Spirometry reference values for an andean high-altitude population

Early effects of acetazolamide on hemoglobin mass and plasma volume in chronic mountain sickness at 5100 m

INTRODUCTION AND OBJECTIVES

Chronic Mountain Sickness (CMS) syndrome, combining excessive erythrocytosis and clinical symptoms in highlanders, remains a public health concern in high-altitude areas, especially in the Andes, with limited therapeutic approaches. The objectives of this study were to assess in CMS-highlanders permanently living in La Rinconada (5100-5300 m, Peru, the highest city in the world), the early efficacy of acetazolamide (ACZ) and atorvastatin to reduce hematocrit (Hct), as well as the underlying mechanisms focusing on intravascular volumes.

MATERIALS AND METHODS

Forty-one males (46±8 years of age) permanently living in La Rinconada for 15 [10-20] years and suffering from CMS were randomized between ACZ (250 mg once-daily; N = 13), atorvastatin (20 mg once-daily; N = 14) or placebo (N = 14) uptake in a double-blinded parallel study. Hematocrit (primary endpoint) as well as arterial blood gasses, total hemoglobin mass (Hb_mass) and intravascular volumes were assessed at baseline and after a mean (±SD) treatment duration of 19±2 days.

RESULTS

ACZ increased PaO₂ by +13.4% (95% CI: 4.3 to 22.5%) and decreased Hct by -5.2% (95% CI: -8.3 to -2.2%), whereas Hct remained unchanged with placebo or atorvastatin. ACZ tended to decrease Hb_mass (-2.6%, 95% CI: -5.7 to 0.5%), decreased total red blood cell volume (RBCV, -5.3%, 95% CI: -10.3 to -0.3%) and increased plasma volume (PV, +17.6%, 95% CI: 4.9 to 30.3%). Atorvastatin had no effect on intravascular volumes, while Hb_mass and RBCV increased in the placebo group (+6.1%, 95% CI: 4.2 to 7.9% and +7.0%, 95%CI: 2.7 to 11.4%, respectively).

CONCLUSIONS

Short-term ACZ uptake was effective to reduce Hct in CMS-highlanders living at extreme altitude >5,000 m and was associated with both an increase in PV and a reduction in RBCV.

Effect of Altitude on Respiratory Functional Status in COVID-19 Survivors: Results from a Latin American Cohort-FIRCOV

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.

A comparative analysis of lung function and spirometry parameters in genotype-controlled natives living at low and high altitude

Background

The reference values for lung function are associated to anatomical and lung morphology parameters, but anthropometry it is not the only influencing factor: altitude and genetics are two important agents affecting respiratory physiology. Altitude and its influence on respiratory function has been studied independently of genetics, considering early and long-term acclimatization.

Objective

The objective of this study is to evaluate lung function through a spirometry study in autochthonous Kichwas permanently living at low and high-altitude.

Methodology

A cross-sectional study of spirometry differences between genetically matched lowland Kichwas from Limoncocha (230 m) at Amazonian basin and high-altitude Kichwas from Oyacachi (3180 m) in Andean highlands. The sample size estimates permitted to recruited 118 patients (40 men and 78 women) from Limoncocha and 95 (39 men and 56 women) from Oyacachi. Chi-square method was used to analyze association or independence of categorical variables, while Student’s t test was applied to comparison of means within quantitative variables. ANOVA, or in the case that the variables didn’t meet the criteria of normality, Kruskal Wallis test were used to compare more than two groups.

Results

The FVC and the FEV₁ were significantly greater among highlanders than lowlanders (p value < 0.001), with a proportion difference of 15.2% for men and 8.5% for women. The FEV₁/FVC was significantly higher among lowlanders than highlanders for men and women. A restrictive pattern was found in 12.9% of the participants.

Conclusion

Residents of Oyacachi had greater FVC and FEV₁ than their peers from Limoncocha, a finding physiologically plausible according to published literature. Lung size and greater ventilatory capacities could be an adaptive mechanism developed by the highlander in response to hypoxia. Our results support the fact that this difference in FVC and FEV₁ is a compensatory mechanism towards lower barometric and alveolar partial pressure of oxygen pressure.

