Acute mountain sickness in a subject with metabolic syndrome at high altitude

Abstract Strapazzon, Giacomo, Annalisa Cogo, and Andrea Semplicini. Acute mountain sickness in a subject with metabolic syndrome at high altitude. High Alt. Med. Biol. 9:245-248, 2008.-Visitors at high altitude are increasing in age and comorbidities, which can lead to a failure in acclimatization. We describe the development of acute mountain sickness (AMS) in a 44-year-old man with metabolic syndrome and the time- and altitude-dependent correlation between the development of AMS and blood pressure and heart rate changes. Our observations support a dominant role of endothelial dysfunction in the pathogenesis of AMS and suggest new behavioral indications.     

Endocrine aspects of high altitude acclimatization and acute mountain sickness

The acute acclimatization to high altitude is underpinned by a diuresis (and to a lesser extent a natriuresis) that facilitates a reduction in plasma volume. This allows a haemoconcentration to occur that increases the oxygen carrying capacity of a given volume of blood, a vital effect in the presence of a reduced partial pressure of oxygen. This critical acclimatization process is orchestrated by the endocrine system. This review will present the key evidence regarding the changes in several important hormones that affect this process.     

Diurnal variations of acute mountain sickness, colour vision, and plasma cortisol and ACTH at high altitude

Time dependence of colour vision in the green/red axis, signs of acute mountain sickness (AMS), and plasma cortisol and ACTH concentrations were studied in eight sea-level male natives exposed 79 h to altitude hypoxia at 4,350 m. Colour vision (CV) was explored every 2 h from 08:00 to 20:00 hours by means of two portable anomaloscopes, one derived from Essilor CHROMOTEST and the other from the OSCAR. Significant diurnal variations in CV were found using both anomaloscopes, major alterations in green relative to red sensitivity being seen in the early morning. AMS scores also showed remarkable diurnal variations, parallel to those of plasma cortisol and CV, with maximum values observed at 08:00 hours. Cortisol diurnal rhythm was maintained in hypoxia, with mean concentrations higher than in normoxia. ACTH followed the same trend, but variations were not significant. Significant correlations were found between instant values of CV, cortisol, and AMS score, but no causal relationship between these variables can be ascertained.     

黄芩苷与红景天胶囊对急性高原病预防作用比较

 目的 探讨黄芩苷胶囊对急性高原病(acute mountain sickness, AMS)的预防作用。方法 采用随机对照的研究方法, 80名急进高原健康男性青年随机分为3组, 黄芩苷组(n=32)、红景天组(n=24)和安慰剂组(n=24)。3组在进入高原前2 d、进入高原后连续3 d分别服用黄芩苷胶囊(0.5 g, 2次/d)、红景天胶囊(0.76 g, 2次/d)和安慰剂(2粒, 2次/d)。检测急进高原前(海拔397 m)和急进高原后(3658 m)受试者氧饱和度、心率、收缩压、舒张压, 彩色多普勒超声测量肺动脉收缩压(pulmonary artery systolic pressure, PASP)和平均肺动脉压(mean pulmonary arterial pressure, MPAP), 统计急进高原后各组的AMS发病率。结果 急进高原后安慰剂组、黄芩苷组和红景天组的AMS发病率分别为58.3%(14/24)、25.0%(8/32)和29.2%(7/24), 与安慰剂组比较, 黄芩苷组及红景天组AMS发病率明显降低, 差异有统计学意义(P<0.05)。与急进高原前比较, 各组受试者急进高原后心率、血压及肺动脉压均升高, 氧饱和度降低(P<0.05);与安慰剂组比较, 黄芩苷组血压及心率明显降低(P<0.05), 红景天组急进高原后氧饱和度升高、肺动脉压降低(P<0.05)。结论 黄芩苷组可能通过降低血压及心率预防AMS的发生, 红景天胶囊可能通过升高氧饱和度, 降低PASP、MPAP预防AMS的发生。     

