Reference equations using segmented regressions for impulse oscillometry in healthy subjects aged 2.7-90 years.

Background: Published reference equations for impulse oscillometry (IOS) usually encompass a specific age group but not the entire lifespan. This may lead to discordant predicted values when two or more non-coincident equations can be applied to the same person, or when a person moves from one equation to the next non-convergent equation as he or she gets older. Thus, our aim was to provide a single reference equation for each IOS variable that could be applied from infancy to old age. Methods: This was an ambispective cross-sectional study in healthy nonsmokers, most of whom lived in Mexico City, who underwent IOS according to international standards. A multivariate piecewise linear regression, also known as segmented regression, was used to obtain reference equations for each IOS variable. Results: In a population of 830 subjects (54.0% female) aged 2.7 to 90 years (54.8% children ≤12 years), segmented regression estimated two breakpoints for age in almost all IOS variables, except for R5-R20 in which only one breakpoint was detected. With this approach, multivariate regressions including sex, age, height and body mass index as independent variables were constructed, and coefficients for calculating predicted value, lower and upper limits of normal, percentage of predicted and z-score were obtained. Conclusions: Our study provides IOS reference equations that include the major determinants of lung function, i.e. sex, age, height and body mass index, that can be easily implemented for subjects of almost any age.

Risk of Pulmonary Fibrosis and Persistent Symptoms Post-COVID-19 in a Cohort of Outpatient Health Workers.

Background: Infection by SARS-CoV-2 has been associated with multiple symptoms; however, still, little is known about persistent symptoms and their probable association with the risk of developing pulmonary fibrosis in patients post-COVID-19. Methods: A longitudinal prospective study on health workers infected by SARS-CoV-2 was conducted. In this work, signs and symptoms were recorded of 149 health workers with a positive PCR test for SARS-CoV-2 at the beginning of the diagnosis, during the active infection, and during post-COVID-19 follow-up. The McNemar chi-square test was used to compare the proportions and percentages of symptoms between the baseline and each follow-up period. Results: The signs and symptoms after follow-up were cardiorespiratory, neurological, and inflammatory. Gastrointestinal symptoms were unusual at the disease onset, but unexpectedly, their frequency was higher in the post-infection stage. The multivariate analysis showed that pneumonia (HR 2.4, IC95%: 1.5−3.8, p < 0.001) and positive PCR tests still after four weeks (HR 5.3, IC95%: 2.3-12.3, p < 0.001) were factors associated with the diagnosis of post-COVID-19 pulmonary fibrosis in this study group. Conclusions: Our results showed that pneumonia and virus infection persistence were risk factors for developing pulmonary fibrosis post-COVID-19, after months of initial infection.

Maximal inspiratory and expiratory flow at moderate altitude: a study of a Latin American population.

BACKGROUND: Peak inspiratory and expiratory flows (PIF, PEF) are parameters used to evaluate the mechanics of the respiratory system. These parameters can vary based on whether they are measured using mechanical devices vs. spirometry and based on the barometric pressure at which the measurements are obtained. Our objectives were (1) to report the normal values and variability of PEF and PIF of a Latin American population living at a moderate altitude (2240 m above sea level), (2) to analyze the adjustment of reference values obtained at sea level with those obtained in healthy subjects living at a moderate altitude, and (3) to assess the correlation between PEF obtained by spirometry (PEFs) and PEF obtained by mechanical devices (PEFm). METHODS: In this prospective and transversal study, men and women with good respiratory health aged between 2.8 and 68 years old were invited to participate. Randomly, they underwent spirometry (to measure PEFs and PIFs) and mechanical flowmetry (to measure PEFm). RESULTS: A total of 314 subjects participated, with an average age of 24.3 ± 16.4 years; 59% were Women. The main determinants for the reference equations were age, weight, height and sex at birth. The agreement of the PEFm, PEFs and PIFs values was inconsistent with that reported by other authors, even at the same barometric pressure. The association between PEFm and PEFs was r = 0.91 (p < 0.001), and the correlation coefficient of concordance was 0.84. CONCLUSIONS: The PEFm, PEFs, and PIFs measurements in individuals living at moderate altitudes are different from those found by other authors in cities with different barometric pressures and ethnicities.

