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The Journal of Physiology Sep 2020Highlanders develop unique adaptative mechanisms to chronic hypoxic exposure, including substantial haemoglobin and haematocrit increases. However, a significant...
KEY POINTS
Highlanders develop unique adaptative mechanisms to chronic hypoxic exposure, including substantial haemoglobin and haematocrit increases. However, a significant proportion of populations living permanently at high altitude develop maladaptive features known as chronic mountain sickness (CMS). This study aimed to assess the effects of permanent life at high altitude on clinical and haemorheological parameters (blood viscosity and red blood cell aggregation) and to compare clinical and haemorheological parameters of dwellers from the highest city in the world according to CMS severity. Blood viscosity increased with altitude, together with haemoglobin concentration and haematocrit. At 5100 m, highlanders with moderate-to-severe CMS had higher blood viscosity mainly at high shear rate and even at corrected haematocrit (40%), with a lower red blood cell aggregation. Blood viscosity may contribute to CMS symptomatology but the increased blood viscosity in CMS patients cannot solely be explained by the rise in haematocrit.
ABSTRACT
Chronic mountain sickness (CMS) is a condition characterised by excessive erythrocytosis (EE). While EE is thought to increase blood viscosity and subsequently to trigger CMS symptoms, the exact relationship between blood viscosity and CMS symptoms remains incompletely understood. We assessed the effect of living at high altitude on haemoglobin, haematocrit and haemorheological parameters (blood viscosity and red blood cell aggregation), and investigated their relationship with CMS in highlanders living in the highest city in the world (La Rinconada, Peru, 5100 m). Ninety-three men participated in this study: 10 Caucasian lowlanders, 13 Andean highlanders living at 3800 m and 70 Andean highlanders living at 5100 m (35 asymptomatic, CMS score ≤5; 15 with mild CMS, CMS score between 6 and 10; 20 with moderate-to-severe CMS, CMS score >10). Blood viscosity was measured at native and corrected haematocrit (40%). Haemoglobin concentration and haematocrit increased with the altitude of residency. Blood viscosity also increased with altitude (at 45 s : 6.7 ± 0.9 mPa s at sea level, 14.0 ± 2.0 mPa s at 3800 m and 27.1 ± 8.8 mPa s at 5100 m; P < 0.001). At 5100 m, blood viscosity at corrected haematocrit was higher in highlanders with moderate-to-severe CMS (at 45 s : 18.9 ± 10.7 mPa s) than in highlanders without CMS (10.2 ± 5.9 mPa s) or with mild CMS (12.1 ± 6.1 mPa s) (P < 0.05). In conclusion, blood viscosity may contribute to CMS symptomatology but the increased blood viscosity in CMS patients cannot solely be explained by the rise in haematocrit.
Topics: Adaptation, Physiological; Altitude; Altitude Sickness; Blood Viscosity; Chronic Disease; Humans; Male; Peru
PubMed: 32445208
DOI: 10.1113/JP279694 -
International Health Feb 2021Nepal's Himalayan range attracts mountaineers, climbers and tourists from all across the globe. Limited recent evidence suggests that exposure to hypoxia at a higher...
BACKGROUND
Nepal's Himalayan range attracts mountaineers, climbers and tourists from all across the globe. Limited recent evidence suggests that exposure to hypoxia at a higher altitude may be a risk factor for hypertension and a protective factor for obesity. The existing urban-rural disparities in Nepal in health and economic resources may be anticipated in the burden of hypertension and obesity, two rapidly growing public health issues, but they remain largely unstudied. Therefore this study aims to assess the association of altitude and urbanization with hypertension and overweight/obesity in Nepal.
METHODS
Data on 10 473 participants from a nationally representative survey, the 2016 Nepal Demographic and Health Survey (NDHS), was used. The NDHS assessed/measured blood pressure, height, weight, urbanization and the altitude of participants' households by following standard procedures. Logistic and linear regression models were used to study the association of altitude (per 100 m increases) and urbanization with hypertension and obesity, or their continuous measurements (i.e. systolic and diastolic blood pressure [SBP and DBP, respectively] and body mass index [BMI]).
RESULTS
The prevalence of hypertension, overweight and obesity was 25.6%, 19.6% and 4.8%, respectively. After controlling for covariates, residents of metropolitan cities had a 30% higher prevalence of overweight/obesity (adjusted prevalence ratio 1.30 [95% confidence interval {CI} 1.11 to 1.52]) than their rural counterparts. For altitude, there was a marginally increased odds of hypertension and overweight/obesity with elevation. Consistently, DBP (β = 0.18 [95% CI 0.09 to 0.27]) and BMI increased with altitude (β = 0.11 [95% CI 0.08 to 0.13]).
