High altitude medicine & biology最新文献

{"title":"<i>Letter:</i> High Altitude Medical Kit.","authors":"James F Bridger, Jeremy S Windsor","doi":"10.1177/15578682261429336","DOIUrl":"10.1177/15578682261429336","url":null,"abstract":"","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"203-204"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147389944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acute High-Altitude Exposure Increases Transcription of Tricarboxylic Acid Cycle Enzymes in Human Duodenal Biopsies.","authors":"Patrick-Pascal Strunz, Raphael N Vuille-Dit-Bille, Heiko Fruehauf, Mark Fox, Andreas Geier, Marco Maggiorini, Max Gassmann, Thomas A Lutz, Oliver Goetze","doi":"10.1177/15578682251374980","DOIUrl":"10.1177/15578682251374980","url":null,"abstract":"<p><p>Strunz, Patrick-Pascal, Raphael N. Vuille-dit-Bille, Heiko Fruehauf, Mark Fox, Andreas Geier, Marco Maggiorini, Max Gassmann, Thomas A. Lutz, and Oliver Goetze. Acute high-altitude exposure increases transcription of tricarboxylic acid cycle enzymes in human duodenal biopsies. <i>High Alt Med Biol</i>. 27:184-188, 2026.</p><p><strong>Background: </strong>A recent study of our group quantifying ¹³C-octanoate metabolism in HA (Capanna Margherita [MG]/4,559 m) showed that acute HA exposure might lead to an increase of the lipolytic and CO₂-producing pathways.</p><p><strong>Objective: </strong>To further test this hypothesis, we investigated intestinal biopsies from the same participants from simultaneously performed endoscopy studies for changes of mRNA-expression levels of the beta-oxidation enzymes and the decarboxylating tricarboxylic acid cycle (TCA) enzymes.</p><p><strong>Methods: </strong>Duodenal biopsies of 16 subjects exposed to HA were sampled via gastro-duodenoscopy at Zurich (baseline ZH, 490 m), on day 2 (MG2) and on day 4 at HA (MG4). After mRNA extraction, quantitative real-time polymerase chain reaction was performed to assess mRNAs expression of TCA cycle enzymes as well as beta-oxidation enzymes.</p><p><strong>Results: </strong>Aconitase mRNA levels increased early (MG2 vs. ZH, <i>p</i> < 0.05) and were still higher at day 4 compared with ZH (MG4 vs. ZH, <i>p</i> < 0.05). Isocitrate dehydrogenase (DH) levels increased with time spent at 4,559 m (MG4 vs. ZH, <i>p</i> < 0.01). The remaining TCA cycle and beta-oxidation enzymes investigated tended to higher values at HA but without reaching significance.</p><p><strong>Conclusion: </strong>We conclude that acute exposure to HA leads to increased transcription of aconitase and isocitrate DH in the duodenal mucosa due to hypobaric hypoxia exposure.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"184-188"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144951957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic Adaptation to Tibetan High Altitude and Hepatocellular Cancer Risk: Integrative Bidirectional Mendelian Randomization and Single-Cell RNA Sequencing Analysis.","authors":"Nimadeji, Yanna Cai, Na Gao","doi":"10.1177/15578682251409078","DOIUrl":"10.1177/15578682251409078","url":null,"abstract":"<p><p>Nimadeji, Yanna Cai, and Na Gao. Genetic adaptation to Tibetan high altitudes and hepatocellular cancer risk: integrative bidirectional Mendelian randomization and single-cell RNA sequencing analysis. <i>High Alt Med Biol.</i> 27:159-167, 2026.</p><p><strong>Background: </strong>The unique genetic adaptations of Tibetans to high-altitude environments may influence disease susceptibility, including hepatocellular carcinoma (HCC).</p><p><strong>Methods: </strong>We employed bidirectional two-sample Mendelian randomization (MR) using genome-wide association study summary statistics: high-altitude adaptation (HAA) data from Tibetan/non-Tibetan East Asians (<i>n</i> = 10,295) and HCC data from BioBank Japan (1,866 cases/195,745 controls). Instrumental variables were selected via genome-wide significance (<i>p</i> < 5 × 10^-8), with inverse variance-weighted random-effects models as primary analysis. MR-Egger regression analysis and Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) global analysis were used to evaluate the pleiotropic effect. Single-cell RNA sequencing from the Hepatocellular Carcinoma Database identified HAA-related differentially expressed genes (DEGs) in HCC tissues, followed by functional enrichment analysis.