Lake Louise Acute Mountain Sickness Research Articles

Acute mountain sickness predicts the emotional state of amateur mountaineers.

Research on amateur mountaineers is scarce, and this study aims to delve into the emotional experiences of ten amateur mountaineers during their ascent using the "Befindlichkeitsskala" (BFS) and Lake Louise Acute Mountain Sickness scoring system (LLS). These subjects were exposed to altitudes of 3140m, 4300m, and 5276m, respectively. We found that LLS scores were negatively correlated with positive emotions (β = -27.54, p < 0.05) and positively correlated with negative emotions (β = 21.97, p < 0.05). At an altitude of 4300m, individuals with AMS exhibited significant differences in depression, anger, excitement, and inactivity compared to climbers without AMS. Upon returning to 3140m after completing the climb, significant differences were observed in emotions such as happiness, calmness, anger, excitement, and depression. Throughout the three-day climb, noteworthy differences emerged in activity, happiness, calmness, inactivity, positive emotions (p < 0.01), negative emotions, and overall emotional scores (p < 0.05). Our study suggests a decline in the emotional well-being of amateur climbers with increasing altitude, highlighting AMS as a pivotal predictive factor for emotional experiences while climbing.

The effects of the menstrual cycle on the physiological responses to exercise in eumenorrheic women at high-altitude

Introduction&#x0D; The acute mountain sickness (AMS) prevalence increases with altitude; i.e.,10-25% at 2,500 m and 50-85% at ~5,000 m (Bärtsch &amp; Swenson, 2013). Women are more likely affected by AMS than men (Richalet et al., 2012). AMS can affect exercise performance. However, the effects of the menstrual cycle (MC) on physiological responses to exercise and on tolerance to high-altitude (HA) remain underexplored. It has been reported that ovarian hormones stimulate ventilation in normoxic conditions (Saaresranta &amp; Polo, 2002). Early findings suggest that running economy is lower in the mid-luteal (ML) compared to the early-follicular (EF) phase in normoxia (Goldsmith &amp; Glaister, 2020). However, cycling efficiency at HA has not been explored yet. Thus, we investigated the effects of acute HA exposure on ventilatory responses at rest and during exercise in healthy females during two different phases of their MC.&#x0D; Methods&#x0D; Sixteen eumenorrheic women (age: 33 ± 7 yr; MC length: 27 ± 2 days; not taking any hormonal contraceptive) took part in this study. First, over a 6-month period, the participants’ MC were monitored using a calendar method. Then, they reached the Torino Hut (3,375 m) by cable car and spent one night at HA on two different MC phases; i.e., during the early-follicular (EF; MC day 4 ± 1) and the mid-luteal (ML; day 20 ± 2) phases. Each time, they underwent a submaximal (1.2 W/kg) test on a cycle ergometer ~17 h after arrival at HA. In addition to this, participants filled in two questionnaires, the Lake Louise AMS Score and the Groningen Sleep Quality Scale, ~16 h after arrival at HA.&#x0D; Results&#x0D; Resting ventilation was significantly higher during EF compared to ML (15.2 ± 1.9 vs. 13.2 ± 2.5 L/min, p = 0.039), while no differences were found for ventilation during exercise (53.9 ± 13.2 vs. 53.5 ± 13.4 L/min, p = 0.695), cycling efficiency (21.7 ± 0.0% vs. 19.8 ± 0.0%, p = 0.244), saturation at rest (92.4 ± 1.3 vs. 91.3 ± 3.2%, p = 0.142) and during exercise (87.2 ± 5.7 vs. 89.0 ± 4.0%, p = 0.528). Moreover, no differences in the Lake Louise AMS (2.2 ± 1.5 vs. 1.7 ± 1.5, p = 0.266) or Groningen (8.0 ± 3.3 vs. 7.5 ± 3.4, p = 0.668) scores were noted between the two MC phases.&#x0D; Discussion/Conclusion&#x0D; Despite a slightly higher resting ventilation during EF, when both oestrogens and progesterone are at their lowest levels, there were no differences in ventilatory responses to exercise and in AMS between the different phases of the MC. Consequently, there is currently very little evidence to aptly recommend a specific MC phase for mountaineering or any other HA activities (Burtscher et al., 2023). Further investigations are requested to assess whether other physiological responses to HA may be influenced by hormonal variations.&#x0D; References&#x0D; Bärtsch, P., &amp; Swenson, E. R. (2013). Acute high-altitude illnesses. New England Journal of Medicine, 368, 2294–2302. https://doi.org/10.1056/NEJMcp1214870&#x0D; Burtscher, J., Raberin, A., Brocherie, F., Malatesta, D., Manferdelli, G., Citherlet, T., Krumm, B., Bourdillon, N., Antero, J., Rasica, L., Burtscher, M. &amp; Millet, G. P. (2023). Recommendations for women in mountain sports and hypoxia training/conditioning. Sports Medicine. Advance online publication. https://doi.org/10.1007/s40279-023-01970-6&#x0D; Goldsmith, E., &amp; Glaister, M. (2020). The effect of the menstrual cycle on running economy. The Journal of Sports Medicine and Physical Fitness, 60(4), 610–617. https://doi.org/10.23736/s0022-4707.20.10229-9&#x0D; Richalet, J.-P., Larmignat, P., Poitrine, E., Letournel, M., &amp; Canouï-Poitrine, F. (2012). Physiological risk factors for severe high-altitude illness: A prospective cohort study. American Journal of Respiratory and Critical Care Medecine, 185(2), 192–198. https://doi.org/10.1164/rccm.201108-1396OC&#x0D; Saaresranta, T., &amp; Polo, O. (2002). Hormones and breathing. American College of Chest Physicians, 122(6), 2165–2182. https://doi.org/10.1378/chest.122.6.2165

