Glycine by enteral route does not improve major clinical outcomes in severe COVID-19: a randomized clinical pilot trial.

There is a worrying scarcity of drug options for patients with severe COVID-19. Glycine possesses anti-inflammatory, cytoprotective, endothelium-protective, and platelet-antiaggregant properties, so its use in these patients seems promising. In this open label, controlled clinical trial, inpatients with severe COVID-19 requiring mechanical ventilation randomly received usual care (control group) or usual care plus 0.5 g/kg/day glycine by the enteral route (experimental group). Major outcomes included mortality, time to weaning from mechanical ventilation, total time on mechanical ventilation, and time from study recruitment to death. Secondary outcomes included laboratory tests and serum cytokines. Patients from experimental (n = 33) and control groups (n = 23) did not differ in basal characteristics. There were no differences in mortality (glycine group, 63.6% vs control group, 52.2%, p = 0.60) nor in any other major outcome. Glycine intake was associated with lower fibrinogen levels, either evaluated per week of follow-up (p < 0.05 at weeks 1, 2, and 4) or as weighted mean during the whole hospitalization (608.7 ± 17.7 mg/dl vs control 712.2 ± 25.0 mg/dl, p = 0.001), but did not modify any other laboratory test or cytokine concentration. In summary, in severe COVID-19 glycine was unable to modify major clinical outcomes, serum cytokines or most laboratory tests, but was associated with lower serum fibrinogen concentration.Registration: ClinicalTrials.gov NCT04443673, 23/06/2020.

Trajectories of sleep duration and quality and their association with mild cognitive impairment, frailty, and all-cause mortality.

OBJECTIVES: To identify longitudinal trajectories of sleep duration and quality and estimate their association with mild cognitive impairment, frailty, and all-cause mortality. METHODS: We used data from three waves (2009, 2014, 2017) of the WHO Study on Global Aging and Adult Health in Mexico. The sample consisted of 2722 adults aged 50 and over. Sleep duration and quality were assessed by self-report. Sleep trajectories were determined by applying growth mixture models. Mixed-effects logistic (mild cognitive impairment) and ordinal logistic (frailty), and Cox proportional hazards (all-cause mortality) models were fitted. RESULTS: Three classes for sleep duration ("optimal-stable," "long-increasing," and "short-decreasing") and quality ("very good-increasing," "very good-decreasing," and "moderate/poor stable") were identified. Compared to the optimal-stable group, the long-increasing trajectory had greater odds for mild cognitive impairment (odds ratio=1.68, 95% CI: 1.01-2.78) and frailty (odds ratio=1.66, 95% CI: 1.13-2.46), and higher risk for all-cause mortality (hazard ratio=1.91, 95% CI: 1.14-3.19); and the short-decreasing class had a higher probability of frailty (odds ratio=1.83, 95% CI: 1.26-2.64). Regarding the sleep quality, the moderate/poor stable trajectory had higher odds of frailty (odds ratio=1.71, 95% CI: 1.18-2.47) than very good-increasing group. CONCLUSIONS: These results have important implications for clinical practice and public health policies, given that the evaluation and treatment of sleep disorders need more attention in primary care settings. Interventions to detect and treat sleep disorders should be integrated into clinical practice to prevent or delay the appearance of alterations in older adults' physical and cognitive function. Further research on sleep quality and duration is warranted to understand their contribution to healthy aging.

Lung function is related to salivary cytokines and hormones in healthy children. An exploratory cross-sectional study.

