Containment of Procedure-Associated Aerosols by an Extractor Tent: effect on nebulised drug particle dispersal

Fennelly, Mehael; Keane, Joseph; Dolan, Lorraine; Plant, Barry J.; O'Connor, David; Sodeau, John; Prentice, Michael B.

BACKGROUND: Several medical procedures involving the respiratory tract are considered ‘aerosol generating’. Aerosols from these procedures may be inhaled by bystanders and there are consequent concerns regarding infection transmission, or, specific to nebulised therapy, secondary drug exposure. AIMS: Assess the efficacy of a proprietary HEPA-filtering extractor tent on reducing the aerosol dispersal of nebulised bronchodilator drugs. METHODS: The study was conducted in an unoccupied outpatient room at St. James’s Hospital, Dublin. A novel real-time, fluorescent particle counter, the Wideband Integrated Bioaerosol Sensor (WIBS), monitored room air continuously for three hours. Baseline airborne particle counts and counts during nebulisation of bronchodilator drug solutions were recorded. FINDINGS: Nebulising within the tent prevented any increase over background levels, nebulising directly into room air resulted in mean fluorescent particle counts of 4.75 x 10(5)/m(3) and 4.21 x 10(5)/m(3) for Ventolin and Ipramol, respectively, representing more than 400-fold increases over the mean background count. >99.3% of drug particles were less than 2 μm in diameter, small enough to enter the lower respiratory tract. CONCLUSION: These results show the extractor tent was completely effective in preventing airborne spread of drug particles of respirable size from nebulised therapy. This suggests extractor tents of this kind would be efficacious in preventing airborne infection from aerosol-generating procedures during the COVID-19 pandemic.