exposure was defined when there was ≥20% normalised smoke concentration. <h3>Results</h3> In the normal lung condition, mean±sd exhaled air dispersion, along the sagittal plane, increased from 186±34 to 264±27 mm and from 207±11 to 332±34 mm when CPAP was increased from 5 to 20 cmH₂O <i>via</i> Respironics and ResMed nasal pillows, respectively. Leakage from the oronasal mask was negligible. Mean±sd exhaled air distances increased from 65±15 to 172±33 mm when HFNC was increased from 10 to 60 L·min⁻¹. Air leakage to 620 mm occurred laterally when HFNC and the interface tube became loose. <h3>Conclusion</h3> Exhaled air dispersion during HFNC and CPAP <i>via</i> different interfaces is limited provided there is good mask interface fitting.