Lim, Kaiser G.

BACKGROUND: Methacholine bronchoprovocation or challenge testing (MCT) is commonly performed to assess airway hyper-responsiveness in the setting of suspected asthma. Nebulization is an aerosol-generating procedure, but little is known about the risks of MCT in the context of the ongoing coronavirus disease 2019 (COVID-19) pandemic. We aimed to quantify and characterize aerosol generation during MCT by using different delivery methods and to assess the impact of adding a viral filter. METHODS: Seven healthy subjects performed simulated MCT in a near particle-free laboratory space with 4 different nebulizers and with a dosimeter. Two devices continuously sampled the ambient air during the procedure, which detected ultrafine particles, from 0.02–1 μm, and particles of sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10 µm, respectively. Particle generation was compared among all the devices, with and without viral filter placement. RESULTS: Ultrafine-particle generation during simulated MCT was significant across all the devices. Ultrafine-particle (0.02–1 μm) concentrations decreased 77%–91% with the addition of a viral filter and varied significantly between unfiltered (P < .001) and filtered devices (P < .001). Ultrafine-particle generation was lowest when using the dosimeter with filtered Hudson nebulizer (1,258 ± 1,644 particle/mL). Ultrafine-particle concentrations with the filtered nebulizer devices using a compressor were higher than particle concentrations detected when using the dosimeter: Monaghan (3,472 ± 1,794 particles/mL), PARI (4,403 ± 2,948), Hudson (6,320 ± 1,787) and AirLife (9,523 ± 5,098). CONCLUSIONS: The high particle concentrations generated during MCT pose significant infection control concerns during the COVID-19 pandemic. Particle generation during MCT was significantly reduced by using breath-actuated delivery and a viral filter, which offers an effective mitigation strategy.

BACKGROUND: Peak flow testing is a common procedure performed in ambulatory care. There are currently no data regarding aerosol generation during this procedure. Given the ongoing debate regarding the potential for aerosol transmission of SARS-CoV-2, we aimed to quantify and characterize aerosol generation during peak flow testing. METHODS: Five healthy volunteers performed peak flow maneuvers in a particle-free laboratory space. Two devices continuously sampled the ambient air during the procedure. One device can detect ultrafine particles 0.02–1 μ m in diameter, while the second device can detect particles 0.3, 0.5, 1.0, 2.0, 5.0, and 10 μ m in diameter. Five different peak flow meters were compared to ambient baseline during masked and unmasked tidal breathing. RESULTS: Ultrafine particles (0.02–1 μ m) were generated during peak flow measurement. There was no significant difference in ultrafine particle mean concentration between peak flow meters ( P = .23): Respironics (1.25 ± 0.47 particles/mL), Philips (3.06 ± 1.22), Clement Clarke (3.55 ± 1.22 particles/mL), Respironics Low Range (3.50 ± 1.52 particles/mL), and Monaghan (3.78 ± 1.31 particles/mL). Ultrafine particle mean concentration with peak flow testing was significantly higher than masked (0.22 ± 0.29 particles/mL) and unmasked tidal breathing (0.15 ± 0.18 particles/mL, P = .01), but the ultrafine particle concentrations were small compared to ambient particle concentrations in a pulmonary function testing room (89.9 ± 8.95 particles/mL). CONCLUSIONS: In this study, aerosol generation was present during peak flow testing, but concentrations were small compared to the background particle concentration in the ambient clinical environment. Surgical masks and eye protection are likely sufficient infection control measures during peak expiratory flow testing in asymptomatic patients with well controlled respiratory symptoms, but COVID-19 testing remains prudent in patients with acute respiratory symptoms prior to evaluation and peak expiratory flow assessment while the community prevalence of SARS-CoV-2 cases remains high.

Background Computed tomography (CT) of the paranasal sinuses is the diagnostic reference standard for chronic rhinosinusitis and related inflammatory sinus pathology. Nasal nitric oxide (nNO) levels have been investigated as a diagnostic tool in sinus disease because it decreases with sinus obstruction. Objective The primary aim of the study was to determine the correlation of passive (baseline) and dynamic (humming) nNO to CT findings of sinus inflammation and to sinonasal symptoms measured by the modified Sinonasal Outcome Test (26 items) (SNOT-26). Methods From June 2015 through January 2016, subjects had baseline and humming nNO levels measured with a chemiluminescence NO analyzer, and each subject underwent CT imaging and completed the SNOT-26 survey. CT images were scored using the Lund–Mackay (LM) system (LM scores >3 indicated sinus inflammation). Correlation was measured by linear and ordinal regression analysis that compared SNOT-26 scores, LM scores, and nNO measurements. Results Fourteen subjects were recruited. LM scores had a positive pairwise correlation with total SNOT-26 scores ( R 2 = .1457; correlation = .3817) and nasal-specific SNOT-26 scores ( R 2 = .4036; correlation = .6353). Baseline nasal nNO scores had a negative pairwise correlation with LM scores ( R 2 = .1580; correlation = −.3582), total SNOT-26 scores ( R 2 = .1515; correlation = −.3893), and nasal-specific SNOT-26 scores ( R 2 = .0805; correlation = −.4343). Although baseline nNO levels correlated with LM and SNOT-26 scores, humming nNO levels did not show a similar correlation. Conclusion Baseline passive nNO may be a useful and inexpensive point-of-care screening test for sinonasal opacification.