Respiratory Particle Emissions in Tracheostomized Outpatients: Comparable to Healthy Volunteers

Humans continuously emit respiratory particles during routine activities (breathing, speaking, coughing), and these can carry pathogens. Particle size and site of origin determine suspension time, deposition, and transmission risk. Tracheostomy makes the airflow bypass the upper airway partly or in full. Its effect on aerosol generation is unclear; therefore, we compared emissions between tracheostomized and healthy volunteers during tidal breathing, deep breathing, speaking, and coughing, and examined differences across activities within the tracheostomized group.

Aerosol emissions of 10 tracheostomized, uninfected volunteers and 16 healthy volunteers were measured with a portable aerosol spectrometer. Tracheostomized participants were measured with and without a heat moisture exchanger. A Mann-Whitney U-test was used to compare aerosol emissions between tracheostomized participants and healthy controls. Wilcoxon signed-rank test was used to compare paired measurements within the same individuals in the tracheostomized group.

Tracheostomy, whether occluded or not occluded, does not produce significantly more aerosol than healthy participants. Most detected particles were < 1 μm (≈90% of measurements), with medium particles ≈50% and large particles uncommon.

In stable outpatients, aerosol emissions did not differ between the three groups across common respiratory activities, suggesting the exhalation route is not a major determinant of emission under these conditions. The impact of tracheostomy care procedures, such as suctioning, was not evaluated in this study.

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