Offline exhaled nitric oxide in children: chemiluminescence vs. electrochemical devices / Óxido nítrico exhalado «fuera de línea¼ en niños: comparación entre equipos de quimioluminiscencia y electroquímicos

Abstract Background: Exhaled nitric oxide (eNO) is a noninvasive marker of airway inflammation that has been used in children, using the "offline" technique. To the extent of our knowledge, no article reported in literature compares the concordance and correlation between the two different technologies used to measure eNO at tidal volume offline. This study aimed to report the concordance and correlation of the eNO measured "offline" at tidal volume, using chemioluminiscence (cl) vs electrochemical devices (eq). Methods: A cross-sectional, observational, and prospective study was conducted in the National Institute of Respiratory Diseases (Instituto Nacional de Enfermedades Respiratorias), Mexico City. Healthy children and those with a lung disease between 1 and 11 years of age were included. The exhaled air sample at tidal volume was obtained by attaching a mask connected to a Mylar® bag. Results: We studied 36 children. The mean ± standard deviation (SD) age of the study population was 6 ± 2.6 years; 25% of the subjects included were healthy, and the rest had a lung disease. The concordance correlation coefficient between the two measuring devices was 0.98 (p < 0.001), with a mean difference of 1.46 ± 3.5 ppb and 95% limits of agreement from -5.3 ppb to 8.3 ppb. The linear regression model equation for the estimation of eNO was eNOcl = (eNOeq·1.0718) - 0.1343 (r2 = 0.97). Conclusions: The measurement of eNO at tidal volume by the offline method can be analyzed by electrochemical devices, and the results are interchangeable with those analyzed by chemiluminescence technology.

Resumen Introducción: El óxido nítrico exhalado (eNO) es un marcador no invasivo de inflamación de la vía aérea que se ha utilizado en niños mediante técnica «fuera de línea¼. Por lo que sabemos, en la literatura no existen reportes que comparen la concordancia y la correlación entre dos técnicas diferentes a volumen corriente. El objetivo de este trabajo es informar la concordancia y la correlación del eNO obtenido por la técnica fuera de línea a volumen corriente en los equipos de quimioluminiscencia (cl) y electroquímico (eq). Métodos: Se realizó un estudio transversal, observacional y prospectivo en el Instituto Nacional de Enfermedades Respiratorias, en Ciudad de México. Se incluyeron niños sanos y con enfermedad pulmonar de 1-11 años de edad. La muestra de aire exhalado se obtuvo a volumen corriente mediante una máscara con conexión a una bolsa de Mylar®. Resultados: Se estudiaron 36 niños. La edad promedio con su desviación estándar de la población de estudio fue de 6 ± 2.6 años. El 25% de los sujetos incluidos estaban sanos y el resto tenían alguna enfermedad pulmonar. El coeficiente de correlación de concordancia entre los dos equipos fue de 0.98 (p < 0.001), con una diferencia media de 1.46 ± 3.5 ppb y unos límites de concordancia del 95% de −5.3 a 8.3 ppb. La ecuación del modelo de regresión lineal del eNO fue eNOcl = (eNOeq·1,0718) − 0.1343 (r2 = 0.97). Conclusiones: La medición del eNO por el método fuera de línea a volumen corriente puede analizarse en dispositivos electroquímicos. Los resultados son intercambiables con los de quimioluminiscencia.

Offline exhaled nitric oxide in children: chemiluminescence vs. electrochemical devices.

