RESUMEN
BACKGROUND: Chronic mountain sickness (CMS) is often associated with vascular dysfunction, but the underlying mechanism is unknown. Sleep-disordered breathing (SDB) frequently occurs at high altitude. At low altitude, SDB causes vascular dysfunction. Moreover, in SDB, transient elevations of right-sided cardiac pressure may cause right-to-left shunting in the presence of a patent foramen ovale (PFO) and, in turn, further aggravate hypoxemia and pulmonary hypertension. We speculated that SDB and nocturnal hypoxemia are more pronounced in patients with CMS compared with healthy high-altitude dwellers, and are related to vascular dysfunction. METHODS: We performed overnight sleep recordings, and measured systemic and pulmonary artery pressure in 23 patients with CMS (mean ± SD age, 52.8 ± 9.8 y) and 12 healthy control subjects (47.8 ± 7.8 y) at 3,600 m. In a subgroup of 15 subjects with SDB, we assessed the presence of a PFO with transesophageal echocardiography. RESULTS: The major new findings were that in patients with CMS, (1) SDB and nocturnal hypoxemia was more severe (P < .01) than in control subjects (apnea-hypopnea index [AHI], 38.9 ± 25.5 vs 14.3 ± 7.8 number of events per hour [nb/h]; arterial oxygen saturation, 80.2% ± 3.6% vs 86.8% ± 1.7%, CMS vs control group), and (2) AHI was directly correlated with systemic blood pressure (r = 0.5216; P = .001) and pulmonary artery pressure (r = 0.4497; P = .024). PFO was associated with more severe SDB (AHI, 48.8 ± 24.7 vs 14.8 ± 7.3 nb/h; P = .013, PFO vs no PFO) and hypoxemia. CONCLUSIONS: SDB and nocturnal hypoxemia are more severe in patients with CMS than in control subjects and are associated with systemic and pulmonary vascular dysfunction. The presence of a PFO appeared to further aggravate SDB. Closure of the PFO may improve SDB, hypoxemia, and vascular dysfunction in patients with CMS. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01182792; URL: www.clinicaltrials.gov.
Asunto(s)
Mal de Altura/epidemiología , Altitud , Foramen Oval Permeable/epidemiología , Hipertensión Pulmonar/epidemiología , Hipoxia/epidemiología , Síndromes de la Apnea del Sueño/epidemiología , Adulto , Mal de Altura/fisiopatología , Presión Sanguínea , Bolivia/epidemiología , Estudios de Casos y Controles , Enfermedad Crónica , Ecocardiografía Transesofágica , Foramen Oval Permeable/diagnóstico por imagen , Foramen Oval Permeable/fisiopatología , Humanos , Hipertensión Pulmonar/diagnóstico por imagen , Hipertensión Pulmonar/fisiopatología , Hipoxia/fisiopatología , Masculino , Persona de Mediana Edad , Polisomnografía , Índice de Severidad de la Enfermedad , Síndromes de la Apnea del Sueño/fisiopatologíaRESUMEN
OBJECTIVE: To assess whether exposure to high altitude induces cognitive dysfunction in young healthy European children and adolescents during acute, short-term exposure to an altitude of 3450 m and in an age-matched European population permanently living at this altitude. STUDY DESIGN: We tested executive function (inhibition, shifting, and working memory), memory (verbal, short-term visuospatial, and verbal episodic memory), and speed processing ability in: (1) 48 healthy nonacclimatized European children and adolescents, 24 hours after arrival at high altitude and 3 months after return to low altitude; (2) 21 matched European subjects permanently living at high altitude; and (3) a matched control group tested twice at low altitude. RESULTS: Short-term hypoxia significantly impaired all but 2 (visuospatial memory and processing speed) of the neuropsychological abilities that were tested. These impairments were even more severe in the children permanently living at high altitude. Three months after return to low altitude, the neuropsychological performances significantly improved and were comparable with those observed in the control group tested only at low altitude. CONCLUSIONS: Acute short-term exposure to an altitude at which major tourist destinations are located induces marked executive and memory deficits in healthy children. These deficits are equally marked or more severe in children permanently living at high altitude and are expected to impair their learning abilities.
