-
JAMA Pediatrics Oct 2020Irrespective of their genetic makeup, children living in an ideal home environment that supports healthy growth have similar growth potential. However, whether this...
IMPORTANCE
Irrespective of their genetic makeup, children living in an ideal home environment that supports healthy growth have similar growth potential. However, whether this potential is true for children residing at higher altitudes remains unknown.
OBJECTIVE
To investigate whether altitude is associated with increased risk of linear growth faltering and evaluate the implications associated with the use of the 2006 World Health Organization growth standards, which have not been validated for populations residing 1500 m above sea level.
DESIGN, SETTINGS, AND PARTICIPANTS
Analysis of 133 nationally representative demographic and health cross-sectional surveys administered in 59 low- and middle-income countries using local polynomial and multivariate regression was conducted. A total of 964 299 height records from 96 552 clusters at altitudes ranging from -372 to 5951 m above sea level were included. Demographic and Health Surveys were conducted between 1992 and 2018.
EXPOSURES
Residence at higher altitudes, above and below 1500 m above sea level, and in ideal home environments (eg, access to safe water, sanitation, and health care).
MAIN OUTCOMES AND MEASURES
The primary outcome was child linear growth deficits expressed in length-for-age/height-for-age z scores (HAZ). Associations between altitude and height among all children and those residing in ideal home environments were assessed. Child growth trajectories above and below 1500 m above sea level were compared and the altitude-mediated height deficits were estimated using multivariable linear regression.
RESULTS
In 2010, a total of 842 million people in the global population (approximately 12%) lived 1500 m above sea level or higher, with 67% in Asia and Africa. Eleven percent of the sample was children who resided 1500 m above sea level or higher. These children were born at shorter length and remained on a lower growth trajectory than children residing in areas less than 1500 m above sea level. The negative association between altitude and HAZ was approximately linear through most part of the altitude distribution, indicating no clear threshold for an abrupt decrease in HAZ. A 1000-m above sea level increase in altitude was associated with a 0.163-unit (95% CI, -0.205 to -0.120 units) decrease in HAZ after adjusting for common risk factors using multivariable linear regressions. The HAZ distribution of children residing in ideal home environments was similar to the 2006 World Health Organization HAZ distribution, but only up to 500 m above sea level.
CONCLUSIONS AND RELEVANCE
The findings of this study suggest that residing at a higher altitude may be associated with child growth slowing even for children living in ideal home environments. Interventions addressing altitude-mediated growth restrictions during pregnancy and early childhood should be identified and implemented.
Topics: Altitude; Body Height; Child, Preschool; Cross-Sectional Studies; Ethiopia; Female; Growth Disorders; Humans; Incidence; Infant; Infant, Newborn; Male; Risk Factors; Socioeconomic Factors
PubMed: 32832998
DOI: 10.1001/jamapediatrics.2020.2386 -
The Journal of Physiology Mar 2016At high altitude, barometric pressure falls and with it inspired P(O2), potentially compromising O2 delivery to the tissues. With sufficient acclimatisation, the... (Review)
Review
At high altitude, barometric pressure falls and with it inspired P(O2), potentially compromising O2 delivery to the tissues. With sufficient acclimatisation, the erythropoietic response increases red cell mass such that arterial O2 content (C(aO2)) is restored; however arterial P(O2)(P(aO2)) remains low, and the diffusion of O2 from capillary to mitochondrion is impaired. Mitochondrial respiration and aerobic capacity are thus limited, whilst reactive oxygen species (ROS) production increases. Restoration of P(aO2) with supplementary O2 does not fully restore aerobic capacity in acclimatised individuals, possibly indicating a peripheral impairment. With prolonged exposure to extreme high altitude (>5500 m), muscle mitochondrial volume density falls, with a particular loss of the subsarcolemmal population. It is not clear whether this represents acclimatisation or deterioration, but it does appear to be regulated, with levels of the mitochondrial biogenesis factor PGC-1α falling, and shows similarities to adapted Tibetan highlanders. Qualitative changes in mitochondrial function also occur, and do so at more moderate high altitudes with shorter periods of exposure. Electron transport chain complexes are downregulated, possibly mitigating the increase in ROS production. Fatty acid oxidation capacity is decreased and there may be improvements in biochemical coupling at the mitochondrial inner membrane that enhance O2 efficiency. Creatine kinase expression falls, possibly impairing high-energy phosphate transfer from the mitochondria to myofibrils. In climbers returning from the summit of Everest, cardiac energetic reserve (phosphocreatine/ATP) falls, but skeletal muscle energetics are well preserved, possibly supporting the notion that mitochondrial remodelling is a core feature of acclimatisation to extreme high altitude.
