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Nafi'an MRT, Sabirin RM, Wibowo RA, Sofyana M, Zahra IH, Wiryawan DA, Wijayatno QJ, Rohman A. Effect of nitrate supplementation on oxygen saturation levels for acute mountain sickness prevention: A systematic review and meta-analysis. Nitric Oxide 2024; 150:27-36. [PMID: 39002891 DOI: 10.1016/j.niox.2024.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 05/27/2024] [Accepted: 07/04/2024] [Indexed: 07/15/2024]
Abstract
PURPOSE This study aimed to systematically review the effect of nitrate supplementation on blood oxygen saturation. METHODS We searched PubMed, Scopus, and Cochrane Library databases from their inception up to October 2022. Two reviewers independently conducted two stages of the screening process to include a randomized controlled trial with nitrate supplementation versus placebo intervention assessing oxygen saturation among lowlanders going to either real or simulated high altitude environments. We used the Cochrane Risk of Bias 2.0 tool to assess the risk of bias in the included studies. Fixed-effect model meta-analyses were conducted for laboratory-based studies. Random-effect meta-analyses were conducted for real-world studies. RESULTS We found 7 trials that met the eligibility criteria. A meta-analysis of studies with some bias concerns showed an increase of 1.26 % in the SpO2 with 44 % I2 during submaximal exercise at simulated high altitudes (GRADE: low). On the contrary, a meta-analysis of studies without heterogeneity showed that nitrate supplementation aggravated oxygen saturation decline (-2.64 %, p = 0.03, GRADE: high) during rest in real high-altitude environments. A meta-analysis also showed that nitrate supplementation did not affect Acute Mountain Sickness (AMS) symptoms (GRADE: high). CONCLUSION Our results suggest that nitrate supplementation did not provide benefits for AMS prevention during rest at high altitudes. The low-quality evidence showing small beneficial effects of nitrate supplementation during exercise calls for further studies.
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Affiliation(s)
| | - Rahmaningsih Mara Sabirin
- Department of Physiology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Jakarta, Indonesia.
| | - Rakhmat Ari Wibowo
- Department of Physiology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Jakarta, Indonesia; Physical Activity for Health Research Centre, Institute of Sport, Physical Education, and Health Sciences, Moray House School of Education and Sport, University of Edinburgh, Edinburgh, UK
| | - Meida Sofyana
- Department of Physiology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Jakarta, Indonesia; School of Physiology, Pharmacology, & Neuroscience, University of Bristol, Bristol, England, UK
| | - Imtiyaz Hafizah Zahra
- School of Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Indonesia
| | - Danindra Ario Wiryawan
- School of Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Indonesia
| | - Qonita Jayanti Wijayatno
- School of Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Indonesia
| | - Abdul Rohman
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia
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Han C, Zheng XX, Zhang WF. High altitude retinopathy: An overview and new insights. Travel Med Infect Dis 2024; 58:102689. [PMID: 38295966 DOI: 10.1016/j.tmaid.2024.102689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/30/2023] [Accepted: 01/15/2024] [Indexed: 02/04/2024]
Abstract
High altitude retinopathy (HAR) is a common ocular disorder that occurs on ascent to high altitude. There are many clinical symptoms, retinal vascular dilatation, retinal edema and hemorrhage are common. These usually do not or slightly affect vision; rarely, severe cases develop serious or permanent vision loss. At present, the research progress of HAR mainly focuses on hemodynamic changes, blood-retinal barrier damage, oxidative stress and inflammatory response. Although the related studies on HAR are limited, it shows that HAR still belongs to hypoxia, and hypobaric hypoxia plays an aggravating role in promoting the development of the disease. Various studies have demonstrated the correlation of HAR with acute mountain sickness (AMS) and high-altitude cerebral edema (HACE), so a deeper understanding of HAR is important. The slow ascent rates and ascent altitude are the key to preventing any altitude sickness. Research on traditional chinese medicine (TCM) and western medicine has been gradually carried out. Further exploration of the pathogenesis and prevention strategies of HAR will provide better guidance for doctors and high-altitude travelers.
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Affiliation(s)
- Cong Han
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
| | - Xing-Xing Zheng
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
| | - Wen-Fang Zhang
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
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Westwood J, Mayhook-Walker I, Simpkins C, Darby-Smith A, Morris D, Normando E. Retinal Vascular Changes in Response to Hypoxia: A High-Altitude Expedition Study. High Alt Med Biol 2024; 25:49-59. [PMID: 38011631 DOI: 10.1089/ham.2023.0084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023] Open
Abstract
Westwood, Jessica, India Mayhook-Walker, Ciaran Simpkins, Andrew Darby-Smith, Dan Morris, and Eduardo Normando. Retinal vascular changes in response to hypoxia: a high-altitude expedition study. High Alt Med Biol. 25:49-59, 2024. Background: Increased tortuosity and engorgement of retinal vasculature are recognized physiological responses to hypoxia. This can lead to high-altitude retinopathy (HAR), but incidence reports are highly variable, and our understanding of the etiological mechanisms remains incomplete. This study quantitatively evaluated retinal vascular changes during an expedition to 4,167 m. Methods: Ten healthy participants summited Mount Toubkal, Morocco. Fundus images were taken predeparture, daily throughout the expedition, and 1 month postreturn. Diameter and tortuosity of four vessels were assessed, in addition to vessel density and features of HAR. Results: Significant (p ≤ 0.05) increases in tortuosity and diameter were observed in several vessels on high-altitude exposure days. There was a strong correlation between altitude and supratemporal retinal artery diameter on days 2, 3, and 6 of the expedition (r = 0.7707, 0.7951, 0.7401, respectively; p < 0.05). There was a significant increase in median vessel density from 6.7% at baseline to 10.0% on summit day. Notably there were no incidences of HAR. Conclusion: Physiological but not pathological changes were seen in this cohort, which gives insight into the state of the cerebral vasculature throughout this expedition. These results are likely attributable to relatively low altitude exposure, a conservative ascent profile, and the cohort's demographic. Future study must include daily retinal images at higher altitudes and take steps to mitigate environmental confounders. This study is relevant to altitude tourists, patients with diabetic retinopathy or retinal vein occlusion, and critically ill patients.
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Affiliation(s)
- Jessica Westwood
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
| | - India Mayhook-Walker
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
| | - Ciaran Simpkins
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
| | - Andrew Darby-Smith
- Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Dan Morris
- Cardiff Eye Unit, University Hospital of Wales, Cardiff, United Kingdom
| | - Eduardo Normando
- Imperial College London Ophthalmology Research Group, Western Eye Hospital, London, United Kingdom
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Dangi M, Sadhukhan A, Kumar P, Bandopadhyay S, Sharma VK, Patra VK, Chaudhary M, Rana V. Retinal Manifestations in High Altitude. High Alt Med Biol 2023; 24:296-301. [PMID: 37527184 DOI: 10.1089/ham.2023.0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023] Open
Abstract
Dangi, Meenu, Arnab Sadhukhan, Poninder Kumar, S. Bandopadhayay, Vijay K. Sharma, V.K. Patra, Manu Chaudhary, and Vipin Rana. Retinal manifestations in high altitude. High Alt Med Biol. 24:296-301, 2023. Aim: To study the high altitude (HA)-related retinal manifestations among security personnel and thus to provide new insights into the characteristics and mechanisms of retinopathy. Materials and Methods: This was a multicentric, nonrandomized prospective observational and descriptive study. We studied 54 security personnel over 1 year, who were referred from HA areas of northern India and north-eastern India for ocular problems. Complete coagulation profile was performed among patients with vascular occlusion. Results: There were total of 54 patients with ages ranging from 22 to 55 years. HA retinopathy was noticed in 28 patients: central retinal vein occlusion (6 patients), branch retinal vein occlusion (4 patients), branch retinal artery occlusion (1 patient), central retinal artery occlusion (4 patients), ocular ischemic syndrome (1 patient), central serous chorioretinopathy (7 patients), acetazolamide-induced maculopathy (1 patient), and solar retinopathy (2 patients). Along with an increased hematocrit, serum homocysteine was raised in the majority of vascular occlusions. The mean age was 38.16 years, the mean altitude was 14,716 ft, and the mean duration of stay was 11.2 weeks. Conclusion: Hypobaric hypoxia due to HA is a potential risk for HA retinopathy and associated vascular occlusions. Aside from increased hematocrit, hyperhomocysteinemia is a potential cause of vascular occlusions.
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Affiliation(s)
- Meenu Dangi
- Department of Ophthalmology, Command Hospital Western Command, Chandimandir, India
| | - Arnab Sadhukhan
- Department of Ophthalmology, Command Hospital Eastern Command, Kolkata, India
| | - Poninder Kumar
- Department of Ophthalmology, Command Hospital Western Command, Chandimandir, India
| | - S Bandopadhyay
- Department of Ophthalmology, Command Hospital Eastern Command, Kolkata, India
| | - Vijay K Sharma
- Department of Ophthalmology, Command Hospital Eastern Command, Kolkata, India
| | - V K Patra
- Department of Ophthalmology, Command Hospital Eastern Command, Kolkata, India
| | - Manu Chaudhary
- Department of Ophthalmology, Command Hospital Western Command, Chandimandir, India
| | - Vipin Rana
- Department of Ophthalmology, Command Hospital Eastern Command, Kolkata, India
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春花, 白玛康卓. [Establishment and Evaluation of a Mice Model of High-Altitude Cerebral Edema]. SICHUAN DA XUE XUE BAO. YI XUE BAN = JOURNAL OF SICHUAN UNIVERSITY. MEDICAL SCIENCE EDITION 2023; 54:1269-1275. [PMID: 38162056 PMCID: PMC10752796 DOI: 10.12182/20231160604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Indexed: 01/03/2024]
Abstract
Objective To establish an animal model of high-altitude cerebral edema (HACE), to explore the altitude and oxygen partial pressure conditions that can lead to obvious clinical manifestations of HACE, and to lay the foundation for further research of the pathogenic mechanisms and intervention strategies of HACE. Methods Male BALB/c mice of 8 weeks old were randomly assigned to Control and HACE groups. The Control group (n=10) was treated with normobaric and normoxic conditions, while the HACE groups were placed in hypobaric hypoxic (HH) chambers for the durations of 6 h, 12 h, 24 h, 48 h and 72 h, respectively, receiving treatments of simulated HH conditions at the altitudes of 4000 m (n=10 for each group receiving different durations of HH treatment), 5000 m (n=10 for each group receiving different durations of HH treatment), and 6000 m (n=10 for each group receiving different durations of HH treatment). HE staining was performed to observe the morphological changes of the brain tissue and the appropriate simulated altitude conditions were selected accordingly for the construction and evaluation of the best HACE model. The HACE model was evaluated in the following ways, the mouse brain was weighed and the cerebral edema was measured accordingly, Evans blue (EB) was injected to determine the permeability of the blood-brain barrier (BBB), and the cell apoptosis was determined by immunofluorescence staining. Results There were no deaths in the groups treated with the HH conditions of the altitudes of 4000 m and 5000 m, while the mortality in the 6000 m altitude treatment groups was 12.2%. HE staining showed no significant changes in brain morphology or structure in the group receiving HH treatment for the altitude of 4000 m. A small amount of brain cell edema was observed in the groups receiving 48 h and 72 h of HH treatment for the altitude of 5000 m. The groups receiving HH treatment for the altitude of 6000 m demonstrated the most prominent modeling effect. HE staining showed increased volume and swelling of brain cells in all the 6000 m groups, especially in the 24 h, 48 h and 72 h treatment groups. In all the 6000 m groups, cell arrangement disorder, gap enlargement, and nuclear contraction were observed. Evaluation of the modeling effect demonstrated that, in the HACE mice model constructed with the HH conditions for the altitude of 6000 m, cerebral edema and EB permeability increased after 12 h HH treatment and there was no obvious apoptosis in the modeling groups receiving different durations of treatment. Conclusion The HACE model can be established effectively by simulating conditions at the altitude of 6000 m (the atmospheric pressure being 47.19 kPa and the oxygen partial pressure being 9.73 kPa) with a HH chamber.
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Affiliation(s)
- 春花
- 西藏大学医学院 (拉萨 850000)Medical College of Tibet University, Lhasa 850000, China
| | - 白玛康卓
- 西藏大学医学院 (拉萨 850000)Medical College of Tibet University, Lhasa 850000, China
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Zhao R, Wang X, Zhou X, Jiang S, Zhang L, Yu Z. Metabolites and gene expression in the myocardium of fasting rats in an acute hypoxic environment. BMC Genomics 2023; 24:251. [PMID: 37165337 PMCID: PMC10173486 DOI: 10.1186/s12864-023-09309-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 04/12/2023] [Indexed: 05/12/2023] Open
Abstract
With the rising demand for entry to extremely high altitudes (HAs), rapid adaptability to extremely hypoxic environments is a challenge that we need to explore. Fasting was used to evaluate acute hypoxia tolerance at HA and was proven to be an effective method for improving the survival rate at extreme HA. Our experiments also showed that fasting pretreatment for 72 h significantly increased the 24 h survival rate of rats at 7620 m from 10 to 85% and protected the myocardium cells of rats. Here, we compared the metabolites and gene expression in the myocardium of SD rats pretreated with fasting and nonfasting at normal altitude and extreme HA. Our findings demonstrated that the dynamic contents of detected differential metabolites (DMs) between different rat groups were consistent with the expression of differentially expressed genes (DEGs), and DM clusters also showed strong correlations with DEG clusters. DM clusters related to amino acids and lipids were significantly lower in the fasting groups, and the correlated DEG clusters were enriched in mitotic pathways, including CDK1, CDC7, NUF2, and MCM6, suggesting that fasting can attenuate mitotic processes in cardiac tissues and reduce the synthesis of amino acids and lipids. L-Glutamine-related metabolites were particularly low at extreme HA without pretreatment but were normal in the fasting groups. The DEGs in the cluster related to L-glutamine-related metabolites were enriched for T-cell receptor V(D)J recombination, the Hippo signaling pathway, the Wnt signaling pathway, the cGMP-PKG signaling pathway, and the mTOR signaling pathway and were significantly downregulated, indicating that the content of L-glutamine decreased at extreme HA, while fasting increased it to adapt to the environment. Moreover, abundant fatty acids were detected when rats were exposed to extreme HA without pretreatment. Our study revealed the fasting and hypoxic environment-related factors in SD rats and provided new insights into the genetic and molecular characteristics in the myocardium, which is critical to developing more potential rapid adaptation methods to extreme HA.