Asunto(s)
Mal de Altura/complicaciones , Trastornos del Conocimiento/etiología , Enfermedad Aguda , Adolescente , Altitud , Niño , Enfermedad Crónica , Cognición/fisiología , Trastornos del Conocimiento/diagnóstico , Trastornos del Conocimiento/fisiopatología , Femenino , Humanos , Hipoxia/complicaciones , Masculino , Trastornos de la Memoria , Pruebas NeuropsicológicasRESUMEN
Epidemiological studies demonstrate a relationship between pathological events during foetal development and future cardiovascular risk and the term 'foetal programming of cardiovascular disease' has been coined to describe this phenomenon. The use of assisted reproductive technologies (ARTs) is growing exponentially and 2-5% of children are now born by this procedure. Emerging evidence indicates that ART represents a novel important example of foetal programming. Assisted reproductive technology may modify the cardiovascular phenotype in two ways: (i) ART involves manipulation of the early embryo which is exquisitely sensitive to environmental insults. In line with this concern, ART alters vascular and cardiac function in children and studies in mice show that ART alters the cardiovascular phenotype by epigenetic alterations related to suboptimal culture conditions. (ii) Assisted reproductive technology markedly increases the risk of foetal insults that augment cardiovascular risk in naturally conceived individuals and are expected to have similar consequences in the ART population. Given the young age of the ART population, it will take another 20-30 years before data on cardiovascular endpoints will be available. What is clear already, however, is that ART emerges as an important cardiovascular risk factor. This insight requires us to revise notions on ART's long-term safety and to engage on a debate on its future. There is an urgent need to better understand the mechanisms underpinning ART-induced alteration of the cardiovascular phenotype, improve the procedure and its long-term safety, and, while awaiting this aim, not to abandon medicine's fundamental principle of doing no harm (to future children) and use ART parsimoniously.
Asunto(s)
Enfermedades Cardiovasculares/etiología , Técnicas Reproductivas Asistidas/efectos adversos , Animales , Enfermedades Cardiovasculares/prevención & control , Niño , Modelos Animales de Enfermedad , Epigénesis Genética/fisiología , Femenino , Desarrollo Fetal/fisiología , Predicción , Humanos , Ratones , Óxido Nítrico Sintasa de Tipo III/metabolismo , Embarazo , Efectos Tardíos de la Exposición Prenatal/etiología , Técnicas Reproductivas Asistidas/tendencias , Factores de Riesgo , Remodelación Vascular/fisiologíaRESUMEN
OBJECTIVES: The aim of this study was to evaluate right ventricular (RV) and left ventricular function and pulmonary circulation in chronic mountain sickness (CMS) patients with rest and stress echocardiography compared with healthy high-altitude (HA) dwellers. BACKGROUND: CMS or Monge's disease is defined by excessive erythrocytosis (hemoglobin >21 g/dl in males, 19 g/dl in females) and severe hypoxemia. In some cases, a moderate or severe increase in pulmonary pressure is present, suggesting a similar pathogenesis of pulmonary hypertension. METHODS: In La Paz (Bolivia, 3,600 m sea level), 46 CMS patients and 40 HA dwellers of similar age were evaluated at rest and during semisupine bicycle exercise. Pulmonary artery pressure (PAP), pulmonary vascular resistance, and cardiac function were estimated by Doppler echocardiography. RESULTS: Compared with HA dwellers, CMS patients showed RV dilation at rest (RV mid diameter: 36 ± 5 mm vs. 32 ± 4 mm, CMS vs. HA, p = 0.001) and reduced RV fractional area change both at rest (35 ± 9% vs. 43 ± 9%, p = 0.002) and during exercise (36 ± 9% vs. 43 ± 8%, CMS vs. HA, p = 0.005). The RV systolic longitudinal function (RV-S') decreased in CMS patients, whereas it increased in the control patients (p < 0.0001) at peak stress. The RV end-systolic pressure-area relationship, a load independent surrogate of RV contractility, was similar in CMS patients and HA dwellers with a significant increase in systolic PAP and pulmonary vascular resistance in CMS patients (systolic PAP: 50 ± 12 mm Hg vs. 38 ± 8 mm Hg, CMS vs. HA, p < 0.0001; pulmonary vascular resistance: 2.9 ± 1 mm Hg/min/l vs. 2.2 ± 1 mm Hg/min/l, p = 0.03). Both groups showed comparable systolic and diastolic left ventricular function both at rest and during stress. CONCLUSIONS: Comparable RV contractile reserve in CMS and HA suggests that the lower resting values of RV function in CMS may represent a physiological adaptation to chronic hypoxic conditions rather than impaired RV function. (Chronic Mountain Sickness, Systemic Vascular Function [CMS]; NCT01182792).
