Respiratory impedance measured using impulse oscillometry in a healthy urban population

Measuring lung mechanics in patients with COPD using the handheld portable rapid expiratory occlusion monitor (REOM): A cross-sectional study

While conventional spirometry is associated with strenuous "forced" maximal respiratory maneuvers and infection control implications, oscillometry is not associated with these issues. However, portability, convenience of use, and interpretation remain common limitations to both techniques. This study tested the concordance and agreement between resistance measurements obtained from the handheld portable REOM device (Reo-f, Reo-s) with those from conventional oscillometry (R19, R5) in PFT-confirmed "mild" (GOLD 1) and "very severe" (GOLD 4) COPD. Unadjusted and adjusted concordance (Spearman correlation) and agreement (Bland-Altman tests) served as co-primary outcomes. Discrimination between GOLD 1 and 4 COPD (Wilcoxon rank sum test, Support Vector Machine (SVM) classifier) and patient user experience (System Utility Scale (SUS), Participant Satisfaction Survey (PSS)) served as secondary outcomes. In 17 participants (GOLD 1 n = 9, GOLD 4 n = 8), adjusted R5-Reo-s (0.95 [0.81, 0.98]) and R19-Reo-f (0.93 [0.79, 0.99]) correlations were very strong, as was agreement (mean differences: -0.07, 0.08, respectively). Statistically significant between-group differences were observed for all four resistance parameters. Reo-s in particular exhibited perfect discrimination between GOLD 1 and 4 disease, with some minor misclassification by Reo-f, R5 (n = 1 each) and R19 (n = 4). User experience scores were excellent. These results support the capacity for REOM as a novel, complementary diagnostic device in COPD.

How best to choose an oscillometer and reference equations for your patients with asthma

The use of oscillometry has significantly advanced in recent years, thanks to the availability of more robust and portable measurement devices. However, a major drawback is the variability among different devices, which leads to noninterchangeable results. This lack of standardization has prevented the establishment of widely accepted reference equations, complicating the implementation of oscillometry in clinical practice. This review aims to clarify these areas, suggesting the adoption of specific guidelines based on the context.

New Classifications of COPD Severity Based on Impulse Oscillometry: A SAIO Grade Base on ECOPD Cohort in China

BACKGROUND

Recently, the severities of chronic obstructive pulmonary disease (COPD) can also be assessed by impulse oscillometry (IOS). This study aimed to explore a new classification of severity of COPD based on IOS and associations with acute exacerbations (AE) in patients with COPD.

METHODS

The data of our study were based on the baseline and 2-year follow-up data of a prospective cohort in China. COPD was defined as post-bronchodilator FEV1/FVC <0.70. A new severity classification (staging of airflow obstruction by IOS, SAIO) was evaluated based on IOS parameters (R5, R5-R20, and X5 z-scores). We quantified using the weighted Bangdiwala B for agreement of severities of COPD between IOS parameters and FEV1%pred. The differences among SAIO stages were performed in symptom scores and imaging using analysis of covariance, and in the AE using Poisson regression.

RESULTS

Overall, 833 patients with COPD were included in this study. The weighted Bangdiwala B of R5, R5-R20, X5 z-scores, and FEV1%pred for evaluating agreement of the severities of COPD was 0.68, 0.70 and 0.83, respectively. The SAIO classifications system identified a greater number of patients with stage III-IV. SAIO provided significant discrimination between the stage I and stage III, IV for symptom scores, emphysema, and air trapping. SAIO provided significant discrimination between the stage I and other stages for AE.

CONCLUSIONS

The SAIO classifications provide discrimination between the stage I and stage III, IV for symptom scores, emphysema, air trapping, and AE, similar to the GOLD classifications.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR1900024643. Registered on 19 July, 2019.

