Healthcare Worker Inhalation Exposure of Fugitive Aerosols During Nebulization Treatment: In Vitro Quantification

Abstract

Background:

Aerosol therapy is crucial for treating respiratory conditions by delivering medication directly to the lungs. However, secondhand aerosol exposure among healthcare workers (HCWs) during nebulization poses significant health risks. This study aimed to quantify the inhalation exposure of clinicians during nebulization treatments.

Methods:

Experiments were conducted at 22°C in an ICU room at Rush University Medical Center, using a simulated adult spontaneous breathing model with breathing parameters of tidal volume 470 mL, frequency 21 breaths/min, and inspiratory time 1.1 s. Nebulization was administered via mouth-breathing with an aerosol mask and tracheostomized breathing with a T-piece or trach collar (tracheostomy tube size 8.0 mm). Two simulated HCW models were positioned at 1 ft and 3 ft from the patient model (Figure 1). The T-piece setup also involved positioning the 1 ft HCW directly facing the T-piece reservoir and at the opposite side of the T-piece reservoir. Albuterol sulfate (15 mg/3 mL) was nebulized via a jet nebulizer in two consecutive sessions, totaling 30 mg in 30 min. The inhaled drug captured on the collecting filters placed between the trachea and the model lung was assayed using ultraviolet spectrophotometry at 276 nm. Particle concentrations at 1 μm were continuously measured at 1 ft and 3 ft from the patient model using two particle concentration counters, with intervals of 20-30 min between experiments to allow particle concentration to return to baseline.

Results:

During nebulization, HCWs’ inhaled doses were similar across all settings, interfaces, and distances (all P >.05), with a peak inhaled dose observed with tracheostomy via trach collar (0.29 ± 0.05 at 1 ft and 0.22 ± 0.05% at 3 ft) (Figure 2A). Particle concentrations were similar at 1 ft and 3 ft, except for the trach collar, where concentrations were higher at 1 ft compared to 3 ft ([1.82 ± 0.33] vs [0.17 ± 0.05 ] x 10⁸ particles/m³), (P = .0286) (Figure 2B).

Conclusions:

Exposure to fugitive aerosol particles during nebulization treatment was consistent across all tested interfaces and patient-HCW distances, with inhaled doses ranging from 0.1% to 0.3%. Further studies are required to assess the potential risk this level of exposure to secondhand fugitive aerosols represents to HCWs.

Figure 1: Experimental setup for quantifying healthcare worker (HCW) inhalation exposure to fugitive aerosols during nebulization treatment. The setup includes a patient manikin connected to a lung simulator via a ventilator, and two clinician manikins positioned at distances of 1 ft and 3 ft from the patient. Collecting filters are placed to capture aerosol particles, while protection filters are used to protect the lung simulators and prevent water buildup. This configuration simulates different scenarios involving mouth-breathing with an aerosol mask and tracheostomized breathing through a T-piece or trach collar.

(A) Inhaled dose (%) of albuterol for healthcare workers (HCWs) positioned at distances of 1 ft and 3 ft from the patient model. The inhaled doses were measured for different scenarios: at the reservoir side, opposite to the reservoir, using a trach collar, and using an aerosol mask.(B) Particle concentration (particles/m³) measured at distances of 1 ft and 3 ft from the patient model. Particle concentrations were recorded for different scenarios: at the reservoir side, opposite to the reservoir, using a trach collar, and using an aerosol mask.