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Affiliation(s)
- Ruzhou Zhao
- Beijing Institute of Biotechnology, Academy of Military Medical Sciences (AMMS), Beijing, China
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, China
| | - Xiaobo Wang
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, China
| | - Xiang Zhou
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, China
- Department of Nuclear Medicine, Xijing Hospital, Air Force Medical University, Xi'an, China
| | - Shuai Jiang
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, China
| | - Lin Zhang
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, China
| | - Zhibin Yu
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, China.
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Ascent rate and the Lake Louise scoring system: An analysis of one year of emergency ward entries for high-altitude sickness at the Mustang district hospital, Nepal. PLoS One 2022; 17:e0276901. [PMID: 36301827 PMCID: PMC9612449 DOI: 10.1371/journal.pone.0276901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/17/2022] [Indexed: 11/19/2022] Open
Abstract
More travellers are making swift ascents to higher altitudes without sufficient acclimatization or pharmaceutical prophylaxis as road connectivity develops in the Himalayan region of Nepal. Our study connects ascent rate with prevalence and severity of acute mountain sickness (AMS) among patients admitted to the emergency ward of the Mustang district hospital in Nepal. A register-based, cross-sectional study was conducted between June 2018 and June 2019 to explore associations of Lake Louise scores with ascent profile, sociodemographic characteristics, and comorbidities using chi-square test, t-test, and Bayesian logistic regression. Of 105 patients, incidence of AMS was 74%, of which 61%, 36%, and 3% were mild, moderate, and severe cases, respectively. In the Bayesian-ordered logistic model of AMS severity, ascent rate (odds ratio 3.13) and smoking (odds ratio 0.16) were significant at a 99% credible interval. Based on the model-derived counterfactual, the risk of developing moderate or severe AMS for a middle-aged, non-smoking male traveling from Pokhara to Muktinath (2978m altitude gain) in a single day is twice that of making the ascent in three days. Ascent rate was strongly associated with the likelihood of developing severe AMS among travellers with AMS symptoms visiting Mustang Hospital's Emergency Ward.
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Savioli G, Ceresa IF, Gori G, Fumoso F, Gri N, Floris V, Varesi A, Martuscelli E, Marchisio S, Longhitano Y, Ricevuti G, Esposito C, Caironi G, Giardini G, Zanza C. Pathophysiology and Therapy of High-Altitude Sickness: Practical Approach in Emergency and Critical Care. J Clin Med 2022; 11:3937. [PMID: 35887706 PMCID: PMC9325098 DOI: 10.3390/jcm11143937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/21/2022] [Accepted: 06/24/2022] [Indexed: 12/26/2022] Open
Abstract
High altitude can be a hostile environment and a paradigm of how environmental factors can determine illness when human biological adaptability is exceeded. This paper aims to provide a comprehensive review of high-altitude sickness, including its epidemiology, pathophysiology, and treatments. The first section of our work defines high altitude and considers the mechanisms of adaptation to it and the associated risk factors for low adaptability. The second section discusses the main high-altitude diseases, highlighting how environmental factors can lead to the loss of homeostasis, compromising important vital functions. Early recognition of clinical symptoms is important for the establishment of the correct therapy. The third section focuses on high-altitude pulmonary edema, which is one of the main high-altitude diseases. With a deeper understanding of the pathogenesis of high-altitude diseases, as well as a reasoned approach to environmental or physical factors, we examine the main high-altitude diseases. Such an approach is critical for the effective treatment of patients in a hostile environment, or treatment in the emergency room after exposure to extreme physical or environmental factors.
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Affiliation(s)
- Gabriele Savioli
- Department of Emergency Medicine and Surgery, IRCCS Fondazione Policlinico San Matteo, 27100 Pavia, Italy;
| | | | - Giulia Gori
- Department of Internal Medicine, University of Pavia, 27100 Pavia, Italy; (G.G.); (F.F.)
| | - Federica Fumoso
- Department of Internal Medicine, University of Pavia, 27100 Pavia, Italy; (G.G.); (F.F.)
| | - Nicole Gri
- School of Medicine, University of Pavia, 27100 Pavia, Italy; (N.G.); (V.F.); (A.V.)
| | - Valentina Floris
- School of Medicine, University of Pavia, 27100 Pavia, Italy; (N.G.); (V.F.); (A.V.)
- Department of Emergency Medicine (ASL AL), San Giacomo Hospital, 15067 Novi Ligure, Italy; (E.M.); (S.M.); (Y.L.)
| | - Angelica Varesi
- School of Medicine, University of Pavia, 27100 Pavia, Italy; (N.G.); (V.F.); (A.V.)
| | - Ermelinda Martuscelli
- Department of Emergency Medicine (ASL AL), San Giacomo Hospital, 15067 Novi Ligure, Italy; (E.M.); (S.M.); (Y.L.)
| | - Sara Marchisio
- Department of Emergency Medicine (ASL AL), San Giacomo Hospital, 15067 Novi Ligure, Italy; (E.M.); (S.M.); (Y.L.)
| | - Yaroslava Longhitano
- Department of Emergency Medicine (ASL AL), San Giacomo Hospital, 15067 Novi Ligure, Italy; (E.M.); (S.M.); (Y.L.)
- Foundation “Ospedale Alba-Bra Onlus”, Department of Emergency Medicine, Anesthesia and Critical Care Medicine, Michele and Pietro Ferrero Hospital, 12060 Verduno, Italy
| | - Giovanni Ricevuti
- Department of Drug Science, University of Pavia, 27100 Pavia, Italy;
| | - Ciro Esposito
- Nephrology and Dialysis Unit, ICS Maugeri, University of Pavia, 27100 Pavia, Italy;
| | - Guido Caironi
- Registered Nurse Supporting Prehospital Emergency Service ASST 118, 22100 Como, Italy;
| | - Guido Giardini
- Neurology and Stroke Unit, Ospedale Regionale “U.Parini”, 11100 Aosta, Italy;
| | - Christian Zanza
- Department of Emergency Medicine (ASL AL), San Giacomo Hospital, 15067 Novi Ligure, Italy; (E.M.); (S.M.); (Y.L.)
- Foundation “Ospedale Alba-Bra Onlus”, Department of Emergency Medicine, Anesthesia and Critical Care Medicine, Michele and Pietro Ferrero Hospital, 12060 Verduno, Italy
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Effects of long-term high-altitude exposure on retinal and choroidal microcirculation. Graefes Arch Clin Exp Ophthalmol 2022; 260:3525-3532. [PMID: 35678838 DOI: 10.1007/s00417-022-05699-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/02/2022] [Accepted: 05/17/2022] [Indexed: 11/04/2022] Open
Abstract
PURPOSE To quantify the effect of long-term high-altitude (HA) exposure on retinal and choroidal microcirculation and to relate these changes to high-altitude polycythemia (HAPC), as a proxy for etiopathogenesis of high-altitude related retinopathy (HAR). METHODS Fifty-one HAPC patients, 50 healthy HA residents, and 43 low altitude (LA) residents were recruited in this study. Optical coherence tomography angiography (OCTA) and enhanced depth imaging (EDI)-OCT images were analyzed. Retinal microvascular metrics included vessel density (VD), skeleton density (SD), fractal dimension (FD), and foveal avascular zone (FAZ). Choroidal microvascular metrics included subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI). All metrics were calculated by ImageJ software and compared among HAPC group, healthy HA group, and LA group. RESULTS In HAPC group, VD (30.62 ± 3.67%), SD (13.25 ± 1.64%), FD (1.79 ± 0.04), and the CVI (63.01 ± 1.42%) were significant lower and SFCT (403.25 ± 94.3 μm) was significant thicker than healthy HA group (all P < 0.001). FAZ area was comparable between two groups (0.42 ± 0.1 vs. 0.4 ± 0.11 mm2, P = 0.411). However, these metrics were not different between healthy HA group and LA group (all P > 0.05) except for FD was lower in HA group (P < 0.001). Pearson's correlation analyses revealed HGB was negatively related with VD (r = - 0.562, P < 0.001) and positively related with SFCT (r = 0.505, P < 0.001) in healthy HA group; however, no associations between HGB and vascular metrics in HAPC group were detected (all P > 0.05). CONCLUSIONS Long-term exposure to HA environment induces retinal and choroidal microcirculation disturbance in HAPC patients. However, these changes were not evident in healthy HA residents because of adaptation.
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Yin X, Li Y, Ma Y, Xie Y, Wang K, Sun D, Liu X, Hao M, Liang M, Zhang S, Guo Y, Jin L, Wang N, Wang J. Thickened Retinal Nerve Fiber Layers Associated With High-Altitude Headache. Front Physiol 2022; 13:864222. [PMID: 35600299 PMCID: PMC9114875 DOI: 10.3389/fphys.2022.864222] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose: This study aimed to quantify the different quadrants of the optic nerve head (ONH) and macular parameters and their changes during exposure to high altitude, and to assess their correlation with high-altitude headache (HAH).Methods: Spectral-domain optical coherence tomography (OCT) was used to quantify changes in the retinal structure in 109 healthy subjects during acute exposure to high altitude (3,700 m). Self-reported symptoms of HAH and acute mountain sickness AMS were assessed using Lake Louise Score (LLS), alongside measurements of physiological parameters (oxygen saturation [SpO2], heart rate [HR], hemoglobin level [Hb], and red blood cell [RBC] count). Measurements were taken before and after exposure to the high-altitude environment. The correlations of these parameters and changes at ONH were examined.Results: With the exposure to high altitude, the incidence of AMS was 44.0% and the frequency of HAH was 67.0% (54.1% mild, 12.9% moderate-severe). As for systemic parameters measured at high altitude, the participants exhibited significantly lower SpO2, higher resting HR, higher Hb, and a higher RBC (all p < 0.05). Key stereometric parameters used to describe ONH [superior, inferior, nasal, temporal, and mean retinal nerve fiber layer (RNFL) thickness] and macula (macular thickness) increased at high altitude compared with baseline. Most parameters of ONH changed, especially superior, inferior, and mean RNFL thickness (p < 0.05). There was a significant correlation between the ratios of RNFL at ONH and HAH [mean thickness (r = 0.246, p = 0.01); inferior (r = 0.216, p = 0.02); nasal (r = 0.193, p = 0.04)]. No associations between parameters of ONH and AMS or LLS were observed.Conclusion: The high-altitude environment can increase RNFL thickness at ONH. Furthermore, we found that the ratios of mean thickness, inferior area, and nasal area correlated positively with HAH, which provides new insights for understanding of the underlying pathological mechanisms of high-altitude retinopathy (HAR).
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Affiliation(s)
- Xianhong Yin
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Yi Li
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- Institute for Six-Sector Economy, Fudan University, Shanghai, China
- International Human Phenome Institutes, Shanghai, China
| | - Yanyun Ma
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- Institute for Six-Sector Economy, Fudan University, Shanghai, China
| | - Yuan Xie
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Kun Wang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Dayan Sun
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Xiaoyu Liu
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Meng Hao
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Meng Liang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Shixuan Zhang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Yuan Guo
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
| | - Li Jin
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- International Human Phenome Institutes, Shanghai, China
- Research Institute of Data Sciences, Fudan University, Shanghai, China
- Research Unit of Dissecting the Population Genetics and Developing New Technologies for Treatment and Prevention of Skin Phenotypes and Dermatological Diseases, Chinese Academy of Medical Sciences (2019RU058), Shanghai, China
- *Correspondence: Jiucun Wang, ; Ningli Wang, ; Li Jin,
| | - Ningli Wang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- *Correspondence: Jiucun Wang, ; Ningli Wang, ; Li Jin,
| | - Jiucun Wang
- Ministry of Education Key Laboratory of Contemporary Anthropology, School of Life Sciences, and Human Phenome Institute, Fudan University, Shanghai, China
- Research Unit of Dissecting the Population Genetics and Developing New Technologies for Treatment and Prevention of Skin Phenotypes and Dermatological Diseases, Chinese Academy of Medical Sciences (2019RU058), Shanghai, China
- *Correspondence: Jiucun Wang, ; Ningli Wang, ; Li Jin,
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11
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Small E, Phillips C, Marvel J, Lipman G. Older Age as a Predictive Risk Factor for Acute Mountain Sickness. Am J Med 2022; 135:386-392.e1. [PMID: 34715059 DOI: 10.1016/j.amjmed.2021.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 10/03/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Older populations are increasing and comprise a substantial portion of high-altitude travelers. Aging physiology may influence susceptibility to acute mountain sickness, though prior research remains inconclusive. The goal of this study was to investigate the relationship between increasing age and acute mountain sickness. METHODS This study was a pooled analysis of 5 prospective randomized controlled trials conducted at White Mountain, California from 2010, 2016-2019 with identical 4-hour rapid ascent from 1242 m to overnight sojourn at 3810 m. Acute mountain sickness was defined by the 2018 Lake Louise Questionnaire criteria. RESULTS There were 491 participants analyzed, 234 (48%) diagnosed with acute mountain sickness and 71 (14%) with moderate acute mountain sickness. Mean age was 37 years (±13). There was no significant correlation between Lake Louise Questionnaire severity and age (r = -0.02; 95% confidence interval [CI], -0.11-0.07, P = .7), 40-year-old dichotomy (t = -0.6; 95% CI, -0.53-0.28, P = .6), or decade of life (P = .4). Logistic regression found no increased odds of acute mountain sickness for increasing age by decade of life (odds ratio [OR] 1.0; 95% CI, 0.97-1.0) or 40-year-old dichotomy (OR 1.4; 95% CI, 0.97-2.1). A history of acute mountain sickness increased odds of acute mountain sickness (OR 3.2; 95% CI, 1.5-7.7). CONCLUSIONS Older age was not associated with incidence nor severity of acute mountain sickness. A history of altitude illness increased odds of acute mountain sickness and should be used for pre-ascent risk stratification.