Background: Exhaled nitric oxide (eNO) is a noninvasive marker of airway inflammation that has been used in children, using the "offline" technique. To the extent of our knowledge, no article reported in literature compares the concordance and correlation between the two different technologies used to measure eNO at tidal volume offline. This study aimed to report the concordance and correlation of the eNO measured "offline" at tidal volume, using chemioluminiscence (cl) vs electrochemical devices (eq). Methods: A cross-sectional, observational, and prospective study was conducted in the National Institute of Respiratory Diseases (Instituto Nacional de Enfermedades Respiratorias), Mexico City. Healthy children and those with a lung disease between 1 and 11 years of age were included. The exhaled air sample at tidal volume was obtained by attaching a mask connected to a Mylar® bag. Results: We studied 36 children. The mean ± standard deviation (SD) age of the study population was 6 ± 2.6 years; 25% of the subjects included were healthy, and the rest had a lung disease. The concordance correlation coefficient between the two measuring devices was 0.98 (p < 0.001), with a mean difference of 1.46 ± 3.5 ppb and 95% limits of agreement from -5.3 ppb to 8.3 ppb. The linear regression model equation for the estimation of eNO was eNOcl = (eNOeq·1.0718) - 0.1343 (r2 = 0.97). Conclusions: The measurement of eNO at tidal volume by the offline method can be analyzed by electrochemical devices, and the results are interchangeable with those analyzed by chemiluminescence technology.

Introducción: El óxido nítrico exhalado (eNO) es un marcador no invasivo de inflamación de la vía aérea que se ha utilizado en niños mediante técnica «fuera de línea¼. Por lo que sabemos, en la literatura no existen reportes que comparen la concordancia y la correlación entre dos técnicas diferentes a volumen corriente. El objetivo de este trabajo es informar la concordancia y la correlación del eNO obtenido por la técnica fuera de línea a volumen corriente en los equipos de quimioluminiscencia (cl) y electroquímico (eq). Métodos: Se realizó un estudio transversal, observacional y prospectivo en el Instituto Nacional de Enfermedades Respiratorias, en Ciudad de México. Se incluyeron niños sanos y con enfermedad pulmonar de 1-11 años de edad. La muestra de aire exhalado se obtuvo a volumen corriente mediante una máscara con conexión a una bolsa de Mylar®. Resultados: Se estudiaron 36 niños. La edad promedio con su desviación estándar de la población de estudio fue de 6 ± 2.6 años. El 25% de los sujetos incluidos estaban sanos y el resto tenían alguna enfermedad pulmonar. El coeficiente de correlación de concordancia entre los dos equipos fue de 0.98 (p < 0.001), con una diferencia media de 1.46 ± 3.5 ppb y unos límites de concordancia del 95% de −5.3 a 8.3 ppb. La ecuación del modelo de regresión lineal del eNO fue eNOcl = (eNOeq·1,0718) − 0.1343 (r2 = 0.97). Conclusiones: La medición del eNO por el método fuera de línea a volumen corriente puede analizarse en dispositivos electroquímicos. Los resultados son intercambiables con los de quimioluminiscencia.

Comparing Spirometric Reference Values From Childhood to Old Age Estimated by LMS and Linear Regression Models / Comparación de los valores de referencia espirométrica de la infancia a la vejez estimada mediante el método LMS y modelos de regresión lineal

Background: Proper reference values for lung function testing are essential for achieving adequate interpretations. The LMS procedure (lambda, mu, sigma) permits continuous analyses of entire populations avoiding gaps in the transition between childhood and adulthood. It also allows more precise calculations of average values, dispersion, and 5th percentiles, which are usually considered the lower limit of normality. The objective of this study was to compare our results fitted with the LMS method with standard multiple linear regression, and with those from international Global Lung Function Initiative (GLI) equations.Methods: Data from 9835 healthy residents of the metropolitan area of Mexico City aged 8–80 years were compiled from several studies: EMPECE, PLATINO, adult Mexican workers and two unpublished studies. The LMS procedure and multiple linear regression models were fit to obtain reference equations using R software.Results: Residuals from the LMS models had a median closer to zero, and smaller dispersion than those from the linear model, but differences although statistically significant were very small and of questionable practical relevance. For example, for females and ln(FEV1), median residual was −0.001 with p25 of −0.08 and p75 of 0.08 for LMS, compared with 0.004 (−0.08, 0.09) [p<0.05] for the linear model. Average spirometric values for a given height for our population, were higher than those predicted by the GLI study.Conclusion: Continuous reference equations for the Mexican population calculated using the LMS technique showed slightly better fit than linear regression models. (AU)