Reference Equations for Within-Breath Respiratory Oscillometry in White Adults

BACKGROUND

Within-breath analysis of oscillometry parameters is a growing research area since it increases sensitivity and specificity to respiratory pathologies and conditions. However, reference equations for these parameters in White adults are lacking and devices using multiple sinusoids or pseudorandom forcing stimuli have been underrepresented in previous studies deriving reference equations. The current study aimed to establish reference ranges for oscillometry parameters, including also the within-breath ones in White adults using multi-sinusoidal oscillations.

METHODS

White adults with normal spirometry, BMI ≤30 kg/m2, without a smoking history, respiratory symptoms, pulmonary or cardiac disease, neurological or neuromuscular disorders, and respiratory tract infections in the previous 4 weeks were eligible for the study. Study subjects underwent oscillometry (multifrequency waveform at 5-11-19 Hz, Resmon PRO FULL, RESTECH Srl, Italy) in 5 centers in Europe and the USA according to international standards. The within-breath and total resistance (R) and reactance (X), the resonance frequency, the area under the X curve, the frequency dependence of R (R5-19), and within-breath changes of X (ΔX) were submitted to lambda-mu-sigma models for deriving reference equations. For each output parameter, an AIC-based stepwise input variable selection procedure was applied.

RESULTS

A total of 144 subjects (age 20.8-86.3 years; height 146-193 cm; BMI 17.42-29.98 kg/m2; 56% females) were included. We derived reference equations for 29 oscillatory parameters. Predicted values for inspiratory and expiratory parameters were similar, while differences were observed for their limits of normality.

CONCLUSIONS

We derived reference equations with narrow confidence intervals for within-breath and whole-breath oscillatory parameters for White adults.

The influence of body mass index on airway resistance in children with sickle cell disease: A longitudinal study based on impulse oscillometry

BACKGROUND

Impulse oscillometry (IOS) is an effective tool for assessing airway mechanics and diagnosing obstructive airway disease (OAD) in children with sickle cell disease (C-SCD). Obesity is known to be associated with OAD, and untreated OAD often leads to hypoxia-related complications in C-SCD. Considering the increasing prevalence of obesity in C-SCD, it is important to explore the influence of body mass index (BMI) on OAD in this disease population.

METHODS

A longitudinal retrospective chart review was conducted on 55 C-SCD (161 IOS observations) and 35 non-SCD asthmatic children (C-Asthma) (58 observations), primarily to investigate the association between BMI and airway resistance in C-SCD and C-Asthma. We conducted generalized linear mixed models (GLMM), adjusted for pharmacotherapies, to demonstrate the influence of BMI on total (R5), central (R20), and peripheral (R5-20) airway resistance and reactance (X5, resonant frequency (Fres)). We further compared age, BMI, and IOS indices between C-SCD and C-Asthma using the Mann-Whitney test.

RESULTS

Age and BMI were not statistically different between the two groups. In C-SCD, BMI was associated with R5 (GLMM t-statistics:3.75, 95%CI:1.01,3.27, p-value<0.001*) and R20 (t-statistics:4.01, 95%CI:1.04,1.15, p-value<0.001*), but not with R5-20 or airway reactance. In asthmatics, BMI was not associated with IOS estimates except Fres (t-statistics: 3.93, 95%CI: -0.06, -0.02, p-value<0.001*). C-SCD demonstrated higher airway resistances (R5 and R20) and reactance (Fres) compared to C-Asthma (Mann-Whitney: p-values<0.05).

CONCLUSION

BMI significantly influenced total and central airway resistance in C-SCD. While higher airway resistances reflected increased OAD in C-SCD than asthmatics, higher Fres perhaps indicated progressive pulmonary involvement in C-SCD.