</p><p><strong>Results: </strong>MR results demonstrated HAA as a causal risk factor for HCC (odds ratio = 2.15 × 10², 95% confidence interval = 1.57-2.96 × 10⁴, <i>p</i> = 0.032), with no reverse causality. Single-cell analysis revealed 23 HAA-associated DEGs in HCC, enriched in immune regulation, DNA metabolism, and cell growth pathways. Notably, genes such as <i>EPAS1</i> and <i>GCH1</i>; Guanosine triphosphate, GTP, previously linked to Tibetan HAA, were found to be differentially expressed in HCC tissues.</p><p><strong>Conclusion: </strong>This study provides statistical and genetic evidence that HAA is a causal risk factor for HCC in Tibetans. The identification of HAA-related genes in HCC tissues offers new insights for targeted prevention and treatment strategies in Tibetan populations.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"159-167"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147432560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Altitude Environment and Chronic Obstructive Pulmonary Disease: Epidemiology, Pathological Mechanisms, and Clinical Management.","authors":"Shuna Wei, Xiaoju Liu","doi":"10.1177/15578682261428873","DOIUrl":"10.1177/15578682261428873","url":null,"abstract":"<p><p>Wei, Shuna, and Xiaoju Liu. High-altitude environment and chronic obstructive pulmonary disease: epidemiology, pathological mechanisms and clinical management. <i>High Alt Med Biol.</i> 27:189-202, 2026Background:Chronic obstructive pulmonary disease (COPD) is a significant global health concern. Environmental factors such as low oxygen and temperature, along with poor living habits in high-altitude areas, contribute to regional variations in the occurrence and progression of COPD. There is currently a lack of systematic reviews on the relationship between high-altitude environments and COPD, which hinders effective prevention and treatment.</p><p><strong>Methods: </strong>This narrative review comprehensively sorts out and analyzes the research on COPD in high-altitude areas from three aspects: epidemiological characteristics, pathophysiological mechanisms, and clinical management.</p><p><strong>Results: </strong>Epidemiologically, COPD mortality increases with altitude; however, prevalence rates remain debated. Pathophysiologically, factors include hypoxia-inducible factor regulation, hemodynamic changes, air pollution particles promoting inflammation and oxidative stress, as well as gene mutations like PPARA and SERPINA1. Clinically managing COPD in high-altitude regions requires individualized approaches that consider environmental conditions.</p><p><strong>Conclusion: </strong>High-altitude environments exacerbate COPD through hypoxic stress, pollutant exposure, and genetic variations. Future efforts should focus on developing a risk prediction model for COPD that incorporates altitude parameters to enhance targeted prevention and treatment strategies in these areas.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"189-202"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147389900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of OXXYSLAB Probiotic Supplementation on Blood Oxygenation and Hypoxic Symptoms in Healthy Individuals: A Controlled Normobaric Hypoxia Trial.","authors":"Manuel Marzola, Massimiliano Marazzato, Roberto Nutini, Adriano Di Marzio, Francesca Baroli, Manuel Paolucci, Matteo De Angelis, Joanna Giuliano, Ambra Menichelli, Guglielmo Sferrati, Carmen Santangelo, Danilo Bondi, Gerardo Bosco, Vittore Verratti","doi":"10.1177/15578682261415833","DOIUrl":"10.1177/15578682261415833","url":null,"abstract":"<p><p>Marzola, Manuel, Massimiliano Marazzato, Roberto Nutini, Adriano Di Marzio, Francesca Baroli, Manuel Paolucci, Matteo De Angelis, Joanna Giuliano, Ambra Menichelli, Guglielmo Sferrati, Carmen Santangelo, Danilo Bondi, Gerardo Bosco, and Vittore Verratti. Effects of OXXYSLAB probiotic supplementation on blood oxygenation and hypoxic symptoms in healthy individuals: A controlled normobaric hypoxia trial. <i>High Alt Med Biol.