Intermittent hypoxemia and sleep fragmentation: associations with daytime alertness in obese sleep apnea patients living at moderate altitude.

BACKGROUND: Although obstructive sleep apnea (OSA) has long been associated with daytime sleepiness, far less is known about its association with the ability to remain awake. The aim of this study was to examine the relative importance of inter-correlated measures of OSA severity (eg, various indices of oxygen saturation and sleep fragmentation) in the ability to stay alert as measured objectively by the Maintenance of Wakefulness Test (MWT), defined by a mean sleep latency of ≥12 min. METHODS: Seventy-eight obese women and men of similar age and body mass index living at altitude (Mexico City) underwent standard polysomnography, MWT, and completed validated sleep-related questionnaires. RESULTS: Men had more severe sleep apnea than women (p = 0.002) and were also less alert on MWT (p = 0.022). Logistic regression models indicated that measures of desaturation consistently predicted MWT-defined alertness, whereas varied measures of sleep fragmentation did not. Nearly a third of the variance (r(2) = 0.304) in MWT-defined alertness was accounted for by the number of desaturations per hour of sleep (p = 0.003), which is considerably higher than other studies have reported in different populations. CONCLUSION: The ability to remain awake in obese patients is best accounted for by hypoxemia rather than sleep fragmentation. Whether the size of this effect reflects differences in the population under study (eg, extent of obesity, racial background, residence at moderate altitude) and/or is a function of the measurement of alertness with the MWT remains uncertain.

[Sleep medicine: development, contributions and perspectives. Report of the work group on sleep medicine]. / Medicina del dormir: desarrollo, contribuciones y perspectivas. Reporte del grupo de trabajo en medicina del dormir.

Sleep is a basic biological process that has an impact on all the functions of the body, and interacts bidirectionally with virtually all of the body systems, so that the sleep disorders are associated with disturbances in other systems, either respiratory, neurological, cardiovascular, endocrine, immune, etc., and vice versa. The complexity of the regulatory mechanisms of sleep and the variety of their disorders, together with the clinical evidence accumulated in recent decades, have led to the birth of a new branch in medicine: the Sleep Medicine, with well defined intrinsic disorders. The consequences of sleep deprivation or fragmentation induced by changes in social and work dynamics, as well as sleep disorders have harmful effects on individuals in the short and long-term, the most important are an elevated risk for vehicular and occupational accidents, cardiovascular damage, cognitive impairment, obesity, diabetes mellitus, among others, impacting individuals of all ages. The sleep clinics and laboratories in Mexico, have made significant contributions, at both the basic and clinical levels, for the diagnosis and treatment of sleep disorders; however, without a specific health policy, we will continue to commit resources only on the attention of its effects and not on prevention, making the impact on the economy and quality of life of patients with sleep disorders, much higher than in developed countries. It is necessary to build a program of medical care to incorporate the Sleep Medicine in the priorities of medical care in the National Institutions of Health at all levels. Solutions and guides to optimize the achievement of the proposed results, and increase efficiency and effectiveness of the resources applied in this new field of Medicine are offered.

[Cardiovascular risk among adults with obstructive sleep apnea syndrome]. / Riesgo cardiovascular en adultos con síndrome de apnea obstructiva del sueño. A 25 años de los primeros estudios de asociación.

Cardiovascular diseases and sleep-disordered breathing have been recognized as a public health problem in Mexico and worldwide. These two groups of disorders are closely associated and the evidence accumulated over the last 25 years indicates that obstructive sleep apnea syndrome (OSAS) is an independent risk factor in systemic arterial hypertension, coronary artery disease and stroke. Other associations have also been described, linking these disorders with pulmonary hypertension, cardiac arrhythmias, sudden death during sleep and congestive heart failure. Treatment with continuous positive airway pressure in patients with OSAS has proven to be an efficient primary and secondary cardiovascular prevention strategy. This article reviews the epidemiological evidence that links OSAS with increased cardiovascular risk, and proposes strategies designed to address this growing health problem.

Autoadjusting positive pressure trial in adults with sleep apnea assessed by a simplified diagnostic approach.

