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OBJECTIVES: This study aimed to evaluate pulmonary diffusing capacity for nitric oxide (DLNO) and pulmonary diffusing capacity for carbon monoxide (DLCO) in Mexican Hispanics born and raised at 2240 m altitude (midlanders) compared with those born and raised at sea level (lowlanders). It also aimed to assess the effectiveness of race-specific reference equations for pulmonary diffusing capacity (white people vs Mexican Hispanics) in minimising root mean square errors (RMSE) compared with race-neutral equations. METHODS: DLNO, DLCO, alveolar volume (VA) and gas transfer coefficients (KNO and KCO) were measured in 392 Mexican Hispanics (5 to 78 years) and compared with 1056 white subjects (5 to 95 years). Reference equations were developed using segmented linear regression (DLNO, DLCO and VA) and multiple linear regression (KNO and KCO) and validated with Least Absolute Shrinkage and Selection Operator. RMSE comparisons between race-specific and race-neutral models were conducted using repeated k-fold cross-validation and random forests. RESULTS: Midlanders exhibited higher DLCO (mean difference: +4 mL/min/mm Hg), DLNO (mean difference: +7 mL/min/mm Hg) and VA (mean difference: +0.17 L) compared with lowlanders. The Bayesian information criterion favoured race-specific models and excluding race as a covariate increased RMSE by 61% (DLNO), 18% (DLCO) and 4% (KNO). RMSE values for VA and KCO were comparable between race-specific and race-neutral models. For DLCO and DLNO, race-neutral equations resulted in 3% to 6% false positive rates (FPRs) in Mexican Hispanics and 20% to 49% false negative rates (FNRs) in white subjects compared with race-specific equations. CONCLUSIONS: Mexican Hispanics born and raised at 2240 m exhibit higher DLCO and DLNO compared with lowlanders. Including race as a covariate in reference equations lowers the RMSE for DLNO, DLCO and KNO and reduces FPR and FNR compared with race-neutral models. This study highlights the need for altitude-specific and race-specific reference equations to improve pulmonary function assessments across diverse populations.

Background: Knowledge of respiratory physiology is essential for the diagnosis and treatment of respiratory diseases. During the coronavirus disease (COVID-19) pandemic, face-to-face education was inadequate, leading to the implementation of virtual programs for pulmonary fellows from Latin America. Objective: This study describes our experience with the implementation of a virtual education program involving pulmonary function tests (PFTs) for pulmonary fellows in Latin America. Methods: A learning program on PFTs was designed by the Department of Respiratory Physiology at the National Institute of Respiratory Diseases in Mexico City, and fellows in pulmonology were invited to participate in the program by their academic professors. The program was performed virtually on an online platform over 3 months. The topics covered included respiratory mechanics, gas exchange, and cardiopulmonary exercise tests. Students were asked to complete an evaluation before and after each lecture as well as before and after the entire course. Results: A total of 205 fellows from 12 countries participated in the course, and fewer than 50% completed assessments before and after the course. The results showed that fellows had relatively high initial knowledge of oxygen desaturation and cardiopulmonary exercise tests, whereas relative deficiencies were found in maximal respiratory pressure and bronchial challenge tests. The highest grade was in the spirometry test, whereas the lowest was in the bronchial challenge test. Overall, the fellows demonstrated improved performance in the post-course evaluations. Conclusion: Virtual education in PFTs is feasible and can have a positive impact on the training of pulmonary fellows from Latin America. [ABSTRACT FROM AUTHOR]