Effects of age on hypoxic tolerance in women

Effects of age on hypoxic tolerance in women

Mountaineering And Altitude Sickness: A Study of AMS Prevalence among Climbers of Mount Kinabalu, Malaysia

Introduction: Adventure tourism has become one of Malaysia’s most attractive tourism demands, and mountain climbing is rapidly becoming a popular recreational sport. Exploring mountain adventures offers a dynamic experience, preserving this fascinating activity, yet the climbers are exposed to the risk of altitude sickness, such as Acute Mountain Sickness (AMS). This study aimed to evaluate the prevalence of AMS and investigate the effects of high-altitude sickness on the climber profile associated with climbing at Mount Kinabalu, Malaysia. Methods:. The Lake Louise acute mountain sickness LLS score questionnaire collected 95 climber’s data at four different altitudes. SPO2 and Pulse rate was (PR) measured using a finger pulse oximeter. In a cohort study, AMS was measured on day one at 1866m (1st station), 3622m (2nd station), and day two at 3810m (3rd station), and 4095m (4th station). Results: At the altitude of 1866 (Timpohon Gate), the prevalence of AMS was 0%, 30% at 3622m (Laban Rata), 34.7% at 3810m (Sayat-Sayat), and 37.9% at 4095m (Low’s Peak). The overall prevalence of AMS was 37.9% and the majority of AMS cases were moderate in severity and the LLS score is significant with Pulse Rate and peripheral capillary oxygen saturation (SPO2). Conclusion: Concisely, this finding has triggered a need for consideration from multi agencies to enhance mountaineering guidance, especially for beginners or inexperienced hikers, for a suitable package for climbing attempts to reduce the incidence of AMS among Mount Kinabalu climbers.

Assessment of hypoxia tolerance to high-altitude exposure following sleep deprivation

Objectives: The adverse effects of hypoxia and sleep deprivation (SD) have been studied separately but there is little literature on their effects when acting in conjunction. Hence, the effects of SD on hypoxia tolerance and cognitive performance when exposed to altitude were investigated. Material and Methods: In a cross-sectional repetitive measure design, 15 healthy volunteers assessed on cognitive performance were made to perform cognitive tests (Dual Task Test, Stroop Test [ST], and Digit Symbol Substitution Test [DSST] of Psychometric Evaluation Designed for Aviators test battery) on the ground and at a simulated altitude of 17,000 ft in a hypobaric chamber on 4 days. On the 2nd and 3rd day, the tests were done following 2 h of SD the previous night, and on the 4th day, the same was repeated following normal recovery sleep. Heart rate (HR) and respiratory rate (RR) were measured on the ground and 17,000 ft. The Lake Louise Acute Mountain Sickness (LLAMS) scores were used to assess the severity of symptoms of hypoxia and time to arterial oxygen desaturation of 75% was used to measure hypoxia tolerance. Results: Although not statistically significant, the LLAMS scores showed an increasing trend on SD days with an improvement in recovery of sleep. No statistically significant differences in the HR (F = 0.569, P = 0.637) and RR (F = 0.569, P = 0.637) were observed across the days of SD or recovery. The time to oxygen desaturation to 75% also showed no significant effect (F = 0.587, P = 0.625). A statistically significant increase in response times of two cognitive tests (ST and DSST) was observed on exposure to altitude on all 4 days. The three cognitive tests did not show any statistically significant effect following 2 h of SD or recovery. Conclusion: The study could not elicit a statistically significant effect of 2 h of SD across 2 consecutive nights on the cognitive performance measures on exposure to hypoxia.