</i> 27:168-176, 2026.</p><p><strong>Background: </strong>OXXYSLAB, a high-dose, multi-strain probiotic, has shown promise in pathological hypoxemia but remains untested under acute normobaric hypoxia (NH) in healthy volunteers. We evaluated whether OXXYSLAB alters peripheral oxygen saturation (SpO₂) and alleviates hypoxia-related symptoms in healthy adults exposed to NH.</p><p><strong>Methods: </strong>In two randomized, double-blind, crossover phases, young adults were exposed to ∼13.5% inspired O₂ for 1 hour (Phase 1: <i>n</i> = 12, 21.6 ± 1.3 years, body mass index [BMI] = 23.2 ± 2.8 kg/m²) or 40 minutes (Phase 2: <i>n</i> = 20, 21.7 ± 1.5 years, BMI = 22.9 ± 3.2 kg/m²). Participants received either a single (8 × 10¹¹ colony-forming unit [CFU]) or double (1.6 × 10¹² CFU) dose of OXXYSLAB or matched placebo in randomized order.</p><p><strong>Results: </strong>NH induced the expected SpO₂ decrease (Phase 1: 90.0 ± 2.1%; Phase 2: 86.7 ± 2.9%), with no significant effect of probiotic supplementation on SpO₂. In Phase 1, a trend toward lower heart rate (Δ = -3.2 bpm) under OXXYSLAB approached significance (<i>p</i> = 0.053); no effect was seen in Phase 2. Notably, headache incidence under probiotic conditions was reduced by 50% (Phase 1) and 62.5% (Phase 2) compared to placebo (<i>p</i> = 0.046 and <i>p</i> = 0.059, respectively).</p><p><strong>Conclusion: </strong>While OXXYSLAB did not enhance systemic oxygenation during acute NH, it significantly attenuated headache, a common symptom of hypoxia. Further research should assess its efficacy under prolonged or clinical hypoxemic conditions.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"168-176"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146029447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Does Hydrogen-Rich Water Reduce Oxidative Stress in Patients with Chronic Mountain Sickness? A Randomized, Blinded, Controlled Trial.","authors":"Fengying Zhang, Yang Zhong, Qiuyue Li, Doudou Hao, Zhiyou Shi, Suying Zhu, Qian Zhang, Yunhong Wu","doi":"10.1177/15578682251401137","DOIUrl":"10.1177/15578682251401137","url":null,"abstract":"<p><p>Zhang, Fengying, Yang Zhong, Qiuyue Li, Doudou Hao, Zhiyou Shi, Suying Zhu, Qian Zhang, and Yunhong Wu. Does hydrogen-rich water reduce oxidative stress in patients with chronic mountain sickness? a randomized, blinded, controlled trial. <i>High Alt Med Biol.</i> 27:133-142, 2026.</p><p><strong>Background: </strong>Oxidative stress is implicated in the pathogenesis of chronic mountain sickness (CMS), providing a rationale for antioxidant therapies. This study evaluated the safety and efficacy of hydrogen-rich water (HRW) as a potential antioxidant in individuals with CMS.</p><p><strong>Methods: </strong>We conducted an 8-week, randomized, blinded, placebo-controlled trial at the Tibetan Hospital of Nagqu, China. Adults with untreated CMS (defined by Qinghai score) were randomly assigned (1:1) to receive 990 ml/day of HRW or placebo using a dynamic minimization method. Participants, clinicians, and investigators were blinded to treatment allocation. The primary efficacy endpoint was change in oxidative stress biomarkers from baseline to week 8, including catalase, glutathione, malondialdehyde (MDA), superoxide dismutase, 8-hydroxy-2'-deoxyguanosine, and total antioxidant capacity (T-AOC). Safety was assessed by adverse event reporting. This trial has been completed and is registered at chictr.org under the identifier ChiCTR2400082685.</p><p><strong>Results: </strong>From July 3 to December 24, 2024, 60 participants were randomized; one in the placebo group did not receive treatment and was excluded from the analysis. At week 8, HRW produced greater changes in MDA and T-AOC compared with placebo: MDA, +2.11 (95% CI: 1.13-3.09; <i>p</i> < 0.001); T-AOC, +2.86 (95% CI: 0.09-5.64; <i>p</i> = 0.043). In participants with body mass index (BMI) ≥24, the increase in MDA was more pronounced (Δ+2.57; <i>p</i> = 0.02 for interaction). Adverse events occurred in 50% (15/30) of the hydrogen group and 37% (11/29) of the placebo group; dizziness was the most common.