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Affiliation(s)
- Elan Small
- Emergency Medicine Residency, Stanford University School of Medicine, Palo Alto, Calif.
| | - Caleb Phillips
- Department of Computational Science, University of Colorado, Boulder
| | - James Marvel
- Department of Emergency Medicine, Stanford University School of Medicine, Palo Alto, Calif
| | - Grant Lipman
- Department of Emergency Medicine, Stanford University School of Medicine, Palo Alto, Calif
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12
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Gasser B, Stouder J. Rescue Emergencies Due to High-Altitude Illnesses Are Rare in Switzerland. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19020865. [PMID: 35055685 PMCID: PMC8776185 DOI: 10.3390/ijerph19020865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 12/31/2021] [Accepted: 01/10/2022] [Indexed: 02/04/2023]
Abstract
Background: Despite a potential high risk of acute mountain sickness (AMS) in the Swiss Alps, there is a lack of analyses concerning its relevance over longer periods. In consequence, the aim of this study is to analyze the prevalence of AMS in comparison to other causes of mountain emergencies in recent years in Switzerland. Material and Methods: Based on the central registry of mountain emergencies of the Swiss Alpine Club (SAC), all cases in the period between 2009 and 2020 were analyzed for AMS including the most severe forms of high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE). Emergencies were assessed for the severity of the event with a National Advisory Committee for Aeronautics (NACA) score. Results: From a total of 4596 high-altitude mountaineering emergencies identified in the observational period, a total number of 352 cases of illnesses were detected. Detailed analysis revealed 85 cases of AMS, 5 cases of HAPE, and 1 case of HACE. The average altitude was 3845 ± 540 m. Most cases were in the canton of Valais, especially in the Monte Rosa region and the mountains of the Mischabel group (Täschhorn, Dom, Südlenz, Nadelhorn, Hohberghorn). There were only three deaths related to high-altitude illnesses; all the other events could be identified as moderate to severe but not life-threatening. Discussion: An emergency due to AMS that requires rescue is unlikely in the Swiss Alps. This does not imply that AMS is not a concern. However, the facts that the maximal altitude is relatively low and that fast self-descents often seem possible probably minimize the likelihood that mountaineers with symptoms contact emergency services.
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13
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Vitreous Hemorrhage following High-Altitude Retinopathy. Case Rep Ophthalmol Med 2021; 2021:7076190. [PMID: 34422422 PMCID: PMC8371664 DOI: 10.1155/2021/7076190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/04/2021] [Indexed: 11/18/2022] Open
Abstract
Purpose To report a case of high-altitude retinopathy with vitreous hemorrhage. Methods An apparently healthy 29-year-old boy presented with a history of floater and slight diminution of vision in the left eye after climbing the mountain 4760 meters high. Results The visual acuity at presentation was 20/20 in the right eye and 20/30 in the left eye. Anterior segment findings of both eyes were unremarkable. Fundus evaluation revealed bilaterally dilated major retinal veins. The right eye revealed clear, quiet vitreous, healthy macula, and pink and smooth optic disc. There was fresh vitreous hemorrhage confined just one disc diameter away at the superior and inferior part of the optic nerve in the left eye. The macula and optic nerve head of this eye grossly looked normal. Complete blood count, haemoglobin, ESR, CRP, sugar, renal function test, lipid panel, and serology for HIV, HCV, VDRL, and HBsAg were normal. The Mantoux test and chest X-ray also revealed normal findings. Physician consultation did not reveal other abnormalities. On the 3rd week of follow-up, his vision was 20/20 in both eyes. Fundus examination revealed clear vitreous in both eyes though some venous dilation and tortuosities were still evident in the left eye. A macular OCT scan showed almost normal-appearing fundus. Conclusions Vitreous hemorrhage following climbing high altitude can be one of the manifestations of high-altitude retinopathy.
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Turner REF, Gatterer H, Falla M, Lawley JS. High-altitude cerebral edema: its own entity or end-stage acute mountain sickness? J Appl Physiol (1985) 2021; 131:313-325. [PMID: 33856254 DOI: 10.1152/japplphysiol.00861.2019] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
High-altitude cerebral edema (HACE) and acute mountain sickness (AMS) are neuropathologies associated with rapid exposure to hypoxia. However, speculation remains regarding the exact etiology of both HACE and AMS and whether they share a common mechanistic pathology. This review outlines the basic principles of HACE development, highlighting how edema could develop from 1) a progression from cytotoxic swelling to ionic edema or 2) permeation of the blood brain barrier (BBB) with or without ionic edema. Thereafter, discussion turns to the available neuroimaging literature in the context of cytotoxic, ionic, or vasogenic edema in both HACE and AMS. Although HACE is clearly caused by an increase in brain water of ionic and/or vasogenic origin, there is very little evidence that this type of edema is present when AMS develops. However, cerebral vasodilation, increased intracranial blood volume, and concomitant intracranial fluid shifts from the extracellular to the intracellular space, as interpreted from changes in diffusion indices within white matter, are observed consistently in persons acutely exposed to hypoxia and with AMS. Therefore, herein we explore the idea that intracellular swelling occurs alongside AMS, and is a critical precursor to extracellular ionic edema formation. We propose that this process produces a subtle modulation of the BBB, which either together with or independent of vasogenic edema provides a transvascular segue from the end-stage of AMS to HACE. Ultimately, this review seeks to shed light on the possible processes underlying HACE pathophysiology, and thus highlights potential avenues for future prevention and treatment.
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Affiliation(s)
- Rachel E F Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Marika Falla
- Center for Mind/Brain Sciences and Centre for Neurocognitive Rehabilitation, University of Trento, Rovereto, Italy
| | - Justin S Lawley
- Division of Performance Physiology & Prevention, Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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Tsai TY, Gozari G, Su YC, Lee YK, Tu YK. Optic nerve sheath diameter changes at high altitude and in acute mountain sickness: meta-regression analyses. Br J Ophthalmol 2020; 106:731-735. [PMID: 33310776 DOI: 10.1136/bjophthalmol-2020-317717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/09/2020] [Accepted: 11/17/2020] [Indexed: 11/04/2022]
Abstract
BACKGROUND/AIMS To assess changes in optic nerve sheath diameter (ONSD) at high altitude and in acute mountain sickness (AMS). METHODS Cochrane Library, EMBASE, Google Scholar and PubMed were searched for articles published from their inception to 31st of July 2020. Outcome measures were mean changes of ONSD at high altitude and difference in ONSD change between subjects with and without AMS. Meta-regressions were conducted to investigate the relation of ONSD change to altitude and time spent at that altitude. RESULTS Eight studies with 248 participants comparing ONSD from sea level to high altitude, and five studies with 454 participants comparing subjects with or without AMS, were included. ONSD increased by 0.14 mm per 1000 m after adjustment for time (95% CI: 0.10 to 0.18; p<0.01). Restricted cubic spline regression revealed an almost linear relation between ONSD change and time within 2 days. ONSD was greater in subjects with AMS (mean difference=0.47; 95% CI: 0.14 to 0.80; p=0.01; I2=89.4%). CONCLUSION Our analysis shows that ONSD changes correlate with altitude and tend to increase in subjects with AMS. Small study number and high heterogeneity are the limitations of our study. Further large prospective studies are required to verify our findings.
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Affiliation(s)
- Tou-Yuan Tsai
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan
| | - George Gozari
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan
| | - Yung-Cheng Su
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Yi-Kung Lee
- Emergency Department, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Yu-Kang Tu
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan .,Department of Dentistry, National Taiwan University Hospital and School of Dentistry, National Taiwan University, Taipei, Taiwan.,Research Center of Big Data and Meta-analysis, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
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Evaluation of Acute Mountain Sickness by Unsedated Transnasal Esophagogastroduodenoscopy at High Altitude. Clin Gastroenterol Hepatol 2020; 18:2218-2225.e2. [PMID: 31778804 DOI: 10.1016/j.cgh.2019.11.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 11/08/2019] [Accepted: 11/15/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS It is not clear how rapid ascent to a high altitude causes the gastrointestinal symptoms of acute mountain sickness (AMS). We assessed the incidence of endoscopic lesions in the upper gastrointestinal tract in healthy mountaineers after a rapid ascent to high altitude, their association with symptoms, and their pathogenic mechanisms. METHODS In a prospective study, 25 mountaineers (10 women; mean age, 43.8 ± 9.5 y) underwent unsedated, transnasal esophagogastroduodenoscopy in Zurich (490 m) and then on 2 test days (days 2 and 4) at a high altitude laboratory in the Alps (Capanna Regina Margherita, 4559 m). Symptoms were assessed using validated instruments for AMS (the acute mountain sickness score and the Lake Louise scoring system) and visual analogue scales (scale, 0-100). Levels of messenger RNAs (mRNAs) in duodenal biopsy specimens were measured by quantitative polymerase chain rection. RESULTS The follow-up endoscopy at high altitude was performed in 19 of 25 patients on day 2 and in 23 of 25 patients on day 4. The frequency of endoscopic lesions increased from 12% at baseline to 26.3% on day 2 and to 60.9% on day 4 (P < .001). The incidence of ulcer disease increased from 0 at baseline to 10.5% on day 2 and to 21.7% on day 4 (P = .014). Mucosal lesions were associated with lower hunger scores (37.3 vs 67.4 in patients without lesions; P = .012). Subjects with peptic lesions had higher levels of HIF2A mRNA, which encodes a hypoxia-induced transcription factor, and ICAM1 mRNA, which encodes an adhesion molecule, compared with subjects without lesions (fold changes, 1.38 vs 0.63; P = .001; and 1.37 vs 0.66; P = .011, respectively). CONCLUSIONS In a prospective study of 25 mountaineers, fast ascent to a high altitude resulted in rapid onset of clinically meaningful mucosal lesions and ulcer disease. Duodenal biopsy specimens from these subjects had increased levels of HIF2A mRNA and ICAM1 mRNA, which might contribute to the formation of hypoxia-induced peptic lesions. Further studies are needed of the mechanisms of this process.
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17
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Sex-based differences in the prevalence of acute mountain sickness: a meta-analysis. Mil Med Res 2019; 6:38. [PMID: 31813379 PMCID: PMC6900850 DOI: 10.1186/s40779-019-0228-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/13/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND When lowlanders rapidly ascend to altitudes > 2500 m, they may develop acute mountain sickness (AMS). The individual susceptibility, ascending velocity, time spent at altitude, activity levels and altitude reached are considered risk factors for AMS. However, it is not clear whether sex is a risk factor. The results have been inconclusive. We conducted a meta-analysis to test whether there were sex-based differences in the prevalence of AMS using Lake Louise Scoring System. METHODS Systematic searches were performed in August 2019 in EMBASE, PubMed, and Web of Science for prospective studies with AMS data for men and women. The titles and abstracts were independently checked in the primary screening step, and the selected full-text articles were independently assessed in the secondary screening step by the two authors (YPH and JLW) based on pre-defined inclusion criteria. The meta-analysis was performed using by the STATA 14.1 software program. A random-effects model was employed. RESULTS Eighteen eligible prospective studies were included. A total of 7669 participants (2639 [34.4%] women) were tested. The results showed that there was a statistically significant higher prevalence rate of AMS in women than in men (RR = 1.24, 95%CI 1.09-1.41), regardless of age or race. Howerver, the heterogeneity was significant in the analysis (Tau2 = 0.0403, Chi2 = 50.15, df = 17; I2 = 66.1%, P = 0.000), it was main caused by different numbers of subjects among the studies (coefficient = - 2.17, P = 0.049). Besides, the results showed that there was no evidence of significant publication bias in the combined studies on the basis of Egger's test (bias coefficient = 1.48, P = 0.052) and Begg's test (P = 0.130). CONCLUSIONS According to this study, the statistically significant finding emerging from this study was that women have a higher prevalence of AMS. However, the authors could not exclude studies where patients were on acetazolamide. Our analysis provided a direction for future studies of the relationship of sex and the risk of AMS, such as the pathological mechanism and prevention research.
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Fisher O, Benson RA, Wayte S, Kimani PK, Hutchinson C, Imray CHE. Multimodal analysis of the effects of dexamethasone on high-altitude cerebral oedema: protocol for a pilot study. Trials 2019; 20:604. [PMID: 31651350 PMCID: PMC6813976 DOI: 10.1186/s13063-019-3681-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 08/25/2019] [Indexed: 11/17/2022] Open
Abstract
Background Acute mountain sickness (AMS) is a cluster of symptoms that commonly occur in those ascending to high altitudes. Symptoms can include headaches, nausea, insomnia and fatigue. Exposure to high altitude can also lead to high-altitude cerebral oedema (HACE), which is a potential cause of death whilst mountaineering. Generally, AMS precedes the development of HACE. Historical studies have demonstrated the effectiveness of regular dexamethasone administration in reducing the symptoms of AMS. However, the mechanism by which dexamethasone works to reduce symptoms AMS remains poorly understood. Further studies, simulating altitude using hypoxic tents, have characterised the effect of prolonged exposure to normobaric hypoxia on cerebral oedema and blood flow using MRI. This randomised trial assesses the effect of dexamethasone on hypoxia-induced cerebral oedema in healthy adult volunteers. Methods/design D4H is a double-blind placebo-controlled randomised trial assessing the effect of dexamethasone on hypoxia-induced cerebral oedema. In total, 20 volunteers were randomised in pairs to receive either 8.25 mg dexamethasone or normal saline placebo intravenously after 8 h of hypoxia with an FiO2 of 12%. Serial MRI images of the brain and spinal cord were obtained at hours 0, 7, 11, 22 and 26 of the study along with serum and urinary markers to correlate with the severity of cerebral oedema and the effect of the intervention. Discussion MRI has been used to identify changes in cerebral vasculature in the development of AMS and HACE. Dexamethasone is effective at reducing the symptoms of AMS; however, the mechanism of this effect is unknown. If this study demonstrates a clear objective benefit of dexamethasone in this setting, future studies may be able to demonstrate that dexamethasone is an effective therapy for oedema associated with brain and spinal cord ischaemia beyond AMS. Trial registration Clinicaltrials.gov, NCT03341676. Registered on 14 November 2017.
