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.

[Lung-cancer screening program in Mexico]. / Detección temprana de cáncer de pulmón en México.

La detección temprana de cáncer pulmonar (CP) en población de alto riesgo tiene el potencial de diagnosticar la enfermedad en estadios tempranos y facilitar el tratamiento oportuno con el fin de disminuir la tasa de mortalidad. En México, como en otros países en vías de desarrollo, además del tabaquismo, la exposición al humo de leña se posiciona como uno de los principales factores de riesgo para desarrollar CP, lo cual no se ha considerado en estudios de tamizaje previamente publicados. Distintas interrogantes surgen en relación con quiénes son las personas que presentan un alto riesgo de desarrollar CP en América Latina, cuál es el costo-beneficio de poner en marcha un programa de detección oportuna de CP en México y cuáles son los obstáculos que los países de la región enfrentan para su implementación.

Lung cancer screening has the potential to be diagnosed at an early stage which increases the possibility of curative treatment in order to decrease the mortality rate. In Mexico, as in other developing nations, along with wood smoke exposure is one of the main risk factors for developing lung cancer, not considered in previously published screening trials. Different questions arise concerning the population at higher risk to develop lung cancer in Latin America, the cost-benefit of implementing a lung cancer screening program and the obstacles facing developing countries when implementing a detection program. To knowledge, there are no lung cancer screening trials in Mexico.

Detección temprana de cáncer de pulmón en México / Lung-cancer screening program in Mexico

Resumen: La detección temprana de cáncer pulmonar (CP) en población de alto riesgo tiene el potencial de diagnosticar la enfermedad en estadios tempranos y facilitar el tratamiento oportuno con el fin de disminuir la tasa de mortalidad. En México, como en otros países en vías de desarrollo, además del tabaquismo, la exposición al humo de leña se posiciona como uno de los principales factores de riesgo para desarrollar CP, lo cual no se ha considerado en estudios de tamizaje previamente publicados. Distintas interrogantes surgen en relación con quiénes son las personas que presentan un alto riesgo de desarrollar CP en América Latina, cuál es el costo-beneficio de poner en marcha un programa de detección oportuna de CP en México y cuáles son los obstáculos que los países de la región enfrentan para su implementación.

Abstract: Lung cancer screening has the potential to be diagnosed at an early stage which increases the possibility of curative treatment in order to decrease the mortality rate. In Mexico, as in other developing nations, along with wood smoke exposure is one of the main risk factors for developing lung cancer, not considered in previously published screening trials. Different questions arise concerning the population at higher risk to develop lung cancer in Latin America, the cost-benefit of implementing a lung cancer screening program and the obstacles facing developing countries when implementing a detection program. To knowledge, there are no lung cancer screening trials in Mexico.

Pediatric asthma treatment: What to do when international guideline recommendations do not agree.

BACKGROUND: There was a need for a solid asthma guideline in Mexico to update and unify asthma management. Because high-quality asthma guidelines exist worldwide, in which the latest evidence on asthma management is summarized, the ADAPTE approach allows for the development of a national asthma guideline based on evidence from already existing guidelines, adapted to national needs. OBJECTIVE: To fuse evidence from the best asthma guidelines and adapt it to local needs with the ADAPTE approach. METHODS: The Appraisal of Guidelines for Research and Evaluation (AGREE) II asthma guidelines were evaluated by a core group to select 3 primary guidelines. For each step of asthma management, clinical questions were formulated and replied according to (1) evidence in the primary guidelines, (2) safety, (3) Cost, and (4) patient preference. The Guidelines Development Group, composed of a broad range of experts from medical specialties, primary care physicians, and methodologists, adjusted the draft questions and replies in several rounds of a Delphi process and 3 face-to-face meetings, taking into account the reality of the situation in Mexico. We present the results of the pediatric asthma treatment part. RESULTS: Selected primary guidelines are from the British Thoracic Society and Scottish Intercollegiate Guidelines Network (BTS/SIGN), Global Initiative for Asthma (GINA), and Spanish Guidelines on the Management of Asthma (GEMA) 2015, with 2016 updates. Recommendations or suggestions were made for asthma treatment in Mexico. In this article, the detailed analysis of the evidence present in the BTS/SIGN, GINA, and GEMA sections on the (non) pharmacologic treatment of pediatric asthma, education, and devices are presented for 2 age groups: children 5 years or younger and children 6 to 11 years old with asthma. CONCLUSION: For the pediatric treatment and patient education sections, applying the AGREE II and Delphi methods is useful to develop a scientifically sustained document, adjusted to the Mexican situation, as is the Mexican Guideline on Asthma.

