Isolated psychosis during exposure to very high and extreme altitude - characterisation of a new medical entity.

BACKGROUND: Psychotic episodes during exposure to very high or extreme altitude have been frequently reported in mountain literature, but not systematically analysed and acknowledged as a distinct clinical entity. METHODS: Episodes reported above 3500 m altitude with possible psychosis were collected from the lay literature and provide the basis for this observational study. Dimensional criteria of the Diagnostic and Statistical Manual of Mental Disorders were used for psychosis, and the Lake Louise Scoring criteria for acute mountain sickness and high-altitude cerebral oedema (HACE). Eighty-three of the episodes collected underwent a cluster analysis to identify similar groups. Ratings were done by two independent, trained researchers (κ values 0.6-1).FindingsCluster 1 included 51% (42/83) episodes without psychosis; cluster 2 22% (18/83) cases with psychosis, plus symptoms of HACE or mental status change from other origins; and cluster 3 28% (23/83) episodes with isolated psychosis. Possible risk factors of psychosis and associated somatic symptoms were analysed between the three clusters and revealed differences regarding the factors 'starvation' (χ2 test, p = 0.002), 'frostbite' (p = 0.024) and 'supplemental oxygen' (p = 0.046). Episodes with psychosis were reversible but associated with near accidents and accidents (p = 0.007, odds ratio 4.44). CONCLUSIONS: Episodes of psychosis during exposure to high altitude are frequently reported, but have not been specifically examined or assigned to medical diagnoses. In addition to the risk of suffering from somatic mountain illnesses, climbers and workers at high altitude should be aware of the potential occurrence of psychotic episodes, the associated risks and respective coping strategies.

Carbonic anhydrase inhibitors and high altitude illnesses.

Carbonic anhydrase (CA) inhibitors, particularly acetazolamide, have been used at high altitude for decades to prevent or reduce acute mountain sickness (AMS), a syndrome of symptomatic intolerance to altitude characterized by headache, nausea, fatigue, anorexia and poor sleep. Principally CA inhibitors act to further augment ventilation over and above that stimulated by the hypoxia of high altitude by virtue of renal and endothelial cell CA inhibition which oppose the hypocapnic alkalosis resulting from the hypoxic ventilatory response (HVR), which acts to limit the full expression of the HVR. The result is even greater arterial oxygenation than that driven by hypoxia alone and greater altitude tolerance. The severity of several additional diseases of high attitude may also be reduced by acetazolamide, including high altitude cerebral edema (HACE), high altitude pulmonary edema (HAPE) and chronic mountain sickness (CMS), both by its CA-inhibiting action as described above, but also by more recently discovered non-CA inhibiting actions, that seem almost unique to this prototypical CA inhibitor and are of most relevance to HAPE. This chapter will relate the history of CA inhibitor use at high altitude, discuss what tissues and organs containing carbonic anhydrase play a role in adaptation and maladaptation to high altitude, explore the role of the enzyme and its inhibition at those sites for the prevention and/or treatment of the four major forms of illness at high altitude.

Visual analog scale (VAS) for assessment of acute mountain sickness (AMS) on Aconcagua.

OBJECTIVE: The Lake Louise AMS Self-Report Score (LLSelf) is a commonly used, validated assessment of acute mountain sickness (AMS). We compared LLSelf and visual analog scales (VAS) to quantify AMS on Aconcagua (6962 m). METHODS: Prospective observational cohort study at Plaza de Mulas base camp (4365 m), Aconcagua Provincial Park, Argentina. Volunteers climbing in January 2009 were enrolled at base camp and ascended at their own pace. They completed the LLSelf, an overall VAS [VAS(o)], and 5 individual VAS [VAS(i)] corresponding to the items of the LLSelf when symptoms were maximal. Composite VAS [VAS(c)] was calculated as the sum of the 5 VAS(i). RESULTS: A total of 127 volunteers consented to the study. Response rate was 52.0%. AMS occurred in 77.3% of volunteers, while 48.5% developed severe AMS. Median (interquartile range, IQR) LLSelf was 4 (3-7). Median (IQR) VAS(o) was 36 mm (23-59). VAS(o) was linear and correlated with LLSelf: slope = 6.7 (95% CI: 4.4-9.0), intercept = 3.0 (95% CI: -10.0-16.1), ρ = 0.71, τ = 0.55, R(2) = 0.45, p < 0.001. Median (IQR) VAS(c) was 29 (13-44). VAS(c) was also linear and correlated with LLSelf: slope = 5.9 (95% CI: 4.9-6.9), intercept = -0.6 (95% CI: -6.3-5.1), ρ = 0.83, τ = 0.68, R(2) = 0.73, p < 0.001. The relationship between the 5 VAS(i) and LLSelf(i) was less significant and less linear than that between VAS(o), VAS(c), and LLSelf. CONCLUSIONS: While both VAS(o) and VAS(c) for assessment of AMS appear to be linear with respect to LLSelf, the amount of scatter within the VAS is considerable. The LLSelf remains the gold standard for the diagnosis of AMS.

[The pathophysiology of acute mountain sickness]. / Patofizjologia ostrej choroby wysokosciowej.

