High altitude medicine & biology最新文献

Guo, Hai, Linjie Cheng, Dilihumaier Duolikun, and Qiaoling Yao. Aerobic exercise training under normobaric hypoxic conditions to improve glucose and lipid metabolism in overweight and obese individuals: a systematic review and meta-analysis. High Alt Med Biol. 24:312-320, 2023. Background: Obesity is a critical public health issue around the world, reaching epidemic proportions in some countries. However, only a few studies have examined the effects of hypoxic training on metabolic parameters in an obese population. This systematic review and meta-analysis aimed to determine the effects of aerobic exercise training under normobaric hypoxic conditions versus normoxic training in improving glucose and lipid metabolism in obese individuals. Methods: A systematic search of PubMed, EMBASE, Web of Science, and Wan Fang databases (up to August 2021) was performed to identify randomized controlled trials (RCTs) of overweight or obese human subjects eligible for inclusion. Main study endpoints were changes in body mass index (BMI), waist/hip (W/H) ratio, leptin, blood glucose and insulin levels, as well as blood lipids between hypoxic and normoxic conditioning. Results: Fourteen RCTs with a total of 413 subjects qualified for inclusion. Pooled analyses revealed that BMI (d = 0.38), W/H ratio (d = 0), blood glucose (d = 0.01), and triglyceride (d = -2.27) were not significantly different between aerobic exercise training under hypoxic and normoxic conditions. However, significant differences were found in heart rate at rest (d = -4.50) between aerobic exercise training under hypoxic versus normoxic conditions. Conclusions: In conclusion, no significant benefits were noted in aerobic exercise training under hypoxic conditions over normoxic conditions in overweight or obese individuals. However, the maximum training heart rate mm was significantly higher under hypoxic conditions than under normoxic conditions. Future studies with larger samples controlling for exercise-related parameters, and addressing the potential modifying effects of level of hypoxia, sex, or age on the role of hypoxic exercise training are warranted. PROSPERO registration number: CRD42020221680.

Rathor, Richa, Sukanya Srivastava, and Geetha Suryakumar. A comparative biochemical study between L-carnosine and β-alanine in amelioration of hypobaric hypoxia-induced skeletal muscle protein loss. High Alt Med Biol. 24:302-311, 2023. Background: Carnosine (CAR; β-alanyl-L-histidine), a biologically active dipeptide is known for its unique pH-buffering capacity, metal chelating activity, and antioxidant and antiglycation property. β-Alanine (ALA) is a nonessential amino acid and used to enhance performance and cognitive functions. Hypobaric hypoxia (HH)-induced muscle protein loss is regulated by multifaceted signaling pathways. The present study investigated the beneficial effects of CAR and ALA against HH-associated muscle loss. Methodology: Simulated HH exposure was performed in an animal decompression chamber. Gastric oral administration of CAR (50 mg·kg^-1) and ALA (450 mg·kg^-1) were given daily for 3 days and at the end of the treatment, hindlimb skeletal muscle tissue was excised for western blot and biochemical assays. Results: Cosupplementation of CAR and ALA alone was able to ameliorate the hypoxia-induced inflammation, oxidative stress (FOXO), ER stress (GRP-78), and atrophic signaling (MuRF-1) in the skeletal muscles. Creatinine phospho kinase activity and apoptosis were also decreased in CAR- and ALA-supplemented rats. However, CAR showed enhanced protection in HH-induced muscle loss as CAR supplementation was able to enhance protein concentration, body weight, and decreased the protein oxidation and ALA administration was not able to restore the same. Conclusions: Hence, the present comprehensive study supports the fact that CAR (50 mg·kg^-1) is more beneficial as compared with ALA (450 mg·kg^-1) in ameliorating the hypoxia-induced skeletal muscle loss.