Cognitive changes at high altitude in healthy climbers and in climbers developing acute mountain sickness

We report the cognitive functions of 17 non-acclimatized mountaineers who ascended from low lands to an altitude of 4,559 m in 24 h and were studied there within 6 h. We found that this rapid ascent to high altitude had small, but differential effects upon cognitive performance depending upon the later development of acute mountain sickness (AMS). Subjects who developed AMS within a 24-48-h stay at high altitude were mildly impaired in short term memory, but improved in conceptual tasks, while subjects who remained healthy had a better short term memory performance but no improvement in cognitive flexibility. Possible explanations for these unexpected effects of high altitude are discussed.     

Symptoms of acute mountain sickness in Sherpas exposed to extremely high altitude

Droma, Yunden, Masayuki Hanaoka, Buddha Basnyat, Amit Arjyal, Pritam Neupane, Anil Pandit, Dependra Sharma, and Keishi Kubo. Symptoms of acute mountain sickness in Sherpas exposed to extremely high altitude. High Alt. Med. Biol. 7:312-314, 2006.--The aim of this field interview was to investigate the current state of affairs concerning acute mountain sickness (AMS) in high-altitude residents, specifically the Sherpas at 3440 m above sea level, when they are exposed rapidly to altitudes significantly higher than their residing altitudes. Out of 105 Sherpas (44 men and 61 women, 31.2 +/- 0.8 yr), 104 had mountain-climbing experiences to 5701.4 +/- 119.1-m altitude in average 3.5 times each year. On the other hand, only 68 out of 111 non-Sherpas (29.9 +/- 0.8 yr) had experience of 1.4 +/- 1.5 climbs to an average 2688.6 +/- 150.4-m altitude in their mountaineering histories (p < 0.0001). Among the 104 Sherpas, 45 (43.3%) complained of at least one AMS symptom (headache, gastrointestinal symptoms, weakness, dizziness, and difficulty sleeping) in their experiences of mountaineering at an average 5518.9 +/- 195.9-m altitude. And 16 out of the 68 non-Sherpas (23.5%) reported the AMS symptoms at a mean altitude of 2750.0 +/- 288.8 m. Moreover, we also noticed that the Sherpa women showed a significantly higher Sa(O(2) ) (93.9 +/- 0.2%) than did Sherpa men (92.4 +/- 0.3%, p = 0.0001) at an altitude of 3440 m. The brief field interview evidenced that Sherpas might suffer from AMS when exposed to altitudes significantly higher than their residing altitude.     

Ocular functions and incidence of acute mountain sickness in women at altitude

The effects of altitude on a series of ocular functions were studied on seven expedition members, all women aged 23-53 years, during the first ascent of the 6798-m peak Brigupanth in the Indian Himalayas. The only consistent change was a decrease in convergence amplitude. The amplitude of accommodation remained stable among the younger climbers, but decreased markedly among the older ones as higher altitudes were reached. There also appeared to be a lessened vascular reactivity to the hypoxia of altitude in the older members. Stereoscopic vision was unimpaired at all altitudes tested and extra-ocular muscle balance remained unaffected in all but two members who had an increase in their baseline phorias. Two of the summit climbers developed retinal hemorrhages. There was an average weight loss of 5.4 kg during the climb, but general health was good. Symptoms of acute mountain sickness were noted infrequently, and there were only moderate changes in the menstrual cycle.     