STUDY OBJECTIVES: To describe our clinical experience with autoadjusting positive airway pressure (APAP) trials carried out on patients with moderate-to-severe obstructive sleep apnea (OSA). METHODS: Consecutive CPAP-naive adults underwent a non-attended home APAP trial (ResMed, Autoset, Spirit). Diagnoses of OSA were established by simplified polygraphy. RESULTS: Data from 208 men and 71 women. The median age (interquartile range) was 51 years (41-59), with an Epworth Sleepiness Scale score of 13.5 (9-19), body mass index of 33 kg/m2 (29-38) and respiratory disturbance index (RDI) of 53 events/h (35-74). The APAP trial results included: hours used per night, 5.5 (4-7); 95th percentile pressure, 10.6 cm H2O (9.4-11.7); 95th percentile leak, 0.3 UL/sec (0.1-0.6); residual RDI, 6.2 events/h (3.9-11.4); and percentage change in RDI, 87% (74-93). The proportion of patients with residual RDI >10 events/h was 29% (95% CI 23.6-34.3). Adherence (> 70% of nights and > 4 h/night) was observed in 72.4% of subjects (95% CI 67-78). Patients with APAP adherence tended to require higher CPAP pressures, had higher rates of residual RDI, and had a lower percentage change in RDI than those with no adherence. As the 95th percentile CPAP pressure increased so too did residual RDI. CONCLUSIONS: The APAP trial was effective in decreasing RDI with an acceptable adherence rate; however, residual OSAwas a frequent finding. Our results support that in up to one-third of patients evaluated by a simplified diagnostic approach, CPAP titration based on 95th percentile pressure may not be sufficient if residual RDI < 10 events/h is considered as a therapeutic target.

Riesgo cardiovascular en adultos con síndrome de apnea obstructiva del sueño: a 25 años de los primeros estudios de asociación / Cardiovascular risk among adults with obstructive sleep apnea syndrome

Las enfermedades cardiovasculares y los trastornos respiratorios durante el sueño representan un grave problema de salud pública en México y el mundo. En los últimos 25 años se han realizado estudios que demuestran que el síndrome de apnea obstructiva del sueño (SAOS) es un factor de riesgo independiente para hipertensión arterial sistémica, cardiopatía isquémica y enfermedad vascular cerebral. Se ha descrito también otras asociaciones con hipertensión arterial pulmonar, arritmias, muerte súbita durante el sueño e insuficiencia cardiaca. El tratamiento con presión positiva continua en la vía aérea en pacientes con SAOS ha mostrado tener un efecto positivo sobre la prevención primaria y secundaria de las principales enfermedades cardiovasculares. En este manuscrito revisamos la evidencia epidemiológica que relaciona el SAOS con incremento en el riesgo cardiovascular y proponemos algunas estrategias para hacer frente al creciente problema del SAOS en su asociación con enfermedades cardiovasculares.

Cardiovascular diseases and sleep-disordered breathing have been recognized as a public health problem in Mexico and worldwide. These two groups of disorders are closely associated and the evidence accumulated over the last 25 years indicates that obstructive sleep apnea syndrome (OSAS) is an independent risk factor in systemic arterial hypertension, coronary artery disease and stroke. Other associations have also been described, linking these disorders with pulmonary hypertension, cardiac arrhythmias, sudden death during sleep and congestive heart failure. Treatment with continuous positive airway pressure in patients with OSAS has proven to be an efficient primary and secondary cardiovascular prevention strategy. This article reviews the epidemiological evidence that links OSAS with increased cardiovascular risk, and proposes strategies designed to address this growing health problem.

[Mechanisms of cardiovascular damage in obstructive sleep apnea]. / Mecanismos de daño cardiovascular en apnea obstructiva del sueño.

Obstructive sleep apnea syndrome (OSAS) is an independent and modifiable risk factor for cardiovascular diseases; however, the pathophysiological mechanisms underlying this association are not yet fully understood. Intermittent hypoxemia, one of the physiological markers of OSAS, is characterized by transient periods of oxygen desaturation followed by reoxygenation. The cycles of hypoxia-reoxygenation are associated with oxidative stress that, in turn, triggers the activation of pathways that lead to cardiovascular damage. These pathways include an increased chemoreflex sensitivity that induces the over-activation of the sympathetic nervous system, decreased baroreflex sensitivity, the activation of systemic inflammation pathways mediated primarily by the nuclear transcriptional factor kappaB that favors the development of atherosclerosis through the synthesis of cytokines and the expression of adhesion molecules, endothelial dysfunction with a decreased availability of nitric oxide, dyslipidemia, insulin resistance and stimulation of the renin-angiotensin system. Other mechanisms proposed include arousals that increase sympathetic activity and exaggerated intrathoracic pressure changes that generate high transmural pressure. Most of these mechanisms respond favorably to treatment with CPAP. A better understanding of the mechanisms of cardiovascular damage opens the possibility of instituting new treatments that will contribute to limiting the cardiovascular consequences associated with OSAS.