</p><p><strong>Conclusion: </strong>HRW demonstrated both pro-oxidative and antioxidative effects in CMS. However, it did not reduce oxidative stress-induced damage and may increase oxidative risk in individuals with higher BMI.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"133-142"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145722331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of Mitochondrial tRNA^Leu 12320 A>G Mutation on Heart Rate Variability and Blood Pressure at Low-Altitude and in a High-Altitude Hypoxic Environment.","authors":"Cuiping Pan, Qunyuan Wang, Minglei Zhang, Ruizhe Li, Yining Liu, Zongbin Li","doi":"10.1177/15578682251411931","DOIUrl":"https://doi.org/10.1177/15578682251411931","url":null,"abstract":"<p><p>Pan, Cuiping, Qunyuan Wang, Minglei Zhang, Ruizhe Li, Yining Liu, and Zongbin Li. Role of mitochondrial tRNA^Leu 12320 A>G mutation on heart rate variability and blood pressure at low altitude and in a high-altitude hypoxic environment. <i>High Alt Med Biol.</i> 27:152-158, 2026.</p><p><strong>Introduction: </strong>Mutations-gene mutations-can exert dual, environment-dependent effects on cardiovascular disease.</p><p><strong>Materials and methods: </strong>We analyzed clinical data and mitochondrial DNA from 84 young Han Chinese men ascending from low-altitude to high-altitude regions (>4,000 m).</p><p><strong>Results: </strong>Nine subjects harbored the mitochondrial tRNA A12320G mutation. Notably, none of these 9 mutation carriers developed acute mountain sickness (AMS), whereas 34 (40.5%) of the 84 volunteers in the cohort were diagnosed with AMS, indicating a significant protective association (<i>p = 0.009</i>). In the low-altitude environment, time domain parameters of heart rate variability (HRV) in the mutant volunteers were significantly lower than those in the unmutated volunteers (SDNN: 141.76 ± 30.75 ms vs.169.08 ± 32.83 ms, <i>p</i> = 0.020; RMSSD: 29.70 ms vs. 41.35 ms, <i>p</i> = 0.022; HRV triangular index: 41.8% vs. 52.4%, <i>p</i> = 0.024; SDSD: 37.4 ms vs. 50.5 ms, <i>p</i> = 0.016; PNN50: 3.1% vs 7.6%, <i>p</i> = 0.008); 24-hour mean systolic blood pressure (118.63 ± 9.54 vs. 113.39 ± 6.30 mmHg, <i>p</i> = 0.029), nocturnal mean diastolic blood pressure (67.37 ± 7.91 vs. 61.11 ± 7.08 mmHg, <i>p</i> = 0.015) were also higher; HRV and blood pressure were not statistically different between the mutant and nonmutant groups in the high-altitude environment. Hematological analysis revealed mutants at high altitude had significantly lower plateletcrit (0.23% vs. 0.26%, <i>p</i> = 0.019) and total protein (72.78 ± 3.84 g/L vs.75 .65 ± 3.0 g/L, <i>p</i> = 0.008).</p><p><strong>Conclusion: </strong>The A12320G mutation acts as a cardiovascular risk factor (reduced HRV, increased blood pressure) at low altitude, whereas at high altitude it was associated with a reduced incidence of AMS, possibly through metabolic adaptive mechanisms, reflecting the environmentally dependent dual roles of this gene effect.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":"27 3","pages":"152-158"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148520249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved Pulmonary Gas Exchange at Altitude Is Due to Pulmonary Vascular Adaptation to Chronic Hypoxia in Urban Residents.","authors":"Robin Willixhofer, Laura Gochicoa-Rangel, Anna Apostolo, Jeness Campodonico, Elisabetta Salvioni, Ada De-Los-Santos-Martínez, Alejandro Reyes-García, Luis Torre-Bouscoulet, Sergio Harari, Federico Tagariello, Piergiuseppe Agostoni","doi":"10.1177/15578682251401133","DOIUrl":"10.1177/15578682251401133","url":null,"abstract":"<p><p>Willixhofer, Robin, Laura Gochicoa-Rangel, Anna Apostolo, Jeness Campodonico, Elisabetta Salvioni, Ada De-Los-Santos-Martínez, Alejandro Reyes-García, Luis Torre-Bouscoulet, Sergio Harari, Federico Tagariello, and Piergiuseppe Agostoni. Improved pulmonary gas exchange at altitudes is due to pulmonary vascular adaptation to chronic hypoxia in urban residents. <i>High Alt Med Biol.