Simonson, Tatum S. Altitude adaptation: A glimpse through various lenses. High Alt Med Biol 16:125–137, 2015.—Recent availability of genome-wide data from highland populations has enabled the identification of adaptive genomic signals. Some of the genomic signals reported thus far among Tibetans, Andeans, and Ethiopians are the same, while others appear unique to each population. These genomic findings parallel observations conveyed by decades of physiological research: different continental populations, resident at high altitude for hundreds of generations, exhibit a distinct composite of traits at altitude. The most commonly reported signatures of selection emanate from genomic segments containing hypoxia-inducible factor (HIF) pathway genes. Corroborative evidence for adaptive significance stems from associations between putatively adaptive gene copies and sea-level ranges of hemoglobin concentration in Tibetans and Amhara Ethiopians, birth weights and metabolic factors in Andeans and Tibetans, maternal uterine artery diameter in Andeans, and protection from chronic mountain sickness in Andean males at altitude. While limited reports provide mechanistic insights thus far, efforts to identify and link precise genetic variants to molecular, physiological, and developmental functions are underway, and progress on the genomics front continues to provide unprecedented movement towards these goals. This combination of multiple perspectives is necessary to maximize our understanding of orchestrated biological and evolutionary processes in native highland populations, which will advance our understanding of both adaptive and non-adaptive responses to hypoxia.
Dehnert, Christoph, Derliz Mereles, Sebastian Greiner, Dagmar Albers, Fabian Scheurlen, Stefanie Zügel, Thomas Böhm, Peter Vock, Marco Maggiorini, Ekkehard Grünig, and Peter Bärtsch. Exaggerated hypoxic pulmonary vasoconstriction without susceptibility to high altitude pulmonary edema. High Alt Med Biol 16 :11–17, 2015.— Background: Abnormally high pulmonary artery pressure (PAP) in hypoxia due to exaggerated hypoxic pulmonary vasoconstriction (HPV) is a key factor for development of high-altitude pulmonary edema (HAPE). It was shown that about 10% of a healthy Caucasian population has an exaggerated HPV that is comparable to the response measured in HAPE-susceptible individuals. Therefore, we hypothesized that those with exaggerated HPV are HAPE-susceptible. Methods and Results: We screened 421 healthy Caucasians naïve to high altitude for HPV using Doppler echocardiography for assessment of systolic PAP in normobaric hypoxia (PASP Hx ; P o 2 corresponding to 4500 m). Subjects with exaggerated HPV and matched controls were exposed to 4559 m with an identical protocol that causes HAPE in 62% of HAPE-S. Screening revealed 39 subjects with exaggerated HPV, of whom 33 (PASP Hx 51±6 mmHg) ascended within 24 hours to 4559 m. Four (13%) of them developed HAPE during the 48 h-stay. This incidence is significantly lower than the recurrence rate of 62% previously observed in HAPE-S in the same setting. None of the control subjects (PASP Hx 33±5 mmHg) developed HAPE. Conclusion: An exaggerated HPV cannot be considered a surrogate maker for HAPE-susceptibility although excessively elevated PAP is a hallmark in HAPE, while a normal HPV appears to protect from HAPE in this study.
Willmann, Gabriel. Ultraviolet keratitis: From the pathophysiological basis to prevention and clinical management. High Alt Med Biol 16:277–282, 2015.—Ultraviolet keratitis is caused by the toxic effects of acute high-dose ultraviolet radiation (UVR) reflecting the sensitivity of the ocular surface to photochemical injury. The clinical syndrome presents with ocular pain, tearing, conjunctival chemosis, blepharospasm, and deterioration of vision typically several hours after exposure, lasting up to 3 days. Mountaineers, skiers, and beach recreationalists are particularly at risk to suffer from ultraviolet (UV) keratitis as the reflectivity of UVR in these environments is extremely high. The aim of this review is to raise awareness about the potential of UV damage on the eye with an emphasis on UV keratitis, to highlight the pathophysiological basis of corneal phototoxicity, and to provide practical guidance for the prevention and clinical management of UV keratitis commonly known as snow blindness.