[Mexican Asthma Guidelines: GUIMA 2017]. / Guía Mexicana del Asma: GUIMA 2017.

BACKGROUND: The need for a national guideline, with a broad basis among specialists and primary care physicians was felt in Mexico, to try unifying asthma management. As several high-quality asthma guidelines exist worldwide, it was decided to select the best three for transculturation. METHODS: Following the internationally recommended methodology for guideline transculturation, ADAPTE, a literature search for asthma guidelines, published 1-1-2007 through 31-12-2015 was conducted. AGREE-II evaluations yielded 3/40 most suitable for transculturation. Their compound evidence was fused with local reality, patient preference, cost and safety considerations to draft the guideline document. Subsequently, this was adjusted by physicians from 12 national medical societies in several rounds of a Delphi process and 3 face-to-face meetings to reach the final version. RESULTS: Evidence was fused from British Thoracic Society Asthma Guideline 2014, Global Initiative on Asthma 2015, and Guía Española del Manejo del Asma 2015 (2016 updates included). After 3 Delphi-rounds we developed an evidence-based document taking into account patient characteristics, including age, treatment costs and safety and best locally available medication. CONCLUSIONS: In cooperation pulmonologists, allergists, ENT physicians, paediatricians and GPs were able to develop an evidence-based document for the prevention, diagnosis and treatment of asthma and its exacerbations in Mexico.

Antecedentes: Con el objetivo de unificar el manejo del asma en México se estructuró una guía clínica que conjunta el conocimiento de diversas especialidades y la atención en el primer nivel de contacto. Se seleccionaron 3 guías publicadas en el ámbito internacional para su transculturación. Métodos: Conforme a la metodología ADAPTE se usó AGREE II después de la búsqueda bibliográfica de guías sobre asma publicadas entre 2007 y 2015. Se fusionó la realidad local con la evidencia de 3/40 mejores guías. El documento inicial fue sometido a la revisión de representantes de 12 sociedades médicas en varias rondas Delphi hasta llegar a la versión final. Resultados: Las guías base fueron la British Thoracic Society Asthma Guideline 2014, la Global Initiative on Asthma 2015 y la Guía Española del Manejo del Asma 2015. Después de 3 rondas Delphi se desarrolló un documento en el que se consideraron las características de los pacientes según edad, costos de los tratamientos y perfiles de seguridad de los fármacos disponibles en México. Conclusión: Con la cooperación de neumólogos, alergólogos, otorrinolaringólogos, pediatras y médicos generales se llegó a un consenso basado en evidencia, en el que se incluyeron recomendaciones sobre prevención, diagnóstico y tratamiento del asma y sus crisis.

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 (DLCO) recommend a weekly biological control test and/or DLCO 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 DLCO instrument. METHODS: We used a new EasyOne Pro system and checked its accuracy using a DLCO simulator with 2 reference gases (concentration A: carbon monoxide [CO] = 0.1% and helium = 6.52%; concentration B: CO = 0.08% and helium = 7.21%) during the first 3 y of use in our large clinical laboratory. To detect instrument drift, a healthy woman (MSC), age 43 y old at baseline, tested herself every week during this period of time. RESULTS: More than 6,000 spirometry and 5,000 DLCO maneuvers were done using this instrument for patients during these 3 y. There were no failures in the daily volume and flow checks or the CO and helium calibration checks performed automatically by the instrument. The differences between the simulator DLCO and the measured DLCO were -0.91 ± 1.33 mL/min/mm Hg and -0.61 ± 1.45 mL/min/mm Hg for concentration A and concentration B, respectively. The results of the 110 biological control tests were: mean 30.8 ± 1.7 mL/min/mm Hg (95% CI 30.5-31.1), coefficient of variation of 5.4% in DLCO, and repeatability of 2.5 mL/min/mm Hg. Only 4 measurements were outside ±3 mL/min/mm Hg (3.6%). Her mean alveolar volume was 4.2 ± 0.25 L with coefficient of variation of 6.2%; her inspired volume was 3.05 ± 0.14 L, and coefficient of variation = 4.5%. CONCLUSIONS: Measurements of DLCO were stable over the 3-y period without any need for manual recalibration of the instrument. The biological control was as good as the DLCO simulator to evaluate this kind of device in a long-term laboratory quality control program.