Asunto(s)
Mal de Altura/diagnóstico por imagen , Ecocardiografía Doppler , Ecocardiografía de Estrés , Ejercicio Físico , Hipertensión Pulmonar/diagnóstico por imagen , Contracción Miocárdica , Función Ventricular Derecha , Aclimatación , Adulto , Altitud , Mal de Altura/fisiopatología , Presión Arterial , Bolivia , Enfermedad Crónica , Prueba de Esfuerzo , Humanos , Hipertensión Pulmonar/fisiopatología , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Circulación Pulmonar , Suiza , Resistencia Vascular , Función Ventricular IzquierdaRESUMEN
BACKGROUND: Acute exposure to high altitude stimulates free radical formation in lowlanders, yet whether this persists during chronic exposure in healthy, well-adapted and maladapted highlanders suffering from chronic mountain sickness (CMS) remains to be established. METHODS: Oxidative-nitrosative stress (as determined by the presence of the biomarkers ascorbate radical [A â¢- ], via electron paramagnetic resonance spectroscopy, and nitrite [NO 2 2 ], via ozone-based chemiluminescence) was assessed in venous blood of 25 male highlanders in Bolivia living at 3,600 m with CMS (n 5 13, CMS 1 ) and without CMS (n 5 12, CMS 2 ). Twelve age- and activity-matched, healthy, male lowlanders were examined at sea level and during acute hypoxia. We also measured fl ow-mediated dilatation (FMD), arterial stiffness defined by augmentation index normalized for a heart rate of 75 beats/min (AIx-75), and carotid intima-media thickness (IMT). RESULTS: Compared with normoxic lowlanders, oxidative-nitrosative stress was moderately increased in the CMS 2 group ( P , .05), as indicated by elevated A â¢- (3,191 457 arbitrary units [AU] vs 2,640 445 AU) and lower NO 2 2 (206 55 nM vs 420 128 nM), whereas vascular function remained preserved. This was comparable to that observed during acute hypoxia in lowlanders in whom vascular dysfunction is typically observed. In contrast, this response was markedly exaggerated in CMS 1 group (A â¢- , 3,765 429 AU; NO 2 2 , 148 50 nM) compared with both the CMS 2 group and lowlanders ( P , .05). This was associated with systemic vascular dysfunction as indicated by lower ( P , .05 vs CMS 2 ) FMD (4.2% 0.7% vs 7.6% 1.7%) and increased AIx-75 (23% 8% vs 12% 7%) and carotid IMT (714 127 m M vs 588 94 m M). CONCLUSIONS: Healthy highlanders display a moderate, sustained elevation in oxidative-nitrosative stress that, unlike the equivalent increase evoked by acute hypoxia in healthy lowlanders, failed to affect vascular function. Its more marked elevation in patients with CMS may contribute to systemic vascular dysfunction.
Asunto(s)
Mal de Altura/fisiopatología , Altitud , Sistema Cardiovascular/fisiopatología , Hipoxia/fisiopatología , Nitrosación/fisiología , Estrés Oxidativo/fisiología , Adaptación Fisiológica/fisiología , Mal de Altura/metabolismo , Antioxidantes/metabolismo , Bolivia , Grosor Intima-Media Carotídeo , Estudios de Casos y Controles , Radicales Libres/metabolismo , Frecuencia Cardíaca/fisiología , Humanos , Hipoxia/metabolismo , Masculino , Persona de Mediana Edad , Óxido Nítrico/metabolismoRESUMEN
High altitude constitutes an exciting natural laboratory for medical research. While initially, the aim of high-altitude research was to understand the adaptation of the organism to hypoxia and find treatments for altitude-related diseases, over the past decade or so, the scope of this research has broadened considerably. Two important observations led to the foundation for the broadening of the scientific scope of high-altitude research. First, high-altitude pulmonary edema (HAPE) represents a unique model which allows studying fundamental mechanisms of pulmonary hypertension and lung edema in humans. Secondly, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary and systemic vascular dysfunction at an early stage. Here, we review studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning lung edema and pulmonary hypertension and to the first direct demonstration of fetal programming of vascular dysfunction in humans.
