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.     

6种药物对部队进入海拔5200m急性高原反应预防效果的对比观察

目的 :筛选预防急性高原反应的药物。方法 :进驻海拔 5 2 0 0m哨卡的某部 118名士兵随机分为 6组。将复方红景天、银杏叶片、酪氨酸、复方党参、乙酰唑胺、异叶青兰组列为A、B、C、D、E、F组 ,每组 18～ 2 0人。于进入高原前 4天开始 ,每日早晚各服药 1次 ,到哨卡第 3天停药 ,连服 12d。部队进驻哨卡第 1～ 7天 ,以军用卫生标准GJB10 98- 91《急性高原反应的诊断和处理原则》随访记录受试者每天的急性高原反应症状 ,然后分度评分。分值高者 ,高原反应症状重。结果 :部队进入哨卡第 1天 ,A组症状评分较C、D、E、F组低 ,C组较A、D、E、F组高 (P <0 .0 1或P <0 .0 5 )。第 3天 ,除F组外 ,C组均高于其它 4组 ,B和E组较D组低 (P <0 .0 5或P <0 .0 1)。第 5天 ,A和B组较C组低 ,A组较D组低 (P <0 .0 5或P <0 .0 1)。第 7天 ,B组较A、C和D组低 ,F组较A、C和B组高 (P <0 .0 5或P <0 .0 1)。结论 :银杏叶片预防急性高原反应效果最好 ,乙酰唑胺和复方红景天次之 ,复方党参较异叶青兰好 ,酪氨酸最差     

Statistical models of acute mountain sickness

Acute mountain sickness (AMS) is caused by exposure to altitudes exceeding 2500 m and often resolves by acclimatization without further ascent. Statistical models of AMS score and the probability of an AMS diagnosis were developed to allow the combination of dissimilar exposures for simultaneous analysis. The study population was 302 trekkers from a previous investigation who provided self-reported symptoms upon arrival at 3840 m during hikes through altitudes of 1500 to 6200 m. AMS score (Hackett scale) was estimated by linear regression and the probability of an AMS diagnosis (Lake Louise criteria) by logistic regression. AMS score or probability was significantly associated with exposure day and altitude. Increased altitude over the prior 3 days resulted in higher estimated AMS score or probability and decreased altitude in lower score or probability. The odds ratio (OR) of AMS was 3.6 if not on acetazolamide. Females appeared slightly more susceptible than males (1.5 OR). The approach offers the advantages of (1) improved statistical power by combining exposures, (2) insight into the dose-response relationship of altitude exposure and AMS risk, (3) quantitative tests for the significance of factors that might affect AMS susceptibility, and (4) practical tools to track individual climbers and plan operational ascents.     

Effect of spironolactone on acute mountain sickness

This study examined the effectiveness of spironolactone as a prophylactic agent for the prevention of acute mountain sickness (AMS). Spironolactone, 25 mg PO QID, or placebo was administered to nine subjects in a double-blind, placebo-controlled, crossover design. Medication was given for 48 h prior to and during a 46-h exposure to 427 mm Hg (4570 m) in a hypobaric chamber. Six subjects demonstrated prevention of either the cerebral or respiratory symptoms of AMS during at least one segment of the altitude sojourn.     

The Environmental Symptoms Questionnaire in acute mountain sickness

A self-completed questionnaire (modified Environmental Symptoms Questionnaire) was evaluated in a study of acute mountain sickness (AMS). The questionnaire scores for headache, nausea, and the general feeling of ill health correlated well with AMS scores obtained by clinical interview. Modifications in the instructions and the phrasing of some of the questions are suggested and we doubt whether factor analysis provides any better data than more simple statistical methods. The questionnaire is a useful additional method for the assessment of symptoms of AMS.     

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.     