CONCLUSION
Urbanization was positively associated with BMI, while altitude showed a marginally positive association with hypertension and overweight/obesity. Given the role of obesity and hypertension in the aetiology of other chronic diseases and subsequently associated mortality and health care costs, residents in urban areas and at higher altitudes may benefit from weight control interventions and BP monitoring, respectively.
Topics: Altitude; Cross-Sectional Studies; Humans; Hypertension; Nepal; Obesity; Prevalence; Risk Factors; Urbanization
PubMed: 32623453
DOI: 10.1093/inthealth/ihaa034 -
Sensors (Basel, Switzerland) Feb 2021: Finger pulse oximeters are widely used to monitor physiological responses to high-altitude exposure, the progress of acclimatization, and/or the potential development... (Review)
Review
: Finger pulse oximeters are widely used to monitor physiological responses to high-altitude exposure, the progress of acclimatization, and/or the potential development of high-altitude related diseases. Although there is increasing evidence for its invaluable support at high altitude, some controversy remains, largely due to differences in individual preconditions, evaluation purposes, measurement methods, the use of different devices, and the lacking ability to interpret data correctly. Therefore, this review is aimed at providing information on the functioning of pulse oximeters, appropriate measurement methods and published time courses of pulse oximetry data (peripheral oxygen saturation, (SpO) and heart rate (HR), recorded at rest and submaximal exercise during exposure to various altitudes. : The presented findings from the literature review confirm rather large variations of pulse oximetry measures (SpO and HR) during acute exposure and acclimatization to high altitude, related to the varying conditions between studies mentioned above. It turned out that particularly SpO levels decrease with acute altitude/hypoxia exposure and partly recover during acclimatization, with an opposite trend of HR. Moreover, the development of acute mountain sickness (AMS) was consistently associated with lower SpO values compared to individuals free from AMS. : The use of finger pulse oximetry at high altitude is considered as a valuable tool in the evaluation of individual acclimatization to high altitude but also to monitor AMS progression and treatment efficacy.
Topics: Acclimatization; Altitude; Altitude Sickness; Humans; Male; Oximetry; Oxygen
PubMed: 33578839
DOI: 10.3390/s21041263 -
The Journal of Maternal-fetal &... Apr 2022To determine whether the full spectrum of hypertensive disorders of pregnancy (HDP) - comprising gestational hypertension; preeclampsia with or without severe features;...
OBJECTIVES
To determine whether the full spectrum of hypertensive disorders of pregnancy (HDP) - comprising gestational hypertension; preeclampsia with or without severe features; eclampsia; and emolysis, levated iver enzymes, and ow latelets (HELLP) Syndrome - is increased at high (≥2500 m, 8250 ft) compared with lower altitudes in Colorado independent of maternal background characteristics, and if so their relationship to neonatal well-being.
METHODS
A retrospective cohort study was conducted using statewide birth-certificate data to compare the frequency of gestational hypertension, preeclampsia (with or without severe features), eclampsia, HELLP Syndrome, or all HDP combined in 617,958 Colorado women who lived at high vs. low altitude (<2500 m) and delivered during the 10-year period, 2007-2016. We also compared blood-pressure changes longitudinally during pregnancy and the frequency of HDP in 454 high (>2500 m)- vs. low (<1700 m)-altitude Colorado residents delivering in 2013 and 2014, and matched for maternal risk factors. Data were compared between altitudes using -tests or chi-square, and by multiple or logistic regression analyses to adjust for risk factors and predict specific hypertensive or neonatal complications.
RESULTS
Statewide, high-altitude residence increased the frequency of each HDP disorder separately or all combined by 33%. High-altitude women studied longitudinally also had more HDP accompanied by higher blood pressures throughout pregnancy. The frequency of low birth weight infants (<2500 g), 5-min Apgar scores <7, and NICU admissions were also greater at high than low altitudes statewide, with the latter being accounted for by the increased incidence of HDP.
CONCLUSIONS
Residence at high altitude constitutes a risk factor for HDP and recommends increased clinical surveillance. The increased incidence also makes high altitude a natural laboratory for evaluating the efficacy of predictive biomarkers or new therapies for HDP.