Lochner, Piergiorgio, Marika Falla, Francesco Brigo, Michael Pohl, and Giacomo Strapazzon. Ultrasonography of the optic nerve sheath diameter for diagnosis and monitoring of acute mountain sickness: A systematic review. High Alt Med Biol. 16:195–203, 2015.— Aims: Despite extensive research on acute mountain sickness (AMS), the underlying pathophysiology remains unclear. Ultrasonography studies have shown that optic nerve sheath diameter (ONSD) correlates with intracranial pressure (ICP) in critical care patients, and recent studies report elevated ONSD values at high altitude. The aim of this review was to elucidate whether 1. measurement of ONSD could shed light on the pathophysiology of AMS, and 2. ultrasonography of the ONSD could support the diagnosis of AMS. Methods: Systematic search of MEDLINE (through Pubmed; from 1966 to 14 October 2014), Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE databases. Results: Six studies with 436 subjects (139 women, 297 men; 406 mostly Caucasian; 30 Nepalese) were included. A marked variability in ONSD was found across studies both at baseline and at high altitude. Conclusion: The variability in ONSD across the included studies and within each study limit the utility of ONSD measurement in the diagnosis of AMS. ONSD measurements might be useful from a population perspective, but the accuracy of optic nerve ultrasonography for single subjects and single point-in-time assessment for diagnosing AMS is questionable due to high individual variability in ONSD.
Waeber, Baptiste, Bengt Kayser, Lionel Dumont, Christopher Lysakowski, Martin R. Tramèr, and Nadia Elia. Impact of study design on reported incidences of acute mountain sickness: A systematic review. High Alt Med Biol 16:204–215, 2015.— Aims: Published incidences of acute mountain sickness (AMS) vary widely. Reasons for this variation, and predictive factors of AMS, are not well understood. We aimed to identify predictive factors that are associated with the occurrence of AMS, and to test the hypothesis that study design is an independent predictive factor of AMS incidence. We did a systematic search (Medline, bibliographies) for relevant articles in English or French, up to April 28, 2013. Studies of any design reporting on AMS incidence in humans without prophylaxis were selected. Data on incidence and potential predictive factors were extracted by two reviewers and crosschecked by four reviewers. Associations between predictive factors and AMS incidence were sought through bivariate and multivariate analyses for different study designs separately. Association between AMS incidence and study design was assessed using multiple linear regression. Results: We extracted data from 53,603 subjects from 34 randomized controlled trials, 44 cohort studies, and 33 cross-sectional studies. In randomized trials, the median of AMS incidences without prophylaxis was 60% (range, 16%–100%); mode of ascent and population were significantly associated with AMS incidence. In cohort studies, the median of AMS incidences was 51% (0%–100%); geographical location was significantly associated with AMS incidence. In cross-sectional studies, the median of AMS incidences was 32% (0%–68%); mode of ascent and maximum altitude were significantly associated with AMS incidence. In a multivariate analysis, study design (p=0.012), mode of ascent (p=0.003), maximum altitude (p<0.001), population (p=0.002), and geographical location (p<0.001) were significantly associated with AMS incidence. Age, sex, speed of ascent, duration of exposure, or history of AMS were inconsistently reported and therefore not further analyzed. Conclusions: Reported incidences and identifiable predictive factors of AMS depend on study design.
Kanekar, Shami, Olena V. Bogdanova, Paul R. Olson, Young-Hoon Sung, Kristen E. D'Anci, and Perry F. Renshaw. Hypobaric hypoxia induces depression-like behavior in female Sprague-Dawley rats, but not males. High Alt Med Biol 16:52–60, 2015—Rates of depression and suicide are higher in people living at altitude, and in those with chronic hypoxic disorders like asthma, chronic obstructive pulmonary disorder (COPD), and smoking. Living at altitude exposes people to hypobaric hypoxia, which can lower rat brain serotonin levels, and impair brain bioenergetics in both humans and rats. We therefore examined the effect of hypobaric hypoxia on depression-like behavior in rats. After a week of housing at simulated altitudes of 20,000 ft, 10,000 ft, or sea level, or at local conditions of 4500 ft (Salt Lake City, UT), Sprague Dawley rats were tested for depression-like behavior in the forced swim test (FST). Time spent swimming, climbing, or immobile, and latency to immobility were measured. Female rats housed at altitude display more depression-like behavior in the FST, with significantly more immobility, less swimming, and lower latency to immobility than those at sea level. In contrast, males in all four altitude groups were similar in their FST behavior. Locomotor behavior in the open field test did not change with altitude, thus validating immobility in the FST as depression-like behavior. Hypobaric hypoxia exposure therefore induces depression-like behavior in female rats, but not in males.