Pulmonary mechanics has been traditionally viewed as determined by lung size and physical factors such as frictional forces and tissue viscoelastic properties, but few information exists regarding potential influences of cytokines and hormones on lung function. Concentrations of 28 cytokines and hormones were measured in saliva from clinically healthy scholar children, purposely selected to include a wide range of body mass index (BMI). Lung function was assessed by impulse oscillometry, spirometry, and diffusing capacity for carbon monoxide, and expressed as z-score or percent predicted. Ninety-six scholar children (55.2% female) were enrolled. Bivariate analysis showed that almost all lung function variables correlated with one or more cytokine or hormone, mainly in boys, but only some of them remained statistically significant in the multiple regression analyses. Thus, after adjusting by height, age, and BMI, salivary concentrations of granulocyte-macrophage colony-stimulating factor (GM-CSF) in boys were associated with zR5-R20 and reactance parameters (zX20, zFres, and zAX), while glucagon inversely correlated with resistances (zR5 and zR20). Thus, in physiological conditions, part of the mechanics of breathing might be influenced by some cytokines and hormones, including glucagon and GM-CSF. This endogenous influence is a novel concept that warrants in-depth characterization.

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.

[Small airway: from definition to treatment]. / Vía aérea pequeña: de la definición al tratamiento.

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), per se. 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.

La vía aérea pequeña, presente desde los orígenes de la humanidad y descrita hace apenas un siglo, se ha descubierto recientemente como el sitio anatómico donde inicia la inflamación provocada por algunas enfermedades pulmonares obstructivas: asma y enfermedad pulmonar obstructiva crónica (EPOC), per se. Se ha identificado disfunción de la vía aérea pequeña en el 91% de los pacientes asmáticos y en una gran proporción de quienes padecen EPOC. En los pacientes sin enfermedad, la vía aérea pequeña representa el 98.8% (4500 mL) del volumen pulmonar total, y solo aporta del 10 al 25% de la resistencia pulmonar total; sin embargo, en sujetos con obstrucción puede suponer el 90% de la resistencia total. A pesar de esto, sus características morfológicas y funcionales permiten que la disfunción pase inadvertida por métodos diagnósticos convencionales, por ejemplo la espirometría. Con base en lo anterior, el objetivo de este estudio fue revisar el panorama general de los métodos disponibles para evaluar la vía aérea pequeña y los posibles tratamientos asociados con esta zona silente.

Altitude and Breathing during Sleep in Healthy Persons and Sleep Disordered Patients: A Systematic Review.

Objetive The aim of this systematic review is to analyze the recent scientific evidence of the clinical effects of altitude on breathing during sleep in healthy persons and sleep disordered patients. Material and Methods A search was carried out in PubMed and Scopus looking for articles published between January 1, 2010 and December 31, 2021, in English and Spanish, with the following search terms: "sleep disorders breathing and altitude". Investigations in adults and carried out at an altitude of 2000 meters above mean sea level (MAMSL) or higher were included. The correlation between altitude, apnea hypopnea index (AHI) and mean SpO2 during sleep was calculated. Results 18 articles of the 112 identified were included. A good correlation was found between altitude and AHI (Rs = 0.66 P = 0.001), at the expense of an increase in the central apnea index. Altitude is inversely proportional to oxygenation during sleep (Rs = -0.93 P = 0.001), and an increase in the desaturation index was observed (3% and 4%). On the treatment of respiratory disorders of sleeping at altitude, oxygen is better than servoventilation to correct oxygenation during sleep in healthy subjects and acetazolamide controlled respiratory events and oxygenation during sleep in patients with obstructive sleep apnea under treatment with CPAP. Conclusions Altitude increases AHI and decreases oxygenation during sleep; oxygen and acetazolamide could be an effective treatment for sleep-disordered breathing at altitude above 2000 MAMSL.

Changes in Oxygenation Levels During Moderate Altitude Simulation (Hypoxia-Induced): A Pilot Study Investigating the Impact of Skin Pigmentation in Pulse Oximetry.