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. METHODS: We recruited healthy adults from Caracas (690 m), Santiago (650 m), Mexico City (2,240 m), and Bogota (2,640 m). DLCO testing was completed using an instrument that exceeds American Thoracic Society/European Respiratory Society 2005 guidelines for spirometry and single-breath DLCO and provided centralized training and a quality assurance program. RESULTS: We included 480 healthy Hispanic adults (58.3% women) with a mean age of 46 y (range 22-83 y). Their mean ± SD single-breath DLCO was 30.4 ± 9.2 mL/min/mm Hg. Results as a percentage of predicted by Crapo's reference values (the closest to obtained values) were 83 ± 10% (Caracas), 91 ± 10% (Santiago), 104 ± 17% (Mexico City), and 118 ± 19% (Bogota), and current suggested adjustments by hemoglobin or altitude did not correct differences, especially in Santiago and Caracas. CONCLUSIONS: We recommend these new single-breath DLCO reference equations to predict single-breath DLCO in Latin America performed with current instruments and procedures and including as a predictor altitude above sea level.

Diagnostic Value of the Morphometric Model and Adjusted Neck Circumference in Adults with Obstructive Sleep Apnea Syndrome.

BACKGROUND: Obstructive sleep apnea syndrome is a major public health problem. The morphometric model and the Sleep Apnea Clinical Score are widely used to evaluate adults; however, neither of these tools has been validated in a Mexican population. OBJECTIVE: To determine the diagnostic value of the morphometric model and the Sleep Apnea Clinical Score and compare them with conventional clinical instruments. METHODS: A total of 97 individuals were recruited prospectively. Initial screening excluded 36, of whom nine were subjects without apnea; the remaining 52 were consecutive patients with obstructive sleep apnea syndrome diagnosed by nocturnal polysomnography. Diagnostic values of each test were calculated. RESULTS: Obstructive sleep apnea syndrome patients had significantly higher scores with both instruments than controls: morphometric model: 61.3 (95% CI: 45.5-75.3) vs. 41.0 (95% CI: 35.6-45.6); Sleep Apnea Clinical Score: 45.3 (95% CI: 39.5-40.3) vs. 36 (95% CI: 34.0-36.5), respectively. For severe cases, the best cutoff point for morphometric model was 46, with a sensitivity of 81% (95% CI: 62.5-92.6) and specificity of 46.7% (95% CI: 66.4-100), while for Sleep Apnea Clinical Score it was > 48, with a sensitivity of 61% (95% CI: 46.1-74.2) and specificity of 80.4% (95% CI: 66-90.6). CONCLUSIONS: A morphometric model value of ≥ 46 or an adjusted neck circumference (Sleep Apnea Clinical Score) > 48 were adequate for diagnosing obstructive sleep apnea syndrome.

Aspergilosis traqueobronquial invasiva en un paciente con púrpura trombocitopénica trombótica tratada con Anti-CD20 / Invasive tracheobronchial aspergillosis in a patient with thrombotic thrombocytopenic purpura (TTP) and immunosuppressed due to the use of steroids and anti-CD20

La aspergilosis invasiva es una complicación que se presenta con mayor frecuencia en pacientes con inmunosupresión. La aspergilosis traqueobronquial es una complicación muy rara con mínimas manifestaciones clínicas. Se informa de una paciente de 53 años con diagnóstico de púrpura trombocitopénica trombótica (PTT) con inmunosupresión por el uso de esteroides y anti CD-20, que presentó hemoptisis en 2 ocasiones; la segunda fue masiva y ocasionó la muerte. Previo al segundo evento de la hemoptisis se logró realizar broncoscopía, que mostró pseudomembranas y ulceración del epitelio bronquial. En el postmortem se logró documentar la presencia de Aspergillus tanto en la biopsia como en el cultivo. Es de gran importancia la sospecha y un reconocimiento temprano de esta patología en pacientes con inmunosupresión por su alta mortalidad.