Parati, Gianfranco, Juan Eugenio Ochoa, Camilla Torlasco, Paolo Salvi, Carolina Lombardi, and Grzegorz Bilo. Aging, high altitude, and blood pressure: A complex relationship. High Alt Biol Med 16:97–109, 2015.—Both aging and high altitude exposure may induce important changes in BP regulation, leading to significant increases in BP levels. By inducing atherosclerotic changes, stiffening of large arteries, renal dysfunction, and arterial baroreflex impairment, advancing age may induce progressive increases in systolic BP levels, promoting development and progression of arterial hypertension. It is also known, although mainly from studies in young or middle-aged subjects, that exposure to high altitude may influence different mechanisms involved in BP regulation (i.e., neural central and reflex control of sympathetic activity), leading to important increases in BP levels. The evidence is less clear, however, on whether and to what extent advancing age may influence the BP response to acute or chronic high altitude exposure. This is a question not only of scientific interest but also of practical relevance given the consistent number of elderly individuals who are exposed for short time periods (either for leisure or work) or live permanently at high altitude, in whom arterial hypertension is frequently observed. This article will review the evidence available on the relationship between aging and blood pressure levels at high altitude, the pathophysiological mechanisms behind this complex association, as well as some questions of practical interest regarding antihypertensive treatment in elderly subjects, and the effects of antihypertensive drugs on blood pressure response during high altitude exposure.
Richalet, Jean-Paul, and François J. Lhuissier. Aging, tolerance to high altitude, and cardiorespiratory response to hypoxia. High Alt Med Biol. 16:117–124, 2015.—It is generally accepted that aging is rather protective, at least at moderate altitude. Some anecdotal reports even mention successful ascent of peaks over 8000 m and even Everest by elderly people. However, very few studies have explored the influence of aging on tolerance to high altitude and prevalence of acute high altitude related diseases, taking into account all confounding factors such as speed of ascent, altitude reached, sex, training status, and chemo-responsiveness. Changes in physiological responses to hypoxia with aging were assessed through a cross-sectional 20-year study including 4675 subjects (2789 men, 1886 women; 14–85 yrs old) and a longitudinal study including 30 subjects explored at a mean 10.4-year interval. In men, ventilatory response to hypoxia increased, while desaturation was less pronounced with aging. Cardiac response to hypoxia was blunted with aging in both genders. Similar results were found in the longitudinal study, with a decrease in cardiac and an increase in ventilatory response to hypoxia with aging. These adaptive responses were less pronounced or absent in post-menopausal untrained women. In conclusion, in normal healthy and active subjects, aging has no deleterious effect on cardiac and ventilatory responses to hypoxia, at least up to the eighth decade. Aging is not a contraindication for high altitude, as far as no pathological condition interferes and physical fitness is compatible with the intensity of the expected physical demand of one's individual. Physiological evaluation through hypoxic exercise testing before going to high altitude is helpful to detect risk factors of severe high altitude-related diseases.
