Towards a Race-Neutral System of Pulmonary Function Test Results Interpretation

Clinical interpretation of DLCO and KCO: From rationale to clinical and research applications

Single-breath methods for measuring the diffusing capacity of the lung for carbon monoxide (DLCO), Krogh's constant for CO (KCO), and alveolar volume (VA) play clinically vital roles in assessing lung diffusion. While the methodology is valid for the kinetics of normal lungs, appropriate interpretations are necessary for lung diseases involving emphysema and/or ventilation heterogeneity. Severe airflow limitations and ventilation heterogeneities lead to the underestimation of lung volume, calculated as VA, relative to the total lung capacity assessed using the helium closed-circuit method. Notably, the relative increase in KCO (DLCO/VA) compared to DLCO-resulting from increased blood flow per alveolar-capillary unit in small lungs with fibrosis-is a distinct feature of interstitial lung disease. Therefore, the combined assessment of DLCO and KCO may help elucidate the pathophysiology of emphysema and/or pulmonary fibrosis. This review aims to explain Krogh's equation, the difference between DLCO and D'LCO, the kinetics, and the clinical application of DLCO (or D'LCO) and KCO. Pulmonary function varies among ethnicities and races; thus, reference equations derived while considering anthropological traits are necessary. Additionally, the link between physiological theory, radiological findings, and the clinical relevance of DLCO and KCO is discussed, mostly based on Japanese studies. In this review, DLCO obtained from the single-breath method is referred to as "D'LCO"; however, for convenience, it is described as "DLCO," with the term "D'LCO" used only where necessary.

Teaching Internal Medicine Residents to Critically Appraise the Role of Race in Pulmonary Function Testing

Introduction

Race-specific equations for spirometry reference values are one example of race-specific algorithms traditionally used in medicine. The American Thoracic Society now recommends use of race-neutral reference equations instead of race-specific equations. However, no published curricula on interpretation of spirometry using race-based compared to race-neutral reference equations exist. We developed a curriculum for internal medicine residents to address this gap and equip providers to interpret spirometry in a race-conscious fashion.

Methods

An internal medicine resident and an attending in pulmonary medicine developed the curriculum and invited other experts to review and edit the material. The internal medicine resident delivered an hour-long, interactive, slide-based, didactic presentation during a weekly, residency-wide videoconference to 45 participants. The presentation included the following components: (1) history of spirometry and race, (2) race-specific equations, (3) race-neutral equations, and (4) clinical implications. The presentation opened with a clinical case and small-group discussions. We conducted pre- and posttest surveys; the posttest survey was designed using the Kirkpatrick model to assess reaction, learning, and anticipated behavioral change. Mean score differences were evaluated for level 2 questions using Cohen's d effect size.

Results

Thirty-eight respondents completed the pretest survey, and 24 completed the posttest survey. Test scores significantly improved after session participation, with Cohen's d ranging from 0.27 to 1.17.

Discussion

This curriculum was successful in engaging participants in critically appraising race-based interpretations of pulmonary function testing. The structure of the curriculum could be repurposed to create didactic content on other examples of race-based clinical algorithms.

Navigating COPD in Aging Populations: Insights Into Pathophysiology and Comprehensive Care

Chronic obstructive pulmonary disease (COPD) poses a significant and growing health burden among aging populations, marked by increasing prevalence and complex management challenges specific to elderly patients. This review explores the multifaceted interplay between COPD and aging, highlighting overlapping pathophysiological processes and comorbidities that complicate diagnosis and treatment. We examine age-specific management strategies, emphasizing the need for tailored approaches that account for the unique physical, cognitive, and health-related quality of life impacts on older adults. Additionally, we discuss preventive treatments and the critical roles of mental health, end-of-life care, and caregiver support in comprehensive disease management. The importance of integrative approaches to enhancing health care delivery is also underscored. Finally, we outline future directions, focusing on novel treatment pathways and the identification of biomarkers for early detection. Addressing these elements is essential for optimizing care in this vulnerable population and alleviating the significant societal and economic impacts of COPD among aging patients.

Relationship between FEV1/FVC and age in children with asthma

INTRODUCTION

Forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) normally decreases through childhood, increases briefly during early adolescence, and then declines throughout life. The physiology behind this temporary increase during early adolescence is not well understood. The objective of this study was to determine if this pattern occurs in children with asthma.

DESIGN

Single-center, cross-sectional, retrospective analysis of pulmonary function tests obtained over a 5-year period in children 5-18 years of age with persistent asthma.

RESULTS

A total of 1793 patients satisfied all inclusion and exclusion criteria. The mean age (±SD) was 10.4 ± 3.8 years. Forty-eight percent were female. Mean FEV1/FVC was 0.83 ± 0.09. FEV1/FVC was lower at 5 years of age than in healthy children, declined from age 5 to 11 by 5.7% compared to 7.3% in healthy girls, and 5.8% compared to 9.4% in healthy boys. FEV1/FVC increased in early adolescence, but at age 16, was 5.6% lower in male children compared to healthy children, and 5.4% lower in females. The ratio was lower in obese children at all ages but demonstrated the same curvilinear shape as healthy children. In absolute terms, FEV1 grew proportionately more than FVC during early adolescence, so the ratio of FEV1/FVC increased during that period. The curvilinear shape of the curve remained in postbronchodilator testing, though significantly blunted.

CONCLUSIONS

FEV1/FVC is lower in children with persistent asthma than healthy children, but the "Shepherd's Hook" pattern is preserved. This was true in obese patients with asthma, although their FEV1/FVC ratios were lower throughout all stages of childhood and adolescence.