Invasive aspergillosis is a complication most commonly developed in immunosuppressed patients. Tracheobronquial aspergillosis is an extremely rare complication with minimal clinical expression. We present the case of a 53-year-old female patient diagnosed with thrombotic thrombocytopenic purpura (TTP) and immunosuppressed due to the use of steroids and anti-CD20, who presented hemoptisis twice; being the second one massive leading to death. Before the second event of hemoptisis, bronchoscopy was performed, which showed pseudomembranes and ulceration of the bronchial epithelium. In the post-mortem examination, the presence of Aspergillus was evidenced by both biopsy and culture. The presumption and early diagnosis of this condition are paramount for immunosuppressed patients due to its high mortality.

Salud respiratoria en América Latina: número de especialistas y formación de recursos humanos / Respiratory Health in Latin America: Number of Specialists and Human Resources Training

América Latina está compuesta por países en vías de desarrollo. Los cerca de 600 millones de habitantes exhiben una transición demográfica que combina un crecimiento significativo de la población con un fenómeno de envejecimiento poblacional progresivo. Esta región del mundo exhibe grandes retos para la salud general y la respiratoria. La mayoría de los países muestran tasas significativas, incluso mayor, de enfermedades respiratorias crónicas o de exposiciones de riesgo. La disponibilidad de recursos humanos para la salud es escasa, particularmente en cuanto a especialistas en enfermedades respiratorias se refiere. Los centros de formación académica son pocos e incluso inexistentes en la mayor parte de los países. El análisis detallado de estas condiciones permitirá reflexionar sobre los principales retos, así como sobre las propuestas para la gestión y la formación de más y mejores recursos humanos en la especialidad

Latin America is made up of a number of developing countries. Demographic changes are occurring in the close to 600 million inhabitants, in whom a significant growth in population is combined with the progressive ageing of the population. This part of the world poses great challenges for general and respiratory health. Most of the countries have significant, or even greater, rates of chronic respiratory diseases or exposure to risk. Human resources in healthcare are not readily available, particularly in the area of respiratory disease specialists. Academic training centers are few and even non-existent in the majority of the countries. The detailed analysis of these conditions provides a basis for reflection on the main challenges and proposals for the management and training of better human resources in this specialist area

Respiratory health in Latin America: number of specialists and human resources training.

Latin America is made up of a number of developing countries. Demographic changes are occurring in the close to 600 million inhabitants, in whom a significant growth in population is combined with the progressive ageing of the population. This part of the world poses great challenges for general and respiratory health. Most of the countries have significant, or even greater, rates of chronic respiratory diseases or exposure to risk. Human resources in healthcare are not readily available, particularly in the area of respiratory disease specialists. Academic training centers are few and even non-existent in the majority of the countries. The detailed analysis of these conditions provides a basis for reflection on the main challenges and proposals for the management and training of better human resources in this specialist area.

Perceptions of short and long sleep duration and comorbid conditions: the PLATINO study.

OBJECTIVES: We aimed to describe the distribution of self-reported sleep duration in adults over the age of 40 years and to analyze the associated risk factors, comorbid conditions, and quality of life (QoL). METHODS: Our study was constructed as a cross-sectional population-based study and is part of the PLATINO (Spanish acronym for the Latin American Project for Research in Pulmonary Obstruction) study. It includes data from Mexico City (Mexico), Montevideo (Uruguay), Santiago (Chile), and Caracas (Venezuela). Data from 4533 individuals were analyzed using a single questionnaire entitled, PLATINO, which was designed to collect data on self-reported sleep symptoms. Spirometry also was performed in accordance with international standards. All statistical analyses took the study design into consideration with adjustments for each city. RESULTS: The prevalence of subjects who reported sleeping <7h was 38.4%, ≥ 7 to <9h was 51.4%, and ≥ 9h was 10.2%. In the multivariate analysis, individuals with shorter sleep duration had higher frequencies of insomnia, increased forced expiratory volume in one second in liters and percentage/forced vital capacity in liters (FEV1/FVC) of predicted ratios, and a higher presence of coughing and phlegm. The main risk factor associated with longer duration of sleep was the number of comorbidities. CONCLUSIONS: Self-reported sleep duration discriminated among groups that differed in sleep-related symptoms, respiratory symptoms, QoL and comorbid conditions.