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Affiliation(s)
- O Fisher
- University Hospital Coventry and Warwickshire, Clifford Bridge Road, Coventry, CV2 2DX, UK. .,University of Warwick, Coventry, UK.
| | - R A Benson
- University Hospital Coventry and Warwickshire, Clifford Bridge Road, Coventry, CV2 2DX, UK.,University of Birmingham, Birmingham, UK
| | - S Wayte
- University Hospital Coventry and Warwickshire, Clifford Bridge Road, Coventry, CV2 2DX, UK
| | | | - C Hutchinson
- University Hospital Coventry and Warwickshire, Clifford Bridge Road, Coventry, CV2 2DX, UK.,University of Warwick, Coventry, UK
| | - C H E Imray
- University Hospital Coventry and Warwickshire, Clifford Bridge Road, Coventry, CV2 2DX, UK.,University of Warwick, Coventry, UK
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Abstract
Mountain climbers may develop specific illnesses that largely depend on the altitude reached and the rate of ascent. The popularity of travel to high altitude destinations, extreme tourist activities and mountain climbing means that neurologists in low-altitude countries are increasingly likely to encounter neurological problems and disorders in people exposed to high altitude. Additionally, they may have to advise patients with pre-existing neurological conditions on the risks of ascent to altitude. This article focuses on neurological-related high-altitude illnesses: acute mountain sickness and high-altitude cerebral oedema, as well as high-altitude retinopathy and other neurological disorders. This overview combines current understood pathogenesis with the experience of managing altitude-related illness at the foot of Mount Kilimanjaro in northern Tanzania, the tallest free-standing mountain in the world.
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Molano Franco D, Nieto Estrada VH, Gonzalez Garay AG, Martí‐Carvajal AJ, Arevalo‐Rodriguez I. Interventions for preventing high altitude illness: Part 3. Miscellaneous and non-pharmacological interventions. Cochrane Database Syst Rev 2019; 4:CD013315. [PMID: 31012483 PMCID: PMC6477878 DOI: 10.1002/14651858.cd013315] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND High altitude illness (HAI) is a term used to describe a group of mainly cerebral and pulmonary syndromes that can occur during travel to elevations above 2500 metres (˜ 8200 feet). Acute mountain sickness (AMS), high altitude cerebral oedema (HACE), and high altitude pulmonary oedema (HAPE) are reported as potential medical problems associated with high altitude ascent. In this, the third of a series of three reviews about preventive strategies for HAI, we assessed the effectiveness of miscellaneous and non-pharmacological interventions. OBJECTIVES To assess the clinical effectiveness and adverse events of miscellaneous and non-pharmacological interventions for preventing acute HAI in people who are at risk of developing high altitude illness in any setting. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) in January 2019. We adapted the MEDLINE strategy for searching the other databases. We used a combination of thesaurus-based and free-text search terms. We scanned the reference lists and citations of included trials and any relevant systematic reviews that we identified for further references to additional trials. SELECTION CRITERIA We included randomized controlled trials conducted in any setting where non-pharmacological and miscellaneous interventions were employed to prevent acute HAI, including preacclimatization measures and the administration of non-pharmacological supplements. We included trials involving participants who are at risk of developing high altitude illness (AMS or HACE, or HAPE, or both). We included participants with, and without, a history of high altitude illness. We applied no age or gender restrictions. We included trials where the relevant intervention was administered before the beginning of ascent. DATA COLLECTION AND ANALYSIS We used the standard methodological procedures employed by Cochrane. MAIN RESULTS We included 20 studies (1406 participants, 21 references) in this review. Thirty studies (14 ongoing, and 16 pending classification (awaiting)) will be considered in future versions of this suite of three reviews as appropriate. We report the results for the primary outcome of this review (risk of AMS) by each group of assessed interventions.Group 1. Preacclimatization and other measures based on pressureUse of simulated altitude or remote ischaemic preconditioning (RIPC) might not improve the risk of AMS on subsequent exposure to altitude, but this effect is uncertain (simulated altitude: risk ratio (RR) 1.18, 95% confidence interval (CI) 0.82 to 1.71; I² = 0%; 3 trials, 140 participants; low-quality evidence. RIPC: RR 3.0, 95% CI 0.69 to 13.12; 1 trial, 40 participants; low-quality evidence). We found evidence of improvement of this risk using positive end-expiratory pressure (PEEP), but this information was derived from a cross-over trial with a limited number of participants (OR 3.67, 95% CI 1.38 to 9.76; 1 trial, 8 participants; low-quality evidence). We found scarcity of evidence about the risk of adverse events for these interventions.Group 2. Supplements and vitaminsSupplementation of antioxidants, medroxyprogesterone, iron or Rhodiola crenulata might not improve the risk of AMS on exposure to high altitude, but this effect is uncertain (antioxidants: RR 0.58, 95% CI 0.32 to 1.03; 1 trial, 18 participants; low-quality evidence. Medroxyprogesterone: RR 0.71, 95% CI 0.48 to 1.05; I² = 0%; 2 trials, 32 participants; low-quality evidence. Iron: RR 0.65, 95% CI 0.38 to 1.11; I² = 0%; 2 trials, 65 participants; low-quality evidence. R crenulata: RR 1.00, 95% CI 0.78 to 1.29; 1 trial, 125 participants; low-quality evidence). We found evidence of improvement of this risk with the administration of erythropoietin, but this information was extracted from a trial with issues related to risk of bias and imprecision (RR 0.41, 95% CI 0.20 to 0.84; 1 trial, 39 participants; very low-quality evidence). Regarding administration of ginkgo biloba, we did not perform a pooled estimation of RR for AMS due to considerable heterogeneity between the included studies (I² = 65%). RR estimates from the individual studies were conflicting (from 0.05 to 1.03; low-quality evidence). We found scarcity of evidence about the risk of adverse events for these interventions.Group 3. Other comparisonsWe found heterogeneous evidence regarding the risk of AMS when ginkgo biloba was compared with acetazolamide (I² = 63%). RR estimates from the individual studies were conflicting (estimations from 0.11 (95% CI 0.01 to 1.86) to 2.97 (95% CI 1.70 to 5.21); low-quality evidence). We found evidence of improvement when ginkgo biloba was administered along with acetazolamide, but this information was derived from a single trial with issues associated to risk of bias (compared to ginkgo biloba alone: RR 0.43, 95% CI 0.26 to 0.71; 1 trial, 311 participants; low-quality evidence). Administration of medroxyprogesterone plus acetazolamide did not improve the risk of AMS when compared to administration of medroxyprogesterone or acetazolamide alone (RR 1.33, 95% CI 0.50 to 3.55; 1 trial, 12 participants; low-quality evidence). We found scarcity of evidence about the risk of adverse events for these interventions. AUTHORS' CONCLUSIONS This Cochrane Review is the final in a series of three providing relevant information to clinicians, and other interested parties, on how to prevent high altitude illness. The assessment of non-pharmacological and miscellaneous interventions suggests that there is heterogeneous and even contradictory evidence related to the effectiveness of these prophylactic strategies. Safety of these interventions remains as an unclear issue due to lack of assessment. Overall, the evidence is limited due to its quality (low to very low), the relative paucity of that evidence and the number of studies pending classification for the three reviews belonging to this series (30 studies either awaiting classification or ongoing). Additional studies, especially those comparing with pharmacological alternatives (such as acetazolamide) are required, in order to establish or refute the strategies evaluated in this review.
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Affiliation(s)
- Daniel Molano Franco
- Fundacion Universitaria de Ciencias de la Salud, Hospital de San JoséDepartment of Critical CareCarrera 19 # 8‐32BogotaBogotaColombia11001
| | - Víctor H Nieto Estrada
- Los Cobos Medical Centre. Grupo Investigacion GRIBOSDepartment of Critical CareBogotaBogotaColombia
| | | | | | - Ingrid Arevalo‐Rodriguez
- Hospital Universitario Ramón y Cajal (IRYCIS), CIBER Epidemiology and Public Health (CIBERESP)Clinical Biostatistics UnitCtra. Colmenar Km. 9,100MadridSpain28034
- Cochrane Associate Centre of MadridMadridSpain
- Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC). Facultad de Ciencias de la Salud Eugenio Espejo, Universidad Tecnológica EquinoccialCochrane EcuadorQuitoEcuador
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Inada M, Taguchi M, Harimoto K, Karasawa Y, Takeuchi M, Ito M. Protective effects of dexamethasone on hypoxia-induced retinal edema in a mouse model. Exp Eye Res 2019; 178:82-90. [DOI: 10.1016/j.exer.2018.09.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 09/09/2018] [Accepted: 09/25/2018] [Indexed: 01/09/2023]
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Wu Y, Zhang C, Chen Y, Luo YJ. Association between acute mountain sickness (AMS) and age: a meta-analysis. Mil Med Res 2018; 5:14. [PMID: 29747689 PMCID: PMC5946480 DOI: 10.1186/s40779-018-0161-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 04/24/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Acute mountain sickness (AMS) is a potentially lethal condition caused by acute hypoxia after ascending to altitudes higher than 2500 m in a short time. The main symptom of AMS is headache. Numerous risk factors of AMS have been examined, including gender, obesity, ascent rate, age and individual susceptibility. In previous studies, age was considered a predisposing factor for AMS. However, different opinions have been raised in recent years. To clarify the association between AMS and age, we conducted this meta-analysis. METHODS We obtained observational studies that explored risk factors for AMS by searching PubMed, Embase, China National Knowledge Internet (CNKI), the Wanfang database and CQVIP for articles published before March 2017. The studies included were required to provide the mean age and its standard deviation for subjects with and without AMS, the maximum altitude attained and the mode of ascent. The Lake Louse Score (LLS) or the Chinese AMS score (CAS) was used to judge the severity of AMS symptoms and incidence. Studies were pooled for the analysis by using a random effects model in RevMan 5.0. Meta-regression and subgroup analyses were conducted to identify sources of heterogeneity using Stata 14.2 and RevMan 5.0. RESULTS In total, 17 studies were included, and the overall number of subjects with and without AMS was 1810 and 3014, respectively. The age ranged from 10 to 76 years. Analysis of the 17 included studies showed that age was not associated with AMS (mean difference (MD) = 0.10; 95% CI: -0.38-0.58; P = 0.69). CONCLUSION This meta-analysis suggests that there is no association between age and the risk of AMS. Race, age, and ascent mode are common sources of heterogeneity, which may provide an analytical orientation for future heterogeneity analyses.
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Affiliation(s)
- Yu Wu
- Department of Military Medical Geography, Army Medical Service Training Base, Army Medical University, Chongqing, 400038, China.,Battalion 5 of Cadet Brigade, Army Medical University, Chongqing, 400038, China
| | - Chi Zhang
- Department of Military Medical Geography, Army Medical Service Training Base, Army Medical University, Chongqing, 400038, China.,Key Laboratory of High Altitude Environmental Medicine of PLA, Army Medical University, Chongqing, 400038, China
| | - Yu Chen
- Department of Military Medical Geography, Army Medical Service Training Base, Army Medical University, Chongqing, 400038, China.,Key Laboratory of High Altitude Environmental Medicine of PLA, Army Medical University, Chongqing, 400038, China
| | - Yong-Jun Luo
- Department of Military Medical Geography, Army Medical Service Training Base, Army Medical University, Chongqing, 400038, China. .,Key Laboratory of High Altitude Environmental Medicine of PLA, Army Medical University, Chongqing, 400038, China.
