Fugitive aerosol therapy emissions during mechanical ventilation: In vitro assessment of the effect of tidal volume and use of protective filters

Background: During mechanical ventilation of a patient requiring ventilatory support, bystanders could potentially be exposed to aerosolised drug. Methods: Fugitive drug aerosol emissions during simulated adult mechanical ventilation was assessed on a dual limb circuit. Tidal volume was set at 270 mL and 820 mL. The use of a protective filter on the exhalation port of the mechanical ventilator was assessed. Results: Higher fugitive aerosol mass concentrations in the local environment were associated with larger tidal volume (0.077 (0.073, 0.091) mg m^–3 at V_t = 820 mL vs. 0.062 (0.056, 0.065) mg m^–3 at V_t = 270 mL) when no protective filter was used. The range of mass median aerodynamic diameters recorded was from 0.93 to 2.96 µm. When a filter was placed on the exhalation port of the mechanical ventilator, no fugitive emissions were recorded. Conclusion: This study confirms that an appropriate filtration protocol mitigates the risk of fugitive emissions being released when patients undergo aerosol therapy during mechanical ventilation. A larger tidal volume resulted in higher fugitive aerosol mass.