Speech motor control and acute mountain sickness

BACKGROUND: An objective method that accurately quantifies the severity of Acute Mountain Sickness (AMS) symptoms is needed to enable more reliable evaluation of altitude acclimatization and testing of potentially beneficial interventions. HYPOTHESIS: Changes in human articulation, as quantified by timed variations in acoustic waveforms of specific spoken words (voice onset time; VOT), are correlated with the severity of AMS. METHODS: Fifteen volunteers were exposed to a simulated altitude of 4300 m (446 mm Hg) in a hypobaric chamber for 48 h. Speech motor control was determined from digitally recorded and analyzed timing patterns of 30 different monosyllabic words characterized as voiced and unvoiced, and as labial, alveolar, or velar. The Environmental Symptoms Questionnaire (ESQ) was used to assess AMS. RESULTS: Significant AMS symptoms occurred after 4 h, peaked at 16 h, and returned toward baseline after 48 h. Labial VOTs were shorter after 4 and 39 h of exposure; velar VOTs were altered only after 4 h; and there were no changes in alveolar VOTs. The duration of vowel sounds was increased after 4 h of exposure and returned to normal thereafter. Only 1 of 15 subjects did not increase vowel time after 4 h of exposure. The 39-h labial (p = 0.009) and velar (p = 0.037) voiced-unvoiced timed separations consonants and the symptoms of AMS were significantly correlated. CONCLUSIONS: Two objective measures of speech production were affected by exposure to 4300 m altitude and correlated with AMS severity. Alterations in speech production may represent an objective measure of AMS and central vulnerability to hypoxia.     

Pulse oximetry in the diagnosis of acute mountain sickness

Acute mountain sickness (AMS) is a common condition in individuals who travel to altitudes over 2000 m. While AMS is an important public health problem, no measurements can reliably support or predict the diagnosis with any degree of confidence. We therefore set out to study whether pulse oximetry data are associated with AMS. We studied 169 subjects who had recently arrived by foot at 3080 m. Subjects completed a demographic survey, which collected data on ascent profiles and AMS symptoms. Resting arterial oxygen saturation and pulse rate were then measured using finger pulse oximetry. Forty-six subjects (27%) had AMS, using the Lake Louise score. Only pulse rate was significantly associated with the presence of AMS (OR: 1.4; 95% CI, 1.1 to 1.9; p < 0.05, backwards stepwise logistical regression). A trend showed worse AMS diagnoses were associated with higher mean pulse rates (p < 0.05, ANOVA linear weighted analysis). While some previous studies have shown an association between decreased oxygen saturation and acute mountain sickness at altitude, our results did not demonstrate such an association. The utility of pulse oximetry remains limited in the diagnosis of AMS. We recommend further study to determine the possible utility of pulse rate in the diagnosis and prediction of AMS.     

Survey of acute mountain sickness on Mauna Kea

Although thousands of people ascend 4205 m to visit the summit of Mauna Kea each year, there has been no information on the rate of altitude illness triggered by such visits. Two surveys were used: one for tourists driving up to the summit and the other for summit astronomy workers staying at lodging facilities at intermediate altitude. The surveys included the standardized Lake Louise Self-report Acute Mountain Sickness (AMS) Questionnaire that, when scored, gave the Lake Louise Symptoms Score (LLSS). Thirty percent of surveyed day visitors and 69% of surveyed professional astronomy staff had AMS, defined as a LLSS score of 3 or greater, with headache. Nine participants reported "disorientation/confusion" or greater consciousness changes. A majority of astronomy professionals reported fatigue, disturbed sleep, reduced activity, and mental status changes. Few took any AMS medications. The incidence of AMS in visitors to Mauna Kea's summit warrants increased education and increased availability of supplemental oxygen at the summit. The absence of reported serious altitude illness in the community is probably due to the rapid descent available on Mauna Kea, with prompt reversibility of adverse effects.     

Reliability and utility of a visual analog scale for the assessment of acute mountain sickness

Acute mountain sickness (AMS) is a common condition that affects people that ascend too rapidly to high altitude. It is typically assessed with the Lake Louise AMS Self-report Score (LLSelf) that uses a categorical numeric rating scale to answer five questions addressing AMS-related symptoms, such as headache. A 100-mm visual analog scale (VAS) is commonly used to assess subjective phenomena such as pain, but this scale has never been used for the self-assessment of AMS. The purpose of this study was to compare a VAS score to the total LLSelf and to evaluate the test-retest and interrater reliability of the VAS when used as an assessment of AMS. Participants (N = 356) completed both the LLSelf and the VAS on the summit of Mt. Whitney (4419 m). There was a significant relationship (r = 0.65, p < 0.01) between the LLSelf (2.8 +/- 2.0, mean +/- SD) and the VAS (14.4 +/- 14.1 mm). Fifty-seven participants were randomly selected for reliability testing of the VAS. Both test-retest reliability (ICC = 0.996, 95% CI = 0.992 to 0.998) and interrater reliability (ICC = 1.000, 95% CI = 0.999 to 1.000) were high. The mean difference in the VAS score between tests was <1 mm, as was the difference between raters. These results demonstrate excellent reliability for the VAS as an assessment of AMS.     