Diagnostic Potential of Oscillometry: A Population-based Approach

Rationale: Respiratory resistance (Rrs) and reactance (Xrs) as measured by oscillometry and their intrabreath changes have emerged as sensitive parameters for detecting early pathological impairments during tidal breathing. Objectives: This study evaluates the prevalence and association of abnormal oscillometry parameters with respiratory symptoms and respiratory diseases in a general adult population. Methods: A total of 7,560 subjects in the Austrian LEAD (Lung, hEart, sociAl, boDy) Study with oscillometry measurements (computed with the Resmon Pro FULL; Restech Srl) were included in this study. The presence of respiratory symptoms and doctor-diagnosed respiratory diseases was assessed using an interview-based questionnaire. Rrs and Xrs at 5 Hz, their inspiratory and expiratory components, the area above the Xrs curve, and the presence of tidal expiratory flow limitation were analyzed. Normality ranges for oscillometry parameters were defined. Measurements and Main Results: The overall prevalence of abnormal oscillometry parameters was 20%. The incidence of abnormal oscillometry increased in the presence of symptoms or diagnoses: 17% (16-18%) versus 27% (25-29%), P < 0.0001. All abnormal oscillometry parameters except Rrs at 5 Hz were significantly associated with respiratory symptoms/diseases. Significant associations were found, even in subjects with normal spirometry, with abnormal oscillometry incidence rates increasing by 6% (4-8%; P < 0.0001) in subjects with symptoms or diagnoses. Conclusions: Abnormal oscillometry parameters are present in one-fifth of this adult population and are significantly associated with respiratory symptoms and disease. Our findings underscore the potential of oscillometry as a tool for detecting and evaluating respiratory impairments, even in individuals with normal spirometry.

Small airway resistance in obese and nonobese patients with obstructive sleep apnea syndrome using impulse oscillometry

Background/aim

There is limited information on the pathologic changes in the small airways among obese and nonobese patients with obstructive sleep apnea syndrome (OSAS). Impulse oscillometry (IOS) measures airway resistance and reactance independently of patient effort. This study aimed to compare airway resistance in small airways using IOS between obese and nonobese patients with OSAS.

Materials and methods

In this real-life cross-sectional study, demographic information was collected from obese and nonobese subjects diagnosed with moderate and severe OSAS without any other underlying diseases. Spirometry and IOS measurements were conducted, and the values of both groups were statistically analyzed.

Results

The nonobese group had a mean age of 45.6 ± 11.7 years (median 45), while the obese group had a mean age of 48.4 ± 9.5 years (median 47.5). The mean body mass index (BMI) for the nonobese group was 26.2 ± 2.1 kg/m2 (median 27 kg/m2), and for the obese group, it was 35.6 ± 6.4 kg/m2 (median 33 kg/m2). Statistically significant differences were observed between the two groups in R5 - R20 percentage, reactance area (AX), and resonant frequency (Fres) values (p < 0.05).

Conclusion

Among obese OSAS patients, there is an increase in resistance in small airways as indicated by IOS values. IOS shows promise as a potential screening tool for diagnosing OSAS.

Correlation of Impulse Oscillometry with Spirometry in Deployed Military Personnel with Airway Obstruction

INTRODUCTION

Evaluation of chronic respiratory symptoms in deployed military personnel has been conducted at Brooke Army Medical Center as part of the Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures III study. Although asthma and airway hyperreactivity have been the most common diagnoses, the clinical findings in these patients may be multifactorial. This study aims to evaluate the utility of impulse oscillometry (IOS) in diagnosing airway obstruction in patients undergoing multiple pulmonary function testing (PFT) studies.

METHODS

Military personnel referred for deployed-related pulmonary symptoms underwent a standardized evaluation at Brooke Army Medical Center and Walter Reed National Military Medical Center over a 5-year span. Initial studies included laboratory tests, high-resolution computed tomography imaging, cardiac evaluation with electrocardiogram, and echocardiography. PFT consisted of full PFTs, forced inspiratory/expiratory pressures, post-spirometry bronchodilator testing, IOS, exhaled nitric oxide, and methacholine challenge testing.