The hypoxia that increases in altitude environment and results from conditions dissimilarity, is the main cause of different forms of the altitude sickness. These range from benign form, called acute mountain sickness (AMS), to the states of direct threat to life, like high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Each organism demonstrates individual, different sensitivity to the conditions of altitude environment. Prior stays on heights help to develop kind of individual memory, which together with physical preparation meaningly decreases, however does not exclude completely, probability of being taken ill. Growing interest in high-mountaineering makes the altitude sickness one of the challenges of modern medicine.

The athlete and high altitude.

Expanding athlete participation in high-altitude environments highlights the importance for a sports physician to have a good understanding of the high-altitude illness (HAI) syndromes: acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE). All may occur in the setting of acute altitude exposure higher than 2500 m; incidence and severity increases as altitudes or ascent rates increase. Once HAI is recognized, proven therapies should be instituted to alleviate symptoms and avert the possibility of critical illness. Allowing for acclimatization is the best strategy for preventing HAI. Acetazolamide and dexamethasone are additional preventive measures for AMS/HACE; nifedipine, salmeterol, and phosphodiesterase inhibitors are useful in preventing HAPE. Along with the immediate hazards of HAI with altitude exposure, the sport physician also should be familiar with altitude/hypoxic training practices used by athletes to enhance fitness and performance.

[Health problems in high mountain conditions]. / Problemy zdrowotne w warunkach wysokogórskich.

Illnesses occurring among people stayed in high mountain conditions are classified in four separated categories. Diseases connected with hypobaria and hypoxia, low temperature, as a result of solar radiation effect, and intensification health problems running until this time asymptomatically belong to them. Knowledge concerning existing threats, prevention, right diagnosis and treatment of illnesses have fundamental significance for success of every expedition or operation realized in high mountains as well as for health and life protection of its participants. This article presents a review of the most often diseases happened during the stay in high mountain environment on the ground of the world literature and own experience.

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.

Validation of a shortened electronic version of the environmental symptoms questionnaire.

The purpose of this study was to validate a shortened (11-item) electronic version of the 67-item paper and pencil Environmental Symptoms Questionnaire (ESQ-III) to assess acute mountain sickness (AMS). Thirty-three volunteers (means +/- SE; 28 +/- 1 yr; 74 +/- 2 kg) were given both the paper and pencil and electronic versions of the ESQ (IPAQ 5550, Hewlett Packard, Palo Alto, CA) to complete one after the other at residence altitude (RA) and after 24-h (PP24), 48-h (PP48), and 72-h (PP72) exposure to 4300 m on the summit of Pikes Peak (PP). The AMS-Cerebral (AMS-C) weighted factor score was calculated from responses to the same 11 items for each version of the ESQ. If AMS-C was >or=0.7, then the individual was classified as having AMS. There were no differences in the AMS-C scores between the paper and pencil and electronic versions of the ESQ at RA (0.05 +/- 0.01 vs. 0.05 +/- 0.02), PP24 (0.76 +/- 0.16 vs. 0.74 +/- 0.15), PP48 (0.61 +/- 0.15 vs. 0.53 +/- 0.14), and PP72 (0.34 +/- 0.09 vs. 0.34 +/- 0.09). There were no differences in the incidence of AMS between the paper and pencil and electronic versions of the ESQ at RA (0% vs. 0%), PP24 (33% vs. 36%), PP48 (27% vs. 27%), and PP72 (21% vs. 21%). The relationships between AMS-C calculated from the two versions of the ESQ at RA (r = 0.43; p = 0.01), PP24 (r = 0.92; p = 0.0001), PP48 (r = 0.82; p = 0.0005), and PP72 (r = 0.95; p = 0.0001) were significant. The relationships between the incidence of AMS calculated from the two version of the ESQ at RA (k = 0.90; p = 0.01), PP24 (k = 0.90; p = 0.01), PP48 (k = 0.91; p = 0.01), and PP72 (k = 0.92; p = 0.01) were significant. Our findings suggest that the shortened electronic version can be substituted for the paper and pencil version of the ESQ to assess AMS.

[High-altitude related illness]. / Maladies de haute altitude.

Development of modern tourist industry facilitates access to high altitude for a growing population of non-acclimatized individuals who frequently are unaware of the hazards related to this environment, which is characterized by low ambient oxygen due to low atmospheric pressure. High-altitude related illnesses therefore represent an emerging medical issue, which may become of concern for every practitioner. Three clinical entities are classically described: acute mountain sickness (AMS), high altitude cerebral edema (HACE) and high altitude pulmonary edema (HAPE), the two latter representing vital emergencies. The present paper presents the current recommendations for their diagnostic, prophylactic and therapeutic management.

High-altitude headache.