Association of Pre-existing Mental Health Conditions with Acute Mountain Sickness at Everest Base Camp.

Hüfner, Katharina, Fabio Caramazza, Evelyn R. Pircher Nöckler, Agnieszka E. Stawinoga, Paolo Fusar-Poli, Sanjeeb S. Bhandari, Buddha Basnyat, Monika Brodmann Maeder, Giacomo Strapazzon, Iztok Tomazin, Ken Zafren, Hermann Brugger, and Barbara Sperner-Unterweger. Association of pre-existing mental health conditions with acute mountain sickness at Everest Base Camp. High Alt Med Biol. 23:338-344, 2022. Background: Mental health disorders are common, but limited data are available regarding the number of people with a past medical history of psychiatric diagnoses going to high altitude (HA). It is also unknown whether mental health conditions are associated with an increased risk of acute mountain sickness (AMS). Methods: We analyzed data from a previous study at Everest Base Camp. Participants self-reported their past medical history and history of substance use and had a brief history taken by a physician. AMS was assessed using the self-reported 2018 Lake Louise AMS Score. Results: Eighty-five participants (66 men and 19 women, age 38 ± 9 years) were included. When questioned by a physician, 28 participants reported prior diagnoses or symptoms compatible with depression (23%), anxiety disorder (6%), post-traumatic stress disorder (1%), and psychosis/psychotic experiences (9%). The prevalence of psychiatric diagnoses in the past medical history was much lower in the self-reported data (2/85) compared to data obtained via physician assessment (28/85). Increased risks of AMS were associated with a past medical history of anxiety disorder (odds ratio [OR] 22.7; confidence interval [95% CI] 2.3-220.6; p < 0.001), depression (OR 3.6; 95% CI 1.2-11.2; p = 0.022), and recreational drug use ever (OR 7.3; 95% CI 1.5-35.5; p = 0.006). Conclusions: Many people who travel to HA have a past medical history of mental health conditions. These individuals have an increased risk of scoring positive for AMS on the Lake Louise Score compared with people without a history of mental health conditions.

Baseline Psychological Traits Contribute to Lake Louise Acute Mountain Sickness Score at High Altitude

Talks, Benjamin James, Catherine Campbell, Stephanie J. Larcombe, Lucy Marlow, Sarah L. Finnegan, Christopher T. Lewis, Samuel J.E. Lucas, Olivia K. Harrison, and Kyle T.S. Pattinson. Baseline psychological traits contribute to Lake Louise Acute Mountain Sickness score at high altitude. High Alt Med Biol. 23:69–77, 2022.Background:Interoception refers to an individual's ability to sense their internal bodily sensations. Acute mountain sickness (AMS) is a common feature of ascent to high altitude that is only partially explained by measures of peripheral physiology. We hypothesized that interoceptive ability may explain the disconnect between measures of physiology and symptom experience in AMS.Methods:Two groups of 18 participants were recruited to complete a respiratory interoceptive task three times at 2-week intervals. The control group remained in Birmingham (140 m altitude) for all three tests. The altitude group completed test 1 in Birmingham, test 2 the day after arrival at 2,624 m, and test 3 at 2,728 m after an 11-day trek at high altitude (up to 4,800 m).Results:By measuring changes to metacognitive performance, we showed that acute ascent to altitude neither presented an interoceptive challenge, nor acted as interoceptive training. However, AMS symptom burden throughout the trek was found to relate to sea level measures of anxiety, agoraphobia, and neuroticism.Conclusions:This suggests that the Lake Louise AMS score is not solely a reflection of physiological changes on ascent to high altitude, despite often being used as such by researchers and commercial trekking companies alike.

No effect of patent foramen ovale on acute mountain sickness and pulmonary pressure in normobaric hypoxia.