Contexto general: Unos valores de referencia apropiados para las pruebas de la función pulmonar son esenciales para realizar unas interpretaciones adecuadas. El método LMS (lambda, mu, sigma) permite realizar análisis continuos de poblaciones enteras evitando brechas en la transición entre la infancia y la edad adulta. También permite cálculos más precisos de valores medios, dispersiones y percentiles 5, que generalmente se consideran el límite inferior de la normalidad. El objetivo de este estudio fue comparar nuestros resultados ajustados con el método LMS con la regresión lineal múltiple estándar y con los de las ecuaciones internacionales de la Iniciativa Global de Función Pulmonar (GLI).Métodos: Se recopilaron datos de 9.835 residentes sanos del área metropolitana de la Ciudad de México con edades comprendidas entre 8 y 80 años a partir de varios estudios: EMPECE, PLATINO, trabajadores adultos mexicanos y 2 estudios no publicados. El método LMS y los modelos de regresión lineal múltiple se ajustaron para obtener ecuaciones de referencia utilizando el software R.Resultados:Los residuos de los modelos LMS tuvieron una mediana más cercana a cero y una dispersión menor que las del modelo lineal, pero las diferencias, aunque estadísticamente significativas, fueron muy pequeñas y de una relevancia práctica cuestionable. Por ejemplo, para las mujeres y el ln(FEV1), la mediana residual fue de −0,001 con p25 de −0,08 y p75 de 0,08 para LMS, en comparación con 0,004 (−0,08, 0,09) (p<0,05) para el modelo lineal. Los valores espirométricos medios para una altura dada para nuestra población fueron más altos que los pronosticados por el estudio GLI.Conclusión: Las ecuaciones de referencia continua para la población mexicana calculadas usando la técnica LMS mostraron un ajuste ligeramente mejor que los modelos de regresión lineal. (AU)

Conocimiento y conciencia de los médicos sobre la osteonecrosis relacionada con bifosfonatos / Knowledge and awareness of physicians about bisphosphonate-related osteonecrosis of the jaws

Objetivo: Determinar el conocimiento y la conciencia que tienen los médicos sobre la osteonecrosis relacionada con bifosfonatos. Material y métodos: Se realizó un estudio transversal, en el cual se encuestó a médicos generales y especialistas con la finalidad de identificar el nivel de conocimientos y conciencia que tienen sobre el tema. Resultados: Se entrevistó a un total de 475 médicos generales y especialistas, de los cuales 210 (44.2%) mencionaron prescribir bifosfonatos, de este grupo 58.1% no envía a los pacientes con el odontólogo para eliminar factores de riesgo, a pesar de que 61.8% de los mismos mencionó conocer las reacciones adversas; 36 médicos (17.4%) han visto a algún paciente con osteonecrosis por bifosfonatos. El 37% de los médicos que prescriben medicamentos consideran que no es necesario remitir a los pacientes al odontólogo. Conclusiones: La prescripción de bifosfonatos en la práctica médica va en aumento, los médicos deben tener el conocimiento adecuado sobre las reacciones adversas de estos medicamentos para así poder referir oportunamente al odontólogo, educar al paciente y poder prevenir complicaciones como la osteonecrosis relacionada con bifosfonatos (AU)

Objectives : To evaluate the knowledge and awareness of physicians about bisphosphonate-related osteonecrosis of the jaws. Material and methods: A cross-sectional survey was carried out among general practitioners and specialized physicians to determine their knowledge and awareness of bisphosphonate-related osteonecrosis of the jaws. Results: Of the 475 interviewed general practitioners and specialized physicians, 210 (44.2%) claimed to prescribe bisphosphonates. A total of 58.1% of these physicians did not refer their patients to the dentist for the elimination of risk factors, despite the fact that 61.8% of them reported knowledge of the adverse reactions of these drugs. Thirty-six physicians (17.4%) had seen some patient with bisphosphonate-related osteonecrosis of the jaws. A total of 37% of the physicians that prescribed drugs considered it not necessary to refer patients to the dentist. Conclusions: Bisphosphonate prescription is increasingly common in medical practice, and physicians must have adequate knowledge of the adverse reactions of these drugs in order to ensure opportune patient referral to the dentist, educate their patients, and avoid complications such as bisphosphonate-related osteonecrosis of the jaws (AU)

Comparing Spirometric Reference Values From Childhood to Old Age Estimated by LMS and Linear Regression Models.

