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 aims 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≤30kg/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 5-11-19Hz, 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: 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.

ß-Blocker Use and Clinical Outcomes in Patients With COPD Following Acute Myocardial Infarction.

Importance: While ß-blockers are associated with decreased mortality in cardiovascular disease (CVD), exacerbation-prone patients with chronic obstructive pulmonary disease (COPD) who received metoprolol in the Beta-Blockers for the Prevention of Acute Exacerbations of Chronic Obstructive Pulmonary Disease (BLOCK-COPD) trial experienced increased risk of exacerbations requiring hospitalization. However, the study excluded individuals with established indications for the drug, raising questions about the overall risk and benefit in patients with COPD following acute myocardial infarction (AMI). Objective: To investigate whether ß-blocker prescription at hospital discharge is associated with increased risk of mortality or adverse cardiopulmonary outcomes in patients with COPD and AMI. Design, Setting, and Participants: This prospective, longitudinal cohort study with 6 months of follow-up enrolled patients aged 35 years or older with COPD who underwent cardiac catheterization for AMI at 18 BLOCK-COPD network hospitals in the US from June 2020 through May 2022. Exposure: Prescription for any ß-blocker at hospital discharge. Main Outcomes and Measures: The primary outcome was time to the composite outcome of death or all-cause hospitalization or revascularization. Secondary outcomes included death, hospitalization, or revascularization for CVD events, death or hospitalization for COPD or respiratory events, and treatment for COPD exacerbations. Results: Among 3531 patients who underwent cardiac catheterization for AMI, prevalence of COPD was 17.1% (95% CI, 15.8%-18.4%). Of 579 total patients with COPD and AMI, 502 (86.7%) were prescribed a ß-blocker at discharge. Among the 562 patients with COPD included in the final analysis, median age was 70.0 years (range, 38.0-94.0 years) and 329 (58.5%) were male; 553 of the 579 patients (95.5%) had follow-up information. Among those discharged with ß-blockers, there was no increased risk of the primary end point of all-cause mortality, revascularization, or hospitalization (hazard ratio [HR], 1.01; 95% CI, 0.66-1.54; P = .96) or of cardiovascular events (HR, 1.11; 95% CI, 0.65-1.92; P = .69), COPD-related or respiratory events (HR, 0.75; 95% CI, 0.34-1.66; P = .48), or treatment for COPD exacerbations (rate ratio, 1.01; 95% CI, 0.53-1.91; P = .98). Conclusions and Relevance: In this cohort study, ß-blocker prescription at hospital discharge was not associated with increased risk of adverse outcomes in patients with COPD and AMI. These findings support use of ß-blockers in patients with COPD and recent AMI.

The role of oscillometry in asthma.

PURPOSE OF REVIEW: Oscillometry is a noninvasive pulmonary function test that has gained significant interest in the evaluation of lung disease. Currently, oscillometry is primarily a research tool, but there is a growing body of evidence supporting its clinical use. This review describes the recent work evaluating the role of oscillometry in the diagnosis and treatment of asthma. RECENT FINDINGS: A large body of observational data supports the ability of oscillometry to distinguish healthy individuals from those with respiratory symptoms or lung disease. Oscillometry may not be as useful as an isolated diagnostic test in asthma, but the combination with other pulmonary function tests may improve its diagnostic ability. Oscillometry can detect peripheral airways dysfunction in asthma, which is associated with symptoms and the risk for exacerbations. To help guide future research, minimal clinically important differences for specific oscillometry variables have been developed. Oscillometry may be useful in monitoring the response to biological therapy and has potential for personalizing treatment for individual patients. Oscillometry also has potential in uncovering unique aspects of the pathophysiology of asthma in obesity. SUMMARY: Oscillometry is a promising tool in the diagnosis and management of asthma. More research is needed to support its routine clinical use.

Utilizing data from the clinical pulmonary function laboratory to teach about respiratory physiology: illustrating airway-parenchymal interdependence.

Here we demonstrate how data from the clinical pulmonary function lab can help students learn about the principle of airway-parenchymal interdependence. We examined the relationship between airway conductance (Gaw) and lung volume (thoracic gas volume, TGV) in 48 patients: 17 healthy; 20 with emphysema, expected to have reduced airway-parenchymal interdependence; and 11 with pulmonary fibrosis, expected to have increased airway-parenchymal interdependence. Our findings support these expectations, with the slope of Gaw vs. TGV being steeper among those with pulmonary fibrosis and flatter among those with emphysema, compared to the slope of the healthy group. This type of analytic approach, using real-world patient data readily available from any pulmonary function laboratory, can be used to explore other fundamental principles of respiratory physiology.NEW & NOTEWORTHY This report demonstrates how common data obtained from the clinical pulmonary function testing laboratory can be used to illustrate important principles of respiratory physiology. Here we show how the relationship between airway conductance and lung volume across different disease states reflects intrinsic differences in airway-parenchymal interdependence.

