Aerosol generation in children undergoing high flow nasal cannula therapy
AbstractObjectiveHigh flow nasal cannula therapy (HFNC) may increase aerosol generation, putting health care workers at increased risk of infection, including from SARS-CoV-2. This study examined whether use of HFNC increases near-field aerosols and if there is a relationship between flow rate and near-field aerosol concentrations.Patients and MethodsSubjects between 30 days and 2 years of age were enrolled. Each child received HFNC therapy at different flow rates over time. Three sampling
... Three sampling stations with particle counters were deployed to measure aerosol generation and dispersion in the room: station one within 0.5 m of the subject, station two at 2 m, and station three on the other side of the room. We also measured carbon dioxide (CO2) and relative humidity. Station three (far-field) measurements were used to adjust the station one (near-field) measurements for room conditions.ResultsWe enrolled ten children ranging from 6-24 months (median 9 months), two with respiratory illness. Elevated CO2 indicated the near-field measurements were in the breathing plane of the subjects. Near-field breathing plane concentrations of aerosols with diameter 0.3 – 10 µm are elevated by the presence of the patient with no HFNC flow, relative to the room far-field, by 0.45 #/cm3. While we observed variability between subjects in their emission and dispersion of particles, we did not find an association between HFNC and near-field elevations of particle counts.ConclusionNear-patient levels of particles with diameter in the 0.3-10 µm range was not affected by the use of HFNC in healthy patients. Further study on older children and children with increased mucus production may be warranted.