What is the central question to this study? Is there a relationship between a patent foramen ovale and the development of acute mountain sickness and an exaggerated increase in pulmonary pressure in response to 7-10h of normobaric hypoxia? What is the main finding and its importance? Patent foramen ovale presence did not increase susceptibility to acute mountain sickness or result in an exaggerated increase in pulmonary artery systolic pressure with normobaric hypoxia. This suggests hypobaric hypoxia is integral to the increased susceptibility to acute mountain sickness previously reported in those with patent foramen ovale, and patent foramen ovale presence alone does not contribute to the hypoxic pulmonary pressor response. Acute mountain sickness (AMS) develops following rapid ascent to altitude, but its exact causes remain unknown. A patent foramen ovale (PFO) is a right-to-left intracardiac shunt present in ∼30% of the population that has been shown to increase AMS susceptibility with high altitude hypoxia. Additionally, high altitude pulmonary oedema (HAPE) is a severe type of altitude illness characterized by an exaggerated pulmonary pressure response, and there is a greater prevalence of PFO in those with a history of HAPE. However, whether hypoxia per se is causing the increased incidence of AMS in those with a PFO and whether a PFO is associated with an exaggerated increase in pulmonary pressure in those without a history of HAPE is unknown. Participants (n=36) matched for biological sex (18 female) and the presence or absence of a PFO (18 PFO+) were exposed to 7-10h of normobaric hypoxia equivalent to 4755m. Presence and severity of AMS was determined using the Lake Louise AMS scoring system. Pulmonary artery systolic pressure, cardiac output and total pulmonary resistance were measured using ultrasound. We found no significant association of PFO with incidence or severity of AMS and no association of PFO with arterial oxygen saturation. Additionally, there was no effect of a PFO on pulmonary pressure, cardiac output or total pulmonary resistance. These data suggest that hypobaric hypoxia is necessary for those with a PFO to have increased incidence of AMS and that presence of PFO is not associated with an exaggerated pulmonary pressor response.

Using machine learning to determine the correlation between physiological and environmental parameters and the induction of acute mountain sickness

BackgroundRecent studies on acute mountain sickness (AMS) have used fixed-location and fixed-time measurements of environmental and physiological variable to determine the influence of AMS-associated factors in the human body. This study aims to measure, in real time, environmental conditions and physiological variables of participants in high-altitude regions to develop an AMS risk evaluation model to forecast prospective development of AMS so its onset can be prevented.ResultsThirty-two participants were recruited, namely 25 men and 7 women, and they hiked from Cuifeng Mountain Forest Park parking lot (altitude: 2300 m) to Wuling (altitude: 3275 m). Regression and classification machine learning analyses were performed on physiological and environmental data, and Lake Louise Acute Mountain Sickness Scores (LLS) to establish an algorithm for AMS risk analysis. The individual R2 coefficients of determination between the LLS and the measured altitude, ambient temperature, atmospheric pressure, relative humidity, climbing speed, heart rate, blood oxygen saturation (SpO2), heart rate variability (HRV), were 0.1, 0.23, 0, 0.24, 0, 0.24, 0.27, and 0.35 respectively; incorporating all aforementioned variables, the R2 coefficient is 0.62. The bagged trees classifier achieved favorable classification results, yielding a model sensitivity, specificity, accuracy, and area under receiver operating characteristic curve of 0.999, 0.994, 0.998, and 1, respectively.ConclusionThe experiment results indicate the use of machine learning multivariate analysis have higher AMS prediction accuracies than analyses utilizing single varieties. The developed AMS evaluation model can serve as a reference for the future development of wearable devices capable of providing timely warnings of AMS risks to hikers.

Echocardiographic Right Ventricular Outflow Track Notch Formation and the Incidence of Acute Mountain Sickness.