He, Jiang, Jianhua Cui, Rui Wang, Liang Gao, Xiaokang Gao, Liu Yang, Qiong Zhang, Jinjun Cao, and Wuzhong Yu. Exposure to hypoxia at high altitude (5380m) for 1 year induces reversible effects on semen quality and serum reproductive hormone levels in young male adults. High Alt Med Biol 16:216-222, 2015.This study investigated the effect of hypoxia at high altitude on the semen quality and the serum reproductive hormone levels in male adults. A total of 52 male soldiers were enrolled in this cohort study. They were exposed to hypoxia at high altitude (5380m) for 12 months when undergoing a service. After exposure, they were followed up for 6 months. The samples of semen and peripheral blood were collected at 1 month before exposure (M0), 6 months of exposure (M6), 12 months of exposure (M12), and 6 months after exposure (M18). The semen quality was assessed with computer-assisted analysis system, and the serum levels of reproductive hormones, including prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were analyzed by ELISA. Compared with those at M0, total sperm count, sperm density, motility, survival rate, and serum levels of LH, PRL and testosterone were significantly decreased, whereas the liquefaction time was significantly prolonged and serum FSH level was significantly increased at M6 (p<0.05). At M12, total sperm count and sperm density increased, whereas sperm motility, survival rate, and the liquefaction time further decreased. Sperm velocities, progression ratios, and lateral head displacements were also decreased. Serum FSH level decreased while serum LH, PRL, and testosterone levels increased. Compared with those at M6, the changes in these detected parameters of semen and hormone at M12 were significant (p<0.05). At M18, all these detected parameters except testosterone level returned to levels comparable to those before exposure. In conclusion, hypoxia at high altitude causes adverse effects on semen quality and reproductive hormones, and these effects are reversible.
He, Jiang, Jianhua Cui, Rui Wang, Liang Gao, Xiaokang Gao, Liu Yang, Qiong Zhang, Jinjun Cao, and Wuzhong Yu. Exposure to hypoxia at high altitude (5380 m) for 1 year induces reversible effects on semen quality and serum reproductive hormone levels in young male adults. High Alt Med Biol 16:216–222, 2015.—This study investigated the effect of hypoxia at high altitude on the semen quality and the serum reproductive hormone levels in male adults. A total of 52 male soldiers were enrolled in this cohort study. They were exposed to hypoxia at high altitude (5380 m) for 12 months when undergoing a service. After exposure, they were followed up for 6 months. The samples of semen and peripheral blood were collected at 1 month before exposure (M0), 6 months of exposure (M6), 12 months of exposure (M12), and 6 months after exposure (M18). The semen quality was assessed with computer-assisted analysis system, and the serum levels of reproductive hormones, including prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were analyzed by ELISA. Compared with those at M0, total sperm count, sperm density, motility, survival rate, and serum levels of LH, PRL and testosterone were significantly decreased, whereas the liquefaction time was significantly prolonged and serum FSH level was significantly increased at M6 ( p <0.05). At M12, total sperm count and sperm density increased, whereas sperm motility, survival rate, and the liquefaction time further decreased. Sperm velocities, progression ratios, and lateral head displacements were also decreased. Serum FSH level decreased while serum LH, PRL, and testosterone levels increased. Compared with those at M6, the changes in these detected parameters of semen and hormone at M12 were significant ( p <0.05). At M18, all these detected parameters except testosterone level returned to levels comparable to those before exposure. In conclusion, hypoxia at high altitude causes adverse effects on semen quality and reproductive hormones, and these effects are reversible.
Levine, Benjamin D. Going high with heart disease: The effect of high altitude exposure in older individuals and patients with coronary artery disease. High Alt Med Biol 16:89–96, 2015.—Ischemic heart disease is the largest cause of death in older men and women in the western world (Lozano et al., 2012 ; Roth et al., 2015 ). Atherosclerosis progresses with age, and thus age is the dominant risk factor for coronary heart disease in any algorithm used to assess risk for cardiovascular events. Subclinical atherosclerosis also increases with age, providing the substrate for precipitation of acute coronary syndromes. Thus the risk of high altitude exposure in older individuals is linked closely with both subclinical and manifest coronary heart disease (CHD). There are several considerations associated with taking patients with CHD to high altitude: a) The reduced oxygen availability may cause or exacerbate symptoms; b) The hypoxia and other associated environmental conditions (exercise, dehydration, change in diet, thermal stress, emotional stress from personal danger or conflict) may precipitate acute coronary events; c) If an event occurs and the patient is far from advanced medical care, then the outcome of an acute coronary event may be poor; and d) Sudden death may occur. Physicians caring for older patients who want to sojourn to high altitude should keep in mind the following four key points: 1). Altitude may exacerbate ischemic heart disease because of both reduced O 2 delivery and paradoxical vasoconstriction; 2). Adverse events, including acute coronary syndromes and sudden cardiac death, are most common in older unfit men, within the first few days of altitude exposure; 3). Ensuring optimal fitness, allowing for sufficient acclimatization (at least 5 days), and optimizing medical therapy (especially statins and aspirin) are prudent recommendations that may reduce the risk of adverse events; 4). A graded exercise test at sea level is probably sufficient for most clinical decision making and will allow for assessment of exercise capacity, and provocable ischemia. Given these considerations, most older individuals with CHD should be able to tolerate exposure to high altitude safely, and with minimal increased risk.