BACKGROUND: Proper reference values for lung function testing are essential for achieving adequate interpretations. The LMS procedure (lambda, mu, sigma) permits continuous analyses of entire populations avoiding gaps in the transition between childhood and adulthood. It also allows more precise calculations of average values, dispersion, and 5th percentiles, which are usually considered the lower limit of normality. The objective of this study was to compare our results fitted with the LMS method with standard multiple linear regression, and with those from international Global Lung Function Initiative (GLI) equations. METHODS: Data from 9835 healthy residents of the metropolitan area of Mexico City aged 8-80 years were compiled from several studies: EMPECE, PLATINO, adult Mexican workers and two unpublished studies. The LMS procedure and multiple linear regression models were fit to obtain reference equations using R software. RESULTS: Residuals from the LMS models had a median closer to zero, and smaller dispersion than those from the linear model, but differences although statistically significant were very small and of questionable practical relevance. For example, for females and ln(FEV1), median residual was -0.001 with p25 of -0.08 and p75 of 0.08 for LMS, compared with 0.004 (-0.08, 0.09) [p<0.05] for the linear model. Average spirometric values for a given height for our population, were higher than those predicted by the GLI study. CONCLUSION: Continuous reference equations for the Mexican population calculated using the LMS technique showed slightly better fit than linear regression models.

Screening tool for restrictive and obstructive ventilatory abnormalities in a population-based survey

Abstract Background: A 6 s spirometry with an inexpensive pocket spirometer efficiently selects individuals for a diagnostic-quality spirometry for airflow limitation, but could also be useful to identify individuals with a restrictive pattern. Objectives: We evaluated an inexpensive simplified spirometer (chronic obstructive pulmonary disease [COPD]-6) as a screening tool to identify spirometric abnormalities. Methods: A population-based survey in Mexico City, with 742 participants performing pre- and post-BD spirometry and a three-maneuver 6 s spirometry (pre-BD) with a COPD-6. We evaluated forced expiratory volume in 1 s (FEV1), FEV6, and FEV1/FEV6 from the COPD-6, crude and expressed as the percentage of predicted (%P), to discriminate post-bronchodilator airflow obstruction (FEV1/forced vital capacity [FVC] <5th percentile) or restriction (FVC or FEV1 <5th percentile with normal FEV1/FVC) through receiver operating characteristics and their area under the curve (AUC). Results: FEV1%P was the best predictor to identify pre- and post-BD ventilatory abnormalities (best cutoff point 87%P, AUC 92% for restrictive pattern, 89% for obstructive pattern, and 91% for any spirometric abnormality). Deriving to clinical spirometry only those with <87%P (26% of the sample) missed only 12% of spirometric abnormalities most of the latter mild. Conclusions: An FEV1 <87%P from a pre-BD 6 s spirometry correctly identified individuals with spirometric ventilatory defects, either obstructive or restrictive.

Screening Tool for Restrictive and Obstructive Ventilatory Abnormalities in a Population-Based Survey.

