Chronotropic index during 6-minute walk and acute respiratory events in COPDGene

BACKGROUND

Lower heart rate (HR) increases during exercise and slower HR recovery (HRR) after exercise are markers of worse autonomic function that may be associated with risk of acute respiratory events (ARE).

METHODS

Data from 6-min walk testing (6MWT) in COPDGene were used to calculate the chronotropic index (CI) [(HR immediately post 6MWT - resting HR)/((220 - age) - resting HR)] and HRR at 1 min after 6MWT completion. We used zero-inflated negative binomial regression to test associations of CI and HRR with rates of any ARE (requiring steroids and/or antibiotics) and severe ARE (requiring emergency department visit or hospitalization), among all participants and in spirometry subgroups (normal, chronic obstructive pulmonary disease [COPD], and preserved ratio with impaired spirometry).

RESULTS

Among 4,484 participants, mean follow-up time was 4.1 years, and 1,966 had COPD. Among all participants, CI-6MWT was not associated with rate of any ARE [adjusted incidence rate ratio (aIRR) 0.98 (0.95-1.01)], but higher CI-6MWT was associated with lower rate of severe ARE [0.95 (0.92-0.99)]. Higher HRR was associated with a lower rate of both any ARE [0.97 (0.95-0.99)] and severe ARE [0.95 (0.92-0.98)]. Results were similar in the COPD spirometry subgroup.

CONCLUSION

Heart rate measures derived from 6MWT tests may have utility in predicting risk of acute respiratory events and COPD exacerbations.

Aerosol Generation from the Respiratory Tract with Various Modes of Oxygen Delivery

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/cm3. 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.

Impact of gastroesophageal reflux on longitudinal lung function and quantitative computed tomography in the COPDGene cohort

Rationale

Gastroesophageal reflux disease (GERD) is a common comorbidity in chronic obstructive pulmonary disease (COPD) and has been associated with increased risk of acute exacerbations, hospitalization, emergency room visits, costs, and quality-of-life impairment. However, it remains unclear whether GERD contributes to the progression of COPD as measured by lung function or computed tomography.

Objective

To determine the impact of GERD on longitudinal changes in lung function and radiographic lung disease in the COPDGene cohort.

Methods

We evaluated 5728 participants in the COPDGene cohort who completed Phase I (baseline) and Phase II (5-year follow-up) visits. GERD status was based on participant-reported physician diagnoses. We evaluated associations between GERD and annualized changes in lung function [forced expired volume in 1 s (FEV₁) and forced vital capacity (FVC)] and quantitative computed tomography (QCT) metrics of airway disease and emphysema using multivariable regression models. These associations were further evaluated in the setting of GERD treatment with proton-pump inhibitors (PPI) and/or histamine-receptor 2 blockers (H₂ blockers).

Results

GERD was reported by 2101 (36.7%) participants at either Phase I and/or Phase II. GERD was not associated with significant differences in slopes of FEV₁ (difference of − 2.53 mL/year; 95% confidence interval (CI), − 5.43 to 0.37) or FVC (difference of − 3.05 mL/year; 95% CI, − 7.29 to 1.19), but the odds of rapid FEV₁ decline of ≥40 mL/year was higher in those with GERD (adjusted odds ratio (OR) 1.20; 95%CI, 1.07 to 1.35). Participants with GERD had increased progression of QCT-measured air trapping (0.159%/year; 95% CI, 0.054 to 0.264), but not other QCT metrics such as airway wall area/thickness or emphysema. Among those with GERD, use of PPI and/or H₂ blockers was associated with faster decline in FEV₁ (difference of − 6.61 mL/year; 95% CI, − 11.9 to − 1.36) and FVC (difference of − 9.26 mL/year; 95% CI, − 17.2 to − 1.28).

Conclusions

GERD was associated with faster COPD disease progression as measured by rapid FEV₁ decline and QCT-measured air trapping, but not by slopes of lung function. The magnitude of the differences was clinically small, but given the high prevalence of GERD, further investigation is warranted to understand the potential disease-modifying role of GERD in COPD pathogenesis and progression.

Clinical trials registration

NCT00608764.

The Oral-Lung Axis: The Impact of Oral Health on Lung Health

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.

Markers of Dental Health Correlate with Daily Respiratory Symptoms in COPD

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 [29-43]) 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.