</i> 27:177-183, 2026.</p><p><strong>Background: </strong>Chronic exposure to high altitude induces physiological adaptations in the lung, but the specific mechanisms of alveolar-capillary gas exchange adaptation in urban populations remain incompletely understood.</p><p><strong>Methods: </strong>We assessed altitude-related alveolar capillary membrane gas diffusion adaptations in Milan (lowlanders, 120 m) and Mexico City (highlanders, 2,240 m). A 1:1 nearest-neighbor matching by age and sex was performed.</p><p><strong>Results: </strong>Comparison between healthy young adults (<i>n</i> = 246, age <40 years) showed higher diffusing capacity for carbon monoxide (D_LCO: 31.7 [27.4-39.0] vs. 28.2 [24.6-32.8] ml/min/mmHg, <i>p</i> < 0.0001) and pulmonary capillary blood volume (Vcap: 105 [87-113] vs. 84 [71-98] ml, <i>p</i> < 0.0001), but lower membrane diffusing capacity (Dm: 50 [45-60] vs. 61 [51.70] ml/min/mmHg, <i>p</i> < 0.0001) in highlanders. The matching procedure yielded 71 pairs (<i>n</i> = 142) with balanced age and sex distributions (standardized mean differences <0.1). These differences remained significant after matching: highlanders showed higher DLCO (31.7 [27.8-39.1] vs. 27.1 [23.7-32.4] ml/min/mmHg, <i>p</i> < 0.0001), higher Vcap (104 [85-124] vs. 78 [65-96] ml, <i>p</i> < 0.0001), and lower Dm (51 [46-60 vs. 57 [50-68] ml/min/mmHg, <i>p</i> = 0.045).</p><p><strong>Conclusions: </strong>These findings suggest vascular, rather than membrane, adaptation to chronic hypoxia in high-altitude urban residents.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"177-183"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145603931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Physiological and Altitude Lowering Effects of Different Supplemental Oxygen Flow Rates at Extreme Simulated Altitude: A Pilot Study.","authors":"Denis J Wakeham, Andrew R Tomlinson, Giorgio Manferdelli, Matthew M Howrey, Anna K Geib, Murugappan Ramanathan, Marcus Payne, Renie Guilliod, James Berry, Tony G Babb, Peter Hackett, Benjamin D Levine, Christopher M Hearon","doi":"10.1177/15578682251396453","DOIUrl":"10.1177/15578682251396453","url":null,"abstract":"<p><p>Wakeham, Denis J., Andrew R. Tomlinson, Giorgio Manferdelli, Matthew M. Howrey, Anna K. Geib, Murugappan Ramanathan, Marcus Payne, Renie Guilliod, James Berry, Tony G. Babb, Peter Hackett, Benjamin D. Levine, and Christopher M. Hearon, Jr. The physiological and altitude lowering effects of different supplemental oxygen flow rates at extreme simulated altitude: a pilot study. <i>High Alt Med Biol.</i> 27:143-151, 2026.</p><p><strong>Background: </strong>Approximately 80% of high-altitude climbers use supplemental oxygen >8,000 meters, yet optimal dosing strategies have not been established.</p><p><strong>Methodology: </strong>Therefore, in six unacclimatized individuals (34 ± 8 years; 2 F/4 M), we quantified the effects of supplemental oxygen flow rates (6, 4, 2, 1 and 0 L/min) using the SUMMIT Oxygen mask at 282 mmHg (rest and cycle ergometry: 60 and 120 Watts) and 253 mmHg (rest only) barometric pressure in a hypobaric chamber. We measured oxygen saturation (SpO₂) and gas fractions in the mask during 4-minute exposures to each flow rate.</p><p><strong>Results: </strong>Resting at 282 mmHg, SpO₂ (6 L/min: 99% ± 0%; 0 L/min: 70% ± 8%, <i>p</i> < 0.001) and mean inspired oxygen fraction decreased (6 L/min: 65.87% ± 14.11%; 0 L/min: 21.50% ± 0.44%, <i>p</i> < 0.001) with lowering of supplemental oxygen. Exercise further decreased SpO₂ and oxygen fractions across all flow rates at 282 mmHg. At 253 mmHg, SpO₂ followed a similar trend to data collected at 282 mmHg (6 L/min: 96% ± 2%; 4 L/min: 93% ± 3%; 2 L/min: 87% ± 3%; 1 L/min: 71% ± 0%; 0 L/min: 66% ± 9%). Furthermore, at rest at 253 mmHg, 2 L/min of supplemental oxygen lowered the equivalent altitude to 4,489 meters.