Yuan, Fangzhengyuan, Zhexue Qin, Chuan Liu, Shiyong Yu, Jie Yang, Jun Jin, Shizhu Bian, Xubin Gao, Jihang Zhang, Chen Zhang, Mingdong Hu, Jingbin Ke, Yuanqi Yang, Jingdu Tian, Chunyan He, Wenzhu Gu, Chun Li, Rongsheng Rao, and Lan Huang. Echocardiographic right ventricular outflow track notch formation and the incidence of acute mountain sickness. High Alt Med Biol. 22:263-273, 2021. Background: High-altitude exposure causes acute mountain sickness (AMS) and increases pulmonary arterial pressure (PAP). The notching of echocardiographic right ventricular outflow tract flow velocity envelope (right ventricular outflow tract [RVOT] notching), is related to increased PAP. We speculate that acute high-altitude exposure may trigger RVOT notching, which may be associated with AMS. Methods: All 130 subjects, ascended to 4,100 m from low altitude by bus within 7 days, underwent physiological and echocardiographic testing. The subjects with a total score of 3 or above and in the presence of a headache were diagnosed with AMS according to Lake Louise criteria. Results: After high-altitude exposure, the incidence of RVOT notching and AMS was 20% and 28.5%, respectively. The subjects with AMS had a higher incidence (37.8%) of RVOT notching than those without AMS (12.9%). Multivariate logistic regression analysis showed that RVOT notching was associated with systolic pulmonary artery pressure (SPAP) (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.05-1.17; p < 0.001) and the occurrence of AMS (OR, 5.48; 95% CI, 1.96-15.35; p = 0.001). Although linear regression analysis showed a weak correlation between SPAP and Lake Louise AMS score in the overall population (r = 0.20, p = 0.020), this correlation was more pronounced in the subpopulation with RVOT notching (r = 0.44, p = 0.023) and SPAP was not related to Lake Louise AMS score in the subpopulation without RVOT notching (r = 0.03, p = 0.698). Among AMS symptoms, the incidence of headache and fatigue were higher in subjects with RVOT notching than those in subjects without RVOT notching. Conclusions: We first observe that high-altitude exposure triggers RVOT notching formation, which is associated with AMS occurrence. Clinical Trials.gov ID: ChiCTR-RCS-12002232.

Visual hallucinations in 246-km mountain ultra-marathoners: An observational study.

Ultra-marathons are typically held over harsh terrains such as mountains, deserts, or other wilderness, and place severe demands on the physical and psychological capabilities of participants. Adventure-race competitors commonly report hallucinations. The goal of this study was to gain insight into visual hallucinations (VHs) during a mountain ultra-marathon. Thirty-one Taiwanese runners who participated in the 2018 Run Across Taiwan Ultra-Marathon, which spans 246 km with an altitude difference of 3266 m and an overall cut-off time of 44 h, volunteered for this study. Self-reported questionnaires on sleep duration, hallucinatory experiences, clinical symptoms of cold- and heat-related illnesses, and the 2018 Lake Louise Acute Mountain Sickness (AMS) Score were recorded prerace, during the summit, immediately postrace, and 3-days postrace. Hematological samples were collected 1 week before, immediately after, and 3 days after the race. Eight ultra-marathoners (six males and two females; seven finishers and one withdrawer) were recruited. Three out of eight (37.5%) subjects (two males and one female) reported experiencing VHs during the last 60 km. Three out of five (60%) lower-ranked subjects experienced VHs. All eight runners slept for <30 min during the race. None of the runners presented with headache either during or after the race to meet the criteria for AMS. None of the runners suffered an abnormal thermoregulatory response or a hypoglycemic episode throughout the ultra-marathon. The changes in blood osmolality immediately postrace were subclinical, despite being statistically significant. Among the three runners with VHs, none presented with severe dehydration or dysnatremia immediately postrace. High-altitude exposure, hyper/hypothermia, dehydration, dysnatermia, or hypoglycemia did not seem to contribute to hallucination onset in our subjects during the event. VHs of ultra-marathoners may be associated with excessive physical exertion and sleep deprivation.

Deceleration Capacity and Periodic Repolarization Dynamics As Predictors of Acute Mountain Sickness.

Hamm, Wolfgang, Sari Kassem, Lukas von Stülpnagel, Florian Maier, Mathias Klemm, Dominik Schüttler, Felix Grabher, Ludwig T. Weckbach, Bruno C. Huber, Axel Bauer, Konstantinos D. Rizas, and Stefan Brunner. Deceleration capacity and periodic repolarization dynamics as predictors of acute mountain sickness. High Alt Med Biol. 21:417-422, 2020. Background: The autonomic nervous system plays an important role in adaptive changes after acute altitude exposure. Periodic repolarization dynamics (PRD) and deceleration capacity (DC) of heart rate are advanced electrocardiogram (ECG)-based parameters reflecting sympathetic (PRD) and parasympathetic (DC) tone. These parameters have not been investigated in the context of acute mountain sickness (AMS) yet. Methods: In 23 healthy individuals (13 women), a high-resolution digital 30-minute ECG in Frank leads configuration was performed in a resting supine position at baseline (521 m altitude) and after a sojourn of 24 hours at the Environmental Research Station Schneefernerhaus (UFS) at Zugspitze (2,650 m altitude). PRD and DC were assessed using validated software. Symptoms of AMS were assessed with the Lake Louise Acute Mountain Sickness Score (LLS). Results: During altitude exposure, PRD significantly increased from 1.50 ± 1.01 (mean ± standard deviation) deg2 to 3.51 ± 4.46 deg2 (p = 0.03). DC significantly decreased from 11.48 ± 2.91 ms to 9.94 ± 2.78 ms (p = 0.001). An increase of PRD and/or a decrease of DC correlated significantly with the level of LLS. The combined finding of an increase of PRD and a decrease of DC had a sensitivity of 100% and a specificity of 76.5% to diagnose AMS (LLS ≥3). Receiver operating characteristic (ROC) analysis showed an AUC (area under the ROC curve) of 0.77. Linear regression analysis revealed a significant association between LLS and an increase in PRD during high-altitude exposure. Conclusions: Our findings show an increase of PRD and a decrease of DC during altitude exposure. Combined PRD and DC analysis may have potential for the diagnosis of AMS.

