Clinical implications of persistently increased blood urea nitrogen/serum creatinine ratio (PI-BUN/Cr) in severe COVID-19 patients.

Background: Patients with COVID-19 may experience a persistent increase in the blood urea nitrogen over creatinine ratio (PI-BUN/Cr). Its elevation could reflect multiple underlying pathophysiological processes beyond prerenal injury but also warrants nuanced interpretation due to its complex interplay with various factors, underscoring the importance of investigating its effects on mortality and acute kidney injury in this population.

Methods: We analized a retrospective and longitudinal cohort of patients admitted to a single center in Mexico City for patients with severe COVID-19.

Reference equations for DLNO and DLCO in Mexican Hispanics: influence of altitude and race.

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).

Reply to: Height seems to be the only variable that determines lung oscillometry indices.

https://bit.ly/3VMUMLz.

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.

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.

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.

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).

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.

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.

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.

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).

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.

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 (Dl) 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 Dl 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 Dl 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.

Longitudinal Evaluation of Lung Function in Patients With Advanced Non-Small Cell Lung Cancer Treated With Concurrent Chemoradiation Therapy.

Purpose: In lung cancer patients, radiation therapy modifies lung architecture, resulting in functional deterioration, which worsens symptoms and reduces quality of life.

Methods And Materials: A multicenter, prospective, longitudinal study was conducted in a cohort of patients with locally advanced and oligometastatic non-small cell lung cancer treated with concurrent chemoradiation therapy (CCRT). A wide array of pulmonary function tests (forced spirometry, body plethysmography, impulse oscillometry, carbon monoxide diffusing capacity, fraction of exhaled nitric oxide, arterial blood gases, and 6-minute walk test) were used to evaluate lung function at baseline; after radiation therapy; and at 6, 12, 24, and 48 weeks after CCRT.

Abnormal pulmonary function tests predict the development of radiation-induced pneumonitis in advanced non-small cell lung Cancer.

Background: Radiation pneumonitis (RP) is a frequent complication of concurrent chemoradiotherapy (CCRT) and is associated with severe symptoms that decrease quality of life and might result in pulmonary fibrosis or death. The aim of this study is to identify whether pulmonary function test (PFT) abnormalities may predict RP in non-small cell lung cancer (NSCLC) patients.

Methods: A prospective multi-institutional study was conducted with locally advanced and oligometastatic NSCLC patients.

Factors that enable or limit the sustained use of improved firewood cookstoves: Qualitative findings eight years after an intervention in rural Mexico.

Objective: The aim of this study was to analyze the factors enabling/limiting the use of improved cookstoves among rural fuel wood users from one mestizo and two indigenous communities eight years after an intervention in the state of Michoacan, in Mexico.

Methods: A qualitative study with an ethnographic perspective was conducted in 2013/2014 based on 62 interviews with women who had participated in an improved firewood cookstove program in 2005. Thematic qualitative content analysis was performed.

Validating Reference Equations for Impulse Oscillometry in Healthy Mexican Children.

Background: The impulse oscillometry system (IOS) measures the impedance (Z) of the respiratory system, but proper interpretation of its results requires adequate reference values. The objectives of this work were: (1) to validate the reference equations for the IOS published previously by our group and (2) to compare the adjustment of new available reference equations for the IOS from different countries in a sample of healthy children.

Methods: Subjects were healthy 4-15-y-old children from the metropolitan area of Mexico City, who performed an IOS test.

[Inpatients days in patients with respiratory diseases and periodontal disease].

Introduction: Periodontal disease is a chronic inflammatory gingival process that has been associated with the severity of respiratory diseases. In Mexico a prevalence of 78% was found in population with social security and > 60 years old. The aim of this study is to establish the association between periodontal disease and respiratory diseases according to the inpatient days.

Long-Term Stability of a Portable Carbon Monoxide Single-Breath Diffusing Capacity Instrument.

Background: The 2005 American Thoracic Society/European Respiratory Society guidelines for single-breath diffusing capacity of the lung for carbon monoxide (D) recommend a weekly biological control test and/or D simulator to detect instrument error drift. Very little has been published regarding the results of such a quality assurance program. Our aim was to analyze the long-term stability of a portable D instrument.

Reference Values for the Diffusing Capacity Determined by the Single-Breath Technique at Different Altitudes: The Latin American Single-Breath Diffusing Capacity Reference Project.

Background: The lung diffusion capacity (DLCO) determined by the single-breath technique greatly helps in the differential diagnosis and classification of severity of common lung diseases. However, widespread use of single-breath DLCO tests in Latin America has been limited, in part, by the lack of appropriate reference values. Our objective was to derive robust reference equations for single-breath DLCO from healthy Hispanic adults, using the most recent guidelines and taking into account altitude above sea level and hemoglobin.

Clinical Characteristics and Mortality of Influenza A H1N1 and Influenza-Like Illness in Mexico City in the 2013-2014 Winter Season.

Background: The 2013-2014 influenza season in Mexico City was severe and mainly due to influenza A H1N1, as was the 2009 pandemic.

Objective: To describe features of the outbreak and to compare the characteristics of patients with and without viral identification.

Methods: We reviewed the medical charts of all individuals with influenza or influenza-like illness admitted to a referral hospital for respiratory diseases in Mexico City from January 2013 to March 2014, whether influenza virus was identified or not.

Effect of Passive Smoking on the Growth of Pulmonary Function and Respiratory Symptoms in Schoolchildren.

Background: Environmental tobacco smoke affects the current and future health of children.

Objective: To determine whether schoolchildren aged 8-17 years old residing at an altitude of 2,240 m and exposed to tobacco smoke at home presented a reduction in the growth of pulmonary function and a greater problem of respiratory symptoms and infections compared with non-exposed children.

Materials And Methods: We followed, with questionnaires and spirometry, 1,632 boys and 1,555 girls from Mexico City and its metropolitan area (the Metropolitan Study to Evaluate the Chronic Effects of Pollution in School-age Children [EMPECE]) every six months for six years.