Bronchodilator response does not associate with asthma control or symptom burden among patients with poorly controlled asthma.

PURPOSE: The purpose of this study was to determine how four different definitions of bronchodilator response (BDR) relate to asthma control and asthma symptom burden in a large population of participants with poorly controlled asthma. PROCEDURES: We examined the baseline change in FEV1 and FVC in response to albuterol among 931 participants with poorly controlled asthma pooled from three clinical trials conducted by the American Lung Association - Airways Clinical Research Centers. We defined BDR based on four definitions and analyzed the association of each with asthma control as measured by the Asthma Control Test or Asthma Control Questionnaire, and asthma symptom burden as measured by the Asthma Symptom Utility Index. MAIN FINDINGS: A BDR was seen in 31-42% of all participants, depending on the definition used. There was good agreement among responses (kappa coefficient 0.73 to 0.87), but only 56% of participants met all four definitions for BDR. A BDR was more common in men than women, in Blacks compared to Whites, in non-smokers compared to smokers, and in non-obese compared to obese participants. Among those with poorly controlled asthma, 35% had a BDR compared to 25% of those with well controlled asthma, and among those with a high symptom burden, 34% had a BDR compared to 28% of those with a low symptom burden. After adjusting for age, sex, height, race, obesity and baseline lung function, none of the four definitions was associated with asthma control or symptom burden. CONCLUSION: A BDR is not associated with asthma control or symptoms in people with poorly controlled asthma, regardless of the definition of BDR used. These findings question the clinical utility of a BDR in assessing asthma control and symptoms.

Respiratory System Dynamics.

While static mechanical forces govern resting lung volumes, dynamic forces determine tidal breathing, airflow, and changes in airflow and lung volume during normal and abnormal breathing. This section will examine the mechanisms, measurement methodology, and interpretation of the dynamic changes in airflow and lung volume that occur in health and disease. We will first examine how the total work of breathing can be described by the parameters of the equation of motion, which determine the pressure required to move air into and out of the lung. This will include a detailed description of airflow characteristics and airway resistance. Next, we will review the changes in pressure and flow that determine maximal forced inspiration and expiration, which result in the maximal flow-volume loop and the clinically important forced expired volume in 1 second. We will also assess the mechanisms and interpretation of bronchodilator responsiveness, dynamic hyperinflation, and airways hyperresponsiveness.

European Respiratory Society/American Thoracic Society technical statement: standardisation of the measurement of lung volumes, 2023 update.

This document updates the 2005 European Respiratory Society (ERS) and American Thoracic Society (ATS) technical standard for the measurement of lung volumes. The 2005 document integrated the recommendations of an ATS/ERS task force with those from an earlier National Heart, Lung, and Blood Institute workshop that led to the publication of background papers between 1995 and 1999 and a consensus workshop report with more in-depth descriptions and discussion. Advancements in hardware and software, new research and emerging approaches have necessitated an update to the 2005 technical standard to guide laboratory directors, physiologists, operators, pulmonologists and manufacturers. Key updates include standardisation of linked spirometry, new equipment quality control and validation recommendations, generalisation of the multiple breath washout concept beyond nitrogen, a new acceptability and grading system with addition of example tracings, and a brief review of imaging and other new techniques to measure lung volumes. Future directions and key research questions are also noted.

The Role of Pulmonary Function Testing in the Diagnosis and Management of COPD.

Pulmonary function testing (PFT) has a long and rich history in the definition, diagnosis, and management of COPD. For decades, spirometry has been regarded as the standard for diagnosing COPD; however, numerous studies have shown that COPD symptoms, pathology, and associated poor outcomes can occur, despite normal spirometry. Diffusing capacity and imaging studies have called into question the need for spirometry to put the "O" (obstruction) in COPD. The role of exercise testing and the ability of PFTs to phenotype COPD are reviewed. Although PFTs play an important role in diagnosis, treatment decisions are primarily determined by symptom intensity and exacerbation history. Although a seminal study positioned FEV1 as the primary predictor of survival, numerous studies have shown that tests other than spirometry are superior predictors of mortality. In years past, using spirometry to screen for COPD was promulgated; however, this only seems appropriate for individuals who are symptomatic and at risk for developing COPD.