Asunto(s)
Mal de Altura/fisiopatología , Endotelio Vascular/embriología , Endotelio Vascular/fisiopatología , Hipertensión Pulmonar/fisiopatología , Edema Pulmonar/fisiopatología , Mal de Altura/complicaciones , Mal de Altura/embriología , Desarrollo Fetal , Humanos , Hipertensión Pulmonar/complicaciones , Hipertensión Pulmonar/embriología , Óxido Nítrico/biosíntesis , Óxido Nítrico/deficiencia , Estrés Oxidativo , Edema Pulmonar/embriología , Edema Pulmonar/etiologíaRESUMEN
La altura constituye un fascinante laboratorio natural para la investigación médica. Si bien al principio el objetivo de la investigación en la altura fue la comprensión de los mecanismos de adaptación del organismo a la hipoxia y la búsqueda de tratamientos para las enfermedades relacionadas con la altura, durante la última década el alcance de esta investigación se ha ampliado considerablemente. Dos importantes observaciones han generado las bases para el crecimiento del alcance científico de la investigación en la altura. Primero, el hecho de que el edema pulmonar agudo de la altura constituye un modelo único para estudiar los mecanismos fundamentales de la hipertensión pulmonar y el edema pulmonar en humanos. Segundo, que la hipoxia ambiental asociada con la exposición a la altura facilita la detección de disfunción vascular pulmonar y sistémica en un estadio precoz. Aquí revisaremos los estudios que, capitalizando estas observaciones, han llevado a la descripción de nuevos mecanismos subyacentes del edema pulmonar y de la hipertensión pulmonar, y a la primera demostración directa de la existencia de una programación fetal sobre la disfunción vascular en humanos.(AU)
High altitude constitutes an exciting natural laboratory for medical research. While initially, the aim of high-altitude research was to understand the adaptation of the organism to hypoxia and find treatments for altitude-related diseases, over the past decade or so, the scope of this research has broadened considerably. Two important observations led to the foundation for the broadening of the scientific scope of high-altitude research. First, high-altitude pulmonary edema (HAPE) represents a unique model which allows studying fundamental mechanisms of pulmonary hypertension and lung edema in humans. Secondly, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary and systemic vascular dysfunction at an early stage. Here, we review studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning lung edema and pulmonary hypertension and to the first direct demonstration of fetal programming of vascular dysfunction in humans.(AU)
RESUMEN
La altura constituye un fascinante laboratorio natural para la investigación médica. Si bien al principio el objetivo de la investigación en la altura fue la comprensión de los mecanismos de adaptación del organismo a la hipoxia y la búsqueda de tratamientos para las enfermedades relacionadas con la altura, durante la última década el alcance de esta investigación se ha ampliado considerablemente. Dos importantes observaciones han generado las bases para el crecimiento del alcance científico de la investigación en la altura. Primero, el hecho de que el edema pulmonar agudo de la altura constituye un modelo único para estudiar los mecanismos fundamentales de la hipertensión pulmonar y el edema pulmonar en humanos. Segundo, que la hipoxia ambiental asociada con la exposición a la altura facilita la detección de disfunción vascular pulmonar y sistémica en un estadio precoz. Aquí revisaremos los estudios que, capitalizando estas observaciones, han llevado a la descripción de nuevos mecanismos subyacentes del edema pulmonar y de la hipertensión pulmonar, y a la primera demostración directa de la existencia de una programación fetal sobre la disfunción vascular en humanos.
High altitude constitutes an exciting natural laboratory for medical research. While initially, the aim of high-altitude research was to understand the adaptation of the organism to hypoxia and find treatments for altitude-related diseases, over the past decade or so, the scope of this research has broadened considerably. Two important observations led to the foundation for the broadening of the scientific scope of high-altitude research. First, high-altitude pulmonary edema (HAPE) represents a unique model which allows studying fundamental mechanisms of pulmonary hypertension and lung edema in humans. Secondly, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary and systemic vascular dysfunction at an early stage. Here, we review studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning lung edema and pulmonary hypertension and to the first direct demonstration of fetal programming of vascular dysfunction in humans.
Asunto(s)
Humanos , Mal de Altura/fisiopatología , Endotelio Vascular/embriología , Endotelio Vascular/fisiopatología , Hipertensión Pulmonar/fisiopatología , Edema Pulmonar/fisiopatología , Mal de Altura/complicaciones , Mal de Altura/embriología , Desarrollo Fetal , Hipertensión Pulmonar/complicaciones , Hipertensión Pulmonar/embriología , Óxido Nítrico/biosíntesis , Óxido Nítrico/deficiencia , Estrés Oxidativo , Edema Pulmonar/embriología , Edema Pulmonar/etiologíaRESUMEN