Topics: Acclimatization; Altitude; Animals; Cell Respiration; Humans; Mitochondria, Muscle
PubMed: 26033622
DOI: 10.1113/JP270079 -
Italian Journal of Pediatrics Mar 2024Asthma is one of the most common non-communicable diseases, and its prevalence and morbidity are influenced by a wide array of factors that are only partially... (Review)
Review
Asthma is one of the most common non-communicable diseases, and its prevalence and morbidity are influenced by a wide array of factors that are only partially understood. In addition to individual predisposition linked to genetic background and early life infections, environmental factors are crucial in determining the impact of asthma both on an individual patient and on a population level.Several studies have examined the role of the environment where asthmatic subjects live in the pathogenesis of asthma. This review aims to investigate the differences in the prevalence and characteristics of asthma between the pediatric population residing at higher altitudes and children living at lower altitudes, trying to define factors that potentially determine such differences. For this purpose, we reviewed articles from the literature concerning observational studies assessing the prevalence of pediatric asthma in these populations and its characteristics, such as spirometric and laboratory parameters and associated sensitization to aeroallergens.Despite the heterogeneity of the environments examined, the hypothesis of a beneficial effect of residing at a higher altitude on the prevalence of pediatric asthma could be confirmed, as well as a good profile on airway inflammation in asthmatic children. However, the possibility of a higher hospitalization risk for asthma in children living at higher altitudes was demonstrated. Moreover, a positive association between residing at a higher altitude and sensitization to pollens and between lower altitude and sensitization to house dust mites could be confirmed in some pediatric patients, even if the results are not homogeneous, probably due to the different geographical and climatic regions considered. Nonetheless, further studies, e.g., extensive and international works, need to be conducted to better understand the complex interplay between different environmental factors, such as altitude, and the pathogenesis of asthma and how its prevalence and characteristics could vary due to climate change.
Topics: Humans; Child; Altitude; Asthma; Genotype; Geography; Hospitalization
PubMed: 38448980
DOI: 10.1186/s13052-023-01492-x -
Sports Medicine (Auckland, N.Z.) Sep 2017To prepare for extremes of heat, cold or low partial pressures of oxygen (O), humans can undertake a period of acclimation or acclimatization to induce... (Review)
Review
To prepare for extremes of heat, cold or low partial pressures of oxygen (O), humans can undertake a period of acclimation or acclimatization to induce environment-specific adaptations, e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. While these strategies are effective, they are not always feasible due to logistical impracticalities. Cross-adaptation is a term used to describe the phenomenon whereby alternative environmental interventions, e.g. HA or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude. HA can attenuate physiological strain at rest and during moderate-intensity exercise at altitude via adaptations allied to improved O delivery to metabolically active tissue, likely following increases in plasma volume and reductions in body temperature. CA appears to improve physiological responses to altitude by attenuating the autonomic response to altitude. While no cross-acclimation-derived exercise performance/capacity data have been measured following CA, post-HA improvements in performance underpinned by aerobic metabolism, and therefore dependent on O delivery at altitude, are likely. At a cellular level, heat shock protein responses to altitude are attenuated by prior HA, suggesting that an attenuation of the cellular stress response and therefore a reduced disruption to homeostasis at altitude has occurred. This process is known as cross-tolerance. The effects of CA on markers of cross-tolerance is an area requiring further investigation. Because much of the evidence relating to cross-adaptation to altitude has examined the benefits at moderate to high altitudes, future research examining responses at lower altitudes should be conducted, given that these environments are more frequently visited by athletes and workers. Mechanistic work to identify the specific physiological and cellular pathways responsible for cross-adaptation between heat and altitude, and between cold and altitude, is warranted, as is exploration of benefits across different populations and physical activity profiles.