Juan Su, Zhanquan Li, Sen Cui, Linhua Ji, Hui Geng, Kexia Chai, Xiaojing Ma, Zhenzhong Bai, Yingzhong Yang, Tana Wuren, Ri-Li Ge, and Matthew T. Rondina. The local HIF-2α/EPO pathway in the bone marrow is associated with excessive erythrocytosis and the increase in bone marrow microvessel density in chronic mountain sickness. High Alt Med Biol. 16:318–330, 2015.— Aim: Chronic mountain sickness (CMS) is characterized by excessive erythrocytosis, and angiogenesis may be involved in the pathogenesis of this disease. The bone marrow niche is the primary site of erythropoiesis and angiogenesis. This study was aimed at investigating the associations of the levels of hypoxia-inducible factors (HIFs), erythropoietin (EPO), and erythropoietin receptor (EPOR), as well as microvessel density (MVD) in the bone marrow with CMS. Results: A total of 34 patients with CMS and 30 control subjects residing in areas at altitudes of 3000–4500 m were recruited for this study. The mRNA and protein expression of HIF-2α and EPO in the bone marrow cells was significantly higher in the CMS patients than in the controls. Moreover, changes in HIF-2α expression in CMS patients were significantly correlated with EPO and hemoglobin levels. In contrast, the expression of mRNA and protein expression of HIF-1α and EPOR did not differ significantly between the CMS and control patients. Increased MVD was observed in the bone marrow of the patients with CMS and it was significantly correlated with hemoglobin. Conclusions: Bone marrow cells of CMS patients may show enhanced activity of the HIF-2α/EPO pathway, and EPO may regulate the erythropoiesis and vasculogenesis through autocrine or/and paracrine mechanisms in the bone marrow niche. The increased MVD in the bone marrow of CMS patients appears to be involved in the pathogenesis of this disease.
Scalzo, Rebecca L., Scott E. Binns, Anna L. Klochak, Gregory R. Giordano, Hunter L.R. Paris, Kyle J. Sevits, Joseph W. Beals, Laurie M. Biela, Dennis G. Larson, Gary J. Luckasen, David Irwin, Thies Schroeder, Karyn L. Hamilton, and Christopher Bell. Methazolamide plus aminophylline abrogates hypoxia-mediated endurance exercise impairment. High Alt Med Biol 16:331–342, 2015.—In hypoxia, endurance exercise performance is diminished; pharmacotherapy may abrogate this performance deficit. Based on positive outcomes in preclinical trials, we hypothesized that oral administration of methazolamide, a carbonic anhydrase inhibitor, aminophylline, a nonselective adenosine receptor antagonist and phosphodiesterase inhibitor, and/or methazolamide combined with aminophylline would attenuate hypoxia-mediated decrements in endurance exercise performance in humans. Fifteen healthy males (26 ± 5 years, body–mass index: 24.9 ± 1.6 kg/m 2 ; mean ± SD) were randomly assigned to one of four treatments: placebo ( n = 9), methazolamide (250 mg; n = 10), aminophylline (400 mg; n = 9), or methazolamide (250 mg) with aminophylline (400 mg; n = 8). On two separate occasions, the first in normoxia (FIO 2 = 0.21) and the second in hypoxia (FIO 2 = 0.15), participants sat for 4.5 hours before completing a standardized exercise bout (30 minutes, stationary cycling, 100 W), followed by a 12.5-km time trial. The magnitude of time trial performance decrement in hypoxia versus normoxia did not differ between placebo (+3.0 ± 2.7 minutes), methazolamide (+1.4 ± 1.7 minutes), and aminophylline (+1.8 ± 1.2 minutes), all with p > 0.09; however, the performance decrement in hypoxia versus normoxia with methazolamide combined with aminophylline was less than placebo (+0.6 ± 1.5 minutes; p = 0.01). This improvement may have been partially mediated by increased SpO 2 in hypoxia with methazolamide combined with aminophylline compared with placebo (73% ± 3% vs. 79% ± 6%; p < 0.02). In conclusion, coadministration of methazolamide and aminophylline may promote endurance exercise performance during a sojourn at high altitude.