Derstine, Mia, Dominique Jean, Beth A. Beidleman, Jacqueline Pichler Hefti, David Hillebrandt, Lenka Horakova, Susi Kriemler, Kasté Mateikaité-Pipiriené, Peter Paal, Alison Rosier, Marija Andjelkovic, and Linda E. Keyes. Acute mountain sickness and high altitude cerebral edema in women: A scoping review-UIAA Medical Commission recommendations. High Alt Med Biol. 24:259-267, 2023. Background: Acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) are illnesses associated with rapid ascent to altitudes over 2,500 m in unacclimatized lowlanders. The aim of this scoping review is to summarize the current knowledge on sex differences in the epidemiology, pathophysiology, symptomatology, and treatment of AMS and HACE, especially in women. Methods and Results: The UIAA Medical Commission convened an international author team to review women's health issues at high altitude and to publish updated recommendations. Pertinent literature from PubMed and Cochrane was identified by keyword search combinations (including AMS, HACE, and high altitude), with additional publications found by hand search. The primary search focus was for articles assessing lowland women sojourning at high altitude. Results: The literature search yielded 7,165 articles, 37 of which were ultimately included. The majority of publications included did not find women at increased risk for AMS or HACE. There was extremely limited sex-specific data on risk factors or treatment. Conclusions: There is a limited amount of data on female-specific findings regarding AMS and HACE, with most publications addressing only prevalence or incidence with regard to sex. As such, general prevention and treatment strategies for AMS and HACE should be used regardless of sex.

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.

Barclay, Holly, Saptarshi Mukerji, Bengt Kayser, and Jui-Lin Fan. Appetite, hypoxia and acute mountain sickness: A 10-hour normobaric hypoxic chamber study. High Alt Med Biol. 24:329-335, 2023. Background: The effects of hypoxia and acute mountain sickness (AMS) on appetite and food preferences are moot, especially during the early phase of hypoxic exposure. We examined the effects of a 10-hour hypoxic exposure on appetite and food preference. Methods: We assessed appetite (hunger, satisfaction, fullness, perceived appetite, and lost appetite), food preferences (sweet, salty, savory, and fatty), and AMS (Lake Louise score) with questionnaires in 27 healthy individuals (13 women) across 10-hour exposures to normobaric normoxia (fraction of inspired O₂ [FiO₂]: 0.21) and normobaric hypoxia (F_iO₂: 0.12, equivalent of 5,000 m) in a randomized, single-blinded manner. Results and Conclusions: Compared with normoxia, hypoxia decreased hunger and appetite (p = 0.040 and <0.001, respectively), which was mediated by a decreased desire for sweet, salty, and fatty foods (p < 0.05 for all). AMS was associated with a decreased desire for sweet (R = -0.438, p = 0.032) and salty foods (R = -0.460, p = 0.024) and greater loss of appetite (R = -0.619, p = 0.018). Our findings suggest that acute hypoxia rapidly suppresses appetite and that AMS development further amplifies anorexia. Clinical Trial Registration Number: ACTRN12618000548235.

Lugnet, Viktor, Miles McDonough, Les Gordon, Mercedes Galindez, Nicolas Mena Reyes, Alison Sheets, Ken Zafren, and Peter Paal. Termination of cardiopulmonary resuscitation in mountain rescue: a scoping review and ICAR MedCom 2023 recommendations. High Alt Med Biol. 24:274-286, 2023. Background: In 2012, the International Commission for Mountain Emergency Medicine (ICAR MedCom) published recommendations for termination of cardiopulmonary resuscitation (CPR) in mountain rescue. New developments have necessitated an update. This is the 2023 update for termination of CPR in mountain rescue. Methods: For this scoping review, we searched the PubMed and Cochrane libraries, updated the recommendations, and obtained consensus approval within the writing group and the ICAR MedCom. Results: We screened a total of 9,102 articles, of which 120 articles met the inclusion criteria. We developed 17 recommendations graded according to the strength of recommendation and level of evidence. Conclusions: Most of the recommendations from 2012 are still valid. We made minor changes regarding the safety of rescuers and responses to primary or traumatic cardiac arrest. The criteria for termination of CPR remain unchanged. The principal changes include updated recommendations for mechanical chest compression, point of care ultrasound (POCUS), extracorporeal life support (ECLS) for hypothermia, the effects of water temperature in drowning, and the use of burial times in avalanche rescue.