The current COVID-19 pandemic has shown us that the pulse oximeter is a key medical device for monitoring blood-oxygen levels non-invasively in patients with chronic or acute illness. It has also emphasised limitations in accuracy for individuals with darker skin pigmentation, calling for new methods to provide better measurements. The aim of our study is to identify the impact of skin pigmentation on pulse oximeter measurements. We also explored the benefits of a multi-wavelength approach with an induced change of arterial oxygen saturation. A total of 20 healthy volunteers were recruited. We used time domain diffuse reflectance spectroscopy (TDDRS) from a broad band light source, collecting spectra from the index finger along with three different pulse oximeters used simultaneously for monitoring purposes. Five acute hypoxic events were induced by administering 11% FiO2, produced by a Hypoxico altitude training system, for 120 sec through a face mask with a one-way valve. Our multi-wavelength approach revealed a correlation between the signature of skin pigmentation and the dynamic range of oxygen saturation measurements. Principal component analysis (PCA) showed separation between a range of different pigmented volunteers (PC1 = 56.00%) and oxygen saturation (PC2 = 22.99%). This emphasises the need to take into account skin pigmentation in oximeter measurements. This preliminary study serves to validate the need to better understand the impact of skin pigmentation absorption on optical readings in pulse oximeters. Multi-wavelength approaches have the potential to enable robust and accurate measurements across diverse populations.

Sex Differences in the Association Between Risk of Obstructive Sleep Apnea, Insomnia, and Frailty in Older Adults.

PURPOSE: To analyze the association between risk of obstructive sleep apnea (OSA), insomnia, sleepiness and self-assessed sleep duration with frailty in older adults. PATIENTS AND METHODS: Cross-sectional study with 1643 older adults (60 to 97 years old) who participated in round 6 (2019) of the Cohort of Obesity Sarcopenia and Obesity in Older Adults of the Mexican Institute of Social Security. The Berlin Questionnaire was used to assess risk of OSA, the Athens Insomnia Scale for insomnia, the Epworth Scale for sleepiness, and sleep duration by self-report. Frailty was assessed with the frailty criteria proposed by Fried. Sociodemographic and health variables were also collected. Statistical analysis was performed with logistic regression and was stratified by sex. RESULTS: This study included 1643 participants (823 men and 820 women). Mean age was 67.1 ± 5.9 years. The percentage of frail older adults was 10.5% (n = 172), with risk of OSA 26.1% (n = 429), with insomnia 30.3% (n = 497) and with sleepiness 18.9% (n = 310). In all participants, risk of OSA and insomnia were associated with frailty. In the stratified analysis by sex, the association between risk of OSA and frailty was observed in women (odds ratio (OR) = 1.84, 95% confidence interval (CI) 1.05, 3.22), but not in men (OR = 1.19, 95% CI: 0.65, 2.19). Insomnia was significantly associated with frailty in women (OR = 2.38, 95% CI: 1.35, 4.20) and in men (OR = 1.88, 95% CI: 1.01, 3.52). Neither sleepiness nor sleep duration was associated with frailty. CONCLUSION: In community-dwelling older adults, both the risk of OSA and insomnia conferred greater odds of presenting frailty in women. It is required to implement strategies aimed at improving sleep hygiene and detecting patients with OSA and insomnia.

Clinical Markers of Chronic Hypoxemia in Respiratory Patients Residing at Moderate Altitude.

Supplemental oxygen (SO) increases survival in hypoxemic patients. In hypoxia, mammals respond by modulating O2-sensitive transducers that stabilize the transcription factor hypoxia-inducible factor-1-alpha (HIF-1α), which transactivates the genes that govern angiogenesis and metabolic pathways. Residing at high altitudes exposes millions of people to hypoxemia with potential adverse consequences on their health. We aimed to identify markers of hypoxemia that can be used in the evaluation of patients in addition to pulse oximetry and arterial blood gases, especially those that could respond after 1 month of oxygen use. We performed a prospective pilot study at 2240 m above sea level, with repeated measurements before and after (b/a) 1-month home oxygen therapy in 70 patients with lung diseases, of which 24/20 have COPD, 41/39 obstructive sleep apnea (OSA), and 5/2 with interstitial lung diseases (ILD), all of them having chronic hypoxemia, as well as 70 healthy subjects as controls. Proteins evaluated included HIF-1α, vascular endothelial growth factor (VEGF), and erythropoietin (EPO). Among the main results, we found that hypoxemic patients had normal levels of HIF-1α but increased EPO compared with healthy controls. VEGF levels were heterogeneous in the sample studied, similar to the control group in COPD, slightly increased in OSA, and decreased in fibrosis. With oxygen treatment, the HIF-1α and EPO decreased in COPD and OSA but not in fibrosis, and VEGF remained constant over time. In conclusion, erythropoietin and HIF-1α identified hypoxemia initially and responded to oxygen. In pulmonary fibrosis, HIF-1α, EPO, and VEGF increased with oxygen therapy, which is likely linked to the disease's pathogenesis and clinical course rather than hypoxemia.