Topics: Acclimatization; Adaptation, Physiological; Altitude; Cold Temperature; Heat Stress Disorders; Hot Temperature; Humans; Hypoxia
PubMed: 28389828
DOI: 10.1007/s40279-017-0717-z -
Revista Peruana de Medicina... Mar 2011The different types of response mechanisms that the organism uses when exposed to hypoxia include accommodation, acclimatization and adaptation. Accommodation is the... (Review)
Review
The different types of response mechanisms that the organism uses when exposed to hypoxia include accommodation, acclimatization and adaptation. Accommodation is the initial response to acute exposure to high altitude hypoxia and is characterized by an increase in ventilation and heart rate. Acclimatization is observed in individuals temporarily exposed to high altitude, and to some extent, it enables them to tolerate the high altitudes. In this phase, erythropoiesis is increased, resulting in higher hemoglobin and hematocrit levels to improve oxygen delivery capacity. Adaptation is the process of natural acclimatization where genetical variations and acclimatization play a role in allowing subjects to live without any difficulties at high altitudes. Testosterone is a hormone that regulates erythropoiesis and ventilation and could be associated to the processes of acclimatization and adaptation to high altitude. Excessive erythrocytosis, which leads to chronic mountain sickness, is caused by low arterial oxygen saturation, ventilatory inefficiency and reduced ventilatory response to hypoxia. Testosterone increases during acute exposure to high altitude and also in natives at high altitude with excessive erythrocytosis. Results of current research allow us to conclude that increase in serum testosterone and hemoglobin is adequate for acclimatization, as they improve oxygen transport, but not for high altitude adaptation, since high serum testosterone levels are associated to excessive erythrocytosis.
Topics: Acclimatization; Adaptation, Physiological; Altitude; Erythropoiesis; Hemoglobins; Humans; Male; Peru; Testosterone
PubMed: 21537776
DOI: 10.1590/s1726-46342011000100015 -
Journal of Physiological Anthropology Mar 2022Anthropometric measures have been classically used to understand the impact of environmental factors on the living conditions of individuals and populations. Most...
BACKGROUND
Anthropometric measures have been classically used to understand the impact of environmental factors on the living conditions of individuals and populations. Most reference studies on development and growth in which anthropometric measures were used were carried out in populations that are located at sea level, but there are few studies carried out in high altitude populations.
OBJECTIVE
The objective of this study was to evaluate the anthropometric and body composition in autochthonous Kiwcha permanently living at low and high altitudes.
METHODOLOGY
A cross-sectional study of anthropometric and body composition between genetically matched lowland Kiwcha from Limoncocha (n = 117), 230 m in the Amazonian basin, and high-altitude Kiwcha from Oyacachi (n = 95), 3800 m in Andean highlands. Student's t-test was used to analyze the differences between continuous variables, and the chi-square test was performed to check the association or independence of categorical variables. Fisher's exact test or Spearman's test was used when the variable had evident asymmetries with histograms prior to the selection of the test.
RESULTS
This study shows that high altitude men are shorter than their counterparts who live at low altitude, with p = 0.019. About body muscle percentage, women at high altitudes have less body muscle percentage (- 24.8%). In comparison, men at high altitudes have significantly more muscle body mass percentage (+ 13.5%) than their lowland counterparts. Body fat percentage was lower among low altitude women (- 15.5%), and no differences were found among men.