</p><p><strong>Conclusion: </strong>All unacclimatized participants were able to tolerate 253 mmHg at rest on as little as 2 L/min of supplemental oxygen.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"143-151"},"PeriodicalIF":1.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145862862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Association Between Chronic High-Altitude Exposure and Increased Pulmonary Vascular Resistance in Healthy High-Altitude Residents: A Systematic Review and Meta-Analysis.","authors":"Julian Müller, Anna Titz, Pascal Yoncaova, Michael Furian, Mona Lichtblau, Ruth McQuillan, Marshall Dozier, Evropi Theodoratou, Silvia Ulrich","doi":"10.1177/15578682261479695","DOIUrl":"https://doi.org/10.1177/15578682261479695","url":null,"abstract":"<p><p>Müller, Julian, Anna Titz, Pascal Yoncaova, Michael Furian, Mona Lichtblau, Ruth McQuillan, Marshall Dozier, Evropi Theodoratou, and Silvia Ulrich.The association between chronic high-altitude exposure and increased pulmonary vascular resistance in healthy high-altitude residents. A systematic review and meta-analysis. <i>High Alt Med Biol.</i> 00:00-00, 2026.</p><p><strong>Background: </strong>At high altitude, hypoxia triggers pulmonary vasoconstriction and vascular remodeling, potentially elevating pulmonary vascular resistance (PVR). Whether chronic high-altitude exposure raises PVR to clinically meaningful levels remain unclear, particularly in the context of long-term physiological adaptation.</p><p><strong>Objectives: </strong>To synthesize and assess the evidence of the association between chronic high-altitude exposure and PVR in healthy high-altitude residents.</p><p><strong>Eligibility criteria: </strong>Peer-reviewed studies reporting PVR measured by echocardiography or right heart catheterization in healthy adults permanently residing at high altitude were eligible. Studies involving acute or intermittent hypoxia exposure, animal subjects, or pediatric populations were excluded.</p><p><strong>Methods: </strong>A systematic literature search was conducted across four electronic databases (Medline, Embase, Scopus, and Web of Science) covering all records from database inception through October 2025. Two reviewers independently screened abstracts and full texts using Covidence software. Risk of bias was assessed using the modified National Heart, Lung, and Blood Institute Quality Assessment Tool. Random-effects meta-analyses were performed. A sensitivity analysis excluded studies with high risk of bias.</p><p><strong>Results: </strong>Out of 464 identified records, 13 studies met eligibility criteria, comprising 854 participants (80% males) across different populations in South America, Asia, and Africa. Most studies were conducted between 3,500 and 4,000 m. The primary pooled PVR estimate was 2.4 WU (2.0-2.8 WU), which slightly exceeds the sea level upper limit of normal (2.0-2.2 WU). Following exclusion of high-risk-of-bias studies, the estimate decreased to 2.2 WU (1.9-2.5 WU), approaching the upper limit of normal. However, substantial heterogeneity was observed in all analyses.</p><p><strong>Limitations: </strong>The small number of included studies, heterogeneity, measurement technique, predominance of male participants, and narrow altitudinal range of most studies limit the generalizability of the findings.</p><p><strong>Conclusions: </strong>Chronic high-altitude exposure is associated with a slight elevation in PVR in otherwise healthy individuals. However, the clinical significance of this elevation remains unknown. These findings highlight the need for altitude-specific reference values, prospective studies, and further investigation into the role of blood viscosity in interpreting PVR at high altitude.</p>","PeriodicalId":12975,"journal":{"name":"High altitude medicine & biology","volume":" ","pages":"15578682261479695"},"PeriodicalIF":1.3,"publicationDate":"2026-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148792464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}