性激素与急性高原病的研究进展

急性高原病（ AMS）是急性暴露于高原（海拔＞2500 m）或由高原进入更高海拔地区时,因高原低氧而在数小时至数天内出现的临床症候群。我国有着西藏、青海等大面积高海拔地区,随着高原旅游及务工人员的剧增, AMS严重威胁急进高原人群的健康、降低劳动能力。目前已知AMS发生率男性明显高于女性,青壮年高于老年和儿童,考虑AMS发生可能受体内性激素水平差异的影响。因此研究性激素与AMS的相关性对阐明AMS病理生理机制、预防和治疗AMS具有重要意义。     

急性高原病合并多脏器功能障碍综合征(附9例报告)

目的：评估急性高原病(AHD)合并多脏器功能障碍综合征(MODS)的诊断标准和依据。方法：参照平原MODS诊断标准对高原现场救护和转院的AHD病例进行回顾性调查，锁定原发病因为高原脑水肿(HACE)、高原肺水肿(HAPE)为调查对象，重点收集与心、肺、脑、肾、肝、血液、肠、代谢八个脏器相关的功能指标，按庐山(1995)，Marshall(1995)，兰州(1999)有关MODS／ARDS评分诊断对各脏器损害程度进行综合评分。结果：9例均在急进高原4500～4700m后急性发病，发病至诊治时间平均≥20．6h。全组均在发生AHD后进行现场救护，其中6例无效转入上一级医院5～9d死于MODS。9例中原发病因为HACE5例，HAPE4例。可明确脏器损害者共有44个脏器，平均每例4，9个脏器受损；其中达到脏器衰竭标准共有34个脏器。平均为3．8个脏器衰竭。9例中5例进行APACHE—Ⅱ评分，分值最低为15分，最高27分，平均21．7分。结论：①HACE或HAPE不是单一脏器受损，而是多脏器受损，MODS是导致死亡的最危险因素；②及时有效地现场救治可能是阻断病情发展、逆转危险结局的重要手段。     

Dexamethasone for prevention and treatment of acute mountain sickness

We wished to determine in a field study the effectiveness of dexamethasone for prevention and treatment of acute mountain sickness (AMS). Prevention Trial: We transported 15 subjects from sea level to 4,400 m (PB = 400 mm Hg) on Denali (Mt. McKinley) by means of a 1-h helicopter flight. In a randomized, double-blind fashion we gave eight subjects a placebo and seven subjects 2 mg dexamethasone orally every 6 h, starting 1 h before take-off. The entire placebo group and five of the dexamethasone group developed AMS within 5 h, and became progressively more ill until 12 h when the trial was terminated. We concluded that 2 mg of dexamethasone every 6 h did not prevent AMS in active soldiers rapidly transported to high altitude. Treatment Trial: We treated 11 of those with moderate to severe AMS (symptom score 4.5 +/- 0.7, range 3 to 11) with 4 mg of dexamethasone every 6 h orally or intramuscularly for 24 h. All were markedly improved at 12 h (symptom score 1.0 +/- 0.3, p less than 0.001, range 0 to 3), but symptoms increased after the drug was discontinued at 24 h (symptom score = 2.4 +/- 0.5). We conclude that dexamethasone in a dosage of 4 mg PO or IM every 6 h is an effective treatment for AMS, but that illness may recur with abrupt discontinuation of the drug.     