[Burnout syndrome among medical residents during the influenza A H1N1 sanitary contigency in Mexico]. / Síndrome de burnout en médicos mexicanos en entrenamiento durante una contingencia sanitaria por virus de influenza A H1N1.

OBJECTIVE: To measure the degree of stress among medical residents at a Third Level Hospital in Mexico City during the sanitary contingency caused by the AH1N1 influenza virus. METHODS: A transversal descriptive study with a non-probabilistic sample of 99 medical residents with different fields of specialization related to respiratory medicine. Researchers applied the Maslach Burnout Inventory questionnaire to evaluate three dimensions: emotional fatigue, depersonalization, and personal fulfillment. The survey was self-administered and anonymous, and the study was conducted during the first AH1N1 influenza virus outbreak (April 23 to May 10, 2009). During that period, the hospital underwent a process of reorganization that included cancelling vacation periods for all medical residents and adjusting duty rosters. RESULTS: The highest proportion of medical residents with burnout syndrome was those in their second year of specialization in the area of pneumology. Results also showed that medical residents under 30 years of age had a higher probability of presenting burnout syndrome. No significant differences were found regarding the residents' place of origin.

Agreement between 95th percentile pressure based on a 7-night auto-adjusting positive airway pressure trial vs. equation-based predictions in sleep apnea.

STUDY OBJECTIVES: to analyze the agreement between effective CPAP-determined on the basis of a 7-night auto-adjusting positive airway pressure (APAP) trial at home with that obtained through 5 different predictive equations. METHODS: Data were collected from consecutive CPAP-naive patients with OSA who underwent a 7-night non-attended home-setting APAP trial. The 95th percentile APAP pressure was considered as the effective CPAP and also as the reference variable against which the equation-based predictions were compared. All patients fulfilled the following criteria: residual respiratory disturbances index (RDI) < 10 events/h, average air leak < 0.4 L/sec and > 4 h of use per night during the APAP trial. RESULTS: A total of 100 consecutive patients (70 men) with the following characteristics were included: mean age 49 +/- 11 years, body mass index 34 +/- 4 kg/m2, diagnostic Epworth Sleepiness Scale score 14 +/- 7, diagnostic RDI 56 +/- 28 events/h, 95th percentile APAP 11 +/- 2 cm H2O, hours of use per night 6.2 +/- 1.3, and residual RDI 5 +/- 2 events/h. A poor level of agreement between the 95th percentile pressure and the pressures obtained through 5 predictive equations was observed (the intra-class correlation coefficient ranged from 0.17 to 0.32). CONCLUSIONS: The disagreement observed between the effective CPAP determined through a 7-night APAP trial and the pressures obtained by the predictive equations suggest that long-term CPAP prescriptions based on predictive equations may be improper.

Prevalence of sleep related symptoms in four Latin American cities.

STUDY OBJECTIVES: to estimate the prevalence of the most common sleep related symptoms (SRS) in the metropolitan areas of Mexico City, Montevideo (Uruguay), Santiago (Chile), and Caracas (Venezuela). METHODS: The study consisted of a multistage cluster sampling of adults aged > or = 40 years living in metropolitan areas. All participants completed a questionnaire on sleep related symptoms. Simplified respiratory polygraphy during sleep was conducted on 188 subjects from Mexico City. Obstructive sleep apnea syndrome was defined as Epworth Sleepiness Scale score > or = 11 and respiratory disturbance index (RDI) > or = 15 events/h; a cut-off of 15 was chosen because of its high sensitivity and specificity in association with the portable monitor used in the study. RESULTS: The study included 4,533 subjects (1,062 in Mexico City, 941 in Montevideo, 1,173 in Santiago, and 1,357 in Caracas). Snoring was reported by 60.2% (95% CI 58.8% to 61.6%), excessive daytime sleepiness by 16.4% (15.3% to 17.5%), observed apneas by 12.3% (11.4% to 13.3%), insomnia by 34.7% (33.3% to 36%), sedative use by 15.1% (14.1% to 16.2%), daytime napping by 29.2% (27.7% to 30.6%), and a combination of snoring, sleepiness, and observed apneas by 3.4% (2.9% to 4%). Men had a higher frequency of snoring and daytime napping, whereas women reported more insomnia and sedative use. Prevalence of OSAS varied from 2.9% among subjects who denied snoring, excessive daytime sleepiness, and observed apneas, to 23.5% among those reporting these 3 symptoms. CONCLUSIONS: A high prevalence of sleep related symptoms and undiagnosed obstructive sleep apnea in Latin America was observed.

