Rationale: Aerosol generation with modes of oxygen therapy such as high-flow nasal cannula and noninvasive positive-pressure ventilation is a concern for healthcare workers during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. The amount of aerosol generation from the respiratory tract with these various oxygen modalities is unknown. Objectives: To measure the size and number concentration of particles and droplets generated from the respiratory tract of humans exposed to various oxygen delivery modalities. Methods: Ten healthy participants with no active pulmonary disease were enrolled. Oxygen modalities tested included nonhumidified nasal cannula, face mask, heated and humidified high-flow nasal cannula, and noninvasive positive-pressure ventilation. Aerosol generation was measured with each oxygen mode while participants performed maneuvers of normal breathing, talking, deep breathing, and coughing. Testing was conducted in a negative-pressure room. Particles with a diameter between 0.37 and 20 μm were measured using an aerodynamic particle spectrometer. Measurements and Main Results: Median particle concentration ranged from 0.041 to 0.168 particles/cm 3 . Median diameter ranged from 1.01 to 1.53 μm. Cough significantly increased the number of particles measured. Measured aerosol concentration did not significantly increase with the use of either humidified high-flow nasal cannula or noninvasive positive-pressure ventilation. This was the case during normal breathing, talking, deep breathing, and coughing. Conclusions: Oxygen delivery modalities of humidified high-flow nasal cannula and noninvasive positive-pressure ventilation do not increase aerosol generation from the respiratory tract in healthy human participants with no active pulmonary disease measured in a negative-pressure room.

Poor oral health has long been recognized as a clinical risk factor for developing lung infections. Recent data using culture-independent techniques assessing the microbiome in healthy subjects have demonstrated that chronic microaspiration establishes a very similar microbial community between the mouth and lung, suggesting these 2 anatomic regions are closely intertwined. Dental disease is driven and aided by a dysbiosis in the oral microbiome, and evidence is mounting that implicates the microbiome in a variety of lung diseases including asthma, COPD, pulmonary fibrosis, and pneumonia. This review describes common dental conditions and potential mechanisms by which poor oral health may contribute to lung disease. We also review the current literature drawing associations between poor oral health and lung disease.

Background: Poor dental health occurs in patients with chronic obstructive pulmonary disease (COPD); some evidence suggests that it may correlate with lower forced expiratory volume in 1 second (FEV1) and 6-minute walk distance, and an increased rate of exacerbations. However, there is no data that examines how dental health may impact the daily respiratory symptoms that COPD patients experience. We prospectively studied indices of dental health and hygiene in patients with COPD and determined their impact on daily respiratory symptoms. Methods: A total of 20 individuals with COPD (median [interquartile range (IQR)] % FEV1 37 [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]) and 10 healthy control individuals with no lung disease were recruited. Dental questionnaires, spirometry, and a dental examination were administered on their initial visit. COPD participants were given an electronic COPD daily diary to document peak expiratory flow and the presence and magnitude of daily breathlessness, cough, sputum production, and wheeze. Results: Compared to healthy controls, COPD participants had less teeth (median 16.5 versus 28, p=0.0001), a trend to a higher plaque index (median 2.2 versus 1.7, p=0.15), and worse oral health-related quality of life (median Oral Health Impact Profile score 12.0 versus 4.5, p=0.02). A greater number of teeth correlated with higher percentage of days with cough (r=0.48, p<0.05) and wheeze (r=0.47, p<0.05). Conclusion: Individuals with severe COPD have poor oral hygiene and oral health-related quality of life. In the setting of poor dentition, a greater number of teeth correlates with more daily respiratory symptoms. More teeth may create a larger reservoir for inflammatory proteins and pathogenic bacteria to be aspirated into the airways. AbstractAbbreviations: chronic obstructive pulmonary disease, COPD; forced expiratory volume in 1 second, FEV1; interquartile range, IQR; National Health and Nutrition Survey, NHANES; plaque index, PI; forced vital capacity, FVC; oral health impact profile, OHIP; oral health impact profile summative score, OHIP-S; oral health impact profile weighted score, OHIP-W

Purpose Some patients with diffuse interstitial lung disease (ILD) undergo bronchoscopy with transbronchial biopsy (TBB) as part of their diagnostic evaluation. It is unclear what the incidence and risk factors for pneumothorax (PTX) following TBB are in this patient population. Methods Ninety-seven subjects with pulmonary fibrosis who underwent a research bronchoscopy with TBB as part of the multicenter Correlating Outcomes with Biochemical Markers to Estimate Time-progression in Idiopathic Pulmonary Fibrosis (COMET) trial were retrospectively reviewed. We compared subjects who developed a PTX during research bronchoscopy with TBB versus those who did not. Results Seven patients (7.2%) experienced a PTX during research bronchoscopy with TBB. Subjects who experienced PTX during TBB had significantly lower DLCO percent predicted (29 ± 8 versus 45 ± 15, P=0.006) and had lower resting room air saturation of peripheral oxygen (SPO2) on 6-minute walk testing (91±10 versus 95±3, P=0.02). No differences between groups were found with respect to age, gender, race, BMI, HRCT characteristics, or number of transbronchial biopsies performed. Conclusion The incidence of PTX following research bronchoscopy with TBB in patients with pulmonary fibrosis was found to be 7.2% in this study. Patients who developed a pneumothorax had greater impairments in gas exchange at baseline evidenced by a lower DLCO % predicted and a lower resting room air SPO2 when compared to subjects without PTX as a complication.

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