Rationale: The use of self-reported race/ethnicity to interpret lung function measurements has historically assumed that the observed differences in lung function between racial and ethnic group were due to thoracic cavity size differences relative to standing height. Very few studies have considered the influence of environmental and social determinants on pulmonary function. Consequently, the use of race and ethnicity specific reference equations may further marginalize disadvantaged populations.Objective: To develop a race-neutral reference equation for spirometry interpretation.Methods: NHANES III data (n=6,984) were re-analyzed with sitting height and the Cormic index to investigate whether body proportions were better predictors of lung function than race and ethnicity. Further, the original Global Lung Function Initiative (GLI) data (n= 74,185) were re-analyzed with inverse-probability weights to create race-neutral GLI Global (2022) equations.Measurements and Main Results: The inclusion of sitting height slightly improved statistical precision of reference equations compared with using standing height alone, but did not explain observed differences in spirometry between the NHANES III race and ethnic groups. GLI-Global (2022) equations, which do not require the selection of race and ethnicity, had similar fit to the GLI-2012 'other' equations and wider limits of normal.Conclusions: The use of a single "Global" spirometry equation reflects the wide range of lung function observed within and between populations. Given the inherent limitations of any reference equation, the use of GLI Global equations to interpret spirometry requires careful consideration of an individual's symptoms and medical history when used to make clinical, employment, and insurance decisions. [ABSTRACT FROM AUTHOR]

Laura Gochicoa-Rangel, Santiago C. Arce, Carlos Aguirre-Franco, Wilmer Madrid-Mejía, Mónica Gutiérrez-Clavería, Lorena Noriega-Aguirre, Patricia Schonffeldt-Guerrero, Agustín Acuña-Izcaray, Arturo Cortés-Telles, Luisa Martínez-Valdeavellano, Federico Isaac Hernández-Rocha, Omar Ceballos-Zúñiga, Rodrigo Del Rio Hidalgo, Sonia Sánchez, Erika Meneses-Tamayo, and Iván Chérrez-Ojeda; and on Behalf of the Respiratory Physiology Project in COVID-19 (FIRCOV). Effect of altitude on respiratory functional status in COVID-19 survivors: results from a Latin American Cohort—FIRCOV. High Alt Med Biol 24:37–48, 2023. Persistent symptoms and lung function abnormalities are common in COVID-19 survivors. Objectives: To determine the effect of altitude and other independent variables on respiratory function in COVID-19 survivors. Methods: Analytical, observational, cross-sectional cohort study done at 13 medical centers in Latin America located at different altitudes above sea level. COVID-19 survivors were invited to perform pulmonary function tests at least 3 weeks after diagnosis. Results: 1,368 participants (59% male) had mild (20%), moderate (59%), and severe (21%) disease. Restriction by spirometry was noted in 32%; diffusing capacity of the lung for carbon monoxide (DLCO) was low in 43.7%; and 22.2% walked less meters during the 6-minute walk test (6-MWT). In multiple linear regression models, higher altitude was associated with better spirometry, DLCO and 6-MWT, but lower oxygen saturation at rest and during exercise. Men were 3 times more likely to have restriction and 5.7 times more likely to have a low DLCO. Those who had required mechanical ventilation had lower DLCO and walked less during the 6-MWT. Conclusions: Men were more likely to have lower lung function than women, even after correcting for disease severity and other factors. Patients living at a higher altitude were more likely to have better spirometric patterns and walked farther but had lower DLCO and oxygen saturation. [ABSTRACT FROM AUTHOR]

The small airway, present since the origins of humanity and described barely a century ago, has recently been discovered as the anatomical site where inflammation begins in some obstructive lung diseases, such as asthma and Chronic Obstructive Pulmonary Disease (COPD), perse. Small airway dysfuction was identified in up to 91% of asthmatic patients and in a large proportion of COPD patients. In subjects without pathology, small airway represent 98.8% (approximately 4500 ml) of the total lung volume, contributing only between 10-25% of the total lung resistance; however, in subjects with obstruction, it can represent up to 90% of the total resistance. Despite this, its morphological and functional characteristics allow its dysfunction to remain undetected by conventional diagnostic methods, such as spirometry. Hence the importance of this review, which offers an overview of the tools available to assess small airway dysfunction and the possible therapies that act in this silent zone. [ABSTRACT FROM AUTHOR]