Acute mountain sickness; prophylactic benefits of antioxidant vitamin supplementation at high altitude

Acute mountain sickness; prophylactic benefits of Free-radical-mediated damage to the blood-brain barrier may be implicated in the pathophysiology of acute mountain sickness (AMS). To indirectly examine this, we conducted a randomized double-blind placebo-controlled trial to assess the potentially prophylactic benefits of enteral antioxidant vitamin supplementation during ascent to high altitude. Eighteen subjects aged 35 +/- 10 years old were randomly assigned double-blind to either an antioxidant (n = 9) or placebo group (n = 9). The antioxidant group ingested 4 capsules/day(-1) (2 after breakfast/2 after evening meal) that each contained 250 mg of L-ascorbic acid, 100 IU of dl-a-tocopherol acetate and 150 mg of alpha-lipoic acid. The placebo group ingested 4 capsules of identical external appearance, taste, and smell. Supplementation was enforced for 3 weeks at sea level and during a 10-day ascent to Mt. Everest base camp (approximately 5,180 m). Antioxidant supplementation resulted in a comparatively lower Lake Louise AMS score at high altitude relative to the placebo group (2.8 +/- 0.8 points versus 4.0 +/- 0.4 points, P = 0.036), higher resting arterial oxygen saturation (89 +/- 5% versus 85 +/- 5%, P = 0.042), and total caloric intake (13.2 +/- 0.6 MJ/day(-1) versus 10.1 +/- 0.7 MJ/day(-1), P = 0.001); the latter is attributable to a lower satiety rating following a standardized meal. These findings indicate that the exogenous provision of water and lipid-soluble antioxidant vitamins at the prescribed doses is an apparently safe and potentially effective intervention that can attenuate AMS and improve the physiological profile of mountaineers at high altitude.     

Severe acute mountain sickness and suspect high altitude cerebral edema related to nitroglycerin use

An elite mountaineer reported severe acute mountain sickness and ataxia during an 8000-m expedition and concomitant use of transdermal nitroglycerin patches aimed to prevent frostbites. Use of nitroglycerin for this purpose is off-label, and its safety has not been assessed. Moreover, a relation between nitrate-induced cerebral vasodilation and high altitude cerebral edema is theoretically possible on a pathophysiological basis. It is our opinion that nitroglycerin use at high altitude should be discouraged, as efficacy in the prevention of frostbites is questionable and safety has not been assessed.     

Effects of propranolol on acute mountain sickness (AMS) and well-being at 4,300 meters of altitude

A number of physiological responses and adjustments occur at high altitude to compensate for hypoxia. We hypothesized that interference with one component of the normal compensatory process, the sympathetic nervous system, would hinder altitude acclimatization and thereby exacerbate acute mountain sickness (AMS) and compromise well-being. Twelve young males (21.2 +/- 0.4 years) received either 80 mg propranolol (PRO; n = 6) or placebo (PLA; n = 6), t.i.d. at sea level (SL) and during the first 15 d of a 19-d residence at 4,300 m (HA). Individuals were randomly assigned to each group. The Environmental Symptoms Questionnaire (ESQ) was administered at SL and twice daily (AM and PM) during the entire altitude exposure in order to assess AMS symptoms and subjective feelings of well-being. Supine heart rate (HR) was determined at rest twice at SL and four times at HA. HR in the PLA group increased 40% over SL values (57 +/- 3 to 80 +/- 4 beats/min) by day 7 at HA (p less than 0.01). HR in the PRO group did not increase above SL values during medication at HA. By 4 d after the medication administration was terminated, HR in the PRO group had increased and did not differ from the PLA group. Throughout the entire altitude exposure, ESQ scores for the PRO group were lower than or similar to the PLA group. Furthermore, cessation of PRO treatment did not result in a change in well-being. These findings suggested that interference with the normal acclimatization process by beta-adrenergic blockade did not exacerbate AMS or reduce feelings of well-being.     