A human being's exposure to altitude, and the consequent hypobarism, entails a complex series of adaptive mechanisms that depend on the rate of ascent and the altitude reached. When these mechanisms fail, so-called acute mountain sickness (AMS) results, with headache as its predominant symptom. It has been observed, nonetheless, that well-acclimated mountaineers may have headache without symptoms of AMS. We consider that high altitude and ensuing hypobarism bring about three possibilities of cephalalgia: the first is covered by the set of AMS clinical manifestations and is undoubtedly the most frequent; the second occurs independently of acute mountain sickness and is probably due exclusively to hypoxia; and the third includes altitude-triggered migraine or migraine-like episodes. These are neurogenic problems secondary to hypoxia caused by hypobarism and, in all events, have a common denominator: hypoxia and a fundamental white organ, the brain.

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.

Acute and severe hypobaric hypoxia-induced muscle oxidative stress in mice: the role of glutathione against oxidative damage.

This study intended to analyze: (1) the effects of acute and severe hypoxia exposure on skeletal muscle oxidative stress and oxidative damage markers; (2) the protective role of the antioxidant glutathione against oxidative damage; and (3) the expression of heat shock protein 70 kDa (HSP70) induced by this hypoxic insult. Forty mice were divided into four groups: control + placebo (C+P), hypoxia + placebo (H+P), control + l-buthionine-[ S, R]-sulfoximine (BSO, a GSH-depleting compound) (C+BSO) and hypoxia + BSO (H+BSO). Hypoxia groups were continuously exposed for 24 h to a hypobaric hypoxic environment equivalent to an altitude of 7000 m and sacrificed immediately after. Control groups were maintained at sea level during the experimental protocol. Analyzed biochemical parameters were: reduced (GSH) and oxidized (GSSG) glutathione, thiobarbituric acid reactive substances (TBARS), sulfhydryl protein groups (SH), N-acetyl-beta- d-glucosaminidase (NAG) and HSP70 protein. Hypoxia (H+P) per se, compared to C+P, induced a significant increase in %GSSG (5.68 vs. 1.14%), TBARS (436.7 vs. 227.9 nM), NAG (4.49 vs. 3.35 U/mg) and HSP70 (178.7 vs. 100%). Compared with H+P, H+BSO showed a significant decrease in total glutathione (19.30 vs. 6.13 nmol/mg) and an additional increase in %GSSG (5.68 vs. 11.33%) and in HSP70 expression (178.7 vs. 202.2%). However, no further oxidative damage was observed in H+BSO. These data suggest that acute hypoxia per se might enhance oxidative stress; however, the glutathione system seems to have a modest role in skeletal muscle protection against hypoxia-induced oxidative stress. Moreover, hypoxia and BSO treatment is a sufficient stimulus to promote HSP70 overexpression.

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.

Ginkgo biloba for the prevention of severe acute mountain sickness (AMS) starting one day before rapid ascent.

Previous studies suggest that 5 days of prophylactic ginkgo decreases the incidence of acute mountain sickness (AMS) during gradual ascent. This trial was designed to determine if ginkgo is an effective prophylactic agent if begun 1 day prior to rapid ascent. In this double-blind, randomized, placebo-controlled trial, 26 participants residing at sea level received ginkgo (60 mg TID) or placebo starting 24 h before ascending Mauna Kea, Hawaii. Subjects were transported from sea level to the summit (4205 m) over 3 hours, including 1 hour at 2835 m. The Lake Louise Self-report Questionnaire constituted the primary outcome measure at baseline, 2835 m, and after 4 h at 4205 m. AMS was defined as a Lake Louise Self-report Score (LLSR) >/= 3 with headache. Subjects who developed severe AMS were promptly transported to lower altitude for the remainder of the study. The ginkgo (n = 12) and placebo (n = 14) groups were well matched (58% vs. 50% female; median age 28 yr, range 22-53 vs. 33 yr, range 21-53; 58% vs. 57% Caucasian). Two (17%) subjects on ginkgo and nine (64%) on placebo developed severe AMS and required descent for their safety (p = 0.021); all recovered without sequelae. Median LLSR at 4205 m was significantly lower for ginkgo versus placebo (4, range 1-8 vs. 5, range 2-9, p = 0.03). Ginkgo use did not reach statistical significance for lowering incidence of AMS compared with placebo (ginkgo 7/12, 58.3% vs. placebo 13/14, 92.9%, p = 0.07). Twenty-one of 26 (81%) subjects developed AMS overall. This is the first study to demonstrate that 1 day of pretreatment with ginkgo 60 mg TID may significantly reduce the severity of AMS prior to rapid ascent from sea level to 4205 m.

[Diagnosis and therapy of acute altitude sickness]. / Klinik und Therapie der akuten Höhenkrankheit.

Today we distinguish cerebral (acute mountain sickness AMS, high altitude cerebral edema HACE) and pulmonal (high altitude pulmonary edema HAPE) altitude disorders. Incidence, predisposition and risk factors of all kinds of altitude sickness vary both individually and geographically. For practical reasons the leading symptoms are essential: altitude headache, ataxia and sudden loss of strength. Depending on the severity of symptoms the main emergency measures are: rest, descent or evacuation, warmth. Additional therapeutical measures can be helpful if a sudden evacuation to lower altitudes is delayed: oxygen, portable hyperbaric chamber, ibuprofen/naproxen, nifedipine, dexamethasone. Acetazolamide should not be used as an emergency therapy any more.