Louis, Alexandre, Charlotte Pröpper, Yann Savina, Corentin Tanne, Guy Duperrex, Paul Robach, Pascal Zellner, Stéphane Doutreleau, Jean-Michel Boulet, Alain Frey, Fabien Pillard, Cristina Pistea, Mathias Poussel, Thomas Thuet, Jean-Paul Richalet, and François Lecoq-Jammes. The impact of COVID-19 on the response to hypoxia. High Alt Med Biol. 24:321-328, 2023. Background: Severe high-altitude illness (SHAI) and coronavirus disease 2019 (COVID-19), while differing in most aspects of pathophysiology, both involve respiratory capacity. We examined the long-term impact of COVID-19 on response to hypoxia in individuals free of symptoms but having tested positive during the pandemic. The need for recommendations for such individuals planning a stay at high altitude are discussed. Methods: This multicenter study recruited participants from the multiSHAI cohort, all of whom had previously undergone a hypoxic exercise test. These participants were classified into two groups depending on whether they had since suffered mild-to-moderate COVID-19 (COVID+) or not (Control) and then asked to retake the test. Primary outcomes were: desaturation induced by hypoxia at exercise (ΔSpE), hypoxic cardiac response at exercise, hypoxic ventilatory response at exercise, and SHAI risk score. Results: A total of 68 participants retook the test, 36 classified in the COVID+ group. Analyses of primary outcomes showed no significant differences between groups. However, the COVID+ group showed significantly increased ventilation (VE) parameters during both hypoxic (p = 0.003) and normoxic exercise (p = 0.007). However, only the VE/oxygen consumption relationship during hypoxic exercise was significantly different. Conclusion: This study demonstrates no negative impact of COVID-19 on response to hypoxia as evaluated by the Richalet test. Clinical Trial Registration: NTC number: NCT05167357.

Horakova, Lenka, Peter Paal, Jacqueline Pichler Hefti, Marija Andjelkovic, Beth A. Beidleman, Mia Derstine, David Hillebrandt, Dominique Jean, Kastė Mateikaitė-Pipirienė, Alison J. Rosier, Susi Kriemler, and Linda E. Keyes. Women's health at high altitude: An introduction to a 7-part series by the International Climbing and Mountaineering Federation Medical Commission. High Alt Med Biol. 24:243-246, 2023. Background: Women have been traveling to high altitude since the inception of modern mountaineering. Although there are distinct female-specific features such as menstruation and menopause relevant to adaptation to and performance at high altitude, very little data exist on women's high-altitude health. To summarize what is known to date, the Medical Commission of the International Climbing and Mountaineering Federation (UIAA) has created a series of articles on women's health, high altitude illness, and performance at high altitude. Methods: Assembling an international author team, two types of manuscripts were developed: (1) reviews on female-specific topics such as pregnancy; (2) reviews on sex differences in high-altitude related illnesses, nutrition, cold injuries, and mortality. Results: The literature search yielded 7,165 articles, with 482 studies meeting the inclusion criteria for full-text review. The authors of individual chapters reviewed these articles and performed additional hand searches. Conclusions: Some important questions on women sojourning and exercising at high altitude have been studied, but many are still awaiting a qualified and evidence-based response. Our seven reviews, to be published in future issues of this journal, summarize what is known about lowland women sojourning at high altitude, provide recommendations, and highlight knowledge gaps in high altitude women's medicine.

Pichler Hefti, Jacqueline, Dominique Jean, Alison Rosier, Mia Derstine, David Hillebrandt, Lenka Horakova, Linda E. Keyes, Kastė Mateikaitė-Pipirienė, Peter Paal, Marija Andjelkovic, Beth Beidlemann, and Susi Kriemler. High-altitude pulmonary edema in women: a scoping review-UIAA Medical Commission Recommendations. High Alt Med Biol. 24:268-273, 2023. Background: High-altitude pulmonary edema (HAPE) can occur >2,500-3,000 m asl and is a life-threatening medical condition. This scoping review aims to summarize the current data on sex differences in HAPE. Methods: The International Climbing and Mountaineering Federation (UIAA) Medical Commission convened an international author team to review women's health issues at high altitude. Pertinent literature from PubMed and Cochrane was identified by keyword search combinations (including HAPE), with additional publications found by hand search. The primary search focus was for original articles that included minimum one woman and at least a rudimentary subgroup analysis. Results: The literature search yielded 7,165 articles, 416 of which were relevant for HAPE, and 7 of which were ultimately included here. Six were case series, consistently reporting a lower HAPE prevalence in women. The one retrospective case-control study reported male HAPE prevalence at 10/100,000 and female at 0.74/100,000. No studies were identified that directly compared sex differences in the prevalence of HAPE. No published data was found for topics other than epidemiology. Conclusions: Few studies and associated methodological limitations allow few conclusions to be drawn. Incidence of HAPE may be lower in women than in men. We speculate that besides physiological aspects, behavioral differences may contribute to this potential sex difference.