Use of a Viral Filter to Reduce Exposure to Exhaled Aerosol Does Not Affect Methacholine Dose Delivery During Bronchoprovocation Testing

Yosuf W. Subat, Todd J. Meyer, Keith D. Torgerud, Kaiser G. Lim, Paul D. Scanlon, Alexander S. Niven

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Methacholine challenge testing (MCT) is a common bronchoprovocation technique used to assess airway hyper-responsiveness. We previously demonstrated that the addition of a viral filter to the nebulizer exhalation limb substantially reduced expelled particles during MCT. Our aim was to evaluate whether this modification affects the delivered dose of methacholine. METHODS: A mechanical ventilator was connected to a lung simulator with breathing frequency 15 breaths/min, tidal volume 500 mL, inspiratory-expiratory ratio 1:1, with a sinusoidal waveform. We compared methacholine dose delivery using the Hudson Micro Mist or AeroEclipse II BAN nebulizers powered by either a dry gas source or a compressor system. A filter placed in line between the nebulizer and test lung was weighed before and after 1 min of nebulized methacholine delivery. Mean inhaled mass was measured with and without a viral filter on the exhalation limb. Dose delivery was calculated by multiplying the mean inhaled mass by the respirable fraction (particles < 5 lm) and inhalation time. Unpaired t test was used to compare methacholine dose delivery with and without viral filter placement. RESULTS: The addition of a viral filter did not significantly affect methacholine dose delivery across all devices tested. Using a 50-psi dry gas source, dose delivered with or without a viral filter did not differ with the Hudson (422.3 lg vs 282.0 lg, P 5.11) or the AeroEclipse nebulizer (563.0 lg vs 657.6 lg, P 5.59). Using the compressor, dose delivered with and without a viral filter did not differ with the Hudson (974.0 lg vs 868.0 lg, P 5.03) or the AeroEclipse nebulizer (818.0 lg vs 628.5 lg, P 5.42). CONCLUSIONS: The addition of a viral filter to the nebulizer exhalation limb did not affect methacholine dose during bronchoprovocation testing. Routine use of a viral filter should be considered to improve pulmonary function technician safety and infection control measures during the ongoing COVID-19 pandemic.

Original languageEnglish (US)
Pages (from-to)899-905
Number of pages7
JournalRespiratory care
Volume67
Issue number8
DOIs
StatePublished - Aug 1 2022

Keywords

  • COVID-19
  • SARS-CoV-2
  • aerosol
  • asthma
  • asthma
  • infection control
  • meth-acholine

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine

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