RESULTS

A total of 360 patients have completed an evaluation to date. In this cohort, 108 patients (30.0%) have evidence of obstruction by spirometry, whereas 74 (20.6%) had IOS values of both an R5 > 150% and X5 < -1.5. Only 32 (8.9%) had evidence of obstruction by both spirometry and IOS, whereas 210 (57.3%) had neither. A comparison among R5 (resistance at 5 Hz), R20 (resistance at 20 Hz), and X5 (reactance at 5 Hz) was performed in those individuals with and without spirometric obstruction. R5 (% predicted) was 156.2 ± 57.4% (obstruction) vs. 129.1 ± 39.6% (no obstruction) (P < .001); R20 (% predicted) was 138.1 ± 37.7% (obstruction) vs. 125.3 ± 31.2% (no obstruction) (P = .007); and X5 (cmH2O/L/s) was -1.62 ± 1.28 (obstruction) vs. -1.25 ± 0.55 (no obstruction) (P < .001).

DISCUSSION

Impulse oscillometry has been advocated as a supplemental pulmonary function test to aid in the diagnosis of airway obstruction. The use of IOS has been primarily used in pediatrics and elderly populations as a validated tool to establish a diagnosis of airway obstruction but is limited in the adult population because of a well-validated set of reference values. Prior studies in adults have most often demonstrated a correlation with an elevated R5 > 150%, elevated resonant frequency, and a negative X5 < -1.5 or a decrease of 30 to 35% in R5 post-bronchodilator.

CONCLUSION

Impulse oscillometry may serve as an adjunct to diagnosis but likely cannot replace a standard spirometric evaluation. Our study highlights the future utility for diagnosing early obstructive disease in the symptomatic individual.

Oscillometry in Lung Function Assessment: A Comprehensive Review of Current Insights and Challenges

Oscillometry, a non-invasive technique for assessing lung function, has gained significant recognition and importance in modern pulmonary medicine. This comprehensive review thoroughly explores its principles, applications, advantages, limitations, recent innovations, and future directions. Oscillometry's primary strength lies in its ability to offer a holistic assessment of lung mechanics. Unlike traditional spirometry, oscillometry captures the natural airflow during quiet breathing, making it suitable for patients of all ages and those with severe respiratory conditions. It provides a comprehensive evaluation of airway resistance, reactance, and compliance, offering insights into lung function that were previously challenging to obtain. In clinical practice, oscillometry finds extensive application in diagnosing and managing respiratory diseases. It plays a pivotal role in asthma, chronic obstructive pulmonary disease (COPD), and interstitial lung diseases. By detecting subtle changes in lung function before symptoms manifest, oscillometry facilitates early interventions, improving disease management and patient outcomes. Oscillometry's non-invasive and patient-friendly nature is precious in pediatric care, where traditional spirometry may be challenging for young patients. It aids in diagnosing and monitoring pediatric respiratory disorders, ensuring that children receive the care they need from an early age. Despite its many advantages, oscillometry faces challenges, such as the need for standardized protocols and the complexity of data interpretation. However, ongoing efforts to establish global standards and provide education and training for healthcare professionals aim to address these issues. Looking ahead, oscillometry holds great promise in the field of personalized medicine. With its ability to tailor treatment plans based on individualized lung function data, healthcare providers can optimize therapy selection and dosing, ultimately improving patient care and quality of life. In conclusion, oscillometry is poised to play an increasingly pivotal role in modern pulmonary medicine. As standardization efforts continue and technology evolves, it is an indispensable tool in the clinician's arsenal for diagnosing, managing, and personalizing respiratory care, ultimately leading to improved patient outcomes and better respiratory health.