La altura constituye un fascinante laboratorio natural para la investigación médica. Si bien al principio el objetivo de la investigación en la altura fue la comprensión de los mecanismos de adaptación del organismo a la hipoxia y la búsqueda de tratamientos para las enfermedades relacionadas con la altura, durante la última década el alcance de esta investigación se ha ampliado considerablemente. Dos importantes observaciones han generado las bases para el crecimiento del alcance científico de la investigación en la altura. Primero, el hecho de que el edema pulmonar agudo de la altura constituye un modelo único para estudiar los mecanismos fundamentales de la hipertensión pulmonar y el edema pulmonar en humanos. Segundo, que la hipoxia ambiental asociada con la exposición a la altura facilita la detección de disfunción vascular pulmonar y sistémica en un estadio precoz. Aquí revisaremos los estudios que, capitalizando estas observaciones, han llevado a la descripción de nuevos mecanismos subyacentes del edema pulmonar y de la hipertensión pulmonar, y a la primera demostración directa de la existencia de una programación fetal sobre la disfunción vascular en humanos.(AU)
High altitude constitutes an exciting natural laboratory for medical research. While initially, the aim of high-altitude research was to understand the adaptation of the organism to hypoxia and find treatments for altitude-related diseases, over the past decade or so, the scope of this research has broadened considerably. Two important observations led to the foundation for the broadening of the scientific scope of high-altitude research. First, high-altitude pulmonary edema (HAPE) represents a unique model which allows studying fundamental mechanisms of pulmonary hypertension and lung edema in humans. Secondly, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary and systemic vascular dysfunction at an early stage. Here, we review studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning lung edema and pulmonary hypertension and to the first direct demonstration of fetal programming of vascular dysfunction in humans.(AU)
RESUMEN
About 30 million people live above 2500 m in the Andean Mountains of South America. Among them are 5.5 million Aymaras, an ethnic group with its own language, living on the altiplano of Bolivia, Peru, and northern Chile at altitudes of up to 4400 m. In this high altitude region traces of human population go back for more than 2000 years with constant evolutionary pressure on its residents for genetic adaptation to high altitude. Aymaras as the assumed direct descendents of the ancient cultures living in this region were the focus of much research interest during the last decades and several distinctive adaptation patterns to life at high altitude have been described in this ethnic group. The aim of this article was to review the physiology and pathophysiology of circulatory adaptation and maladaptation to longtime altitude exposure in Aymaras and Caucasians.
Asunto(s)
Aclimatación , Mal de Altura/etnología , Fenómenos Fisiológicos Cardiovasculares , Hipoxia/etnología , Indígenas Sudamericanos , Policitemia/etnología , Población Blanca , Altitud , Mal de Altura/sangre , Bolivia/etnología , Chile/etnología , Medicina Basada en la Evidencia , Humanos , Hipertensión Pulmonar/etnología , Hipoxia/sangre , Óxido Nítrico/sangre , Perú/etnología , Circulación Pulmonar , Ventilación Pulmonar , América del Sur/etnologíaRESUMEN
BACKGROUND: Chronic mountain sickness (CMS) is an important public health problem and is characterized by exaggerated hypoxemia, erythrocytosis, and pulmonary hypertension. While pulmonary hypertension is a leading cause of morbidity and mortality in patients with CMS, it is relatively mild and its underlying mechanisms are not known. We speculated that during mild exercise associated with daily activities, pulmonary hypertension in CMS is much more pronounced. METHODS: We estimated pulmonary artery pressure by using echocardiography at rest and during mild bicycle exercise at 50 W in 30 male patients with CMS and 32 age-matched, healthy control subjects who were born and living at an altitude of 3,600 m. RESULTS: The modest, albeit significant difference of the systolic right-ventricular-to-right-atrial pressure gradient between patients with CMS and controls at rest (30.3 +/- 8.0 vs 25.4 +/- 4.5 mm Hg, P 5 .002) became more than three times larger during mild bicycle exercise (56.4 +/- 19.0 vs 39.8 +/- 8.0 mm Hg, P < .001). CONCLUSIONS: Measurements of pulmonary artery pressure at rest greatly underestimate pulmonary artery pressure during daily activity in patients with CMS. The marked pulmonary hypertension during mild exercise associated with daily activity may explain why this problem is a leading cause of morbidity and mortality in patients with CMS.
Asunto(s)
Mal de Altura/complicaciones , Prueba de Esfuerzo/métodos , Ejercicio Físico/fisiología , Hipertensión Pulmonar/etiología , Presión Esfenoidal Pulmonar/fisiología , Mal de Altura/epidemiología , Mal de Altura/fisiopatología , Bolivia/epidemiología , Enfermedad Crónica , Prueba de Esfuerzo/efectos adversos , Humanos , Hipertensión Pulmonar/epidemiología , Hipertensión Pulmonar/fisiopatología , Masculino , Persona de Mediana Edad , Morbilidad/tendencias , Pronóstico , Tasa de Supervivencia/tendenciasRESUMEN
Obesity, insulin resistance and associated cardiovascular complications are reaching epidemic proportions worldwide and represent a major public health problem. Over the past decade, evidence has accumulated indicating that insulin administration, in addition to its metabolic effects, also has important cardiovascular actions. The sympathetic nervous system and the L-arginine-nitric oxide pathway are the central players in the mediation of insulin's cardiovascular actions. Based on recent animal and human research, we demonstrate that both defective and augmented NO synthesis represent a central defect triggering many of the metabolic, vascular and sympathetic abnormalities characteristic of insulin-resistant states. These observations provide the rationale for the use of pharmaceutical drugs releasing small and physiological amounts of NO and/or inhibitors of NO overproduction as a future treatment for insulin resistance and associated comorbidities.
