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High Altitude Medicine & Biology Jun 2022Nicolaou, Laura, Anne Steinberg, Rodrigo M. Carrillo-Larco, Stella Hartinger, Andres G. Lescano, and William Checkley. Living at high altitude and COVID-19 mortality in...
Nicolaou, Laura, Anne Steinberg, Rodrigo M. Carrillo-Larco, Stella Hartinger, Andres G. Lescano, and William Checkley. Living at high altitude and COVID-19 mortality in Peru. . 23:146-158, 2022. Previous studies have reported a lower severity of COVID-19 infections at higher altitudes; however, this association may be confounded by various factors. We examined the association between living at altitude and COVID-19 mortality in Peru adjusting for population density, prevalence of comorbidities, indicators of socioeconomic status, and health care access. Utilizing administrative data across 196 provinces located at varying altitudes (sea level to 4,373 m), we conducted a two-stage analysis of COVID-19 deaths between March 19 and December 31, 2020, Peru's first wave. We first calculated cumulative daily mortality rate for each province and fit lognormal cumulative distribution functions to estimate total mortality rate, and start, peak, and duration of the first wave. We then regressed province-level total mortality rate, start, peak, and duration of the first wave as a function of altitude adjusted for confounders. There were 93,528 recorded deaths from COVID-19 (mean age 66.5 years, 64.5% male) for a cumulative mortality of 272.5 per 100,000 population between March 19 and December 31, 2020. We did not find a consistent monotonic trend between living at higher altitudes and estimated total mortality rate for provinces at 500 - 1,000 m (-12.1 deaths per 100,000 population per 100 m, 95% familywise confidence interval -27.7 to 3.5) or > 1,000 m (-0.3, -2.7 to 2.0). We also did not find consistent monotonic trends for the start, peak, and duration of the first wave beyond the first 500 m. Our findings suggest that living at high altitude may not confer a lower risk of death from COVID-19.
Topics: Aged; Altitude; COVID-19; Female; Humans; Male; Peru; Prevalence
PubMed: 35483043
DOI: 10.1089/ham.2021.0149 -
Respiratory Care May 2022
Topics: Altitude; Humans; Hypoxia
PubMed: 35473840
DOI: 10.4187/respcare.09897 -
BMJ Clinical Evidence Mar 2010Up to half of people who ascend to heights above 2500 m may develop acute mountain sickness, pulmonary oedema, or cerebral oedema, with the risk being greater at higher... (Review)
Review
INTRODUCTION
Up to half of people who ascend to heights above 2500 m may develop acute mountain sickness, pulmonary oedema, or cerebral oedema, with the risk being greater at higher altitudes, and with faster rates of ascent.
METHODS AND OUTCOMES
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent, and to treat, acute mountain sickness? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
RESULTS
We found 17 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
CONCLUSIONS
In this systematic review we present information relating to the effectiveness and safety of the following interventions: acetazolamide, descent versus resting, dexamethasone, gingko biloba, and slow ascent.
Topics: Acetazolamide; Acute Disease; Altitude; Altitude Sickness; Ginkgo biloba; Humans; Pulmonary Edema
PubMed: 21718562
DOI: No ID Found -
Veterinary Medicine and Science Jul 2022This review covers the challenges of broiler chickens at high altitude, with the focus on growth performance and physiological response. The review also sheds light on... (Review)
Review
This review covers the challenges of broiler chickens at high altitude, with the focus on growth performance and physiological response. The review also sheds light on nutritional and management interventions that help overcome the challenges raised at high altitude. Reduced concentration of atmospheric oxygen is by far the biggest challenge that remarkably affect growth performance and livability of broiler chickens reared in high altitude area. Broiler chickens have endured intensive genetic selection, which potentially predispose them to several metabolic disorders. Hypoxia is an overriding factor that may increase the incidence of metabolic disorders, mainly ascites syndrome at high altitude. Commercial broiler strains cannot fully achieve their genetic potential when raising at highland regions. Careful nutrition and management considerations are required to prevent metabolic disorders when raising broilers at high altitude. In ovo or in-feed nutraceuticals such as l-carnitine and guanidinoacetic acid as well as pharmaceuticals, texture of feed and the use of proper sources and levels of dietary energy and protein are important factors that need to be carefully considered for rearing broiler chickens at high altitude. Management strategies such as lighting programs have been shown to be effective to circumvent ascites prevalence. Special breeding programs may also be considered to develop strains with resistance to ascites.