Window of opportunity for respiratory oscillometry: A review of recent research

Oscillometry has been around for almost 70 years, but there are still many unknowns. The test is performed during tidal breathing and is therefore free from patient-dependent factors that could influence the results. The Forced Oscillation Technique (FOT), which requires minimal patient cooperation, is gaining ground, particularly with elderly patients and children. In pulmonology, it is a valuable tool for assessing obstructive conditions (with a distinction between central and peripheral obstruction) and restrictive disorders (intrapulmonary and extrapulmonary). Its sensitivity allows the assessment of bronchodilator and bronchoconstrictor responses. Different lung diseases show different patterns of changes in FOT, especially studied in asthma and chronic obstructive pulmonary disease. Because of these differences, many studies have analysed the usefulness of this technique in different areas of medicine. In this paper, the authors would like to present the basics of oscillometry with the areas of its most recent clinical applications.

D-ROMs and PAT Tests Reveal a High Level of Oxidative Stress in Patients with Severe Well-Controlled Asthma, and D-ROMs Are Positively Correlated with R20 Values That Indicate Approximate Central Airway Resistance

BACKGROUND

The derivatives-reactive oxygen metabolites (d-ROMs) and plasma antioxidant capacity (PAT) tests are oxidative indexes. Severe asthma has been related to oxidative stress. We aimed to investigate d-ROMs and PAT values in severely controlled asthmatics and the correlation of these values with lung function.

METHODS

Blood samples were collected from severely controlled asthmatics and centrifuged at 3000 rpm for 10 min. The supernatant was collected. The assays were performed within three hours of collection. The fraction of exhaled nitric oxide (FeNO), impulse oscillometry (IOS), and spirometry were determined. Symptom control was recorded using the asthma control test (ACT).

RESULTS

Approximately 40 patients with severe controlled asthma (75%: women), mean age of 62 ± 12 years, were recruited. Approximately 5% had obstructive spirometry. The IOS revealed airway abnormalities even though the spirometric results were within the normal range, with it being more sensitive than spirometry. The D-ROMs and PAT test values were higher than normal, indicating oxidative stress in severe asthmatics with controlled asthma. D-ROMs were positively correlated with R20 values, indicating central airway resistance.

CONCLUSIONS

The IOS technique revealed an otherwise hidden airway obstruction with spirometry. The D-ROMs and PAT tests revealed a high level of oxidative stress in severe controlled asthmatics. D-ROMs correlate with R20, indicating central airway resistance.

Role of small airway dysfunction in unexplained exertional dyspnoea

Background

Isolated small airway abnormalities may be demonstrable at rest in patients with normal spirometry; however, the relationship of these abnormalities to exertional symptoms remains uncertain. This study uses an augmented cardiopulmonary exercise test (CPET) to include evaluation of small airway function during and following exercise to unmask abnormalities not evident with standard testing in individuals with dyspnoea and normal spirometry.

Methods

Three groups of subjects were studied: 1) World Trade Center (WTC) dust exposure (n=20); 2) Clinical Referral (n=15); and Control (n=13). Baseline evaluation included respiratory oscillometry. Airway function during an incremental workload CPET was assessed by: 1) tidal flow versus volume curves during exercise to assess for dynamic hyperinflation and expiratory flow limitation; and 2) post-exercise spirometry and oscillometry to evaluate for airway hyperreactivity.

Results

All subjects demonstrated normal baseline forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC). Dyspnoea was reproduced during CPET in WTC and Clinical Referral groups versus Control without abnormality in respiratory pattern and minute ventilation. Tidal flow-volume curves uncovered expiratory flow limitation and/or dynamic hyperinflation with increased prevalence in WTC and Clinical Referral versus Control (55%, 87% versus 15%; p<0.001). Post-exercise oscillometry uncovered small airway hyperreactivity with increased prevalence in WTC and Clinical Referral versus Control (40%, 47% versus 0%, p<0.05).

Conclusions

We uncovered mechanisms for exertional dyspnoea in subject with normal spirometry that was attributable to either small airway dysfunction during exercise and/or small airway hyperreactivity following exercise. The similarity of findings in WTC environmentally exposed and clinically referred cohorts suggests broad relevance for these evaluations.

