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Near-field airborne particle concentrations in young children undergoing high-flow nasal cannula therapy: a pilot
E T Gall1, A Laguerre1, M Noelck2
1Department of Mechanical and Materials Engineering, Portland State University, Portland, OR, USA.
Insights
High-flow nasal cannula therapy (HFNC) did not increase near-patient aerosol particle counts in children. This study suggests HFNC use may not significantly elevate healthcare worker exposure risk to airborne pathogens.
Area of Science:
- Pediatric respiratory care
- Infectious disease transmission
- Aerosol science
Background:
- High-flow nasal cannula therapy (HFNC) is utilized in pediatric care but may pose risks to healthcare workers due to increased aerosol generation, particularly concerning SARS-CoV-2.
- Understanding aerosol dispersion during HFNC is crucial for implementing effective infection control measures.
Purpose of the Study:
- To investigate if HFNC use in children generates more aerosols in the near-field environment.
- To determine if HFNC flow rate correlates with aerosol particle concentration and dispersion.
Main Methods:
- Particle concentrations and dispersion were measured at various distances from pediatric subjects (4 weeks to 24 months) receiving HFNC at different flow rates.
- Near-field measurements within 0.5m were adjusted using far-field room measurements, with CO2 and humidity also monitored.
- The study focused on aerosols with a diameter of 0.3-10 μm.
Main Results:
- Near-field breathing plane aerosol concentrations (0.3-10 μm) were slightly elevated by the patient's presence without HFNC compared to the room's far-field.
- Despite observed variability in particle emission and dispersion among subjects, HFNC use at any flow rate showed no association with increased near-field particle counts.
- Elevated CO2 levels confirmed measurements were taken within the breathing plane.
Conclusions:
- The particle sampling methodology is practical for hospital settings, with adjusted near-patient aerosol and CO2 levels potentially serving as exposure risk proxies.
- This pilot study indicates that HFNC in pediatric patients does not significantly impact near-patient aerosol levels (0.3-10 μm) or CO2 concentrations.
Background:
High-flow nasal cannula therapy (HFNC) may increase aerosol generation, putting healthcare workers at risk, including from SARS-CoV-2.
Aim:
To examine whether use of HFNC increases near-field aerosols and whether there is an association with flow rate.
Methods:
Subjects aged four weeks to 24 months were recruited. Each child received HFNC therapy at different flow rates. Three stations with particle counters were deployed to measure particle concentrations and dispersion in the room: station 1 within 0.5 m, station 2 at 2 m, and station 3 on the other side of the room. Carbon dioxide (CO2) and relative humidity were measured. Far-field measurements were used to adjust the near-field measurements.
Findings:
Ten children were enrolled, aged from 6 to 24 months (median: 9). Elevated CO2 indicated that the near-field measurements were in the breathing plane. Near-field breathing plane concentrations of aerosols with diameter 0.3-10 μm were elevated by the presence of the patient with no HFNC flow, relative to the room far-field, by 0.45 particles/cm3. Whereas variability between subjects in their emission and dispersion of particles was observed, no association was found between HFNC use, at any flow rate, and near-field particle counts.
Conclusion:
This method of particle sampling is feasible in hospital settings; correcting the near-patient aerosol and CO2 levels for the room far-field may provide proxies of exposure risk to pathogens generated. In this pilot, near-patient levels of particles with a diameter between 0.3 and 10 μm and CO2 were not affected by the use of HFNC.
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