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Gonzalez Garay AG, Molano Franco D, Nieto Estrada VH, Martí‐Carvajal AJ, Arevalo‐Rodriguez I. Interventions for preventing high altitude illness: Part 2. Less commonly-used drugs. Cochrane Database Syst Rev 2018; 3:CD012983. [PMID: 29529715 PMCID: PMC6494375 DOI: 10.1002/14651858.cd012983] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND High altitude illness (HAI) is a term used to describe a group of mainly cerebral and pulmonary syndromes that can occur during travel to elevations above 2500 metres (˜ 8200 feet). Acute mountain sickness (AMS), high altitude cerebral oedema (HACE) and high altitude pulmonary oedema (HAPE) are reported as potential medical problems associated with high altitude ascent. In this second review, in a series of three about preventive strategies for HAI, we assessed the effectiveness of five of the less commonly used classes of pharmacological interventions. OBJECTIVES To assess the clinical effectiveness and adverse events of five of the less commonly used pharmacological interventions for preventing acute HAI in participants who are at risk of developing high altitude illness in any setting. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) in May 2017. We adapted the MEDLINE strategy for searching the other databases. We used a combination of thesaurus-based and free-text search terms. We scanned the reference lists and citations of included trials and any relevant systematic reviews that we identified for further references to additional trials. SELECTION CRITERIA We included randomized controlled trials conducted in any setting where one of five classes of drugs was employed to prevent acute HAI: selective 5-hydroxytryptamine(1) receptor agonists; N-methyl-D-aspartate (NMDA) antagonist; endothelin-1 antagonist; anticonvulsant drugs; and spironolactone. We included trials involving participants who are at risk of developing high altitude illness (AMS or HACE, or HAPE, or both). We included participants with and without a history of high altitude illness. We applied no age or gender restrictions. We included trials where the relevant medication was administered before the beginning of ascent. We excluded trials using these drugs during ascent or after ascent. DATA COLLECTION AND ANALYSIS We used the standard methodological procedures employed by Cochrane. MAIN RESULTS We included eight studies (334 participants, 9 references) in this review. Twelve studies are ongoing and will be considered in future versions of this review as appropriate. We have been unable to obtain full-text versions of a further 12 studies and have designated them as 'awaiting classification'. Four studies were at a low risk of bias for randomization; two at a low risk of bias for allocation concealment. Four studies were at a low risk of bias for blinding of participants and personnel. We considered three studies at a low risk of bias for blinding of outcome assessors. We considered most studies at a high risk of selective reporting bias.We report results for the following four main comparisons.Sumatriptan versus placebo (1 parallel study; 102 participants)Data on sumatriptan showed a reduction of the risk of AMS when compared with a placebo (risk ratio (RR) = 0.43, CI 95% 0.21 to 0.84; 1 study, 102 participants; low quality of evidence). The one included study did not report events of HAPE, HACE or adverse events related to administrations of sumatriptan.Magnesium citrate versus placebo (1 parallel study; 70 participants)The estimated RR for AMS, comparing magnesium citrate tablets versus placebo, was 1.09 (95% CI 0.55 to 2.13; 1 study; 70 participants; low quality of evidence). In addition, the estimated RR for loose stools was 3.25 (95% CI 1.17 to 8.99; 1 study; 70 participants; low quality of evidence). The one included study did not report events of HAPE or HACE.Spironolactone versus placebo (2 parallel studies; 205 participants)Pooled estimation of RR for AMS was not performed due to considerable heterogeneity between the included studies (I² = 72%). RR from individual studies was 0.40 (95% CI 0.12 to 1.31) and 1.44 (95% CI 0.79 to 2.01; very low quality of evidence). No events of HAPE or HACE were reported. Adverse events were not evaluated.Acetazolamide versus spironolactone (1 parallel study; 232 participants)Data on acetazolamide compared with spironolactone showed a reduction of the risk of AMS with the administration of acetazolamide (RR = 0.36, 95% CI 0.18 to 0.70; 232 participants; low quality of evidence). No events of HAPE or HACE were reported. Adverse events were not evaluated. AUTHORS' CONCLUSIONS This Cochrane Review is the second in a series of three providing relevant information to clinicians and other interested parties on how to prevent high altitude illness. The assessment of five of the less commonly used classes of drugs suggests that there is a scarcity of evidence related to these interventions. Clinical benefits and harms related to potential interventions such as sumatriptan are still unclear. Overall, the evidence is limited due to the low number of studies identified (for most of the comparison only one study was identified); limitations in the quality of the evidence (moderate to low); and the number of studies pending classification (24 studies awaiting classification or ongoing). We lack the large and methodologically sound studies required to establish or refute the efficacy and safety of most of the pharmacological agents evaluated in this review.
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Affiliation(s)
- Alejandro G Gonzalez Garay
- National Institute of PediatricsMethodology Research UnitInsurgentes Sur 3700 ‐ CCol. Insurgentes Cuicuilco, CoyoacanMexico CityDistrito FederalMexico04530
| | - Daniel Molano Franco
- Fundacion Universitaria de Ciencias de la Salud, Hospital de San JoséDepartment of Critical CareCarrera 19 # 8‐32BogotaBogotaColombia11001
| | - Víctor H Nieto Estrada
- Fundacion Universitaria Sanitas, Colombia ClinicDepartment of Critical CareCarrera 19 # 8‐32BogotaBogotaColombia11001
| | | | - Ingrid Arevalo‐Rodriguez
- Universidad Tecnológica EquinoccialCochrane Ecuador. Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC). Facultad de Ciencias de la Salud Eugenio EspejoAv. Mariscal Sucre s/n y Av. Mariana de JesúsQuitoEcuador
- Hospital Universitario Ramon y Cajal (IRYCIS)Clinical Biostatistics UnitMadridSpain
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Abstract
The investigation of commercial diving accidents has indicated that the danger of anoxia, from the inhalation of gases not containing oxygen, is not fully recognized. The problem is more common in a variety of general industrial situations and is an occasional cause of death in anaesthesia. It is a particular hazard with inert gases, which, because they are recognized to be non-toxic, give a false sense of security. The pathological findings consist of pulmonary oedema and petechial haemorrhages, mainly in the brain, lungs and myocardium. Whenever possible, a minimum oxygen content should be included in all gases liable to be respired, but where this is not possible, oxygen analysers and alarms should be provided. Where a general hazard exists, personnel must be warned of the danger.
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Affiliation(s)
- P B James
- Wolfson Institute of Occupational Health, Ninewells Medical School, Dundee
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25
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Tian X, Zhang B, Jia Y, Wang C, Li Q. Retinal changes following rapid ascent to a high-altitude environment. Eye (Lond) 2018; 32:370-374. [PMID: 28912514 PMCID: PMC5811714 DOI: 10.1038/eye.2017.195] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/26/2017] [Indexed: 01/26/2023] Open
Abstract
PurposeTo determine what impact rapid ascension to a high-altitude environment has on the retina with the aim of preventing and treating high-altitude oculopathy.Patients and methodsParticipants in the study were members of the Chinese military assigned to the high-altitude environment of the Tibetan plateau. Ninety-one participants were enrolled in the study. Optical coherence tomography was used to measure the thickness of retina-related indicators. Measurements were taken before and after exposure to the high-altitude environment and upon return to the baseline altitude.ResultsFollowing exposure to the high-altitude environment in Tibet, there was a significant increase in retinal nerve fiber layer (RNFL) thickness in the temporal and nasal quadrants of the optic disc, whilst a significant decrease in RNFL thickness in the inferior optic disc was also observed. A significant increase in RNFL thickness in the superior and inferior macula was also evident, along with a significant increase in the ganglion cell layer thickness in the superior macula. Upon return to the baseline altitude, all measurements returned to baseline levels except for the RNFL of the inferior macula, which was significantly thicker. Pathological changes were also documented in the eyes of nine participants upon returning to baseline altitude, including ischemic optic neuropathy, myopia, and cortical amaurosis.ConclusionsThe high-altitude environment can have a negative impact on the health of the retina and may contribute to the incidence of various eye diseases. This study deepens the understanding of what impact a high-altitude environment has on retina and provides reliable data for blindness prevention and treatment.
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Affiliation(s)
- X Tian
- Department of Ophthalmology, the 153rd Central Hospital of PLA, Zhengzhou, China
| | - B Zhang
- Department of Ophthalmology, the 153rd Central Hospital of PLA, Zhengzhou, China
| | - Y Jia
- Department of Ophthalmology, the 153rd Central Hospital of PLA, Zhengzhou, China
| | - C Wang
- Department of Ophthalmology, the 153rd Central Hospital of PLA, Zhengzhou, China
| | - Q Li
- Department of Ophthalmology, the 153rd Central Hospital of PLA, Zhengzhou, China
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26
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Estimated incidence of high altitude retinal hemorrhages. Graefes Arch Clin Exp Ophthalmol 2017; 256:231-232. [PMID: 28879420 DOI: 10.1007/s00417-017-3795-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/19/2017] [Accepted: 08/28/2017] [Indexed: 10/18/2022] Open
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Beidleman BA, Fulco CS, Cadarette BS, Cymerman A, Buller MJ, Salgado RM, Posch AM, Staab JE, Sils IV, Yurkevicius BR, Luippold AJ, Welles AP, Muza SR. Is normobaric hypoxia an effective treatment for sustaining previously acquired altitude acclimatization? J Appl Physiol (1985) 2017; 123:1214-1227. [PMID: 28705998 DOI: 10.1152/japplphysiol.00344.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/06/2017] [Accepted: 07/06/2017] [Indexed: 12/25/2022] Open
Abstract
This study examined whether normobaric hypoxia (NH) treatment is more efficacious for sustaining high-altitude (HA) acclimatization-induced improvements in ventilatory and hematologic responses, acute mountain sickness (AMS), and cognitive function during reintroduction to altitude (RA) than no treatment at all. Seventeen sea-level (SL) residents (age = 23 ± 6 yr; means ± SE) completed in the following order: 1) 4 days of SL testing; 2) 12 days of HA acclimatization at 4,300 m; 3) 12 days at SL post-HA acclimatization (Post) where each received either NH (n = 9, [Formula: see text] = 0.122) or Sham (n = 8; [Formula: see text] = 0.207) treatment; and 4) 24-h reintroduction to 4,300-m altitude (RA) in a hypobaric chamber (460 Torr). End-tidal carbon dioxide pressure ([Formula: see text]), hematocrit (Hct), and AMS cerebral factor score were assessed at SL, on HA2 and HA11, and after 20 h of RA. Cognitive function was assessed using the SynWin multitask performance test at SL, on HA1 and HA11, and after 4 h of RA. There was no difference between NH and Sham treatment, so data were combined. [Formula: see text] (mmHg) decreased from SL (37.2 ± 0.5) to HA2 (32.2 ± 0.6), decreased further by HA11 (27.1 ± 0.4), and then increased from HA11 during RA (29.3 ± 0.6). Hct (%) increased from SL (42.3 ± 1.1) to HA2 (45.9 ± 1.0), increased again from HA2 to HA11 (48.5 ± 0.8), and then decreased from HA11 during RA (46.4 ± 1.2). AMS prevalence (%) increased from SL (0 ± 0) to HA2 (76 ± 11) and then decreased at HA11 (0 ± 0) and remained depressed during RA (17 ± 10). SynWin scores decreased from SL (1,615 ± 62) to HA1 (1,306 ± 94), improved from HA1 to HA11 (1,770 ± 82), and remained increased during RA (1,707 ± 75). These results demonstrate that HA acclimatization-induced improvements in ventilatory and hematologic responses, AMS, and cognitive function are partially retained during RA after 12 days at SL whether or not NH treatment is utilized.NEW & NOTEWORTHY This study demonstrates that normobaric hypoxia treatment over a 12-day period at sea level was not more effective for sustaining high-altitude (HA) acclimatization during reintroduction to HA than no treatment at all. The noteworthy aspect is that athletes, mountaineers, and military personnel do not have to go to extraordinary means to retain HA acclimatization to an easily accessible and relevant altitude if reexposure occurs within a 2-wk time period.
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Affiliation(s)
- Beth A Beidleman
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts;
| | - Charles S Fulco
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Bruce S Cadarette
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Allen Cymerman
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Mark J Buller
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Roy M Salgado
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Alexander M Posch
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Janet E Staab
- Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts; and
| | - Ingrid V Sils
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Beau R Yurkevicius
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | | | - Alexander P Welles
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Stephen R Muza
- Scientifc Strategic Management Office, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Nieto Estrada VH, Molano Franco D, Medina RD, Gonzalez Garay AG, Martí‐Carvajal AJ, Arevalo‐Rodriguez I. Interventions for preventing high altitude illness: Part 1. Commonly-used classes of drugs. Cochrane Database Syst Rev 2017; 6:CD009761. [PMID: 28653390 PMCID: PMC6481751 DOI: 10.1002/14651858.cd009761.pub2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND High altitude illness (HAI) is a term used to describe a group of cerebral and pulmonary syndromes that can occur during travel to elevations above 2500 metres (8202 feet). Acute hypoxia, acute mountain sickness (AMS), high altitude cerebral oedema (HACE) and high altitude pulmonary oedema (HAPE) are reported as potential medical problems associated with high altitude. In this review, the first in a series of three about preventive strategies for HAI, we assess the effectiveness of six of the most recommended classes of pharmacological interventions. OBJECTIVES To assess the clinical effectiveness and adverse events of commonly-used pharmacological interventions for preventing acute HAI. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OVID), Embase (OVID), LILACS and trial registries in January 2017. We adapted the MEDLINE strategy for searching the other databases. We used a combination of thesaurus-based and free-text terms to search. SELECTION CRITERIA We included randomized-controlled and cross-over trials conducted in any setting where commonly-used classes of drugs were used to prevent acute HAI. DATA COLLECTION AND ANALYSIS We used standard methodological procedures as expected by Cochrane. MAIN RESULTS We included 64 studies (78 references) and 4547 participants in this review, and classified 12 additional studies as ongoing. A further 12 studies await classification, as we were unable to obtain the full texts. Most of the studies were conducted in high altitude mountain areas, while the rest used low pressure (hypobaric) chambers to simulate altitude exposure. Twenty-four trials provided the intervention between three and five days prior to the ascent, and 23 trials, between one and two days beforehand. Most of the included studies reached a final altitude of between 4001 and 5000 metres above sea level. Risks of bias were unclear for several domains, and a considerable number of studies did not report adverse events of the evaluated interventions. We found 26 comparisons, 15 of them comparing commonly-used drugs versus placebo. We report results for the three most important comparisons: Acetazolamide versus placebo (28 parallel studies; 2345 participants)The risk of AMS was reduced with acetazolamide (risk ratio (RR) 0.47, 95% confidence interval (CI) 0.39 to 0.56; I2 = 0%; 16 studies; 2301 participants; moderate quality of evidence). No events of HAPE were reported and only one event of HACE (RR 0.32, 95% CI 0.01 to 7.48; 6 parallel studies; 1126 participants; moderate quality of evidence). Few studies reported side effects for this comparison, and they showed an increase in the risk of paraesthesia with the intake of acetazolamide (RR 5.53, 95% CI 2.81 to 10.88, I2 = 60%; 5 studies, 789 participants; low quality of evidence). Budenoside versus placebo (2 parallel studies; 132 participants)Data on budenoside showed a reduction in the incidence of AMS compared with placebo (RR 0.37, 95% CI 0.23 to 0.61; I2 = 0%; 2 studies, 132 participants; low quality of evidence). Studies included did not report events of HAPE or HACE, and they did not find side effects (low quality of evidence). Dexamethasone versus placebo (7 parallel studies; 205 participants)For dexamethasone, the data did not show benefits at any dosage (RR 0.60, 95% CI 0.36 to 1.00; I2 = 39%; 4 trials, 176 participants; low quality of evidence). Included studies did not report events of HAPE or HACE, and we rated the evidence about adverse events as of very low quality. AUTHORS' CONCLUSIONS Our assessment of the most commonly-used pharmacological interventions suggests that acetazolamide is an effective pharmacological agent to prevent acute HAI in dosages of 250 to 750 mg/day. This information is based on evidence of moderate quality. Acetazolamide is associated with an increased risk of paraesthesia, although there are few reports about other adverse events from the available evidence. The clinical benefits and harms of other pharmacological interventions such as ibuprofen, budenoside and dexamethasone are unclear. Large multicentre studies are needed for most of the pharmacological agents evaluated in this review, to evaluate their effectiveness and safety.