Topics: Altitude; Animals; Ascites; Chickens; Diet
PubMed: 35290706
DOI: 10.1002/vms3.784 -
Journal of Applied Physiology... Feb 2022High-altitude exposure results in a hyperventilatory-induced respiratory alkalosis followed by renal compensation (bicarbonaturia) to return arterial blood pH (pHa)...
High-altitude exposure results in a hyperventilatory-induced respiratory alkalosis followed by renal compensation (bicarbonaturia) to return arterial blood pH (pHa) toward sea-level values. However, acid-base balance has not been comprehensively examined in both lowlanders and indigenous populations-where the latter are thought to be fully adapted to high altitude. The purpose of this investigation was to compare acid-base balance between acclimatizing lowlanders and Andean and Sherpa highlanders at various altitudes (∼3,800, ∼4,300, and ∼5,000 m). We compiled data collected across five independent high-altitude expeditions and report the following novel findings: ) at 3,800 m, Andeans ( = 7) had elevated pHa compared with Sherpas ( = 12; < 0.01), but not to lowlanders ( = 16; 9 days acclimatized; = 0.09); 2) at 4,300 m, lowlanders ( = 16; 21 days acclimatized) had elevated pHa compared with Andeans ( = 32) and Sherpas ( = 11; both < 0.01), and Andeans had elevated pHa compared with Sherpas ( = 0.01); and ) at 5,000 m, lowlanders ( = 16; 14 days acclimatized) had higher pHa compared with both Andeans ( = 66) and Sherpas ( = 18; < 0.01, and = 0.03, respectively), and Andean and Sherpa highlanders had similar blood pHa ( = 0.65). These novel data characterize acid-base balance acclimatization and adaptation to various altitudes in lowlanders and indigenous highlanders. Lowlander, Andean, and Sherpa arterial blood data were combined across five independent high-altitude expeditions in the United States, Nepal, and Peru to assess acid-base status at ∼3,800, ∼4,300, and ∼5,000 m. The main finding was that Andean and Sherpa highlander populations have more acidic arterial blood, due to elevated arterial carbon dioxide and similar arterial bicarbonate compared with acclimatizing lowlanders at altitudes ≥4,300 m.
Topics: Acclimatization; Acid-Base Equilibrium; Altitude; Altitude Sickness; Expeditions; Humans
PubMed: 35023761
DOI: 10.1152/japplphysiol.00757.2021 -
Revista de Investigacion Clinica;... Jan 2022A large world population resides at moderate altitude. In the Valley of Mexico (2,240 m above sea level), its inhabitants, breathe approximately 29% more on average and... (Review)
Review
A large world population resides at moderate altitude. In the Valley of Mexico (2,240 m above sea level), its inhabitants, breathe approximately 29% more on average and have 10% increased hemoglobin concentrations compared to sea level residents, among other differences. These compensations reduce but not eliminate the impact of altitude hypoxemia. The objective of the manuscript is to review and describe the information available on health and disease at moderate altitudes, mainly with data in Spanish language from Latin-American countries. Young adults in Mexico City have an SaO2 between 92% and 94% versus 97% at sea level, frequently decreasing below 90% during sleep and intense exercise. It is likely that among the population living at this altitude, lung growth, and development during pregnancy and infancy are enhanced, and that after residing for several tens of thousands of years, more important adaptations in oxygen transport and utilization have developed, but we are not certain about it. For patients with respiratory diseases, residing at moderate altitudes implies increased hypoxemia and clinical deterioration, unless supplementary oxygen is prescribed or patients move to sea level. Hyperventilation increases exposure of residents to air pollutants compared to those living in cities with similar concentrations of pollutants, although at sea level. Humans evolved at sea level and lack the best-known adaptations to reside at moderate or high altitudes. Residents of moderate altitudes breathe deeply the city´s air with all its pollutants, and more often require supplementary oxygen.