Topics: Altitude; Blood Pressure; Female; Humans; Hypertension, Pregnancy-Induced; Infant; Infant, Newborn; Pre-Eclampsia; Pregnancy; Retrospective Studies
PubMed: 32228111
DOI: 10.1080/14767058.2020.1745181 -
Sensors (Basel, Switzerland) Aug 2022Industry 4.0, smart homes, and the Internet of Things are boosting the employment of autonomous aerial vehicles in indoor environments, where localization is still...
Industry 4.0, smart homes, and the Internet of Things are boosting the employment of autonomous aerial vehicles in indoor environments, where localization is still challenging, especially in the case of close and cluttered areas. In this paper, we propose a Visual Inertial Odometry localization method based on fiducial markers. Our approach enables multi-rotor aerial vehicle navigation in indoor environments and tackles the most challenging aspects of image-based indoor localization. In particular, we focus on a proper and continuous pose estimation, working from take-off to landing, at several different flying altitudes. With this aim, we designed a map of fiducial markers that produces results that are both dense and heterogeneous. Narrowly placed tags lead to minimal information loss during rapid aerial movements while four different classes of marker size provide consistency when the camera zooms in or out according to the vehicle distance from the ground. We have validated our approach by comparing the output of the localization algorithm with the ground-truth information collected through an optoelectronic motion capture system, using two different platforms in different flying conditions. The results show that error mean and standard deviation can remain constantly lower than 0.11 m, so not degrading when the aerial vehicle increases its altitude and, therefore, strongly improving similar state-of-the-art solutions.
Topics: Algorithms; Altitude; Internet; Motion; Movement
PubMed: 35957353
DOI: 10.3390/s22155798 -
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 -
Frontiers in Immunology 2023Ascending to high altitude can induce a range of physiological and molecular alterations, rendering a proportion of lowlanders unacclimatized. The prediction of acute...
BACKGROUND
Ascending to high altitude can induce a range of physiological and molecular alterations, rendering a proportion of lowlanders unacclimatized. The prediction of acute mountain sickness (AMS) prior to ascent to high altitude remains elusive.
METHODS
A total of 40 participants were enrolled for our study in the discovery cohort, and plasma samples were collected from all individuals. The subjects were divided into severe AMS-susceptible (sAMS) group, moderate AMS-susceptible (mAMS) group and non-AMS group based on the Lake Louise Score (LLS) at both 5000m and 3700m. Proteomic analysis was conducted on a cohort of 40 individuals to elucidate differentially expressed proteins (DEPs) and associated pathways between AMS-susceptible group and AMS-resistant group at low altitude (1400m) and middle high-altitude (3700m). Subsequently, a validation cohort consisting of 118 individuals was enrolled. The plasma concentration of selected DEPs were quantified using ELISA. Comparative analyses of DEPs among different groups in validation cohort were performed, followed by Receiver Operating Characteristic (ROC) analysis to evaluate the predictive efficiency of DEPs for the occurrence of AMS.
RESULTS
The occurrence of the AMS symptoms and LLS differed significantly among the three groups in the discovery cohort (<0.05), as well as in the validation cohort. Comparison of plasma protein profiles using GO analysis revealed that DEPs were primarily enriched in granulocyte activation, neutrophil mediated immunity, and humoral immune response. The comparison of potential biomarkers between the sAMS group and non-AMS group at low altitude revealed statistically higher levels of AAT, SAP and LTF in sAMS group (=0.01), with a combined area under the curve(AUC) of 0.965. Compared to the mAMS group at low altitude, both SAP and LTF were found to be significantly elevated in the sAMS group, with a combined AUC of 0.887. HSP90-α and SAP exhibited statistically higher levels in the mAMS group compared to the non-AMS group at low altitude, with a combined AUC of 0.874.
CONCLUSION
Inflammatory and immune related biological processes were significantly different between AMS-susceptible and AMS-resistant groups at low altitude and middle high-altitude. SAP, AAT, LTF and HSP90-α were considered as potential biomarkers at low altitude for the prediction of AMS.
Topics: Humans; Altitude Sickness; Altitude; Proteomics; Acute Disease; Biomarkers
PubMed: 37841248
DOI: 10.3389/fimmu.2023.1237465 -
Journal of Applied Gerontology : the... Jun 2022To assess the association between municipality altitude and quality of life (QOL) of older people in Colombia.
OBJECTIVE
To assess the association between municipality altitude and quality of life (QOL) of older people in Colombia.