Association between physiological responses after exercise at low altitude and acute mountain sickness upon ascent is sex-dependent

Background:Acute mountain sickness (AMS) is the mildest form of acute altitude illnesses,and consists of nonspecific symptoms when unacclimatized persons ascend to elevation of ≥2500 m.Risk factors of AMS include:the altitude,individual susceptibility,ascending rate and degree of pre-acclimatization.In the current study,we examined whether physiological response at low altitude could predict the development of AMS.Methods:A total of 111 healthy adult healthy volunteers participated in this trial;and 99 (67 men and 32 women)completed the entire study protocol.Subjects were asked to complete a 9-min exercise program using a mechanically braked bicycle ergometer at low altitude (500m).Heart rate,blood pressure (BP) and pulse oxygen saturation (SpO2)were recorded prior to and during the last minute of exercise.The ascent from 500m to 4100m was completed in 2 days.AMS was defined as ≥3 points in a 4-item Lake Louise Score,with at least one point from headache wat 6-8 h after the ascent.Results:Among the 99 assessable subjects,47 (23 men and 24 women) developed AMS at 4100 m.In comparison to the subjects without AMS,those who developed AMS had lower proportion of men (48.9％ vs.84.6％,P＜0.001),height(168.4±5.9cm vs.171.3±6.1cm,P=0.019),weight (62.0±10.0kg vs.66.7±8.6kg,P=0.014) and proportion of smokers(23.4％ vs.51.9％,P=0.004).Multivariate regression analysis revealed the following independent risks for AMS:female sex (odds ratio (OR)=6.32,P＜0.001),SpO2 change upon exercise at low altitude (OR=0.63,P=0.002) and systolic BP change after the ascent (OR=0.96,P=0.029).Women had larger reduction in SpO2 after the ascent,higher AMS percentage and absolute AMS score.Larger reduction of SpO2 after exercise was associated with both AMS incidence(P=0.001) and AMS score (P＜0.001) in men but not in women.Conclusions:Larger SpO2 reduction after exercise at low altitude was an independent risk for AMS upon ascent.Such an association was more robust in men than in women.Trial registration:Chinese Clinical Trial Registration,ChiCTR1900025728.Registered 6 September 2019.     

High altitude headache and acute mountain sickness at moderate elevations in a military population during battalion-level training exercises

Few studies have evaluated high altitude headache (HAH) and acute mountain sickness (AMS) in military populations training at moderate (1,500-2,500 m) to high altitudes (>2,500 m). In the current study, researchers interviewed active duty personnel training at Marine Corps Mountain Warfare Training Center. Participants were asked about HAH and AMS symptoms, potential risk factors, and medications used. In a sample of 192 U.S. Navy and Marine Corps personnel, 14.6% reported AMS (Lake Louise Criteria > or = 3) and 28.6% reported HAH. Dehydration and recent arrival at altitude (defined as data collected on days 2-3) were significantly associated with AMS; decreased sleep allowance was significantly associated with HAH. Although ibuprofen/Motrin users were more likely to screen positive for AMS, among AMS-positive participants, ibuprofen/Motrin users had decreased likelihood of reporting robust AMS relative to non-ibuprofen/Motrin users (p < 0.01). These results suggest that maintenance of hydration and adequate sleep allowance may be critical performance requirements at altitude. Further, ibuprofen/Motrin may be a reasonable treatment for the symptoms of AMS and HAH, although further study is warranted.     

急进高原新兵对高原及急性高原病的认知调查及防病建议

目的 调查新兵对高原地理及急性高原病（AHAD）认知情况,为降低新兵AHAD发病率、提高高原适应能力和作战能力提供建议和参考.方法 对急进海拔3650 m高原地区的280名新兵进行平原及高原跟踪问卷调查,并对结果进行分析.结果 新兵对高原地理及AHAD的认知率普遍较差,只有18.92%的新兵了解,71.79%的新兵渴望了解.结论 应该采取多种措施,加强对新兵高原地理及AHAD的认知教育.     

