Evaluating the factors that affect fugitive emissions during nebulisation events

Many healthcare workers and bystanders may be needlessly exposed to medication during nebulisation intended for a patient. This study was completed to quantify the potential for fugitive emissions during simulated mechanical ventilation, and whether varying tidal volume, distance and use of filters were significant factors affecting the emitted mass concentration. A mechanical ventilator (MV) was set up with an artificial lung to simulate a patient requiring assisted breathing. Two aerodynamic particle sizers (APS) were placed at a distance of 0.8 m and 2.0 m from the ventilator to measure mass concentration. A vibrating mesh nebuliser (VMN) was used to nebulise 4 mg of salbutamol. Tidal volume (Vt) was varied at Vt = 270 ml and 820 ml (based on an average adult of 69 kg, 4ml per kg and 12ml per kg respectively). A single membrane expiratory filter, a pleated hydrophobic filter and no filter were used at the exhale port of the ventilator to investigate their impact on fugitive emissions.

It was found that at higher tidal volumes, higher mass concentrations were detected. Also, when a filter is placed on the MV it significantly reduces secondary aerosols. This indicates that the ventilatory parameters have an impact on the emitted mass concentrations.

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