Seo, Yongsuk, Keith Burns, Curtis Fennell, Jung-Hyun Kim, John Gunstad, Ellen Glickman, and John McDaniel. . The influence of exercise on cognitive performance in normobaric hypoxia. High Alt Med Biol 16:298–305, 2015.—Although previous reports indicate that exercise improves cognitive function in normoxia, the influence of exercise on cognitive function in hypoxia is unknown. The purpose of this study was to determine if the impaired cognitive function in hypoxia can be restored by low to moderate intensity exercise. Sixteen young healthy men completed the ANAM versions of the Go/No-Go task (GNT) and Running Memory Continuous Performance Task (RMCPT) in normoxia to serve as baseline (B-Norm) (21% O 2 ). Following 60 minutes of exposure to normobaric hypoxia (B-Hypo) (12.5% O 2 ), these tests were repeated at rest and during cycling exercise at 40% and 60% of adjusted V o 2max . At B-Hypo, the % correct ( p ≤0.001) and throughput score ( p ≤0.001) in RMCPT were significantly impaired compared to B-Norm. During exercise at 40% ( p =0.023) and 60% ( p =0.006) of adjusted V o 2max , the throughput score in RMCPT improved compared to B-Hypo, and there was no significant difference in throughput score between the two exercise intensities. Mean reaction time also improved at both exercise intensities compared to B-Hypo ( p ≤0.028). Both peripheral oxygen saturation (Sp o 2 ) and regional cerebral oxygen saturation (rS o 2 ) significantly decreased during B-Hypo ( p ≤0.001) and further decreased at 40% ( p ≤0.05) and 60% ( p ≤0.039) exercise. There was no significant difference in Sp o 2 or rS o 2 between two exercise intensities. These data indicate that low to moderate exercise (i.e., 40%–60% adjusted V o 2max ) may attenuate the risk of impaired cognitive function that occurs in hypoxic conditions.
Darocha, Tomasz, Sylweriusz Kosinski, Maciej Moskwa, Anna Jarosz, Dorota Sobczyk, Robert Galazkowski, Marcin Slowik, and Rafal Drwila. The role of hypothermia coordinator: A case of hypothermic cardiac arrest treated with ECMO. High Alt Biol Med 16:352-355, 2015.—We present a description of emergency medical rescue procedures in a patient suffering from severe hypothermia who was found in the Babia Gora mountain range (Poland). After diagnosing the symptoms of II/III stage hypothermia according to the Swiss Staging System, the Mountain Rescue Service notified the coordinator from the Severe Accidental Hypothermia Center (CLHG) Coordinator in Krakow and then kept in constant touch with him. In accordance with the protocol for managing such situations, the coordinator started the procedure for patients in severe hypothermia with the option of extracorporeal warming and secured access to a device for continuous mechanical chest compression. After reaching the hospital, extracorporeal warming with ECMO support in the arteriovenuous configuration was started. The total duration of circulatory arrest was 150 minutes. The rescue procedures were supervised by the coordinator, who was on 24-hour duty and was reached by means of an alarm phone. The task of the coordinator is to consult the management of hypothermia cases, use his knowledge and experience to help in the diagnosis and treatment. and if the need arises refer the patient for ECMO at CLHG. Good coordination, planning, predicting possible problems, and acting in accordance with the agreed procedures in the scheme, make it possible to shorten the time of reaching the destination hospital and implement effective treatment.