Reference equations for oscillometry and their differences among populations: a systematic scoping review

Respiratory oscillometry is gaining global attention over traditional pulmonary function tests for its sensitivity in detecting small airway obstructions. However, its use in clinical settings as a diagnostic tool is limited because oscillometry lacks globally accepted reference values. In this scoping review, we systematically assessed the differences between selected oscillometric reference equations with the hypothesis that significant heterogeneity existed between them. We searched bibliographic databases, registries and references for studies that developed equations for healthy adult populations according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A widely used Caucasian model was used as the standard reference and compared against other models using Bland-Altman and Lin's concordance correlational analyses. We screened 1202 titles and abstracts, and after a full-text review of 67 studies, we included 10 in our analyses. Of these, three models had a low-to-moderate agreement with the reference model, particularly those developed from non-Caucasian populations. Although the other six models had a moderate-to-high agreement with the standard model, there were still significant sex-specific variations. This is the first systematic analysis of the heterogeneity between oscillometric reference models and warrants the validation of appropriate equations in clinical applications of oscillometry to avoid diagnostic errors.

Decrements in lung function and respiratory abnormalities associated with exposure to diacetyl and 2,3-pentanedione in coffee production workers

Coffee production workers are exposed to complex mixtures of gases, dust, and vapors, including the known respiratory toxins, diacetyl, and 2,3-pentanedione, which occur naturally during coffee roasting and are also present in flavorings used to flavor coffee. This study evaluated the associations of these two α-diketones with lung function measures in coffee production workers. Workers completed questionnaires, and their lung function was assessed by spirometry and impulse oscillometry (IOS). Personal exposures to diacetyl, 2,3-pentanedione, and their sum (Sum_DA+PD) were assigned to participants, and metrics of the highest 95th percentile (P95), cumulative, and average exposure were calculated. Linear and logistic regression models for continuous and binary/polytomous outcomes, respectively, were used to explore exposure-response relationships adjusting for age, body mass index, tenure, height, sex, smoking status, race, or allergic status. Decrements in percent predicted forced expiratory volume in 1 second (ppFEV₁) and forced vital capacity (ppFVC) were associated with the highest-P95 exposures to 2,3-pentanedione and Sum_DA+PD. Among flavoring workers, larger decrements in ppFEV₁ and ppFVC were associated with highest-P95 exposures to diacetyl, 2,3-pentanedione, and Sum_DA+PD. Abnormal FEV₁, FVC, and restrictive spirometric patterns were associated with the highest-P95, cumulative, and average exposures for all α-diketone metrics; some of these associations were also present among flavoring and non-flavoring workers. The combined category of small and peripheral airways plus small and large airways abnormalities on IOS had elevated odds for highest-P95 exposure to α-diketones. These results may be affected by the small sample size, few cases of abnormal spirometry, and the healthy worker effect. Associations between lung function abnormalities and exposure to α-diketones suggest it may be prudent to consider exposure controls in both flavoring and non-flavoring settings.

Physiological Impairments on Respiratory Oscillometry and Future Exacerbations in Chronic Obstructive Pulmonary Disease Patients without a History of Frequent Exacerbations

Respiratory oscillometry allows measuring respiratory resistance and reactance during tidal breathing and may predict exacerbations in patients with chronic obstructive pulmonary disease (COPD). While the Global Initiative for Chronic Obstructive Lung Disease (GOLD) advocates the ABCD classification tool to determine therapeutic approach based on symptom and exacerbation history, we hypothesized that in addition to spirometry, respiratory oscillometry complemented the ABCD tool to identify patients with a high risk of exacerbations. This study enrolled male outpatients with stable COPD who were prospectively followed-up over 5 years after completing mMRC scale and COPD assessment test (CAT) questionnaires, post-bronchodilator spirometry and respiratory oscillometry to measure resistance, reactance, and resonant frequency (Fres), and emphysema quantitation on computed tomography. Total 134 patients were classified into the GOLD A, B, C, and D groups (n = 48, 71, 5, and 9) based on symptoms on mMRC and CAT and a history of exacerbations in the previous year. In univariable analysis, higher Fres was associated with an increased risk of exacerbation more strongly than other respiratory oscillometry indices. Fres was closely associated with forced expiratory volume in 1 sec (FEV₁). In multivariable Cox-proportional hazard models of the GOLD A and B groups, either lower FEV₁ group or higher Fres group was associated with a shorter time to the first exacerbation independent of the GOLD group (A vs B) and emphysema severity. Adding respiratory oscillometry to the ABCD tool may be useful for risk estimation of future exacerbations in COPD patients without frequent exacerbation history.