Asunto(s)
Hipoglucemiantes/farmacología , Resistencia a la Insulina/fisiología , Insulina/farmacología , Óxido Nítrico/biosíntesis , Sistema Nervioso Simpático/efectos de los fármacos , Animales , Disponibilidad Biológica , Enfermedades Cardiovasculares/etiología , Enfermedades Cardiovasculares/fisiopatología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Homeostasis , Humanos , Hipertensión/etiología , Hipertensión/fisiopatología , Óxido Nítrico/deficiencia , Óxido Nítrico/farmacología , Donantes de Óxido Nítrico/farmacología , Óxido Nítrico Sintasa de Tipo I/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Óxido Nítrico Sintasa de Tipo III/metabolismo , Ratas , Sistema Nervioso Simpático/fisiopatologíaRESUMEN
Invasive studies suggest that healthy children living at high altitude display pulmonary hypertension, but the data to support this assumption are sparse. Nitric oxide (NO) synthesized by the respiratory epithelium regulates pulmonary artery pressure, and its synthesis was reported to be increased in Aymara high-altitude dwellers. We hypothesized that pulmonary artery pressure will be lower in Aymara children than in children of European ancestry at high altitude, and that this will be related to increased respiratory NO. We therefore compared pulmonary artery pressure and exhaled NO (a marker of respiratory epithelial NO synthesis) between large groups of healthy children of Aymara (n = 200; mean +/- SD age, 9.5 +/- 3.6 years) and European ancestry (n = 77) living at high altitude (3,600 to 4,000 m). We also studied a group of European children (n = 29) living at low altitude. The systolic right ventricular to right atrial pressure gradient in the Aymara children was normal, even though significantly higher than the gradient measured in European children at low altitude (22.5 +/- 6.1 mm Hg vs 17.7 +/- 3.1 mm Hg, p < 0.001). In children of European ancestry studied at high altitude, the pressure gradient was 33% higher than in the Aymara children (30.0 +/- 5.3 mm Hg vs 22.5 +/- 6.1 mm Hg, p < 0.0001). In contrast to what was expected, exhaled NO tended to be lower in Aymara children than in European children living at the same altitude (12.4 +/- 8.8 parts per billion [ppb] vs 16.1 +/- 11.1 ppb, p = 0.06) and was not related to pulmonary artery pressure in either group. Aymara children are protected from hypoxic pulmonary hypertension at high altitude. This protection does not appear to be related to increased respiratory NO synthesis.
Asunto(s)
Altitud , Espiración/fisiología , Hipertensión Pulmonar/etnología , Óxido Nítrico/metabolismo , Presión Esfenoidal Pulmonar/fisiología , Adaptación Fisiológica , Adolescente , Aire/análisis , Bolivia/epidemiología , Niño , Preescolar , Europa (Continente)/etnología , Femenino , Humanos , Hipertensión Pulmonar/etiología , Hipertensión Pulmonar/fisiopatología , Hipoxia/complicaciones , Hipoxia/metabolismo , Hipoxia/fisiopatología , Incidencia , Lactante , Masculino , Factores de RiesgoRESUMEN
There is evidence that high altitude populations may be better protected from hypoxic pulmonary hypertension than low altitude natives, but the underlying mechanism is incompletely understood. In Tibetans, increased pulmonary respiratory NO synthesis attenuates hypoxic pulmonary hypertension. It has been speculated that this mechanism may represent a generalized high altitude adaptation pattern, but direct evidence for this speculation is lacking. We therefore measured systolic pulmonary-artery pressure (Doppler chocardiography) and exhaled nitric oxide (NO) in 34 healthy, middle-aged Bolivian high altitude natives and in 34 age- and sex-matched, well-acclimatized Caucasian low altitude natives living at high altitude (3600 m). The mean+/-SD systolic right ventricular to right atrial pressure gradient (24.3+/-5.9 vs. 24.7+/-4.9 mmHg) and exhaled NO (19.2+/-7.2 vs. 22.5+/-9.5 ppb) were similar in Bolivians and Caucasians. There was no relationship between pulmonary-artery pressure and respiratory NO in the two groups. These findings provide no evidence that Bolivian high altitude natives are better protected from hypoxic pulmonary hypertension than Caucasian low altitude natives and suggest that attenuation of pulmonary hypertension by increased respiratory NO synthesis may not represent a universal adaptation pattern in highaltitude populations.