Spirometry quality-control strategies in a multinational study of the prevalence of chronic obstructive pulmonary disease.

UNLABELLED: We report the characteristics of a centralized spirometry quality-control program developed for a population-based survey of the prevalence of chronic obstructive pulmonary disease in 5 cities: São Paulo, Brazil; México City, México; Montevideo, Uruguay; Santiago, Chile; and Caracas, Venezuela (the Latin American Project for the Investigation of Obstructive Lung Diseases [PLATINO]). METHODS: We developed and used a 3-level quality-control system. Level 1: The spirometer used in the survey (EasyOne), gives quality-control messages to the user/clinician. All the spirometry technicians were trained by the same team, with the aim of meeting what became the 2005 spirometry quality criteria of the American Thoracic Society/European Respiratory Society (ATS/ERS). Level 2: In each of the 5 cities a local supervisor identified poor-quality spirometries that needed to be repeated. Level 3: Once a week during the survey, all spirometry results were sent via e-mail to the study's quality-control center in México City for review and feedback. RESULTS: In the overall totals at the end of the study, 94% of the 5,315 subjects had spirometries that met the 1994 ATS quality criteria, and 89% met the 2005 ATS/ERS criteria. In their overall totals at the end of the study, 90% of the 64 spirometry technicians were successful in getting 86% of their subjects to meet the 1994 ATS criteria, and got 75% of their subjects to meet the 2005 ATS/ERS criteria. In the first 10 subjects they tested, 90% of the 64 spirometry technicians were successful in getting 70% of their subjects to meet the 1994 ATS criteria, and got 60% of their subjects to meet the 2005 ATS/ERS criteria. CONCLUSIONS: Standardization of equipment, training, and supervision of spirometry is essential in a multinational spirometry survey. Centralized quality control can be done via e-mail with good reliability and low cost.

[Agreement between oxygen desaturation index and apnea-hypopnea index in adults with suspected obstructive sleep apnea at an altitude of 2240 m]. / Indice de desaturación de oxígeno frente a índice de apneas-hipopneas en adultos con sospecha de apnea obstructiva durante el sueño a 2.240 m de altitud.

OBJECTIVE: Altitude can affect the diagnostic accuracy of portable monitors used to diagnose suspected obstructive sleep apnea syndrome on the basis of oxygen desaturation measurements. The aim of this study was to determine agreement between the desaturation index measured by oximetry and the apnea-hypopnea index measured by polysomnography in Mexico City (2240 m above sea level). We also wished to determine agreement between the desaturation index and the respiratory disturbance index measured by monitoring airflow with a single-channel recording device. PATIENTS AND METHODS: We used standard polysomnography and nocturnal oximetry to simultaneously measure the apnea-hypopnea index and the desaturation index, respectively, in a group of 38 patients aged over 18 years with suspected obstructive sleep apnea syndrome. In a second group of 30 patients, we compared the desaturation index to the respiratory disturbance index, which we measured using a single-channel device monitoring nasal airflow. RESULTS: The mean (SD) intraclass correlation coefficient between the apnea-hypopnea index and the desaturation index was 0.89 (0.03) (95% confidence interval, 0.83-0.96), and the mean of the differences was -0.9 (14.2). The mean intraclass correlation coefficient for the desaturation index and the respiratory disturbance index was 0.93 (0.02) (95% confidence interval, 0.89-0.97), and the mean of the differences was -6.6 (8.3). CONCLUSIONS: Agreement was high between the desaturation index and both the apnea-hypopnea index and the respiratory disturbance index in adults with suspected obstructive sleep apnea syndrome in Mexico City.