Kasprzak, Zbigniew, Ewa liwicka, Karol Hennig, ucja Pilaczyska-Szczeniak, Anna Huta-Osiecka, and Alicja Nowak. Vitamin D, iron metabolism, and diet in alpinists during a 2-week high-altitude climb. High Alt Med Biol 16:230-235, 2015.A defensive mechanism against hypobaric hypoxia at high altitude is erythropoesis. Some authors point to the contribution of vitamin D to the regulation of this process. The aim of the present study was to assess the 25-hydroxycholecalciferol (25(OH)D) level and its associations with iron metabolic and inflammatory indices in participants of a 2-week mountaineering expedition. The study sample included 9 alpinists practicing recreational mountain climbing. Every 2 or 3 days they set up a different base between 3200 and 3616m with the intention of climbing 4000m peaks in the Mont Blanc massif. Before their departure for the mountains and 2 days after returning to the sea level anthropometric parameters, hematological parameters, serum levels of 25(OH)D and iron metabolic indices were measured in all the participants. The composition of the participants' diet was also evaluated. The comparative analysis showed a significant decrease in body mass, BMI values, total iron, and 25(OH)D concentrations (p<0.05). Also significant increases in unsaturated iron-binding capacity, hematocrit, and C-reactive protein concentrations (p<0.05) were found. It can be concluded that the 2-week climbing expedition contributed to the reduction of 25(OH)D levels and these changes were associated with modulation of immune processes. Moreover, the climbers' diet requires some serious modifications.
Kasprzak, Zbigniew, Ewa Śliwicka, Karol Hennig, Łucja Pilaczyńska-Szcześniak, Anna Huta-Osiecka, and Alicja Nowak. Vitamin D, iron metabolism, and diet in alpinists during a 2-week high-altitude climb. High Alt Med Biol 16:230–235, 2015.—A defensive mechanism against hypobaric hypoxia at high altitude is erythropoesis. Some authors point to the contribution of vitamin D to the regulation of this process. The aim of the present study was to assess the 25-hydroxycholecalciferol (25(OH)D) level and its associations with iron metabolic and inflammatory indices in participants of a 2-week mountaineering expedition. The study sample included 9 alpinists practicing recreational mountain climbing. Every 2 or 3 days they set up a different base between 3200 and 3616 m with the intention of climbing 4000 m peaks in the Mont Blanc massif. Before their departure for the mountains and 2 days after returning to the sea level anthropometric parameters, hematological parameters, serum levels of 25(OH)D and iron metabolic indices were measured in all the participants. The composition of the participants' diet was also evaluated. The comparative analysis showed a significant decrease in body mass, BMI values, total iron, and 25(OH)D concentrations ( p <0.05). Also significant increases in unsaturated iron-binding capacity, hematocrit, and C-reactive protein concentrations ( p <0.05) were found. It can be concluded that the 2-week climbing expedition contributed to the reduction of 25(OH)D levels and these changes were associated with modulation of immune processes. Moreover, the climbers' diet requires some serious modifications.
Bloch, Konrad E., Tsogyal D. Latshang, and Silvia Ulrich. Patients with obstructive sleep apnea at altitude. High Alt Med Biol 16:110–116, 2015.—Obstructive sleep apnea (OSA) is highly prevalent in the general population, in particular in men and women of older age. In OSA patients sleeping near sea level, the apneas/hypopneas associated with intermittent hypoxemia are predominantly due to upper airway collapse. When OSA patients stay at altitudes above 1600 m, corresponding to that of many tourist destinations, hypobaric hypoxia promotes frequent central apneas in addition to obstructive events, resulting in combined intermittent and sustained hypoxia. This induces strong sympathetic activation with elevated heart rate, cardiac arrhythmia, and systemic hypertension. There are concerns that these changes expose susceptible OSA patients, in particular those with advanced age and co-morbidities, to an excessive risk of cardiovascular and other adverse events during a stay at altitude. Based on data from randomized trials, it seems advisable for OSA patients to use continuous positive airway pressure treatment with computer controlled mask pressure adjustment (autoCPAP) in combination with acetazolamide during an altitude sojourn. If CPAP therapy is not feasible, acetazolamide alone is better than no treatment at all, as it improves oxygenation and sleep apnea and prevents excessive blood pressure rises of OSA patients at altitude.