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Affiliation(s)
- Víctor H Nieto Estrada
- Fundacion Universitaria Sanitas, Colombia ClinicDepartment of Critical CareCarrera 19 # 8‐32BogotaBogotaColombia11001
| | - Daniel Molano Franco
- Fundacion Universitaria de Ciencias de la Salud, Hospital de San JoséDepartment of Critical CareCarrera 19 # 8‐32BogotaBogotaColombia11001
| | - Roger David Medina
- Fundación Universitaria de Ciencias de la SaludDivision of ResearchCarrera 19 # 8‐32Bogotá D.C.Colombia
| | - Alejandro G Gonzalez Garay
- National Institute of PediatricsMethodology Research UnitInsurgentes Sur 3700 ‐ CCol. Insurgentes Cuicuilco, CoyoacanMexico CityDistrito FederalMexico04530
| | | | - Ingrid Arevalo‐Rodriguez
- Universidad Tecnológica EquinoccialCochrane Ecuador. Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC). Facultad de Ciencias de la Salud Eugenio EspejoAv. Mariscal Sucre s/n y Av. Mariana de JesúsQuitoEcuador
- Hospital Universitario Ramon y Cajal (IRYCIS)Clinical Biostatistics UnitMadridSpain
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Luks AM, Swenson ER, Bärtsch P. Acute high-altitude sickness. Eur Respir Rev 2017; 26:26/143/160096. [PMID: 28143879 PMCID: PMC9488514 DOI: 10.1183/16000617.0096-2016] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 10/23/2016] [Indexed: 12/28/2022] Open
Abstract
At any point 1–5 days following ascent to altitudes ≥2500 m, individuals are at risk of developing one of three forms of acute altitude illness: acute mountain sickness, a syndrome of nonspecific symptoms including headache, lassitude, dizziness and nausea; high-altitude cerebral oedema, a potentially fatal illness characterised by ataxia, decreased consciousness and characteristic changes on magnetic resonance imaging; and high-altitude pulmonary oedema, a noncardiogenic form of pulmonary oedema resulting from excessive hypoxic pulmonary vasoconstriction which can be fatal if not recognised and treated promptly. This review provides detailed information about each of these important clinical entities. After reviewing the clinical features, epidemiology and current understanding of the pathophysiology of each disorder, we describe the current pharmacological and nonpharmacological approaches to the prevention and treatment of these diseases. Lack of acclimatisation is the main risk factor for acute altitude illness; descent is the optimal treatmenthttp://ow.ly/45d2305JyZ0
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Affiliation(s)
- Andrew M Luks
- Dept of Medicine, Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, WA, USA
| | - Erik R Swenson
- Dept of Medicine, Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, WA, USA.,Medical Service, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
| | - Peter Bärtsch
- Dept of Internal Medicine, University Clinic Heidelberg, Heidelberg, Germany
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30
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Xin X, Dang H, Zhao X, Wang H. Effects of Hypobaric Hypoxia on Rat Retina and Protective Response of Resveratrol to the Stress. Int J Med Sci 2017; 14:943-950. [PMID: 28924365 PMCID: PMC5599917 DOI: 10.7150/ijms.19391] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 06/28/2017] [Indexed: 12/24/2022] Open
Abstract
High-altitude retinopathy represents retinal functional changes associated with environmental challenges imposed by hypobaric hypoxia, but the detailed cellular and molecular mechanism underlying this process remains unclear. Our current investigation was to explore the effect of hypobaric hypoxia on the rat retina and determine whether resveratrol has a protective efficacy on the hypoxic damage to the retina. Experiment rats were randomly grouped as the control group, hypoxia group and resveratrol intervention group. The hypoxia group and the resveratrol intervention group were maintained in a low-pressure oxygen cabin, and the resveratrol intervention group was given daily intraperitoneal injections with resveratrol. We found that hypobaric hypoxia increased thioredoxin 1 (Trx1) and thioredoxin 2 (Trx2) expression in retinas, and resveratrol treatment significantly reversed these changes (P < 0.05, P < 0.05 respectively). In comparison with controls, hypoxia upregulated the mRNA expression levels of caspase3 (P < 0.001), caspase9 (P < 0.01), heat shock protein 70 (Hsp70) (P < 0.05), heat shock protein 90 (Hsp90) (P < 0.001) and hypoxia-inducible factor-1 (HIF-1) (P < 0.05). Resveratrol administration caused a significant decrease in the gene expression of caspase3 (P< 0.001), HSP90 (P < 0.05) and HIF-1 mRNA (P < 0.01) as well as an increase in HSP70 mRNA when compared with the hypoxia group. These findings indicated that resveratrol exerted an anti-oxidative role by modulating hypoxia stress- associated genes and an anti-apoptosis role by regulating apoptosis-related cytokines. In conclusion, hypobaric hypoxia may have a pathological impact on rat retinas. The intervention of resveratrol reverses the effect induced by hypobaric hypoxia and elicits a protective response to the stress.
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Affiliation(s)
- Xiaorong Xin
- Department of Ophthalmology, Qinghai Red Cross Hospital, Xining, Qinghai, China
| | - Hong Dang
- Department of Ophthalmology, Qinghai Red Cross Hospital, Xining, Qinghai, China
| | - Xiaojing Zhao
- Department of Ophthalmology, Qinghai Red Cross Hospital, Xining, Qinghai, China
| | - Haohao Wang
- Department of Ophthalmology, Qinghai Red Cross Hospital, Xining, Qinghai, China
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31
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Horiuchi M, Endo J, Akatsuka S, Uno T, Jones TE. Prevalence of acute mountain sickness on Mount Fuji: A pilot study. J Travel Med 2016; 23:taw024. [PMID: 27147731 DOI: 10.1093/jtm/taw024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/04/2016] [Indexed: 11/14/2022]
Abstract
BACKGROUND Few studies have investigated climbing-related acute mountain sickness (AMS) on Mt Fuji. Although several studies of AMS have been conducted elsewhere, Mt Fuji is unique because there are many mountain lodges between the fifth station (a common starting point for climbers at an altitude of 2305 m) and the summit (3776 m), and many climbers commonly sleep overnight at mountain lodges during their ascents. This study surveyed the prevalence of AMS among climbers on Mt Fuji to determine which factors, if any, were related to the risk of developing AMS. METHODS This study collected data from 345 participants who climbed Mt Fuji in August 2013, including information regarding age, sex, climbing experience and whether the climber stayed at a mountain lodge (n = 239). AMS was surveyed using the Lake Louise Score (LLS) questionnaire. The item on perceived sleep quality was excluded for those who did not stay at a mountain lodge (n = 106). RESULTS The overall prevalence of AMS was 29.5% (≥ 3 LLS with headache). According to a univariate analysis, AMS was not associated with sex (male vs female), age group (20-29, 30-39, 40-49 or >50 years) or stay at a mountain lodge (single day vs overnight stay). Conversely, prior experience climbing Mt Fuji (no prior attempts vs one or more prior attempts) was related to the risk of AMS. In addition, there was a significant deviation in the number of participants reporting poor sleep, and total sleep time was significantly shorter in participants with AMS. CONCLUSIONS These preliminary findings suggest that no single factor can explain the risk for developing AMS while climbing Mt Fuji. In addition, impaired perceived sleep quality was associated with the severity of AMS in climbers who stayed overnight at a mountain lodge.
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Affiliation(s)
- Masahiro Horiuchi
- Division of Human Environmental Science, Mt Fuji Research Institute, Kami-Yoshida 5597-1, Fuji-Yoshida-City, Yamanashi, 4030005, Japan and
| | - Junko Endo
- Division of Human Environmental Science, Mt Fuji Research Institute, Kami-Yoshida 5597-1, Fuji-Yoshida-City, Yamanashi, 4030005, Japan and
| | - Shin Akatsuka
- Division of Human Environmental Science, Mt Fuji Research Institute, Kami-Yoshida 5597-1, Fuji-Yoshida-City, Yamanashi, 4030005, Japan and
| | - Tadashi Uno
- Division of Human Environmental Science, Mt Fuji Research Institute, Kami-Yoshida 5597-1, Fuji-Yoshida-City, Yamanashi, 4030005, Japan and
| | - Thomas E Jones
- Division of Human Environmental Science, Mt Fuji Research Institute, Kami-Yoshida 5597-1, Fuji-Yoshida-City, Yamanashi, 4030005, Japan and
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Kumar K, Sharma S, Vashishtha V, Bhardwaj P, Kumar A, Barhwal K, Hota SK, Malairaman U, Singh B. Terminalia arjuna bark extract improves diuresis and attenuates acute hypobaric hypoxia induced cerebral vascular leakage. JOURNAL OF ETHNOPHARMACOLOGY 2016; 180:43-53. [PMID: 26771070 DOI: 10.1016/j.jep.2016.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/08/2015] [Accepted: 01/02/2016] [Indexed: 06/05/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Terminalia arjuna (Roxb. ex DC.) Wight & Arn. (T. arjuna) has been widely used in the traditional ayurvedic system of medicine as a cardioprotectant and for acute and chronic renal diseases supporting its ethnopharmacological use. AIM OF THE STUDY The present study aimed at evaluating the diuretic action of an alcoholic extract of T. arjuna and its possible use as a prophylactic to prevent vascular leakage during acute mountain sickness at high altitude. MATERIALS AND METHODS Rats were exposed to hypobaric hypoxia simulated to an altitude of 27,000 ft. in a decompression chamber for 12h. T. arjuna bark extract was administered at a single dose of 150 mg/kg (p.o.) to male Sprague Dawley rats (200 ± 20 g) 30 min prior to exposure. Total urine volume was measured during exposure to hypobaric hypoxia. The animals were then investigated for cerebral vascular leakage and serum concentration of sodium, potassium, renin, angiotensin-II, aldosterone and atrial natriuretic peptide (ANP). RESULTS T. arjuna ameliorated acute hypobaric hypoxia induced decrease in glomerular filtration rate (p<0.5), increased total urine output (p<0.5) and prevented cerebral vascular leakage in hypoxic rats. T. arjuna treated animals also showed decrease in serum levels of renin (p<0.001) and angiotensin-II (p<0.5) as compared to placebo treated animals. Administration of T. arjuna attenuated acute hypobaric hypoxia induced oxidative stress, improved aldosterone levels and altered electrolyte balance in animals through ANP dependent mechanism. CONCLUSION Results of the present study indicate towards diuretic potential of hydro-alcoholic extract of T. arjuna bark and provide evidence for its novel application as a prophylactic to attenuate acute hypobaric hypoxia induced cerebral vascular leakage through ANP mediated modulation of renin-angiotensin-aldosterone system.
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Affiliation(s)
- Kushal Kumar
- Defence Institute of High Altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh 901205, India
| | - Sarika Sharma
- Post Graduate Institute of Medical Research Education and Research, Chandigarh 160012, India
| | - Vivek Vashishtha
- Defence Institute of High Altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh 901205, India
| | - Pushpender Bhardwaj
- Defence Institute of High Altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh 901205, India
| | - Ashish Kumar
- Defence Institute of High Altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh 901205, India
| | - Kalpana Barhwal
- Defence Institute of High Altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh 901205, India
| | - Sunil Kumar Hota
- Defence Institute of High Altitude Research, Defence Research and Development Organisation, C/o 56 APO, Leh-Ladakh 901205, India.
| | | | - Baljinder Singh
- Post Graduate Institute of Medical Research Education and Research, Chandigarh 160012, India
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Barker KR, Conroy AL, Hawkes M, Murphy H, Pandey P, Kain KC. Biomarkers of hypoxia, endothelial and circulatory dysfunction among climbers in Nepal with AMS and HAPE: a prospective case-control study. J Travel Med 2016; 23:taw005. [PMID: 26984355 PMCID: PMC5731443 DOI: 10.1093/jtm/taw005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/11/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND The mechanisms underlying acute mountain sickness (AMS) and high-altitude pulmonary edema (HAPE) are not fully understood. We hypothesized that regulators of endothelial function, circulatory homeostasis, hypoxia and cell stress contribute to the pathobiology of AMS and HAPE. METHODS We conducted a prospective case-control study of climbers developing altitude illness who were evacuated to the CIWEC clinic in Kathmandu, compared to healthy acclimatized climbers. ELISA was used to measure plasma biomarkers of the above pathways. RESULTS Of the 175 participants, there were 71 cases of HAPE, 54 cases of AMS and 50 acclimatized controls (ACs). Markers of endothelial function were associated with HAPE: circulating levels of endothelin-1 (ET-1) were significantly elevated and levels of sKDR (soluble kinase domain receptor) were significantly decreased in cases of HAPE compared to AC or AMS. ET-1 levels were associated with disease severity as indicated by oxygen saturation. Angiopoietin-like 4 (Angptl4) and resistin, a marker of cell stress, were associated with AMS and HAPE irrespective of severity. Corin and angiotensin converting enzyme, regulators of volume homeostasis, were significantly decreased in HAPE compared to AC. CONCLUSION Our findings indicate that regulators of endothelial function, vascular tone and cell stress are altered in altitude illness and may mechanistically contribute to the pathobiology of HAPE.