Asunto(s)
Aclimatación/fisiología , Altitud , Presión Sanguínea/fisiología , Monitoreo del Ambiente , Indígenas Sudamericanos , Población Blanca , Adulto , Bolivia , Humanos , Hipertensión Pulmonar/diagnóstico , Hipertensión Pulmonar/etnología , Hipertensión Pulmonar/fisiopatología , Masculino , Óxido Nítrico/metabolismo , Oximetría , Arteria Pulmonar/fisiología , Factores de RiesgoRESUMEN
High altitude constitutes an exciting natural laboratory for medical research. Over the past decade, it has become clear that the results of high-altitude research may have important implications not only for the understanding of diseases in the millions of people living permanently at high altitude, but also for the treatment of hypoxemia-related disease states in patients living at low altitude. High-altitude pulmonary edema (HAPE) is a life-threatening condition occurring in predisposed, but otherwise healthy subjects, and, therefore, allows to study underlying mechanisms of pulmonary edema in humans, in the absence of confounding factors. Over the past decade, evidence has accumulated that HAPE results from the conjunction of two major defects, augmented alveolar fluid flooding resulting from exaggerated hypoxic pulmonary hypertension, and impaired alveolar fluid clearance related to defective respiratory transepithelial sodium transport. Here, after a brief presentation of the clinical features of HAPE, we review this novel concept. We provide experimental evidence for the novel concept that impaired pulmonary endothelial and epithelial nitric oxide synthesis and/or bioavailability may represent the central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and alveolar fluid flooding. We demonstrate that exaggerated pulmonary hypertension, while possibly a condition sine qua non, may not be sufficient to cause HAPE, and how defective alveolar fluid clearance may represent a second important pathogenic mechanism. Finally, we outline how this insight gained from studies in HAPE may be translated into the management of hypoxemia related disease states in general.
Asunto(s)
Mal de Altura/complicaciones , Hipertensión Pulmonar/complicaciones , Circulación Pulmonar , Edema Pulmonar/etiología , Sistema Nervioso Simpático , Mal de Altura/tratamiento farmacológico , Mal de Altura/fisiopatología , Disponibilidad Biológica , Transporte Biológico/fisiología , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Canales Epiteliales de Sodio/fisiología , Humanos , Hipertensión Pulmonar/tratamiento farmacológico , Hipertensión Pulmonar/fisiopatología , Óxido Nítrico/biosíntesis , Alveolos Pulmonares/efectos de los fármacos , Circulación Pulmonar/fisiología , Edema Pulmonar/tratamiento farmacológico , Edema Pulmonar/fisiopatología , Sodio/farmacocinética , Sodio/uso terapéutico , Sistema Nervioso Simpático/fisiopatologíaRESUMEN
La altura, fascinante laboratorio natural de investigación médica, provee resultados con importantes implicancias para la comprensión de enfermedades que afectan a millones de personas que viven en ella, asi como para el tratamiento de enfermedades ligadas a la hipoxemia en pacientes que viven en baja altitud. El edema pulmonar de altura (EPA) es una entidad que pone en peligro la vida y que ocurre en sujetos predispuestos pero sanos. Esto permite estudiar los mecanismos subyacentes del edema pulmonar en humanos, sin la presencia de factores que presten a la confusión como enfermedades concomitantes. El EPA resulta de la conjunción de dos defectos mayores: acumulación de líquido en el espacio alveolar debido a una hipertensión pulmonar hipóxica exagerada, y alteración en la eliminación del mismo por un defecto en el transporte transepitelial alveolar de sodio. En esta revisión, describimos brevemente las características clínicas y revisaremos este novedoso concepto. Proveemos evidencia experimental de como la síntesis alterada de óxido nítrico y/o la disminución de su biodisponibilidad representan el defecto central que predispone a la vasoconstricción pulmonar hipóxica exagerada y a la acumulación de líquido en el espacio alveolar. Mostramos que la hipertensión pulmonar hipóxica exagerada, per se, no es suficiente para producir un EPA, y que una alteración en la eliminación del fluido del espacio alveolar representa un segundo mecanismo fisiopatológico importante. Finalmente, describimos cómo los nuevos aportes obtenidos de los estudios del EPA pueden ser trasladados al manejo de otros estados patológicos ligados a la hipoxemia. (AU)