Dietary patterns and sleep disorders in Mexican adults from a National Health and Nutrition Survey.

Given the high prevalence of multiple non-communicable chronic diseases in Mexico, the aim of the present study was to assess the association between dietary patterns and sleep disorders in a national representative sample of 5076 Mexican adults (20-59 years) from the 2016 National Health and Nutrition Survey. Through a cross-sectional study, we used the Berlin sleep symptoms questionnaire to estimate the proportion of adults with insomnia, obstructive sleep apnoea (OSA) and other related problems such as daytime symptoms and inadequate sleep duration. Dietary data were collected through a seven-day semi-quantitative food frequency questionnaire, and dietary patterns were determined through cluster analysis. Associations between dietary patterns and sleep disorders were assessed by multivariate logistic regression models adjusted for age, sex, well-being, rural/urban area type, geographical region, tobacco use, physical activity level and energy intake. Three dietary patterns were identified: traditional (high in legumes and tortilla), industrialised (high in sugar-sweetened beverages, fast foods, and alcohol, coffee or tea) and mixed (high in meat, poultry, fruits and vegetables). Multivariate logistic regression showed that the industrialised pattern yielded higher odds for daytime symptoms (OR 1⋅49; 95 % CI 1⋅12, 1⋅99) and OSA (OR 1⋅63; 95 % CI 1⋅21, 2⋅19) compared with the traditional pattern. In conclusion, dietary patterns are associated with sleep disorders in Mexican adults. Further research is required to break the vicious cycle of poor-quality diet, sleep symptoms and health.

Salivary concentrations of cytokines and other analytes in healthy children.

BACKGROUND: Blood has been the usual biological fluid for measuring analytes, but there is mounting evidence that saliva may be also useful for detecting cytokines in a noninvasive way. Thus, in this study we aimed to determine concentration of cytokines and other analytes in saliva from a population of healthy children. METHODS: We collected un-stimulated whole saliva samples from clinically healthy children, and concentration of 17 cytokines and 12 other analytes were measured in supernatants. All values were adjusted by albumin content and were log-transformed before multivariate statistical analysis. RESULTS: We included 114 children (53.5% females) between 6.0 and 11.9 years old. The highest concentrations (medians, pg/µg albumin) were seen for visfatin (183.70) and adiponectin (162.26) and the lowest for IL-13 and IL-2 (~0.003). Albumin concentration was associated with age (rS = 0.39, p < 0.001). In the multivariate analysis, five analytes (C peptide, ghrelin, GLP-1, glucagon, leptin) inversely correlated with age and positively with height-for-age. Age was also positively associated with PAI-1, while height-for-age was also positively associated with insulin and visfatin. Finally, BMI-for-age had a positive correlation with GM-CSF and insulin. CONCLUSIONS: Herein, we provided concentration values for 29 analytes in saliva from healthy children that may be useful as preliminary reference framework in the clinical research setting.

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.