Systemic Blood Pressure Variation During a 12-Hour Exposure to Normobaric Hypoxia (4500 m).

This study was aimed at evaluating a potential association between blood pressure variation and acute mountain sickness (AMS) during acute exposure to normobaric hypoxia. A total of 77 healthy subjects (43 males, 34 females) were exposed to a simulated altitude of 4500 m for 12 hours. Peripheral oxygen saturation, heart rate, systemic blood pressure, and Lake Louise AMS scores were recorded before and during (30 minutes, 3, 6, 9, and 12 hours) hypoxic exposure. Blood pressure dips were observed at 3-hour mark. However, systolic blood pressure fell more pronounced from baseline during the initial 30 minutes in normobaric hypoxia (-17.5 vs. -11.0 mmHg, p = 0.01) in subjects suffering from AMS (AMS+; n = 56) than in those remaining unaffected from AMS (AMS-; n = 21); values did not differ between groups over the subsequent time course. Our data may suggest a transient autonomic dysfunction resulting in a more pronounced blood pressure drop during initial hypoxic exposure in AMS+ compared with AMS- subjects.

Psychometric Validation of Hindi Version of 2018 Lake Louise Acute Mountain Sickness Scoring System

Psychometric Validation of Hindi Version of 2018 Lake Louise Acute Mountain Sickness Scoring System

A Signature of Circulating microRNAs Predicts the Susceptibility of Acute Mountain Sickness.

Background: Acute mountain sickness (AMS) is a common disabling condition in individuals experiencing high altitudes, which may progress to life-threatening high altitude cerebral edema. Today, no established biomarkers are available for prediction the susceptibility of AMS. MicroRNAs emerge as promising sensitive and specific biomarkers for a variety of diseases. Thus, we sought to identify circulating microRNAs suitable for prediction the susceptible of AMS before exposure to high altitude.Methods: We enrolled 109 healthy man adults and collected blood samples before their exposure to high altitude. Then we took them to an elevation of 3648 m for 5 days. Circulating microRNAs expression was measured by microarray and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). AMS was defined as Lake Louise score ≥3 and headache using Lake Louise Acute Mountain Sickness Scoring System.Results: A total of 31 microRNAs were differentially expressed between AMS and Non-AMS groups, 15 up-regulated and 16 down-regulated. Up-regulation of miR-369-3p, miR-449b-3p, miR-136-3p, and miR-4791 in patients with AMS compared with Non-AMS individuals were quantitatively confirmed using qRT-PCR (all, P < 0.001). With multiple logistic regression analysis, a unique signature encompassing miR-369-3p, miR-449b-3p, and miR-136-3p discriminate AMS from Non-AMS (area under the curve 0.986, 95%CI 0.970–1.000, P < 0.001, LR+: 14.21, LR–: 0.08). This signature yielded a 92.68% sensitivity and a 93.48% specificity for AMS vs. Non-AMS.Conclusion: The study here, for the first time, describes a signature of three circulating microRNAs as a robust biomarker to predict the susceptibility of AMS before exposure to high altitude.

