Paediatric headbox as aerosol and droplet barrier

Background High-flow nasal oxygen (HFNO) is frequently used in hospitals, producing droplets and aerosols that could transmit SARS-CoV-2. Aim To determine if a headbox could reduce droplet and aerosol transmission from patients requiring HFNO. Methods The size and dispersion of propylene glycol (model for patient-derived infectious particles) was measured using a spectrometer and an infant mannequin receiving 10-50 L/min of HFNO using (1) no headbox, (2) open headbox, (3) headbox-blanket or (4) headbox with a high-efficiency particulate (HEP) filter covering the neck opening. Results All headbox set-ups reduced the dispersal of droplets and aerosols compared with no headbox. The headbox-blanket system increased aerosol dispersal compared with the open headbox. The fraction of aerosols retained in the headbox for HFNO of 10 and 50 L/min was, respectively, as follows: (1) open headbox: 82.4% and 42.2%; (2) headbox-blanket: 56.8% and 39.5%; (3) headbox-HEP filter: 99.9% and 99.9%. Conclusion A HEP-filter modified headbox may serve as an effective droplet and aerosol barrier adjunct for the protection of staff caring for children receiving HFNO.