Prevalencia de síntomas de sueño y riesgo de apnea obstructiva del sueño en México / Prevalence of sleep symptoms and risk of obstructive sleep apnea in Mexico

Resumen: Objetivo: Estimar la prevalencia nacional de síntomas asociados con el sueño (SAS) en México, y su distribución por región, localidad y sexo. Material y métodos: Estudio transversal con muestreo probabilístico, representativo a nivel nacional en adultos mayores de 20 años. Se aplicó un cuestionario sobre duración de sueño, insomnio, uso de hipnóticos y riesgo de síndrome de apnea obstructiva del sueño (SAOS). Resultados: Los SAS más frecuentes fueron ronquido (48.5%) y dificultad para dormir (36.9%). Se identificó riesgo elevado de SAOS en 27.3% de los adultos, y se incrementa por índice de masa corporal (RM=1.1), edad (RM=1.03) y habitar zona urbana (RM=1.37). Se reportó insomnio en 18.8% de los participantes, que predomina en mujeres (RM=1.88). La duración promedio de sueño fue de 7.6 ± 3 horas; 28.4% de los adultos duermen <7 horas/noche. Conclusiones: Existe una elevada prevalencia de SAS. Uno de cada cuatro adultos mexicanos tiene elevada probabilidad de padecer SAOS. La detección y tratamiento de SAS pudieran minimizar los efectos deletéreos en la salud.

Abstract: Objective: To estimate the prevalence of sleep related symptoms (SRS) in Mexico, and their distribution by region, urbanization and gender. Materials and methods: Cross-sectional study using a national probabilistic sample among adults over 20 years old. We applied the Berlin questionnaire for sleep apnea risk (OSA) and questions on sleep duration, insomnia and sedative use. Results: The most frequent SRS were snoring 48.5% and difficulty falling asleep 36.9%. High risk for OSA was found in 27.3% of adults, increases with BMI (OR=1.1), age (OR=1.03) and urban residence (OR=1.37). Insomnia was in 18.8% with female predominance (OR=1.91). Average sleep time was 7.6 ±3 hours; 28.4% of adults sleep <7 h/night. Conclusions: SRS are highly prevalent. One in four Mexican adults have an elevated risk for OSA. Their detection and treatment could minimize detrimental health outcomes for them.

[Prevalence of sleep symptoms and risk of obstructive sleep apnea in Mexico.] / Prevalencia de síntomas de sueño y riesgo de apnea obstructiva del sueño en México.

OBJECTIVE: To estimate the prevalence of sleep related symptoms (SRS) in Mexico, and their distribution by region, urbanization and gender. MATERIALS AND METHODS: Cross-sectional study using a national probabilistic sample among adults over 20 years old. We applied the Berlin questionnaire for sleep apnea risk (OSA) and questions on sleep duration, insomnia and sedative use. RESULTS: The most frequent SRS were snoring 48.5% and difficulty falling asleep 36.9%. High risk for OSA was found in 27.3% of adults, increases with BMI (OR=1.1), age (OR=1.03) and urban residence (OR=1.37). Insomnia was in 18.8% with female predominance (OR=1.91). Average sleep time was 7.6 ±3 hours; 28.4% of adults sleep <7 h/night. CONCLUSIONS: SRS are highly prevalent. One in four Mexican adults have an elevated risk for OSA. Their detection and treatment could minimize detrimental health outcomes for them.

OBJETIVO: Estimar la prevalencia nacional de síntomas asociados con el sueño (SAS) en México, y su distribución por región, localidad y sexo. MATERIAL Y MÉTODOS: Estudio transversal con muestreo probabilístico, representativo a nivel nacional en adultos mayores de 20 años. Se aplicó un cuestionario sobre duración de sueño, insomnio, uso de hipnóticos y riesgo de síndrome de apnea obstructiva del sueño (SAOS). RESULTADOS: Los SAS más frecuentes fueron ronquido (48.5%) y dificultad para dormir (36.9%). Se identificó riesgo elevado de SAOS en 27.3% de los adultos, y se incrementa por índice de masa corporal (RM=1.1), edad (RM=1.03) y habitar zona urbana (RM=1.37). Se reportó insomnio en 18.8% de los participantes, que predomina en mujeres (RM=1.88). La duración promedio de sueño fue de 7.6 ± 3 horas; 28.4% de los adultos duermen <7 horas/ noche. CONCLUSIONES: Existe una elevada prevalencia de SAS. Uno de cada cuatro adultos mexicanos tiene elevada probabilidad de padecer SAOS. La detección y tratamiento de SAS pudieran minimizar los efectos deletéreos en la salud.

