How High-Flow Nasal Cannula Is Impacted by Nasogastric/Esophageal Tube: A Bench Study.

High-flow nasal cannula (HFNC) is a common noninvasive respiratory therapy for respiratory failure, offering positive airway pressure and dead space clearance. In critically ill patients, additional nasal tubes for feeding or monitoring are often required, but their effect on HFNC performance is not well understood. This bench study evaluated the impact of nasal tube placement on dead space clearance, nasopharyngeal pressure, and airway resistance using standard and asymmetrical cannulas. Inserting a 5-Fr tube with a standard cannula had very little effect, whereas bigger sizes (12-Fr and 16-Fr) slightly increased airway pressure and reduce Co2 clearance. An asymmetrical cannula exhibited variable effects depending on the side of the tube placement. Higher pressure and better clearance were achieved with a tube placed in the smaller cannula side. However, if occlusion of the two nares becomes excessive with the tube in place, downsizing the cannula might be recommended.