Cysteinyl leukotriene blockade does not prevent acute mountain sickness

BACKGROUND: Acute Mountain Sickness (AMS) is a multi-system disorder that is characterized by headache, anorexia, nausea, vomiting, insomnia, lassitude, and malaise. The syndrome is common in unacclimatized low altitude residents who rapidly ascend to terrestrial elevations exceeding 2,500 m. AMS may be a manifestation of hypoxia-induced cerebral edema resulting, in part, from increased capillary permeability. HYPOTHESIS: We hypothesized that cysteinyl leukotrienes (CysLTs) may be involved in the pathogenesis of AMS, as these compounds are known to increase endothelial permeability. METHODS: To test this hypothesis, we orally administered a CysLTs type-1 receptor antagonist (montelukast) to 11 subjects prior to and during exposure to high altitude (4,300 m) in a hypobaric chamber in a randomized, placebo-controlled, crossover design. We measured the resulting prevalence and/or severity of AMS, plasma CysLTs levels and urinary CysLTE4, and associated physiological responses. RESULTS: At 12 h exposure, AMS prevalence and symptom severity was lower (p = 0.002) during montelukast administration compared with placebo, but not different at 22 h exposure. Plasma CysLTs and urinary LTE4 levels were not significantly elevated at 22 h exposure, nor did these CysLTs levels correlate with AMS severity. Compared with placebo, montelukast administration was not associated with any significant differences in physiologic measures at sea level or high altitude. CONCLUSIONS: These results do not support a role for the CysLTs mediating the early development of AMS through the CysLT-1 receptor.     

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.     

Oral contraceptives, exercise, and acute mountain sickness in women

BACKGROUND: Previous research has found that exercise exacerbated acute mountain sickness (AMS) in men. PURPOSE: The current study tested this relationship in women taking oral contraceptives. METHODS: We studied seven women at 428 mmHg for 10 h; once while at rest (R) and once while performing intermittent exercise (EX). RESULTS: AMS scores had a slight increase at 9 vs. 0 h at altitude in both trials (p < 0.05). Resting measurements of ventilation (VE), arterial oxygen saturation (SPO2), end tidal O2 (PETO2), and end tidal CO2 (PETCO2) were not different over time or between trials (p > 0.05). While fluid intake did not change, urine output increased during the 0-3 h period, regardless of trial, and returned to baseline values by the 6-9 h period (218 +/- 37 vs. 121 +/- 22 ml x h(-1); p < 0.05). During exercise, SPO2 significantly dropped compared with similar time points in R (73.1 +/- 1.1 vs. 85.7 +/- 1.8%; p < 0.05). Despite exercise-induced desaturation, the AMS scores were not significantly different between R and EX. CONCULSION: These results suggest that oral contraceptives may cause a compensation for the physiological responses to exercise critical for the development of AMS.     

Body temperature, autonomic responses, and acute mountain sickness

A few studies have reported increased body temperature (T(o)) associated with acute mountain sickness (AMS), but these usually include exercise, varying environmental conditions over days, and pulmonary edema. We wished to determine whether T(o) would increase with AMS during early exposure to simulated altitude at rest. Ninety-four exposures of 51 men and women to reduced P(B) (423 mmHg = 16,000 ft = 4850 m) were carried out for 8 to 12 h. AMS was evaluated by LL and AMS-C scores near end of exposure, and T(o) was measured by oral digital thermometer before altitude and after 1 (A1), 6 (A6), and last (A12) h at simulated altitude. Other measurements included ventilation, O(2) consumption and autonomic indicators of plasma catecholamines, HR, and HR variability. Average T(o) increased by 0.5 degrees F from A1 to A12 in all subjects (p < 0.001). Comparison between 16 subjects with lowest AMS scores (mean LL = 1.0, range = 0 to 2.5) and 16 other subjects with highest AMS scores (mean LL = 7.4, range = 5 to 11) demonstrated a transient decline in T(o) from A1 to A6 in AMS, in contrast to a rise in non-AMS (p = 0.001). Catecholamines, HR, and HR variability (increased low F/high F ratio) indicated significant elevation of sympathetic activity in AMS, where T(o) fell, but no change in metabolic rate. The apparently greater heat loss during early AMS suggests increased hypoxic vasodilation in spite of enhanced sympathetic drive. Greater hypoxic vasodilation and elevated HR in AMS in the absence of other changes suggest that augmentation of beta-adrenergic tone may be involved in early AMS pathophysiology.     

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.