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Affiliation(s)
- Kevin R Barker
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, ON, Canada
| | - Andrea L Conroy
- Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, ON, Canada
| | - Michael Hawkes
- Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, ON, Canada, Division of Infectious Diseases, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada and
| | - Holly Murphy
- CIWEC Hospital and Travel Medicine Center, Kathmandu, Nepal
| | - Prativa Pandey
- CIWEC Hospital and Travel Medicine Center, Kathmandu, Nepal
| | - Kevin C Kain
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada, Sandra Rotman Centre for Global Health, University Health Network-Toronto General Hospital, Toronto, ON, Canada, The Tropical Disease Unit, Department of Medicine, University of Toronto, Toronto, ON, Canada,
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Lawley JS, Levine BD, Williams MA, Malm J, Eklund A, Polaner DM, Subudhi AW, Hackett PH, Roach RC. Cerebral spinal fluid dynamics: effect of hypoxia and implications for high-altitude illness. J Appl Physiol (1985) 2016; 120:251-62. [DOI: 10.1152/japplphysiol.00370.2015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/17/2015] [Indexed: 12/24/2022] Open
Abstract
The pathophysiology of acute mountain sickness and high-altitude cerebral edema, the cerebral forms of high-altitude illness, remain uncertain and controversial. Persistently elevated or pathological fluctuations in intracranial pressure are thought to cause symptoms similar to those reported by individuals suffering cerebral forms of high-altitude illness. This review first focuses on the basic physiology of the craniospinal system, including a detailed discussion of the long-term and dynamic regulation of intracranial pressure. Thereafter, we critically examine the available literature, based primarily on invasive pressure monitoring, that suggests intracranial pressure is acutely elevated at altitude due to brain swelling and/or elevated sagittal sinus pressure, but normalizes over time. We hypothesize that fluctuations in intracranial pressure occur around a slightly elevated or normal mean intracranial pressure, in conjunction with oscillations in arterial Po2 and arterial blood pressure. Then these modest fluctuations in intracranial pressure, in concert with direct vascular stretch due to dilatation and/or increased blood pressure transmission, activate the trigeminal vascular system and cause symptoms of acute mountain sickness. Elevated brain water (vasogenic edema) may be due to breakdown of the blood-brain barrier. However, new information suggests cerebral spinal fluid flux into the brain may be an important factor. Regardless of the source (or mechanisms responsible) for the excess brain water, brain swelling occurs, and a “tight fit” brain would be a major risk factor to produce symptoms; activities that produce large changes in brain volume and cause fluctuations in blood pressure are likely contributing factors.
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Affiliation(s)
- Justin S. Lawley
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, Texas
- UT Southwestern Medical Center, Dallas, Texas
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, Texas
- UT Southwestern Medical Center, Dallas, Texas
| | - Michael A. Williams
- Sandra and Malcolm Berman Brain & Spine Institute, Dept. of Neurology, Sinai Hospital, Baltimore, Maryland
| | - Jon Malm
- Department of Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - David M. Polaner
- Departments of Anesthesiology and Pediatrics, University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, Colorado
| | - Andrew W. Subudhi
- Department of Biology, University of Colorado, Colorado Springs, Colorado
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
| | | | - Robert C. Roach
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado; and
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Abstract
Acute high-altitude illness is an encompassing term for the range of pathology that the unacclimatised individual can develop at increased altitude. This includes acute mountain sickness, high-altitude cerebral oedema and high-altitude pulmonary oedema. These conditions represent an increasing clinical problem as more individuals are exposed to the hypobaric hypoxic environment of high altitude for both work and leisure. In this review of acute high-altitude illness, the epidemiology, risk factors and pathophysiology are explored, before their prevention and treatment are discussed. Appropriate ascent rate remains the most effective acute high-altitude illness prevention, with pharmacological prophylaxis indicated in selected individuals. Descent is the definitive treatment for acute high-altitude illness, with the adjuncts of oxygen and specific drug therapies.
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Affiliation(s)
- Tom Smedley
- UCL Centre for Altitude, Space and Extreme Environment Medicine, Portex Unit, Institute of Child Health, London, UK ; Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Michael Pw Grocott
- Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, Faculty of Medicine, University of Southampton, University Hospital Southampton NHS Foundation Trust, Southampton, UK ; Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK ; NIHR Southampton Respiratory Biomedical Research Unit, Southampton, UK
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Lochner P, Falla M, Brigo F, Pohl M, Strapazzon G. Ultrasonography of the Optic Nerve Sheath Diameter for Diagnosis and Monitoring of Acute Mountain Sickness: A Systematic Review. High Alt Med Biol 2015; 16:195-203. [DOI: 10.1089/ham.2014.1127] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Piergiorgio Lochner
- Department of Neurology, General Hospital of Merano, Merano, Italy
- Department of Neurology, University A. Avogadro, Novara, Italy
| | - Marika Falla
- Department of Neurology and Psychiatry, Sapienza University, Roma, Italy
- Department of Neurology, General Hospital of Bolzano, Bolzano, Italy
| | - Francesco Brigo
- Department of Neurology, General Hospital of Merano, Merano, Italy
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - Michael Pohl
- EURAC Institute of Mountain Emergency Medicine, Bolzano, Italy
- Landeskrankenhaus Bregenz, Austria
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Pitman JT, Thapa GB, Stuart Harris N. Field Ultrasound Evaluation of Central Volume Status and Acute Mountain Sickness. Wilderness Environ Med 2015; 26:319-26. [DOI: 10.1016/j.wem.2015.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 02/09/2015] [Accepted: 02/16/2015] [Indexed: 11/26/2022]
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Wilson MH, Imray CHE. The cerebral venous system and hypoxia. J Appl Physiol (1985) 2015; 120:244-50. [PMID: 26294747 DOI: 10.1152/japplphysiol.00327.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/13/2015] [Indexed: 01/24/2023] Open
Abstract
Most hypobaric hypoxia studies have focused on oxygen delivery and therefore cerebral blood inflow. Few have studied venous outflow. However, the volume of blood entering and leaving the skull (∼700 ml/min) is considerably greater than cerebrospinal fluid production (0.35 ml/min) or edema formation rates and slight imbalances of in- and outflow have considerable effects on intracranial pressure. This dynamic phenomenon is not necessarily appreciated in the currently taught static "Monro-Kellie" doctrine, which forms the basis of the "Tight-Fit" hypothesis thought to underlie high altitude headache, acute mountain sickness, and high altitude cerebral edema. Investigating both sides of the cerebral circulation was an integral part of the 2007 Xtreme Everest Expedition. The results of the relevant studies performed as part of and subsequent to this expedition are reviewed here. The evidence from recent studies suggests a relative venous outflow insufficiency is an early step in the pathogenesis of high altitude headache. Translation of knowledge gained from high altitude studies is important. Many patients in a critical care environment develop hypoxemia akin to that of high altitude exposure. An inability to drain the hypoxemic induced increase in cerebral blood flow could be an underappreciated regulatory mechanism of intracranial pressure.
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Affiliation(s)
- Mark H Wilson
- The Centre for Altitude, Space and Extreme Environment Medicine, University College London, London, United Kingdom; The Birmingham Medical Research Expeditionary Society, Queen Elizabeth Hospital, Edgbaston, Birmingham, United Kingdom; Imperial Neurotrauma Centre, Imperial College, St Mary's Hospital, London, United Kingdom; Institute of Pre-Hospital Care, London's Air Ambulance, Royal London Hospital, Whitechapel, United Kingdom; and
| | - Christopher H E Imray
- The Centre for Altitude, Space and Extreme Environment Medicine, University College London, London, United Kingdom; The Birmingham Medical Research Expeditionary Society, Queen Elizabeth Hospital, Edgbaston, Birmingham, United Kingdom; Department of Surgery, Warwick Medical School, UHCW NHS Trust, Warwick, United Kingdom
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Swenson ER. Pharmacology of acute mountain sickness: old drugs and newer thinking. J Appl Physiol (1985) 2015; 120:204-15. [PMID: 26294748 DOI: 10.1152/japplphysiol.00443.2015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 08/12/2015] [Indexed: 01/09/2023] Open
Abstract
Pharmacotherapy in acute mountain sickness (AMS) for the past half century has largely rested on the use of carbonic anhydrase (CA) inhibitors, such as acetazolamide, and corticosteroids, such as dexamethasone. The benefits of CA inhibitors are thought to arise from their known ventilatory stimulation and resultant greater arterial oxygenation from inhibition of renal CA and generation of a mild metabolic acidosis. The benefits of corticosteroids include their broad-based anti-inflammatory and anti-edemagenic effects. What has emerged from more recent work is the strong likelihood that drugs in both classes act on other pathways and signaling beyond their classical actions to prevent and treat AMS. For the CA inhibitors, these include reduction in aquaporin-mediated transmembrane water transport, anti-oxidant actions, vasodilation, and anti-inflammatory effects. In the case of corticosteroids, these include protection against increases in vascular endothelial and blood-brain barrier permeability, suppression of inflammatory cytokines and reactive oxygen species production, and sympatholysis. The loci of action of both classes of drug include the brain, but may also involve the lung as revealed by benefits that arise with selective administration to the lungs by inhalation. Greater understanding of their pluripotent actions and sites of action in AMS may help guide development of better drugs with more selective action and fewer side effects.
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Affiliation(s)
- Erik R Swenson
- Veterans Affairs Puget Sound Health Care System, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington, Seattle
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Berger MM, Macholz F, Mairbäurl H, Bärtsch P. Remote ischemic preconditioning for prevention of high-altitude diseases: fact or fiction? J Appl Physiol (1985) 2015; 119:1143-51. [PMID: 26089545 DOI: 10.1152/japplphysiol.00156.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/17/2015] [Indexed: 01/14/2023] Open
Abstract
Preconditioning refers to exposure to brief episodes of potentially adverse stimuli and protects against injury during subsequent exposures. This was first described in the heart, where episodes of ischemia/reperfusion render the myocardium resistant to subsequent ischemic injury, which is likely caused by reactive oxygen species (ROS) and proinflammatory processes. Protection of the heart was also found when preconditioning was performed in an organ different from the target, which is called remote ischemic preconditioning (RIPC). The mechanisms causing protection seem to include stimulation of nitric oxide (NO) synthase, increase in antioxidant enzymes, and downregulation of proinflammatory cytokines. These pathways are also thought to play a role in high-altitude diseases: high-altitude pulmonary edema (HAPE) is associated with decreased bioavailability of NO and increased generation of ROS, whereas mechanisms causing acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) seem to involve cytotoxic effects by ROS and inflammation. Based on these apparent similarities between ischemic damage and AMS, HACE, and HAPE, it is reasonable to assume that RIPC might be protective and improve altitude tolerance. In studies addressing high-altitude/hypoxia tolerance, RIPC has been shown to decrease pulmonary arterial systolic pressure in normobaric hypoxia (13% O2) and at high altitude (4,342 m). Our own results indicate that RIPC transiently decreases the severity of AMS at 12% O2. Thus preliminary studies show some benefit, but clearly, further experiments to establish the efficacy and potential mechanism of RIPC are needed.
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Affiliation(s)
- Marc Moritz Berger
- Department of Anesthesiology, Perioperative and General Critical Care Medicine, Salzburg General Hospital, Paracelsus Medical University, Salzburg, Austria; Department of Anesthesiology, University of Heidelberg, Heidelberg, Germany;
| | - Franziska Macholz
- Department of Anesthesiology, Perioperative and General Critical Care Medicine, Salzburg General Hospital, Paracelsus Medical University, Salzburg, Austria
| | - Heimo Mairbäurl
- Department of Internal Medicine VII, Division of Sports Medicine, University of Heidelberg, Heidelberg, Germany; and Translational Lung Research Center Heidelberg, German Center for Lung Research, Heidelberg, Germany
| | - Peter Bärtsch
- Department of Internal Medicine VII, Division of Sports Medicine, University of Heidelberg, Heidelberg, Germany; and
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Berger MM, Köhne H, Hotz L, Hammer M, Schommer K, Bärtsch P, Mairbäurl H. Remote ischemic preconditioning delays the onset of acute mountain sickness in normobaric hypoxia. Physiol Rep 2015; 3:3/3/e12325. [PMID: 25742960 PMCID: PMC4393159 DOI: 10.14814/phy2.12325] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Acute mountain sickness (AMS) is a neurological disorder occurring when ascending too fast, too high. Remote ischemic preconditioning (RIPC) is a noninvasive intervention protecting remote organs from subsequent hypoxic damage. We hypothesized that RIPC protects against AMS and that this effect is related to reduced oxidative stress. Fourteen subjects were exposed to 18 hours of normoxia (21% oxygen) and 18 h of normobaric hypoxia (12% oxygen, equivalent to 4500 m) on different days in a blinded, randomized order. RIPC consisted of four cycles of lower limb ischemia (5 min) and 5 min of reperfusion, and was performed immediately before the study room was entered. A control group was exposed to hypoxia (12% oxygen, n = 14) without RIPC. AMS was evaluated by the Lake Louise score (LLS) and the AMS-C score of the Environmental Symptom Questionnaire. Plasma concentrations of ascorbate radicals, oxidized sulfhydryl (SH) groups, and electron paramagnetic resonance (EPR) signal intensity were measured as biomarkers of oxidative stress. RIPC reduced AMS scores (LLS: 1.9 ± 0.4 vs. 3.2 ± 0.5; AMS-C score: 0.4 ± 0.1 vs. 0.8 ± 0.2), ascorbate radicals (27 ± 7 vs. 65 ± 18 nmol/L), oxidized SH groups (3.9 ± 1.4 vs. 14.3 ± 4.6 μmol/L), and EPR signal intensity (0.6 ± 0.2 vs. 1.5 ± 0.4 × 10(6)) after 5 h in hypoxia (all P < 0.05). After 18 hours in hypoxia there was no difference in AMS and oxidative stress between RIPC and control. AMS and plasma markers of oxidative stress did not correlate. This study demonstrates that RIPC transiently reduces symptoms of AMS and that this effect is not associated with reduced plasma levels of reactive oxygen species.
