BACKGROUND: There is a persistent concern over the risk of respiratory pathogen transmission, including SARS-CoV-2, via the formation of aerosols (ie, a suspension of microdroplets and residual microparticles after evaporation) generated during high-flow nasal cannula (HFNC) oxygen therapy in critically ill patients. This concern is fueled by limited available studies on this subject. In this study, we tested our hypothesis that HFNC treatment is not associated with increased aerosol formation as compared to conventional oxygen therapy. METHODS: We used laser light scattering and a handheld particle counter to detect and quantify aerosols in healthy subjects and in adults with acute respiratory disease, including COVID-19, during HFNC or conventional oxygen therapy. RESULTS: The use of HFNC was not associated with increased formation of aerosols as compared to conventional oxygen therapy in both healthy subjects (n 5 3) and subjects with acute respiratory disease, including COVID-19 (n 5 17). CONCLUSIONS: In line with scarce previous clinical and experimental findings, our results indicate that HFNC itself does not result in overall increased aerosol formation as compared to conventional oxygen therapy. This suggests there is no increased risk of respiratory pathogen transmission to health care workers during HFNC.

Non-invasive ventilation (NIV) is increasingly used in the supportive treatment of acute respiratory failure in children in the pediatric intensive care unit (PICU). However, finding an optimal fitting commercial available NIV face mask is one of the major challenges in daily practice, in particular for young children and those with specific facial features. Large air leaks and pressure-related skin injury due to suboptimal fit are important complications associated with NIV failure. Here, we describe a case of a 4-year old boy with cardiofaciocutaneous syndrome and rhinovirus-associated hypoxic acute respiratory failure who was successfully supported with NIV delivered by a simple anesthetic mask connected to a headgear by an in-house developed and 3D printed adaptor. This case is an example of the clinical challenge related to pediatric NIV masks in the PICU, but also shows the potential of alternative NIV interfaces e.g., by using a widely available and relatively cheap simple anesthetic mask. Further personalized strategies (e.g., by using 3D scanning and printing techniques) that optimize NIV mask fitting in children are warranted.

ConclusionReference values and equations could be defined for VDalv and VCO2. More subsequent research is warranted to confirm the current findings and validate the presented prediction equations