Phenytoin: ineffective against acute mountain sickness

Phenytoin sodium was evaluated for its effect on the development and intensity of acute mountain sickness (AMS) because of its ability to reduce intracellular Na+ concentrations in brain and thereby minimize any tendency to increase cellular volume, a hypothetical cause of AMS. Six men aged 19-35 were exposed to approximately 4600 m altitude in a hypobaric chamber for 52 h on two occasions separated by 10 d at sea level. Subjects received wither phenytoin or placebo for 18 h before (700 mg, divided dose) and throughout (100 mg t.i.d.) each altitude exposure in a double-blind, repeated-measures (crossover) design. Phenytoin serum concentrations ranged from 4.4-13.9 micrograms/ml during altitude exposure. Twice daily questionnaires and clinical evaluations showed no marked benefit from phenytoin on the occurrence, severity, or duration of AMS symptoms: headache, nausea, insomnia, and general malaise. Overall, 1 subject felt better, 2 felt worse, 1 felt the same; 2 were not suitably comparable. There was no observed relationship between serum levels and symptoms of AMS. Moderate degrees of weakness and dizziness were each reported by 3 subjects with phenytoin but not with placebo, however. Resting pulmonary ventilation, end-tidal PO2 and PCO2, map reading abilities and respiratory mask donning times were not affected by phenytoin. Under the conditions of this trial, phenytoin did not appear to be useful in managing AMS.     

急进高原人群肾上腺皮质机能状态与急性高原病的相关性探讨

目的探讨肾上腺皮质激素与急性高原病的关系。方法分别在低海拔区和高海拔区不同时间抽取534名急进高原人群的肘静脉血,放免法检测血浆皮质醇（F）、醛固酮（ALD）、肾素活性（PRA）、血管紧张素Ⅱ（A1I）及睾酮（T）等水平;采用症状评分法评价高原反应程度,分析急进高原人群肾上腺皮质机能状态与急性高原病发病之间的相关关系。结果血浆F、AⅡ含量随海拔增高而增高,PRA下降,以F含量增高最显著,而ALD及T变化不明显;进入高原后,随着时问延长,血浆F、AⅡ和T含量明显下降;实验同时表明,在平原血浆F测定值明显低于正常的人易发生急性高原病。结论急进高原人群的肾上腺皮质激素水平与急性高原病的发病明显相关。     

A Tibetan with chronic mountain sickness followed by high altitude pulmonary edema on reentry

Chronic mountain sickness (CMS) and high altitude pulmonary edema (HAPE) each occur rarely in Tibetans, and they have previously not been reported in the same person. Here we describe a 37-year-old native Tibetan man with CMS at 4300 m, who developed HAPE after his return home from a 12-day visit to sea level. Possible common pathogenetic factors included a poor ventilatory response to hypoxia, accentuated hypoxemia, pulmonary hypertension, and increased blood volume. In addition, strenuous exercise and high levels (to approximately 1000 ng/L) of plasma atrial natriuretic peptide may have contributed to HAPE.     

Comparing questionnaires for the assessment of acute mountain sickness

Exposure to high altitude in nonacclimatized subjects may lead to acute mountain sickness (AMS). AMS is a syndrome characterized by headache accompanied by one or more other symptoms, such as light-headedness, dizziness, loss of appetite, nausea, vomiting, fatigue, lassitude, and trouble sleeping. Assessing the presence and degree of AMS can be done using self-administered questionnaires like the Lake Louise Questionnaire (LLQ) and the Environmental Symptoms Questionnaire-III (ESQ-III). We compared LLQ and ESQ-III in 266 trekkers of different nationalities trekking over a 5400-m-high pass to assess if the two questionnaires identify the same population as suffering from AMS and to see whether using English questionnaires poses problems for nonnative English-speaking persons. The use of English questionnaires by nonnative English speakers influenced the outcome for some nationalities. For criterion scores yielding similar prevalence of AMS, ESQ-III labeled 20% of cases differently (AMS or no AMS) when compared to LLQ. Correlations between similar individual questions of ESQ-III and LLQ were variable, and there was considerable scatter between ESQ-III and LLQ scores. In conclusion, English questionnaires may pose problems in some international settings, and ESQ-III and LLQ may identify different populations as suffering from AMS.