COPD in Smoking and Non-Smoking Community Members Exposed to the World Trade Center Dust and Fumes

Background: The characteristics of community members exposed to World Trade Center (WTC) dust and fumes with Chronic Obstructive Pulmonary Disease (COPD) can provide insight into mechanisms of airflow obstruction in response to an environmental insult, with potential implications for interventions. Methods: We performed a baseline assessment of respiratory symptoms, spirometry, small airway lung function measures using respiratory impulse oscillometry (IOS), and blood biomarkers. COPD was defined by the 2019 GOLD criteria for COPD. Patients in the WTC Environmental Health Center with <5 or ≥5 pack year smoking history were classified as nonsmoker-COPD (ns-COPD) or smoker-COPD (sm-COPD), respectively. Main Results: Between August 2005 and March 2018, 467 of the 3430 evaluated patients (13.6%) fit criteria for COPD. Among patients with COPD, 248 (53.1%) were ns-COPD. Patients with ns-COPD had measures of large airway function (FEV1) and small airway measures (R5−20, AX) that were less abnormal than those with sm-COPD. More ns-COPD compared to sm-COPD had a bronchodilator (BD) response measured by spirometry (24 vs. 14%, p = 0.008) or by IOS (36 vs. 21%, p = 0.002). Blood eosinophils did not differ between ns-COPD and sm-COPD, but blood neutrophils were higher in sm-COPD compared to ns-COPD (p < 0.001). Those with sm-COPD were more likely to be WTC local residents than ns-COPD (p = 0.007). Conclusions: Spirometry findings and small airway measures, as well as inflammatory markers, differed between patients with ns-COPD and sm-COPD. These findings suggest potential for differing mechanisms of airway injury in patients with WTC environmental exposures and have potential therapeutic implications.

A Strategy for Field Evaluations of Exposures and Respiratory Health of Workers at Small- to Medium-Sized Coffee Facilities

Coffee production is a global industry with roasteries throughout the world. Workers in this industry are exposed to complex mixtures of gases, dusts, and vapors including carbon monoxide, carbon dioxide, coffee dust, allergens, alpha-diketones, and other volatile organic compounds (VOCs). Adverse respiratory health outcomes such as respiratory symptoms, reduced pulmonary function, asthma, and obliterative bronchiolitis can occur among exposed workers. In response to health hazard evaluations requests received from 17 small- to medium-sized coffee facilities across the United States, the National Institute for Occupational Safety and Health conducted investigations during 2016-2017 to understand the burden of respiratory abnormalities, exposure characteristics, relationships between exposures and respiratory effects, and opportunities for exposure mitigation. Full-shift, task-based, and instantaneous personal and area air samples for diacetyl, 2,3-pentanedione and other VOCs were collected, and engineering controls were evaluated. Medical evaluations included questionnaire, spirometry, impulse oscillometry, and fractional exhaled nitric oxide. Exposure and health assessments were conducted using standardized tools and approaches, which enabled pooling data for aggregate analysis. The pooled data provided a larger population to better address the requestors' concern of the effect of exposure to alpha-diketones on the respiratory heath of coffee workers. This paper describes the rationale for the exposure and health assessment strategy, the approach used to achieve the study objectives, and its advantages and limitations.