Topics: Adaptation, Physiological; Altitude; Humans; Hypoxia; Mexico; Oxygen; Young Adult
PubMed: 34495023
DOI: 10.24875/RIC.21000159 -
Reviews on Environmental Health Jun 2023Traveling to high altitudes for entertainment or work is sometimes associated with acute high altitude pathologies. In the past, scientific literature from the lowlander... (Review)
Review
Traveling to high altitudes for entertainment or work is sometimes associated with acute high altitude pathologies. In the past, scientific literature from the lowlander point of view was primarily based on mountain climbing. Sea level scientists developed all guidelines, but they need modifications for medical care in high altitude cities. Acute Mountain Sickness, High Altitude Pulmonary Edema, and High Altitude Cerebral Edema are medical conditions that some travelers can face. We present how to diagnose and treat acute high altitude pathologies, based on 51 years of high altitude physiology research and medical practice in hypobaric hypoxic diseases in La Paz, Bolivia (3,600 m; 11,811 ft), at the High Altitude Pulmonary and Pathology Institute (HAPPI - IPPA). These can occasionally present after flights to high altitude cities, both in lowlanders or high-altitude residents during re-entry. Acute high altitude ascent diseases can be adequately diagnosed and treated in high altitude cities following the presented guidelines. Treating these high-altitude illnesses, we had no loss of life. Traveling to a high altitude with sound medical advice should not be feared as it has many benefits. Nowadays, altitude descent and evacuation are not mandatory in populated highland cities, with adequate medical resources.
Topics: Humans; Altitude Sickness; Altitude; Brain Edema; Pulmonary Edema; Bolivia; Acute Disease
PubMed: 35487499
DOI: 10.1515/reveh-2021-0172 -
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 Environmental... Feb 2023This report aims to summarise the scientific knowledge around hydration, nutrition, and metabolism at high altitudes and to transfer it into the practical context of... (Review)
Review
This report aims to summarise the scientific knowledge around hydration, nutrition, and metabolism at high altitudes and to transfer it into the practical context of extreme altitude alpinism, which, as far as we know, has never been considered before in the literature. Maintaining energy balance during alpine expeditions is difficult for several reasons and requires a deep understanding of human physiology and the biological basis for altitude acclimation. However, in these harsh conditions it is difficult to reconcile our current scientific knowledge in sports nutrition or even for mountaineering to high-altitude alpinism: extreme hypoxia, cold, and the logistical difficulties intrinsic to these kinds of expeditions are not considered in the current literature. Requirements for the different stages of an expedition vary dramatically with increasing altitude, so recommendations must differentiate whether the alpinist is at base camp, at high-altitude camps, or attempting the summit. This paper highlights nutritional recommendations regarding prioritising carbohydrates as a source of energy and trying to maintain a protein balance with a practical contextualisation in the extreme altitude environment in the different stages of an alpine expedition. More research is needed regarding specific macro and micronutrient requirements as well as the adequacy of nutritional supplementations at high altitudes.
Topics: Humans; Altitude; Mountaineering; Hypoxia; Altitude Sickness; Acclimatization
PubMed: 36833880
DOI: 10.3390/ijerph20043186 -
Journal of Travel Medicine Jun 2023Altitude sojourns increasingly attract individuals of all ages and different health statuses due to the appeal of high-altitude destinations worldwide and easy access to... (Review)
Review
BACKGROUND
Altitude sojourns increasingly attract individuals of all ages and different health statuses due to the appeal of high-altitude destinations worldwide and easy access to air travel. The risk of acute mountain sickness (AMS) when flying to high-altitude destinations remains underemphasized. Thus, this review aims to evaluate the altitude-dependent AMS incidence depending on the mode of ascending, e.g. by air vs terrestrial travel.
METHODS
A literature search was performed to identify the observational studies assessing AMS incidence after acute ascent of primarily healthy adults to real high altitude. In addition, placebo arms of interventional trials evaluating the prophylactic efficacy of various drugs have been separately analysed to confirm or refute the findings from the observational studies. Linear regression analyses were used to evaluate the altitude-dependent AMS incidence.
RESULTS
Findings of 12 observational studies, in which the AMS incidence in 11 021 individuals ascending to 19 different altitudes (2200-4559 m) was evaluated, revealed an impressive 4.5-fold steeper increase in the AMS incidence for air travel as compared with slower ascent modes, i.e. hiking or combined car and/or air travel and hiking. The higher AMS incidence following transportation by flight vs slower means was also confirmed in placebo-treated participants in 10 studies of drug prophylaxis against AMS.
CONCLUSIONS
Due to the short time span in going from low to high altitude, reduced acclimatization likely is the main reason for a higher AMS risk when travelling to high-altitude destinations by flight. To avoid frustrating travel experiences and health risks, appropriate and timely medical advice on how to prepare for air travel to high altitude is of vital importance. Effective preparation options include the use of modern pre-acclimatization strategies and pharmacological prophylaxis by acetazolamide or dexamethasone, or even considering alternate itineraries with more gradual ascent.
Topics: Adult; Humans; Altitude Sickness; Altitude; Acute Disease; Acetazolamide; Air Travel
PubMed: 36694981
DOI: 10.1093/jtm/taad011