BACKGROUND: A 6 s spirometry with an inexpensive pocket spirometer efficiently selects individuals for a diagnostic-quality spirometry for airflow limitation, but could also be useful to identify individuals with a restrictive pattern. OBJECTIVES: We evaluated an inexpensive simplified spirometer (chronic obstructive pulmonary disease [COPD]-6) as a screening tool to identify spirometric abnormalities. METHODS: A population-based survey in Mexico City, with 742 participants performing pre- and post-BD spirometry and a three-maneuver 6 s spirometry (pre-BD) with a COPD-6. We evaluated forced expiratory volume in 1 s (FEV1), FEV6, and FEV1/FEV6 from the COPD-6, crude and expressed as the percentage of predicted (%P), to discriminate post-bronchodilator airflow obstruction (FEV1/forced vital capacity [FVC] < 5th percentile) or restriction (FVC or FEV1 <5th percentile with normal FEV1/FVC) through receiver operating characteristics and their area under the curve (AUC). RESULTS: FEV1%P was the best predictor to identify pre- and post-BD ventilatory abnormalities (best cutoff point 87%P, AUC 92% for restrictive pattern, 89% for obstructive pattern, and 91% for any spirometric abnormality). Deriving to clinical spirometry only those with < 87%P (26% of the sample) missed only 12% of spirometric abnormalities most of the latter mild. CONCLUSIONS: An FEV1 < 87%P from a pre-BD 6 s spirometry correctly identified individuals with spirometric ventilatory defects, either obstructive or restrictive.

Determination of the phenotypic age in residents of Mexico City: effect of accelerated ageing on lung function and structure.

INTRODUCTION: Phenotypic age better represents age-related biological dysregulation than chronological age. Recently, a multisystem-based ageing measure, which integrates chronological age and nine biomarkers, was proposed. METHODS: Phenotypic age was determined in 774 residents of Mexico City over 60 years old and without respiratory problems. We arbitrarily classified as "accelerated" ageing, those showing >4 years compared with their chronological age, and "slowed" ageing, those with <4 years compared with chronological age. Demographic risk factors were analysed with structured questionnaires. Lung structure was evaluated by high-resolution computed tomography and functional competence was analysed by forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), diffusion capacity of carbon monoxide (D LCO), and the 6-minute walk test (6MWT). RESULTS: Overall, 13% of this cohort showed accelerated ageing, which was corroborated with four independent biomarkers of ageing, 42% had normal ageing and 46% had slowed ageing. Risk factors associated with accelerated ageing were male sex (OR 4.4, 95% CI 2.4-7.9; p<0.01), diabetes mellitus (OR 9.7, 95% CI 5.5-17.2; p<0.01), and long-term sleep duration (OR 2.9 95% CI 1.34-6.35, p<0.01). Among smokers, there was a slight but significant association with the number of pack-years. Subjects with accelerated ageing showed decreased FVC (p<0.0001), FEV1 (p<0.0001), D LCO (p<0.02) and walking distance in the 6MWT (p=0.0001). Slowed-ageing subjects presented less frequently with emphysematous lesions compared with those with accelerated ageing. CONCLUSIONS: A small but significant proportion of residents of Mexico City age rapidly, which is associated with male sex, diabetes, and long-term sleep duration. They exhibit lower levels of lung function and develop emphysema more frequently.

Risk factors associated with the detection of pulmonary emphysema in older asymptomatic respiratory subjects.

BACKGROUND: Several lung structural and functional abnormalities may occur associated with aging, including emphysema. In this study, we evaluated the frequency and risk factors associated with emphysema in respiratory asymptomatic individuals enrolled in our Lung Aging Program. From a cohort of 687 subjects, we found by high-resolution computed tomography (HRCT) 29 individuals (4%) with emphysematous changes that were compared with 87 controls (3:1) randomly selected from the same cohort. METHODS: This was a transversal, observational, case-control study where we examined demographics and functional characteristics, as well as telomere length and serum Klotho concentration, two conditions that have been associated with aging and some aging-associated diseases including emphysema. RESULTS: Individuals with subclinical pulmonary emphysema were older (72 ± 9 versus 67 ± 6 years), and primarily smoker males with low body mass index. Despite that they were asymptomatic, two of them exhibited a decrease of forced expiratory volume in 1 s (FEV1), with a lower FEV1/FVC suggesting airway obstruction. Cigarette smoking (OR = 5.43, CI95% 1.8-16.7), family history of lung disease (OR = 4.32, CI95% 1.0-19.0) and lower body mass index (OR 7.22, CI95% 1.2-3.5) were risk factors for the development of lung emphysematous changes. No association was found with telomere length and Klotho serum concentration. CONCLUSION: Our findings reveal that a small but important percentage of older people without respiratory symptoms, present pulmonary emphysema and indicate that smoking exposure and genetic background may contribute to etiological factors.