[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.

Índice 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 / Agreement between oxygen desaturation index and apnea-hypopnea index in adults with suspected obstructive sleep apnea at an altitude of 2240 m

Objetivo: La altitud puede afectar la rentabilidad diagnóstica de los monitores portátiles basados en la desaturación de oxígeno en pacientes con sospecha de síndrome de apneas obstructivas durante el sueño (SAOS). Nuestro propósito es comparar, en Ciudad de México (2.240 m de altitud), el índice de desaturaciones, obtenido con un oxímetro, con el índice polisomnográfico de apneas-hipopneas. Se comparó también el índice de desaturaciones con el índice respiratorio obtenido con un monitor monocanal de detección de flujo. Pacientes y métodos: A 38 pacientes mayores de 18 años con sospecha de SAOS, se les realizaron simultáneamente una polisomnografía estándar y una oximetría nocturna (Remmers Sleep Recorder, Sagatech, Calgary, Alberta, Canadá) para identificar el índice de apneas-hipopneas y el índice de desaturaciones, respectivamente. En otro grupo de 30 pacientes se comparó el índice de desaturaciones con el índice respiratorio basado en flujo obtenido de un sistema monocanal de flujo nasal (ApneaLink, ResMed Corp., Poway, CA, EE.UU.). Resultados: El coeficiente de correlación intraclase entre el índice de apneas-hipopneas y el de desaturaciones fue de 0,89 ± 0,03 (intervalo de confianza del 95%, 0,83-0,96); la media de las diferencias fue de ­0,9 ± 14,2. Al comparar el índice de desaturaciones y el índice respiratorio basado en el flujo nasal, el coeficiente de correlación intraclase fue de 0,93 ± 0,02 (intervalo de confianza del 95%, 0,89-0,97), y la media de las diferencias, de ­6,6 ± 8,3. Conclusiones: En Ciudad de México, en adultos con sospecha de SAOS, se observó una alta concordancia entre el índice polisomnográfico de apneas-hipopneas y el índice de desaturaciones, así como entre éste y el índice respiratorio basado en el flujo nasal

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 apnea­hypopnea 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 apnea­hypopnea 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 apnea­hypopnea 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 apnea­hypopnea index and the respiratory disturbance index in adults with suspected obstructive sleep apnea syndrome in Mexico City

[Continuous positive airway pressure used by adults with obstructive sleep apneas after prescription in a public referral hospital in Mexico City]. / Uso de CPAP en adultos con síndrome de apneas obstructivas durante el sueño después de prescripción en un hospital público de referencia de la Ciudad de México.

OBJECTIVE: The aim of this study was to analyze the frequency of initiation of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea syndrome (OSAS) in a referral hospital in Mexico City serving mainly patients without public health insurance coverage and to assess their level of adherence. PATIENTS AND METHODS: Patients with OSAS diagnosed by polysomnography or by simplified respiratory polygraphy for whom nasal CPAP was prescribed were enrolled in the study. Titration of CPAP was performed during polysomnography or with an automatic CPAP device. Compliance with treatment was assessed during a medical visit or by telephone interview. RESULTS: A total of 304 patients were enrolled upon prescription of nasal CPAP; 169 (55.5%) either purchased a device or were provided with one by the social security system. The patients most seriously ill and who had public health insurance coverage were the ones who most often acquired a device. These patients took 1.5 months to obtain the equipment and had a compliance rate of 80% at a mean 34 months of follow-up. The respiratory events index was correlated with compliance, whereas excessive daytime sleepiness (Epworth scale score) and body mass index were predictors of therapeutic CPAP pressure. CONCLUSIONS: Nearly half the patients who were prescribed CPAP did not acquire the device. Most of those who acquired a device adhered to the treatment. In Mexico access to procedures for diagnosing OSAS is limited and access to treatment is also restricted for patients who do not have public health insurance coverage.