METHODS
Cross-sectional study with data from the Colombian Demographic and Health Survey Older Adult Questionnaire 2015 ( = 13,970). QOL was measured in six domains: physical health, psychological health, functional status, social relations, medical history and economic status. Regression analyses were carried out adjusting by individual and contextual level variables.
RESULTS
Low altitude was associated with better QOL: physical health (OR = 1.92, 95%CI 1.47-2.52), psychological health (OR = 1.59, 95%CI 1.26-2.00), functional status (OR=1.80, 95%CI 1.45-2.23), social relations (OR = 2.16 95%CI 1.73-2.70), and medical history (OR = 1.57, 95%CI 1.37-1.81). Economic status was not associated with altitude.
DISCUSSION
Living at high altitude was associated with lower QOL for Colombian older adults. This finding encourages further study of high altitude and health outcomes among older adults in Colombia and other countries with populations living at high altitudes.
Topics: Aged; Altitude; Colombia; Cross-Sectional Studies; Humans; Quality of Life; Socioeconomic Factors
PubMed: 35426334
DOI: 10.1177/07334648221078577 -
Brazilian Journal of Microbiology :... Dec 2020There are many kinds of microorganisms in the gastrointestinal tract of mammals, some of which are closely related to the host. Rumen microorganisms are essential for...
There are many kinds of microorganisms in the gastrointestinal tract of mammals, some of which are closely related to the host. Rumen microorganisms are essential for normal physiological activities of their host by decomposing plant crude lignin and providing essential nutrients. The composition and diversity of this microbial population are influenced by the host, environment, and diet. Despite its importance, little is known about the effects of factors such as altitude variation on rumen microbial population abundance and diversity in different ruminants. Here, we described the changes in overall rumen bacteria in four groups of cattle, including the Zhongdian yellow cattle and Zhongdian yaks, grazing at high altitudes (3600 m); the Jiangcheng yellow cattle and Jiangcheng buffalo were kept at an altitude of 1100 m. We found that there was a significant difference in rumen bacterial abundance of the Zhongdian yellow cattle and Zhongdian yaks at high altitude and there was obvious homogeneity in rumen bacterial abundance and diversity in the Jiangcheng yellow cattle and Jiangcheng buffalo at low altitude. Therefore, our research concluded that under the same dietary environment, there were differences in the abundance and diversity of certain bacteria in the rumen of different breeds of cattle, indicating that host genetic factors and intestinal microorganisms related to altitudinal variation had a greater influence on rumen bacterial abundance in the cattle.
Topics: Altitude; Animal Feed; Animals; Bacteria; Cattle; Gastrointestinal Microbiome; Phylogeny; Rumen
PubMed: 32949385
DOI: 10.1007/s42770-020-00380-4 -
International Journal of Sports... Jun 2023Altitude training is often regarded as an indispensable tool for the success of elite endurance athletes. Historically, altitude training emerged as a key strategy to... (Review)
Review
BACKGROUND
Altitude training is often regarded as an indispensable tool for the success of elite endurance athletes. Historically, altitude training emerged as a key strategy to prepare for the 1968 Olympics, held at 2300 m in Mexico City, and was limited to the "Live High-Train High" method for endurance athletes aiming for performance gains through improved oxygen transport. This "classical" intervention was modified in 1997 by the "Live High-Train Low" (LHTL) model wherein athletes supplemented acclimatization to chronic hypoxia with high-intensity training at low altitude.
PURPOSE
This review discusses important considerations for successful implementation of LHTL camps in elite athletes based on experiences, both published and unpublished, of the authors.
APPROACH
The originality of our approach is to discuss 10 key "lessons learned," since the seminal work by Levine and Stray-Gundersen was published in 1997, and focusing on (1) optimal dose, (2) individual responses, (3) iron status, (4) training-load monitoring, (5) wellness and well-being monitoring, (6) timing of the intervention, (7) use of natural versus simulated hypoxia, (8) robustness of adaptative mechanisms versus performance benefits, (9) application for a broad range of athletes, and (10) combination of methods. Successful LHTL strategies implemented by Team USA athletes for podium performance at Olympic Games and/or World Championships are presented.
CONCLUSIONS
The evolution of the LHTL model represents an essential framework for sport science, in which field-driven questions about performance led to critical scientific investigation and subsequent practical implementation of a unique approach to altitude training.
Topics: Humans; Sports; Hypoxia; Altitude; Acclimatization; Awards and Prizes; Oxygen Consumption
PubMed: 37116895
DOI: 10.1123/ijspp.2022-0501