The effects of different body positions on pulmonary function in healthy adults

Abstract Introduction: Pulmonary function testing, or spirometry, is a validated, globally recognized test that contributes to the diagnosis, staging, and longitudinal follow-up of lung diseases. The exam is most often performed in a sitting position in clinical practice; hence, there are no predicted values for its performance in other positions, such as in different decubitus. Objective: The present study aimed to evaluate the effects of position on pulmonary function test results in healthy adults. Methods: Forty-two healthy adults of both sexes, divided into male (MG) and female groups (FG), were provided respiratory questionnaires. Subsequently, the pulmonary function test was conducted to evaluate the ventilatory parameters of forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and FEV1/FVC ratio in the sitting (S), dorsal decubitus (DD), right lateral decubitus (RLD), and left lateral decubitus (LLD) positions. A comparison of the parametric data was performed via one-way analysis of variance followed by Tukey post-hoc tests. Correlations between the S position variables along with the other positions were evaluated using the Pearson test. Results: The mean and standard error for the FVC values of the MG at positions DD (4.3 ± 0.7/L), RLD (4.1 ± 0.6/L) and LLD (4.1 ± 0.6/L) were lower when compared to S (5.05 ± 0.6 L). There was a strong positive correlation between the values of FVC, FEV1, and FEV1/FVC in the S position compared to other positions analyzed in both groups. Conclusion: Body positioning altered the parameters of the pulmonary function test in healthy adults.

Effects of genetics and altitude on lung function

OBJECTIVES

The aim of this work is to present a review on the impact of genetics and altitude on lung function from classic and recent studies.

DATA SOURCE

A systematic search has been carried out in different databases of scientific studies, using keywords related to lung volumes, spirometry, altitude and genetics.

RESULTS

The results of this work have been structured into three parts. First, the relationship between genes and lung function. Next, a review of the genetic predispositions related to respiratory adaptation of people who inhabit high-altitude regions for millennia. Finally, temporary effects and long-term acclimatisation on respiratory physiology at high altitude are presented.

CONCLUSIONS

The works focused on the influence of genetics and altitude on lung function are currently of interest in terms of studying the interactions between genetic, epigenetic and environmental factors in the configuration of the pathophysiological adaptation patterns.

Spirometry in Central Asian Lowlanders and Highlanders, a Population Based Study

Introduction: The purpose of the study was to establish spirometric reference values for a Central Asian population of highlanders and lowlanders.

Methods: Spirometries from a population-based cross-sectional study performed in 2013 in rural areas of Kyrgyzstan were analyzed. Using multivariable linear regression, Global Lung Function Initiative (GLI) equations were fitted separately for men and women, and altitude of residence (700–800 m, 1,900–2,800 m) to data from healthy, never-smoking Kyrgyz adults. The general GLI equation was applied: Predicted value=ea0+a1× ln(Height)+a2× ln(Age)+b1× ln(Age100)+b2× ln(Age100)2+b3× ln(Age100)3            +b4× ln(Age100)4+b5× ln(Age100)5

Results: Of 2,784 screened Kyrgyz, 448 healthy, non-smoking highlanders (379 females) and 505 lowlanders (368 females), aged 18–91 years, were included. Predicted FVC in Kyrgyz fit best with GLI “North-East Asians,” predicted FEV₁ fit best with GLI “Other/Mixed.” Predicted FEV₁/FVC was lower than that of all GLI categories. Age- and sex-adjusted mean FVC and FEV₁ were higher in highlanders (+0.138l, +0.132l) than in lowlanders (P < 0.001, all comparisons), but FEV₁/FVC was similar.

Conclusion: We established prediction equations for an adult Central Asian population indicating that FVC is similar to GLI “North-East Asian” and FEV₁/FVC is lower than in all other GLI population categories, consistent with a relatively smaller airway caliber. Central Asian highlanders have significantly greater dynamic lung volumes compared to lowlanders, which may be due to environmental and various other effects.

Reference values for spirometric parameters in healthy children living in a Colombian city located at 2640 m altitude

OBJECTIVES

To identify the spirometric equations that are most appropriate for use in children and adolescents living in Bogota, Colombia after evaluating a set of relevant previously-developed equations, including the Global Lung Function Initiative (GLI) 2012 spirometry reference equations.

METHODS

Healthy children aged between 6 and 17 years that were attending two randomly-selected schools in Bogota were invited to participate in the study, from January 2017 to January 2018. All participants underwent spirometry, following the procedures recommended by the American Thoracic Society/European Respiratory Society (ATS/ERS) Task Force. To identify the model or group of models that best predict each spirometric parameter in our population, we performed extensive residuals analyses and constructed Bland-Altman plots.

RESULTS

Three hundred twenty-six spirometric tests (149 boys, 177 girls) formed the reference data set. Knudson and GLI-2012 spirometry reference equations proved to be the most accurate in predicting the majority of spirometry parameters in both sexes and both age groups, each providing the lowest median prediction error in the residual analyses or the narrowest limits of agreement in the Bland-Altman plots in approximately one-third of the spirometry parameters analyzed.

CONCLUSION

For the majority of spirometry parameters, we recommend the use of Knudson and GLI-2012 spirometry reference equations for evaluating the respiratory function of children living in Bogota, Colombia, a city located at an altitude of 2640 m. Future investigations should target additional spirometric equations from Latin American populations living at moderate to high altitude to improve the GLI-2012 equations.