CONCLUSIONS
This is the first study to be performed in two genotyped controlled matching populations located at different altitudes to our best knowledge. The anthropometric differences vary according to sex, demonstrating that high altitude populations are, in general, lighter and shorter than their low altitude controls. Men at high altitude have more muscled bodies compared to their lowland counterparts, but their body age was older than their actual age.
Topics: Adult; Altitude; Anthropometry; Body Composition; Cross-Sectional Studies; Female; Genotype; Humans; Male
PubMed: 35272696
DOI: 10.1186/s40101-022-00280-6 -
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi =... Apr 2022Smart wearable devices play an increasingly important role in physiological monitoring and disease prevention because they are portable, real-time, dynamic and... (Review)
Review
Smart wearable devices play an increasingly important role in physiological monitoring and disease prevention because they are portable, real-time, dynamic and continuous.The popularization of smart wearable devices among people under high-altitude environment would be beneficial for the prevention for heart and brain diseases related to high altitude. The current review comprehensively elucidates the effects of high-altitude environment on the heart and brain of different population and experimental subjects, the characteristics and applications of different types of wearable devices, and the limitations and challenges for their application. By emphasizing their application values, this review provides practical reference information for the prevention of high-altitude disease and the protection of life and health.
Topics: Altitude; Brain Diseases; Heart; Humans; Monitoring, Physiologic; Wearable Electronic Devices
PubMed: 35523565
DOI: 10.7507/1001-5515.202108084 -
Environmental Research Sep 2022Existing studies reported higher altitudes reduce the COVID-19 infection rate in the United States, Colombia, and Peru. However, the underlying reasons for this...
Existing studies reported higher altitudes reduce the COVID-19 infection rate in the United States, Colombia, and Peru. However, the underlying reasons for this phenomenon remain unclear. In this study, regression analysis and mediating effect model were used in a combination to explore the altitudes relation with the pattern of transmission under their correlation factors. The preliminary linear regression analysis indicated a negative correlation between altitudes and COVID-19 infection in China. In contrast to environmental factors from low-altitude regions (<1500 m), high-altitude regions (>1500 m) exhibited lower PM2.5, average temperature (AT), and mobility, accompanied by high SO and absolute humidity (AH). Non-linear regression analysis further revealed that COVID-19 confirmed cases had a positive correlation with mobility, AH, and AT, whereas negatively correlated with SO, CO, and DTR. Subsequent mediating effect model with altitude-correlated factors, such as mobility, AT, AH, DTR and SO, suffice to discriminate the COVID-19 infection rate between low- and high-altitude regions. The mentioned evidence advance our understanding of the altitude-mediated COVID-19 transmission mechanism.
Topics: Altitude; COVID-19; China; Colombia; Humans; Meteorological Concepts; Meteorology
PubMed: 35405128
DOI: 10.1016/j.envres.2022.113214 -
Praxis Apr 2021
Topics: Altitude; Cardiovascular Diseases; Humans; Travel
PubMed: 33906444
DOI: 10.1024/1661-8157/a003654 -
Sensors (Basel, Switzerland) Nov 2022This paper introduces a technique to transform between geometric and barometric estimates of altitude and vice-versa. Leveraging forecast numerical weather models, the...
This paper introduces a technique to transform between geometric and barometric estimates of altitude and vice-versa. Leveraging forecast numerical weather models, the method is unbiased and has a vertical error with a standard deviation of around 30 m (100 ft), regardless of aircraft altitude, which makes it significantly more precise than established comparable conversion functions. This result may find application in various domains of civil aviation, including vertical RNP, systemized airspace, and automatic landing systems.
Topics: Aircraft; Altitude; Aviation; Weather
PubMed: 36501962
DOI: 10.3390/s22239263