Quality of Pulmonary Function Tests in Participants with Down Syndrome / Calidad de los test de función pulmonar en participantes con síndrome de Down

Introduction: People with Down syndrome (DS) have high respiratory morbidity, evaluating their respiratory health with standardized, objective tests is desirable. Thus, the objective of this study was to evaluate the technical quality of Pulmonary Function Tests (PFTs) to determine which ones are most suitable for this population. Methods: Participants included children, teenagers and adults with DS, 5 years of age or older (n = 302). The technical quality of the impulse oscillometry system (IOS), forced spirometry, lung-diffusing capacity for carbon monoxide (DLCO), and 6-min walk test (6MWT) were analyzed by age group. Capnography and pulse oximetry were included in the study. Technical quality was determined on the basis of current international PFTs standards. Results: Fifty-one percent of participants were males. A total of 184 participants (71%) who completed the IOS fulfilled the quality criteria, while 210 (70%) completed the 6MWT. Performance on forced spirometry and DLCO was poor. All pulse oximetries and 96% percent heart rates obtained had good quality, but exhaled carbon dioxide (PetCO2) and respiratory rate (RR) showed deficient repeatability. Conclusions: IOS appears to be the most reliable instrument for evaluating lung mechanics in individuals with DS

Introducción: Las personas con síndrome de Down (SD) tienen una elevada morbilidad respiratoria, por lo que se recomienda evaluar su salud respiratoria con test objetivos estandarizados. El objetivo de este estudio fue evaluar la calidad técnica de los test de función pulmonar (TFP) para determinar cuáles son los más adecuados para este tipo de población. Métodos: Entre los participantes se incluyeron niños, adolescentes y adultos con SD y edad ≥ 5 años (n = 302). Se analizaron por grupos de edad la calidad técnica de la oscilometría de impulso (IOS), la oscilometría forzada, la capacidad pulmonar de difusión del monóxido de carbono (DLCO) y de la prueba de la marcha de 6 minutos (6MWT). Se incluyeron en el análisis la capnografía y la oximetría de pulso. La calidad técnica se determinó de acuerdo con los estándares internaciones actuales para los TFP. Resultados: El 51% de los pacientes eran varones. Un total de 184 participantes (71%) cumplieron los criterios de calidad de la IOS, mientras que 201 (70%) completaron la prueba 6MWT. El desempeño de la espirometría forzada y de la DLCO fue reducido. Todas las oximetrías de pulso que se obtuvieron, así como el 96% de las frecuencias de pulso presentaron buena calidad. Sin embargo, tanto el dióxido de carbono exhalado (PetCO2) como la frecuencia respiratoria (FR) presentaron una reproducibilidad deficiente. Conclusiones: La IOS parece ser la herramienta más fiable para la evaluación de la mecánica pulmonar en individuos con SD

Quality of Pulmonary Function Tests in Participants with Down Syndrome.

INTRODUCTION: People with Down syndrome (DS) have high respiratory morbidity, evaluating their respiratory health with standardized, objective tests is desirable. Thus, the objective of this study was to evaluate the technical quality of Pulmonary Function Tests (PFTs) to determine which ones are most suitable for this population. METHODS: Participants included children, teenagers and adults with DS, 5 years of age or older (n=302). The technical quality of the impulse oscillometry system (IOS), forced spirometry, lung-diffusing capacity for carbon monoxide (DLCO), and 6-min walk test (6MWT) were analyzed by age group. Capnography and pulse oximetry were included in the study. Technical quality was determined on the basis of current international PFTs standards. RESULTS: Fifty-one percent of participants were males. A total of 184 participants (71%) who completed the IOS fulfilled the quality criteria, while 210 (70%) completed the 6MWT. Performance on forced spirometry and DLCO was poor. All pulse oximetries and 96% percent heart rates obtained had good quality, but exhaled carbon dioxide (PetCO2) and respiratory rate (RR) showed deficient repeatability. CONCLUSIONS: IOS appears to be the most reliable instrument for evaluating lung mechanics in individuals with DS.