Uso de CPAP en adultos con síndrome de apneas obstructivas durante el sueño después de prescripción en un hospital público de referencia de la Ciudad de México / Continuous positive airway pressure used by adults with obstructive sleep apneas after prescription in a public referral Hospital in Mexico city

Objetivo: El propósito del estudio ha sido analizar la frecuencia de inicio de tratamiento con presión positiva continua de la vía aérea (CPAP) y su cumplimiento en pacientes con síndrome de apneas obstructivas durante el sueño (SAOS), en un hospital de referencia de la Ciudad de México que atiende predominantemente a pacientes sin seguridad social. Pacientes y métodos: Se incluyó a pacientes con SAOS diagnosticados por poliomnografía o poligrafía respiratoria simplificada, a quienes se prescribió CPAP nasal. La titulación de ésta se realizó durante la polisomnografía o con un equipo automático de CPAP. El cumplimiento del tratamiento se evaluó en consulta o por entrevista telefónica. Resultados: Se incluyó a un total de 304 pacientes con prescripción de CPAP nasal. De ellos, 169 (55,5%) adquirieron el equipo (ya fuera por compra o gratuitamente a través de la seguridad social). Los pacientes más graves y con seguridad social fueron los que más frecuentemente lo adquirieron. Este grupo tardó 1,5 meses en obtener el equipo y tuvo un 80% de cumplimiento a los 34 meses de seguimiento medio. El índice respiratorio se asoció al cumplimiento, mientras que la somnolencia diurna excesiva (puntuación de Epworth) y el índice de masa corporal fueron predictores de la presión terapéutica de CPAP. Conclusiones: Casi la mitad de los pacientes a quienes se prescribió CPAP no adquirió el equipo. La mayoría de quienes lo adquirieron cumplió el tratamiento. En México, además del limitado acceso a los métodos diagnósticos de SAOS, el tratamiento está restringido en los pacientes diagnosticados que carecen de seguridad social

Objective: The aim of this study was to analyze the frequency of initiation of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea syndrome (OSAS) in a referral hospital in Mexico City serving mainly patients without public health insurance coverage and to assess their level of adherence. Patients and methods: Patients with OSAS diagnosed by polysomnography or by simplified respiratory polygraphy for whom nasal CPAP was prescribed were enrolled in the study. Titration of CPAP was performed during polysomnography or with an automatic CPAP device. Compliance with treatment was assessed during a medical visit or by telephone interview. Results: A total of 304 patients were enrolled upon prescription of nasal CPAP; 169 (55.5%) either purchased a device or were provided with one by the social security system. The patients most seriously ill and who had public health insurance coverage were the ones who most often acquired a device. These patients took 1.5 months to obtain the equipment and had a compliance rate of 80% at a mean 34 months of follow-up. The respiratory events index was correlated with compliance, whereas excessive daytime sleepiness (Epworth scale score) and body mass index were predictors of therapeutic CPAP pressure. Conclusions: Nearly half the patients who were prescribed CPAP did not acquire the device. Most of those who acquired a device adhered to the treatment. In Mexico access to procedures for diagnosing OSAS is limited and access to treatment is also restricted for patients who do not have public health insurance coverage

Otras consecuencias de los trastornos del dormir: A propósito de los accidentes vehiculares / Other consequences of sleep disorders: Regarding vehicular accidents

Los accidentes vehiculares son una causa frecuente de morbimortalidad en México y en el mundo, con incalculables costos directos e indirectos asociados. Existe una necesidad urgente de implementar medidas útiles para su prevención. La somnolencia excesiva diurna (SED) es un factor de riesgo para sufrir accidentes y es un síntoma común a varios trastornos del sueño, particularmente para aquellos que afectan el patrón respiratorio. El propósito de este manuscrito es revisar la prevalencia de SED, así como sus principales causas; además, se describe la asociación entre SED y accidentes vehiculares, las formas para medir objetivamente la SED, y proponemos algunas estrategias para reconocerla con la finalidad de contribuir en la implementation de programas preventivos.

Vehicular accidents are a frequent cause of morbility and mortality in Mexico and worldwide with incalculable associated direct and indirect costs. There is an urgent need to implement useful tools for their prevention. Excessive daytime sleepiness (EDS) is a risk factor for accidents and a common symptom shared by several sleep disorders, particularly relevant to those involving the respiratory pattern. The aim of this manuscript is to review EDS prevalence and its main causes; the association between EDS and vehicle accidents is described and the way to objectively meassure EDS. We propose some strategies to recognize it to contribute with preventive programs.