Effects of dietary nitrate supplementation on symptoms of acute mountain sickness and basic physiological responses in a group of male adolescents during ascent to Mount Everest Base Camp

The purpose of this study was to investigate the effects of dietary nitrate supplementation, in the form of beetroot juice, on acute mountain sickness (AMS) symptoms and physiological responses, in a group of young males trekking to Mount Everest Base Camp (EBC). Forty healthy male students (mean age (SD): 16 (1) yrs) trekked to EBC over 11 days. Following an overnight fast, each morning participants completed the Lake Louise AMS questionnaire and underwent a series of physiological tests: resting blood pressure as well as resting and exercising heart rate, respiratory rate, and peripheral oxygen saturation. The exercise test consisted of a standardised 2-min stepping protocol and measurements were taken in the last 10 s. Participants in the intervention arm of the study consumed 140 ml of concentrated beetroot juice daily, containing approximately 10 mmol of nitrate, while those in the control arm consumed 140 ml of concentrated blackcurrant cordial with negligible nitrate content. Drinks were taken for the first seven days at high altitude (days 2–8), in two equal doses; one with breakfast, and one with the evening meal. Mixed modelling revealed no significant between-groups difference in the incidence of AMS (Odds Ratio – nitrate vs. control: 1.16 (95% CI: 0.59; 2.29)). Physiological changes occurring during ascent to high altitude generally were not significantly different between the two groups (Model Coef (95% CI) – average difference nitrate vs. control: systolic blood pressure, 0.16 (−4.47; 4.79); peripheral oxygen saturation, 0.28 (−0.85; 1.41); heart rate, −0.48 (−8.47; 7.50) (Model Coef (95% CI) – relative difference nitrate vs. control: ventilatory rate, 0.95 (0.82; 1.08)). Modelling revealed that diastolic blood pressure was 3.37 mmHg (0.24; 6.49) higher for participants in the beetroot juice, however this difference was no larger than that found at baseline and no interaction effect was observed. Supplementation with dietary nitrate did not significantly change symptoms of AMS or alter key physiological variables, in a group of adolescent males during a high altitude trekking expedition. There was no evidence of harm from dietary nitrate supplementation in this context. Given the wide confidence intervals in all models, a larger sample size would be required to exclude a false negative result. Our data suggest that prolonged oral nitrate supplementation is safe and feasible at altitude but has little physiological or clinical effect.

Studies on the association of angiotensinogen polymorphisms and hypoxia acclimatization

To research the effects of gene polymorphisms of AGT at G-217A and T174M loci on incidence and the hypoxia acclimation to acute mountain sickness (AMS). Step 1:61 Han students origin low landers were exposed in acute hypoxia at 4 800 m altitude-equivalent for 6 hours, and took the supine bicycle exercise for 20 min at quantitative load of 60 r/min, 80 W after entering the cabin for 30 min, then the AMS were evaluated by the Lake Louise acute mountain sickness scoring system (LLS). The physical index of heart rate (HR), ambulatory blood pressure and oxygen saturation (SpO2) were measured during exercise. Step 2:The physical index was measured again in acute hypoxic exposure after 3 weeks increasing hypoxia exercise (At an increasing altitude of 2 500 m, 3 500 m, 4 800 m, time of 2 hours/day, 4 days/week, and in moderate intensity of exercise). PCR-RFLP was used to determine the genotypes and alleles frequencies of AGT at G-217A and T174M loci. In step 1 the hypoxic exposure, for the G-217A locus in AGT, there was no significant difference between GG and GA+AA gene tester. While in step 2 the hypoxic exposure, the SpO2 of GG gene was lower than GA+AA gene obviously (P<0.05). No significant differences of AMS incidence, VE, SpO2, HR and blood pressure were detected in different genotypes and alleles at T174M locusin both hypoxic exposures. The G-217A may be the genetics sign of hypoxia acclimation. There is no obvious rel-evancy between the T174M polymorphism and the occurrence of AMS/hypoxia acclimation.

Incidence and risk factors associated with acute mountain sickness in children trekking on Jade Mountain, Taiwan.

Acute mountain sickness (AMS) is a pathophysiological symptom complex that occurs in high-altitude areas. The incidence of AMS on Jade Mountain, the highest peak in Taiwan (3952 m), has been reported to be ∼36%. There is a lack of data in children trekking at altitude in Taiwan. The purpose of this study was to determine the incidence, risk factors and symptoms of AMS in children trekking on Jade Mountain, Taiwan. This prospective cohort study included a total of 96 healthy non-acclimatized children aged 11-12 years who trekked from an elevation of 2600-3952 m in 3 days. The Lake Louise AMS score was used to record symptoms associated with AMS. AMS were reported in 59% of children trekking on Jade Mountain over a 3 day period. AMS incidence increased significantly with increasing altitude. The most common AMS symptom was headache, followed by fatigue or weakness, difficulty sleeping, dizziness or lightheadedness and gastrointestinal symptoms. Children who had experienced upper respiratory infection (URI) within the 7 days before their trek tended to have a greater risk for development of AMS. AMS incidence did not significantly differ according to gender, recent acute gastroenteritis, menstruation and body mass index. The incidence of AMS in children trekking on Jade Mountain is greater than that observed in adults, and was associated with altitude and recent URI.

