Investigation of Fugitive Aerosols Released into the Environment during High-Flow Therapy

Abstract

Background: Nebulised medical aerosols are designed to deliver drugs to the lungs to aid in the treatment of respiratory diseases. However, an unintended consequence is the potential for fugitive emissions during patient treatment, which may pose a risk factor in both clinical and homecare settings. Methods: The current study examined the potential for fugitive emissions, using albuterol sulphate as a tracer aerosol during high-flow therapy. A nasal cannula was connected to a head model or alternatively, a interface was connected to a tracheostomy tube in combination with a simulated adult and paediatric breathing profile. Two aerodynamic particle sizers (APS) recorded time-series aerosol concentrations and size distributions at two different distances relative to the simulated patient. Results: The results showed that the quantity and characteristics of the fugitive emissions were influenced by the interface type, patient type and supplemental gas-flow rate. There was a trend in the adult scenarios; as the flow rate increased, the fugitive emissions and the mass median aerodynamic diameter (MMAD) of the aerosol both decreased. The fugitive emissions were comparable when using the adult breathing profiles for the nasal cannula and tracheostomy interfaces; however, there was a noticeable distinction between the two interfaces when compared for the paediatric breathing profiles. The highest recorded aerosol concentration was 0.370 ± 0.046 mg m−3 from the tracheostomy interface during simulated paediatric breathing with a gas-flow rate of 20 L/min. The averaged MMAD across all combinations ranged from 1.248 to 1.793 µm by the APS at a distance of 0.8 m away from the patient interface. Conclusions: Overall, the results highlight the potential for secondary inhalation of fugitive emissions released during simulated aerosol treatment with concurrent high-flow therapy. The findings will help in developing policy and best practice for risk mitigation from fugitive emissions.

Fugitive Aerosol Therapy Emissions during Mechanical Ventilation: In Vitro Assessment of the Effect of Tidal Volume and Use of Protective Filters

“…At a distance of 0.8 m from the ventilator, higher aerosol mass concentrations were found consistently for each measurement compared to the 2.0 m distance, in line with previous studies (McGrath et al, 2019a;McGrath et al, 2019b). Interestingly, when comparing Figs.…”

“…These studies focused on a visual approach and did not obtain quantitative data regarding fugitive emissions. Recent studies have proceeded to quantify aerosol mass concentrations of fugitive emissions from various nebulisers and patient interfaces including; facemasks, mouthpiece combination, nasal cannula and tracheostomy reporting mass fugitive emissions as high as 0.370 ± 0.046 mg m −3 (Elmashae et al, 2019;McGrath et al, 2019a;McGrath et al, 2019b;Oilier et al, 2019). It is evident from these studies that aerosol is emitted into the surrounding environment when a patient undergoes respiratory therapy, and secondary exposure is a factor for HCWs and bystanders to consider.…”

Advances in Pulmonary Drug Delivery

“…The non-deposited, exhaled dose, however, can be a significant health hazard in both clinical and homecare settings. In two publications, McGrath and colleagues used nebulised albuterol sulphate solution when they investigated fugitive aerosol emissions from two commercially available nebulisers in combination with an open or valved facemask or using a mouthpiece with and without a filter [ 20 ] and during high flow nasal cannula (HFNC, see below for more on HFNC) therapy [ 21 ], respectively. It was shown that the MMAD of the fugitively-emitted aerosols was less than 1 µm, while the initially generated aerosols were between 2 and 5 µm.…”

Defining a Regulatory Strategy for ATMP/Aerosol Delivery Device Combinations in the Treatment of Respiratory Disease

“…Several recent studies highlight the risks, the differences between devices, and the steps that can be taken to reduce the risk of unintended inhalation of fugitive emissions. Briefly, the guidance is that closed-circuit nebulizer systems, such as vibrating mesh nebulizers, should be used, and open circuit nebulizer systems, such as jet nebulizers that require a break in the patient circuit should be avoided [ 106 , 107 , 108 , 109 , 110 ].…”