What Have We Learned About Transmission of Coronavirus Disease-2019: Implications for Pulmonary Function Testing and Pulmonary Procedures.

Because of the potential for high aerosol transmission during pulmonary function testing and pulmonary procedures, performing these tests and procedures must be considered carefully during the coronavirus disease-2019 (COVID-19) pandemic. Much has been learned about the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by aerosols and the potential for such transmission through pulmonary function tests and pulmonary procedures, and subsequently preventative practices have been enhanced and developed to reduce the risk of transmission of virus to patients and personnel. This article reviews what is known about the potential for transmission of SARS-CoV-2 during pulmonary function testing and pulmonary procedures and the recommended mitigation steps to prevent the spread of COVID-19.

Race and Ethnicity in Pulmonary Function Test Interpretation: An Official American Thoracic Society Statement.

Current American Thoracic Society (ATS) standards promote the use of race and ethnicity-specific reference equations for pulmonary function test (PFT) interpretation. There is rising concern that the use of race and ethnicity in PFT interpretation contributes to a false view of fixed differences between races and may mask the effects of differential exposures. This use of race and ethnicity may contribute to health disparities by norming differences in pulmonary function. In the United States and globally, race serves as a social construct that is based on appearance and reflects social values, structures, and practices. Classification of people into racial and ethnic groups differs geographically and temporally. These considerations challenge the notion that racial and ethnic categories have biological meaning and question the use of race in PFT interpretation. The ATS convened a diverse group of clinicians and investigators for a workshop in 2021 to evaluate the use of race and ethnicity in PFT interpretation. Review of evidence published since then that challenges current practice and continued discussion concluded with a recommendation to replace race and ethnicity-specific equations with race-neutral average reference equations, which must be accompanied with a broader re-evaluation of how PFTs are used to make clinical, employment, and insurance decisions. There was also a call to engage key stakeholders not represented in this workshop and a statement of caution regarding the uncertain effects and potential harms of this change. Other recommendations include continued research and education to understand the impact of the change, to improve the evidence for the use of PFTs in general, and to identify modifiable risk factors for reduced pulmonary function.

Real-world diffusing capacity simulation data: how well do they fit current European Respiratory Society/American Thoracic Society acceptability criteria?

ERS/ATS D LCO standards recommend acceptability ranges for weekly D LCO simulation testing performed with a 3-L syringe. On some devices, the ERS/ATS limits may exceed or not fit a 3-sd range, in which case, simulation ranges based on 3 sd may be appropriate. https://bit.ly/3Z0YoZL.

Effect of Race and Ethnicity on Pulmonary Function Testing Interpretation: An American College of Chest Physicians (CHEST), American Association for Respiratory Care (AARC), American Thoracic Society (ATS), and Canadian Thoracic Society (CTS) Evidence Review and Research Statement.

BACKGROUND: Calls have been made to discontinue the routine use of race and ethnicity in medicine. Specific to respiratory medicine, the use of race- and ethnicity-specific reference equations for the interpretation of pulmonary function test (PFT) results has been questioned. RESEARCH QUESTIONS: Three key questions were addressed: (1) What is the current evidence supporting the use of race- and ethnicity-specific reference equations for the interpretation of PFTs? (2) What are the potential clinical implications of the use or nonuse of race and ethnicity in interpreting PFT results? and (3) What research gaps and questions must be addressed and answered to understand better the effect of race and ethnicity on PFT results interpretation and potential clinical and occupational health implications? STUDY DESIGN AND METHODS: A joint multisociety (American College of Chest Physicians, American Association for Respiratory Care, American Thoracic Society, and Canadian Thoracic Society) expert panel was formed to undertake a comprehensive evidence review and to develop a statement with recommendations to address the research questions. RESULTS: Several assumptions and gaps, both in the published literature and in our evolving understanding of lung health, were identified. It seems that many past perceptions and practices regarding the effect of race and ethnicity on PFT results interpretation are based on limited scientific evidence and measures that lack reliability. INTERPRETATION: A need exists for more and better research that will inform our field about these many uncertainties and will serve as a foundation for future recommendations in this area. The identified shortcomings should not be discounted or dismissed because they may enable flawed conclusions, unintended consequences, or both. Addressing the identified research gaps and needs would allow a better-a more informed-understanding of the effects of race and ethnicity on PFT results interpretation.