The 6-Minute Walk Test as a Predictor of Summit Success on Denali

To test whether the 6-minute walk test (6MWT), including postexercise vital sign measurements and distance walked, predicts summit success on Denali, AK. This was a prospective observational study of healthy volunteers between the ages of 18 and 65 years who had been at 4267 m for less than 24 hours on Denali. Physiologic measurements were made after the 6MWT. Subjects then attempted to summit at their own pace and, at the time of descent, completed a Lake Louise Acute Mountain Sickness Questionnaire and reported maximum elevation reached. One hundred twenty-one participants enrolled in the study. Data were collected on 111 subjects (92% response rate), of whom 60% summited. On univariate analysis, there was no association between any postexercise vital sign and summit success. Specifically, there was no significant difference in the mean postexercise peripheral oxygen saturation (Spo2) between summiters (75%) and nonsummiters (74%; 95% CI, -3 to 1; P = .37). The distance a subject walked in 6 minutes (6MWTD) was longer in summiters (617 m) compared with nonsummiters (560 m; 95% CI, 7.6 to 106; P = .02). However, this significance was not maintained on a multivariate analysis performed to control for age, sex, and guide status (P = .08), leading to the conclusion that 6MWTD was not a robust predictor of summit success. This study did not show a correlation between postexercise oxygen saturation or 6MWTD and summit success on Denali.

Hypobaric Hypoxia Induces Hypercoagulability Due to an Increase in Microparticles

Studies investigating the role of hypoxia on coagulation, either by going to high altitude or after a long-haul flight, reveal contrasting results. Previous work from our group suggests that the cellular part of the blood is involved in causing a prothrombotic phenotype. Therefore this study investigated the effect of hypobaric hypoxia on blood coagulation, focusing on the role of cellular components.After approval from the local medical ethics committee, 16 healthy participants (aged 20 to 50 years old) were included in this study. Exclusion criteria were a history of cardiovascular disease or pulmonary disease, impaired mobility, and medication known to interfere with coagulation. Participants ascended by cable car to 3,883 meters above sea level, after acclimatizing to altitude for 6 days. At 50 meters and 3,883 meters above sea level, blood was drawn and vital signs (SpO2, heart rate) and the Lake Louise acute mountain sickness questionnaire (LLQ) were recorded. The following tests were performed on whole blood: hemoglobin (Hb), hematocrit (Ht), leucocyte count (L), platelet count (PC) and mean platelet volume (MPV); thrombin generation (TG) in whole blood (WB-TG) with 0.5 pM tissue factor (TF); platelet activation test (PAc-T) triggered by adenosine diphosphate (ADP), thrombin receptor activating peptide (TRAP) and collagen related peptide (CRP) in end concentrations of respectively 10 µM, 30 µM and 1 µg ml-1. The remainder of the blood was centrifuged to obtain platelet rich plasma (PRP) (once for 15 minutes at 230 g) and platelet poor plasma (PPP) (twice for 10 minutes at 2,821 g). PRP was used to test PRP-TG (1 pM TF) and plasma was used for PPP-TG (1 pM TF) and microparticles (MP)-TG (0 pM TF). The paired t-test with p <0.05 was used to determine statistical significance within participants.At 3,883 meters above sea level, oxygen saturation decreased and heart rate increased significantly. LLQ scores revealed mild acute mountain sickness (AMS) symptoms. One participant was withdrawn from the study at 3,030 meters due to moderate AMS. After applying TG in PPP, PRP and whole blood, we found that peak height and endogenous thrombin potential (ETP) were increased. Interestingly, we found a decrease in platelet activation and a decreased MPV. To find an explanation for the increased TG in the different media, we performed a TG assay specially designed to detect microparticles. As with the PPP-TG, PRP-TG and WB-TG, we found an increase in ETP and peak height, proving increased content of MPs.In conclusion, we found that exposure to hypobaric hypoxia increased TG in PPP, PRP and in whole blood. In contrast we found that platelet activation was decreased, indicating that platelets do not play a role in hypoxia-induced hypercoagulability. The increase in peak and ETP in the MP-sensitive TG assay indicates that MPs play a major role in hypoxia-induced hypercoagulability. DisclosuresDe Laat:Synapse bv: Employment.