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Affiliation(s)
- Marc M Berger
- Department of Anesthesiology, University of Heidelberg, Heidelberg, Germany Department of Anesthesiology, Perioperative and General Critical Care Medicine, Salzburg General Hospital Paracelsus Medical University, Salzburg, Austria
| | - Hannah Köhne
- Department of Anesthesiology, University of Heidelberg, Heidelberg, Germany
| | - Lorenz Hotz
- Department of Anesthesiology, University of Heidelberg, Heidelberg, Germany Department of Anesthesiology, Perioperative and General Critical Care Medicine, Salzburg General Hospital Paracelsus Medical University, Salzburg, Austria
| | - Moritz Hammer
- Department of Internal Medicine VII, Division of Sports Medicine, University of Heidelberg, Heidelberg, Germany
| | - Kai Schommer
- Department of Internal Medicine VII, Division of Sports Medicine, University of Heidelberg, Heidelberg, Germany
| | - Peter Bärtsch
- Department of Internal Medicine VII, Division of Sports Medicine, University of Heidelberg, Heidelberg, Germany
| | - Heimo Mairbäurl
- Department of Internal Medicine VII, Division of Sports Medicine, University of Heidelberg, Heidelberg, Germany
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Thakur KT, Zunt JR. Approach to the international traveler with neurological symptoms. FUTURE NEUROLOGY 2015. [DOI: 10.2217/fnl.14.64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ABSTRACT International travelers commonly contract illnesses while abroad, with the highest risk in those who spend extended time in developing countries. As travel to worldwide destinations becomes more accessible, neurologists should be aware of travel-related infections and noninfectious conditions presenting with neurological manifestations. Travelers may present with a myriad of neurologic symptoms, including confusion, headache, weakness and sensory symptoms. In this review, we discuss the general approach to the returning traveler with neurological symptoms and discuss the differential diagnosis of symptoms commonly encountered in practice.
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Affiliation(s)
- Kiran T Thakur
- Division of Neuroinfectious Disease & Neuroimmunology, Department of Neurology, Johns Hopkins Hospital, 600 North Wolfe Street, Meyer 6–113, Baltimore, MD 21205, USA
| | - Joseph R Zunt
- Department of Neurology, Global Health, Medicine (Infectious Diseases) & Epidemiology, University of Washington, Seattle, WA, USA
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[High altitude retinopathy: report of 3 cases]. J Fr Ophtalmol 2014; 37:629-34. [PMID: 25199490 DOI: 10.1016/j.jfo.2014.04.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 04/22/2014] [Accepted: 04/23/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE To report three cases of vision loss occurring at high altitude. OBSERVATIONS Three patients aged 27 to 52 years presented with scotoma and/or visual acuity deficit upon their return from high altitude expeditions above 6000 m. Fundus examination revealed multiple posterior pole hemorrhages, resolving completely by two months. DISCUSSION Exposure to hypobaric hypoxia at high altitude leads to adaptation mechanisms in order to maintain retinal oxygenation. Certain individuals have an inadequate autoregulatory response and develop signs of "high altitude retinopathy" (HAR), including retinal hemorrhages most often, with occasional vitreous hemorrhage, optic nerve head edema and retinal vein occlusion. The pathophysiology of HAR is not well understood. Identified risk factors include altitude above 4000 m, rapid ascent and personal susceptibility. Age and fitness are unrelated. Association with acute mountain sickness, high-altitude pulmonary edema and high-altitude cerebral edema is still controversial. CONCLUSION Retinal hemorrhages occurring after high-altitude hiking are an early manifestation of HAR and are part of high-altitude illness. HAR usually occurs at altitudes above 4000 m, is generally asymptomatic, and spontaneously regresses. A maladaptive autoregulatory response to hypobaric hypoxia appears to be the cause of HAR.
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Affiliation(s)
- Mark H. Wilson
- The Brain Injury Centre—St Mary's Hospital, Imperial College, London, United Kingdom
- Birmingham Medical Research Expeditionary Society, Birmingham, United Kingdom
- The Institute of Pre-Hospital Care, London's Air Ambulance, Barts and the London Medical School, Queen Mary University of London, The Helipad, The Royal London Hospital, Whitechapel, United Kingdom
| | - Alex Wright
- Birmingham Medical Research Expeditionary Society, Birmingham, United Kingdom
| | - Christopher H.E. Imray
- University Hospital Coventry and Warwickshire NHS Trust and Warwick Medical School, Coventry, United Kingdom
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Update on High Altitude Cerebral Edema Including Recent Work on the Eye. High Alt Med Biol 2014; 15:112-22. [DOI: 10.1089/ham.2013.1142] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Lawley JS, Alperin N, Bagci AM, Lee SH, Mullins PG, Oliver SJ, Macdonald JH. Normobaric hypoxia and symptoms of acute mountain sickness: Elevated brain volume and intracranial hypertension. Ann Neurol 2014; 75:890-8. [PMID: 24788400 DOI: 10.1002/ana.24171] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 04/24/2014] [Accepted: 04/27/2014] [Indexed: 01/31/2023]
Abstract
OBJECTIVE The study was undertaken to determine whether normobaric hypoxia causes elevated brain volume and intracranial pressure in individuals with symptoms consistent with acute mountain sickness (AMS). METHODS Thirteen males age = (26 (sd 6)) years were exposed to normobaric hypoxia (12% O2 ) and normoxia (21% O2 ). After 2 and 10 hours, AMS symptoms were assessed alongside ventricular and venous vessel volumes, cerebral blood flow, regional brain volumes, and intracranial pressure, using high-resolution magnetic resonance imaging. RESULTS In normoxia, neither lateral ventricular volume (R(2) = 0.07, p = 0.40) nor predominance of unilateral transverse venous sinus drainage (R(2) = 0.07, p = 0.45) was related to AMS symptoms. Furthermore, despite an increase in cerebral blood flow after 2 hours of hypoxia (hypoxia vs normoxia: Δ148ml/min(-1) , 95% confidence interval [CI] = 58 to 238), by 10 hours, when AMS symptoms had developed, cerebral blood flow was normal (Δ-51ml/min(-1) , 95% CI = -141 to 39). Conversely, at 10 hours brain volume was increased (Δ59ml, 95% CI = 8 to 110), predominantly due to an increase in gray matter volume (Δ73ml, 95% CI = 25 to 120). Therefore, cerebral spinal fluid volume was decreased (Δ-40ml, 95% CI = -67 to -14). The intracranial pressure response to hypoxia varied between individuals, and as hypothesized, the most AMS-symptomatic participants had the largest increases in intracranial pressure (AMS present, Δ7mmHg, 95% CI = -2.5 to 17.3; AMS not present, Δ-1mmHg, 95% CI = -3.3 to 0.5). Consequently, there was a significant relationship between the change in intracranial pressure and AMS symptom severity (R(2) = 0.71, p = 0.002). INTERPRETATION The data provide the strongest evidence to date to support the hypothesis that the "random" nature of AMS symptomology is explained by a variable intracranial pressure response to hypoxia.
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Affiliation(s)
- Justin S Lawley
- Extremes Research Group, School of Sport, Health, and Exercise Sciences, Bangor University, Gwynedd, United Kingdom; Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, TX
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Subudhi AW, Bourdillon N, Bucher J, Davis C, Elliott JE, Eutermoster M, Evero O, Fan JL, Houten SJV, Julian CG, Kark J, Kark S, Kayser B, Kern JP, Kim SE, Lathan C, Laurie SS, Lovering AT, Paterson R, Polaner DM, Ryan BJ, Spira JL, Tsao JW, Wachsmuth NB, Roach RC. AltitudeOmics: the integrative physiology of human acclimatization to hypobaric hypoxia and its retention upon reascent. PLoS One 2014; 9:e92191. [PMID: 24658407 PMCID: PMC3962396 DOI: 10.1371/journal.pone.0092191] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 02/19/2014] [Indexed: 11/19/2022] Open
Abstract
An understanding of human responses to hypoxia is important for the health of millions of people worldwide who visit, live, or work in the hypoxic environment encountered at high altitudes. In spite of dozens of studies over the last 100 years, the basic mechanisms controlling acclimatization to hypoxia remain largely unknown. The AltitudeOmics project aimed to bridge this gap. Our goals were 1) to describe a phenotype for successful acclimatization and assess its retention and 2) use these findings as a foundation for companion mechanistic studies. Our approach was to characterize acclimatization by measuring changes in arterial oxygenation and hemoglobin concentration [Hb], acute mountain sickness (AMS), cognitive function, and exercise performance in 21 subjects as they acclimatized to 5260 m over 16 days. We then focused on the retention of acclimatization by having subjects reascend to 5260 m after either 7 (n = 14) or 21 (n = 7) days at 1525 m. At 16 days at 5260 m we observed: 1) increases in arterial oxygenation and [Hb] (compared to acute hypoxia: PaO2 rose 9±4 mmHg to 45±4 while PaCO2 dropped a further 6±3 mmHg to 21±3, and [Hb] rose 1.8±0.7 g/dL to 16±2 g/dL; 2) no AMS; 3) improved cognitive function; and 4) improved exercise performance by 8±8% (all changes p<0.01). Upon reascent, we observed retention of arterial oxygenation but not [Hb], protection from AMS, retention of exercise performance, less retention of cognitive function; and noted that some of these effects lasted for 21 days. Taken together, these findings reveal new information about retention of acclimatization, and can be used as a physiological foundation to explore the molecular mechanisms of acclimatization and its retention.
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Affiliation(s)
- Andrew W. Subudhi
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado, United States of America
| | - Nicolas Bourdillon
- Institute of Sports Sciences and Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Jenna Bucher
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States of America
| | - Christopher Davis
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Jonathan E. Elliott
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States of America
| | - Morgan Eutermoster
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Oghenero Evero
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Jui-Lin Fan
- Institute of Sports Sciences and Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Lemanic Doctoral School of Neuroscience, University of Lausanne, Lausanne, Switzerland
| | - Sonja Jameson-Van Houten
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Colleen G. Julian
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Jonathan Kark
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Sherri Kark
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Bengt Kayser
- Institute of Sports Sciences and Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Julia P. Kern
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States of America
| | - See Eun Kim
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States of America
| | - Corinna Lathan
- AnthroTronix, Inc., Silver Spring, Maryland, United States of America
| | - Steven S. Laurie
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States of America
| | - Andrew T. Lovering
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States of America
| | - Ryan Paterson
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - David M. Polaner
- Departments of Anesthesiology and Pediatrics, University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, Colorado, United States of America
| | - Benjamin J. Ryan
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - James L. Spira
- United States Department of Veterans Affairs, National Center for PTSD, Pacific Islands Health Care System, and Department of Psychiatry, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii, United States of America
| | - Jack W. Tsao
- Wounded, Ill & Injured Directorate (M9), United States Navy Bureau of Medicine and Surgery, Falls Church, Virginia, United States of America
| | - Nadine B. Wachsmuth
- Department of Sports Medicine/Sports Physiology, University of Bayreuth, Bayreuth, Germany
| | - Robert C. Roach
- Altitude Research Center, Department of Emergency Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
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Abstract
High altitude retinopathy is a condition often seen among mountain climbers or among persons who reach high altitudes rapidly. In this report, we describe a case of a 57 year old healthy gentleman who presented with diminution of vision in both the eyes associated with retinal hemorrhages and the spontaneous resolution of the same.
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Affiliation(s)
- Muna P Bhende
- Sri Bhagwan Mahavir Vitreoretinal Services, Vision Research Foundation, Sankara Nethralaya, Chennai, India
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Zafren K. Prevention of high altitude illness. Travel Med Infect Dis 2014; 12:29-39. [DOI: 10.1016/j.tmaid.2013.12.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 12/05/2013] [Accepted: 12/10/2013] [Indexed: 11/28/2022]
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Singh M, Tulsawani R, Koganti P, Chauhan A, Manickam M, Misra K. Cordyceps sinensis increases hypoxia tolerance by inducing heme oxygenase-1 and metallothionein via Nrf2 activation in human lung epithelial cells. BIOMED RESEARCH INTERNATIONAL 2013; 2013:569206. [PMID: 24063008 PMCID: PMC3770031 DOI: 10.1155/2013/569206] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 07/11/2013] [Accepted: 07/11/2013] [Indexed: 12/30/2022]
Abstract
Cordyceps sinensis, an edible mushroom growing in Himalayan regions, is widely recognized in traditional system of medicine. In the present study, we report the efficacy of Cordyceps sinensis in facilitating tolerance to hypoxia using A549 cell line as a model system. Treatment with aqueous extract of Cordyceps sinensis appreciably attenuated hypoxia induced ROS generation, oxidation of lipids and proteins and maintained antioxidant status similar to that of controls via induction of antioxidant gene HO1 (heme oxygenase-1), MT (metallothionein) and Nrf2 (nuclear factor erythroid-derived 2-like 2). In contrast, lower level of NF κ B (nuclear factor kappaB) and tumor necrosis factor- α observed which might be due to higher levels of HO1, MT and transforming growth factor- β . Further, increase in HIF1 (hypoxia inducible factor-1) and its regulated genes; erythropoietin, vascular endothelial growth factor, and glucose transporter-1 was observed. Interestingly, Cordyceps sinensis treatment under normoxia did not regulate the expression HIF1, NF κ B and their regulated genes evidencing that Cordyceps sinensis per se did not have an effect on these transcription factors. Overall, Cordyceps sinensis treatment inhibited hypoxia induced oxidative stress by maintaining higher cellular Nrf2, HIF1 and lowering NF κ B levels. These findings provide a basis for possible use of Cordyceps sinensis in tolerating hypoxia.
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Affiliation(s)
- Mrinalini Singh
- Defence Institute of Physiology and Allied Science, Lucknow Road, Timarpur, Delhi 110 054, India
| | - Rajkumar Tulsawani
- Defence Institute of Physiology and Allied Science, Lucknow Road, Timarpur, Delhi 110 054, India
| | - Praveen Koganti
- Defence Institute of Physiology and Allied Science, Lucknow Road, Timarpur, Delhi 110 054, India
| | - Amitabh Chauhan
- Defence Institute of Physiology and Allied Science, Lucknow Road, Timarpur, Delhi 110 054, India
| | - Manimaran Manickam
- Defence Institute of Physiology and Allied Science, Lucknow Road, Timarpur, Delhi 110 054, India
| | - Kshipra Misra
- Defence Institute of Physiology and Allied Science, Lucknow Road, Timarpur, Delhi 110 054, India
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