High altitude constitutes an exciting natural laboratory for medical research. Over the past decade, it has become clear that the results of high-altitude research may have important implications not only for the understanding of diseases in the millions of people living permanently at high altitude, but also for the treatment of hypoxemia-related disease states in patients living at low altitude. High-altitude pulmonary edema (HAPE) is a life-threatening condition occurring in predisposed, but otherwise healthy subjects, and, therefore, allows to study underlying mechanisms of pulmonary edema in humans, in the absence of confounding factors. Over the past decade, evidence has accumulated that HAPE results from the conjunction of two major defects, augmented alveolar fluid flooding resulting from exaggerated hypoxic pulmonary hypertension, and impaired alveolar fluid clearance related to defective respiratory transepithelial sodium transport. Here, after a brief presentation of the clinical features of HAPE, we review this novel concept. We provide experimental evidence for the novel concept that impaired pulmonary endothelial and epithelial nitric oxide synthesis and/or bioavailability may represent the central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and alveolar fluid flooding. We demonstrate that exaggerated pulmonary hypertension, while possibly a condition sine qua non, may not be sufficient to cause HAPE, and how defective alveolar fluid clearance may represent a second important pathogenic mechanism. Finally, we outline how this insight gained from studies in HAPE may be translated into the management of hypoxemia related disease states in general. (AU)
Asunto(s)
Humanos , Mal de Altura/fisiopatología , Edema Pulmonar/etiología , Hipertensión Pulmonar/complicaciones , Sistema Nervioso Simpático , Circulación Pulmonar , Mal de Altura/complicaciones , Mal de Altura/tratamiento farmacológico , Edema Pulmonar/tratamiento farmacológico , Edema Pulmonar/fisiopatología , Hipertensión Pulmonar/tratamiento farmacológico , Hipertensión Pulmonar/fisiopatología , Transporte Biológico/fisiología , Canales Epiteliales de Sodio/fisiología , Alveolos Pulmonares/efectos de los fármacos , Sodio/farmacocinética , Sodio/uso terapéutico , Óxido Nítrico/biosíntesis , Óxido Nítrico/farmacocinética , Sistema Nervioso Simpático/fisiopatología , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Circulación Pulmonar/fisiología , Disponibilidad BiológicaRESUMEN
La altura, fascinante laboratorio natural de investigación médica, provee resultados con importantes implicancias para la comprensión de enfermedades que afectan a millones de personas que viven en ella, asi como para el tratamiento de enfermedades ligadas a la hipoxemia en pacientes que viven en baja altitud. El edema pulmonar de altura (EPA) es una entidad que pone en peligro la vida y que ocurre en sujetos predispuestos pero sanos. Esto permite estudiar los mecanismos subyacentes del edema pulmonar en humanos, sin la presencia de factores que presten a la confusión como enfermedades concomitantes. El EPA resulta de la conjunción de dos defectos mayores: acumulación de líquido en el espacio alveolar debido a una hipertensión pulmonar hipóxica exagerada, y alteración en la eliminación del mismo por un defecto en el transporte transepitelial alveolar de sodio. En esta revisión, describimos brevemente las características clínicas y revisaremos este novedoso concepto. Proveemos evidencia experimental de como la síntesis alterada de óxido nítrico y/o la disminución de su biodisponibilidad representan el defecto central que predispone a la vasoconstricción pulmonar hipóxica exagerada y a la acumulación de líquido en el espacio alveolar. Mostramos que la hipertensión pulmonar hipóxica exagerada, per se, no es suficiente para producir un EPA, y que una alteración en la eliminación del fluido del espacio alveolar representa un segundo mecanismo fisiopatológico importante. Finalmente, describimos cómo los nuevos aportes obtenidos de los estudios del EPA pueden ser trasladados al manejo de otros estados patológicos ligados a la hipoxemia.
High altitude constitutes an exciting natural laboratory for medical research. Over the past decade, it has become clear that the results of high-altitude research may have important implications not only for the understanding of diseases in the millions of people living permanently at high altitude, but also for the treatment of hypoxemia-related disease states in patients living at low altitude. High-altitude pulmonary edema (HAPE) is a life-threatening condition occurring in predisposed, but otherwise healthy subjects, and, therefore, allows to study underlying mechanisms of pulmonary edema in humans, in the absence of confounding factors. Over the past decade, evidence has accumulated that HAPE results from the conjunction of two major defects, augmented alveolar fluid flooding resulting from exaggerated hypoxic pulmonary hypertension, and impaired alveolar fluid clearance related to defective respiratory transepithelial sodium transport. Here, after a brief presentation of the clinical features of HAPE, we review this novel concept. We provide experimental evidence for the novel concept that impaired pulmonary endothelial and epithelial nitric oxide synthesis and/or bioavailability may represent the central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and alveolar fluid flooding. We demonstrate that exaggerated pulmonary hypertension, while possibly a condition sine qua non, may not be sufficient to cause HAPE, and how defective alveolar fluid clearance may represent a second important pathogenic mechanism. Finally, we outline how this insight gained from studies in HAPE may be translated into the management of hypoxemia related disease states in general.