Small airway dysfunction in chronic hypersensitivity pneumonitis.

BACKGROUND AND OBJECTIVE: Lung biopsies from patients with hypersensitivity pneumonitis (HP) have demonstrated small airway (SA) involvement, but there is no information concerning SA function in HP, and it is unknown whether pharmacological treatment could modify its function. SA function in patients with chronic HP using ultrasonic pneumography (UPG) and impulse oscillometry (IOS) was explored. We also compared initial results with those obtained after 4 weeks of standardized treatment with azathioprine and prednisone. METHODS: The study group consisted of adults with recent diagnoses of HP. All patients completed UPG, IOS, spirometry, body plethysmography, single-breath carbon monoxide diffusing capacity (DLCO ) and the 6-min walk test (6MWT). The fraction of exhaled nitric oxide (FENO ) was obtained to assess eosinophilic airway inflammation. Measurements were taken at diagnosis and after 4 weeks of treatment. RESULTS: A total of 20 consecutive patients (16 women) with chronic HP participated in the study. Median age was 50 years (interquartile range (IQR): 42-54). At diagnosis, the UPG phase 3 slope was abnormally high, consistent with maldistribution of ventilation. For IOS, all patients had low reactance at 5 Hz (X5) and elevated reactance area (AX) reflecting low compliance, and only eight (40%) patients had elevated R5 (resistance at 5 Hz (total)) and R5-20 (resistance at 5 Hz-resistance at 20 Hz (peripheral)) attributed to SA resistance. In contrast, FENO parameters were within normal limits. After treatment, forced vital capacity (FVC), the 6-min walk distance and the distribution of ventilation showed significant improvement, although DLCO did not. CONCLUSION: Patients with chronic HP have SA abnormalities that are partially revealed by the UPG and IOS tests. Lung volumes, but not gas exchange, improved after treatment with azathioprine and prednisone.

Variability of FeNO in healthy subjects at 2240 meters above sea level.

Fraction of exhaled nitric oxide (FeNO) is a marker of eosinophilic airway inflammation. Altitude above sea level can affect measurements of this index, but there is only limited information regarding the diurnal variation (ante meridiem vs. post meridiem) and reproducibility of FeNO on consecutive days at moderate altitudes. To evaluate the diurnal variability of FeNO and assess its reproducibility over five consecutive days in healthy individuals living at 2240 m, and to compare the FeNO readings taken with two different analyzers. Healthy non-smoking adults were measured using NIOX MINO(®) or NOA 280i(®) devices. One group (n = 10) had readings taken morning and afternoon for five consecutive days with the NIOX MINO(®) equipment; while the second group (n = 17) was measured on only one morning but by both the electrochemical analyzer (NIOX MINO(®)) and the chemiluminescence method (NOA 280i(®)). The study group consisted of 27 subjects aged 28.7 ± 6 years. Morning and afternoon FeNO measurements were 15.2 ± 7.5 ppb and 15.2 ± 7.9 ppb (p = 0.9), respectively. The coefficient of variation (CV) of these measurements (a.m. vs. p.m.) was 10.7 %, and the coefficient of repeatability (CR), 4.2 ppb. The concordance correlation coefficient (CCC) between the two measures (morning vs. afternoon) was 0.91. The CV and CR of the five morning readings were 15.4 % and 4.3 ppb, respectively; while those of the five afternoon measures were 13.6 % and 3.5 ppb, respectively. The CCC between the NIOX MINO(®) equipment and the NOA-280i(®) device was 0.8, with 95 % limits of agreement of -8.35 to 0.29 ppb. In adults living at 2240 m above sea level, FeNO measurements show minimal diurnal variation, and readings are reproducible (<15 %) over a period of at least five consecutive days; however, the FeNO measurements obtained with the NIOX MINO(®) and NOA 280i(®) devices are not interchangeable due to the wide limits of agreement recorded.