Inspiratory Capacity and Vital Capacity of Healthy Subjects 9-81 Years of Age at Moderate-High Altitude.

BACKGROUND: Measurements of inspiratory capacity (IC) and vital capacity (VC) are used to recognize dynamic hyperinflation, but appropriate reference values are required to achieve accurate clinical interpretations. Altitude above sea level is a potential determining factor for lung volumes, including IC and VC. OBJECTIVE: To describe IC and VC for healthy people who live in Mexico City at an altitude of 2,240 m above sea level. METHODS: Healthy subjects ages 9-81 y completed slow spirometry by following 2005 American Thoracic Society/European Respiratory Society standards. Once associations were explored, linear regression models were constructed and values were compared with those from previously published equations. RESULTS: A total of 441 healthy subjects (55.1% women) participated. The mean age was 32 y (minimum age, 9 y; maximum age, 81 y). IC and VC measurements were associated with sex, age, height, and weight. An accelerated increase in IC and VC was evident from 9 to 20 y of age, followed by a gradual decrease in both sexes. In general, IC was higher in our population than predicted by previously published reference equations. CONCLUSIONS: IC in healthy people at 2,240 m above sea level was higher than that of previous reports about European and Latin-American subjects of the same height, sex, and age who were at sea level. The present study provided robust reference values for persons who lived at a moderate altitude.

Diffusing Capacity of the Lung for Carbon Monoxide in Mexican/Latino Children. Quality Control and Reference Values.

RATIONALE: Single-breath diffusing capacity of the lung for carbon monoxide (DlCOsb) values are used to evaluate gas exchange; however, the quality of maneuvers performed by children has not been evaluated, and reference values for young people living at moderate altitudes are not well established. OBJECTIVES: Our objectives were 1) to determine whether DlCOsb maneuvers performed by a pediatric population would meet 2017 European Respiratory Society/American Thoracic Society (ERS/ATS) quality control standards; and 2) to report normal DlCOsb values for Mexican/Latino children and adolescents living at moderate altitudes. METHODS: This study involved healthy young people 4-20 years of age from the metropolitan area of Mexico City (2,240 m above sea level) who were recruited in schools from July 2014 to August 2017. DlCOsb testing was performed according to the 2005 ATS/ERS standards, and the quality control of each maneuver was analyzed according to the 2017 ERS/ATS standards. We constructed models for DlCOsb with linear and quadratic terms for weight, height, and age as independent variables using shrinkage statistics, variance inflation factors, the Akaike information criterion, and R2 to compare the results of different models. RESULTS: Results were obtained for 420 individuals (53% boys) with a mean age of 11.7 ± 4.5 standard deviation (SD) years; 47% of maneuvers from children age 4-6 years were grade A (13% grade B), and 90% of those in children older than 13 years were grade A or B. Forty-six percent of the subjects had a DlCOsb repeatability of <1 ml/min/mm Hg. The mean DlCOsb was higher for boys than for girls (32.4 ± 13.6 [SD] vs. 24.1 ± 7.5 ml/min/mm Hg, respectively). The reference equation for boys was DlCOsb = exp(1.63469 + [0.03251 × age] + [0.00846 × height] + [0.00304 × weight]), R2 = 0.87; for girls, the best equation was DlCOsb = exp(1.56516 + [0.0193 × age] + [0.00893 × height] + [0.00273 × weight]), R2 = 0.75. The single-breath transfer coefficient of the lung for carbon monoxide remained constant with age and height, with a lower limit of normal of 6.5 ml/min/mm Hg/L in boys and 5.4 ml/min/mm Hg/L in girls. Measured DlCOsb was higher than predicted by other authors (P < 0.001 by paired t test). CONCLUSIONS: Individuals 4-20 years of age can complete high-quality DlCOsb tests. Children and adolescents living at 2,240 m have higher DlCOsb values than those living at sea level. Reference equations for DlCOsb obtained at sea level are poor predictors of the values measured at moderate altitude.