The Incidence, Importance, and Prophylaxis of Acute Mountain Sickness

Hackett, PeterH.; Rennie, Drummond; Levine, Harry

doi:10.1016/s0140-6736(76)91677-9

Cited by 634 publications

(439 citation statements)

References 8 publications

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“…This recommendation, the specifics of which vary slightly depending on the resource cited [52,101,102], derives largely from observational data [103,104] and has only been examined in a prospective, randomised manner in a single study [24]. Because local terrain and logistical factors often prevent adherence to these specific altitude limits on a day-by-day basis, individuals should instead focus on the ascent rate averaged over the entire trip [105].…”

Section: Nonpharmacological Measures Slow Ascentmentioning

confidence: 99%

Acute high-altitude sickness

2017

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At any point 1-5 days following ascent to altitudes ⩾2500 m, individuals are at risk of developing one of three forms of acute altitude illness: acute mountain sickness, a syndrome of nonspecific symptoms including headache, lassitude, dizziness and nausea; high-altitude cerebral oedema, a potentially fatal illness characterised by ataxia, decreased consciousness and characteristic changes on magnetic resonance imaging; and high-altitude pulmonary oedema, a noncardiogenic form of pulmonary oedema resulting from excessive hypoxic pulmonary vasoconstriction which can be fatal if not recognised and treated promptly. This review provides detailed information about each of these important clinical entities. After reviewing the clinical features, epidemiology and current understanding of the pathophysiology of each disorder, we describe the current pharmacological and nonpharmacological approaches to the prevention and treatment of these diseases.

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Section: Nonpharmacological Measures Slow Ascentmentioning

confidence: 99%

Acute high-altitude sickness

2017

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“…It may occur in subjects ascending to Ͼ2,500 m and is reported in 53% of those at Ͼ4,000-m altitude (6,22).…”

mentioning

confidence: 99%

Autonomic cardiovascular regulation in subjects with acute mountain sickness

Lanfranchi¹,

Colombo²,

Cremona³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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The aims of this study were 1) to evaluate whether subjects suffering from acute mountain sickness (AMS) during exposure to high altitude have signs of autonomic dysfunction and 2) to verify whether autonomic variables at low altitude may identify subjects who are prone to develop AMS. Forty-one mountaineers were studied at 4,559-m altitude. AMS was diagnosed using the Lake Louise score, and autonomic cardiovascular function was explored using spectral analysis of R-R interval and blood pressure (BP) variability on 10-min resting recordings. Seventeen subjects (41%) had AMS. Subjects with AMS were older than those without AMS (P Ͻ 0.01). At high altitude, the lowfrequency (LF) component of systolic BP variability (LFSBP) was higher (P ϭ 0.02) and the LF component of R-R variability in normalized units (LFRRNU) was lower (P ϭ 0.001) in subjects with AMS. After 3 mo, 21 subjects (43% with AMS) repeated the evaluation at low altitude at rest and in response to a hypoxic gas mixture. LFRRNU was similar in the two groups at baseline and during hypoxia at low altitude but increased only in subjects without AMS at high altitude (P Ͻ 0.001) and did not change between low and high altitude in subjects with AMS. Conversely, LFSBP increased significantly during short-term hypoxia only in subjects with AMS, who also had higher resting BP (P Ͻ 0.05) than those without AMS. Autonomic cardiovascular dysfunction accompanies AMS. Marked LFSBP response to short-term hypoxia identifies AMS-prone subjects, supporting the potential role of an exaggerated individual chemoreflex vasoconstrictive response to hypoxia in the genesis of AMS.hypoxia; autonomic nervous system; heart rate; blood pressure ACUTE MOUNTAIN SICKNESS (AMS) is a complex syndrome characterized by headache, gastrointestinal symptoms, weakness, insomnia, and certain neurological signs, including ataxia and changes in mental status (1). It may occur in subjects ascending to Ͼ2,500 m and is reported in 53% of those at Ͼ4,000-m altitude (6,22).AMS is generally harmless and transient but may occasionally progress to the more serious life-threatening cerebral and pulmonary forms of mountain sickness, i.e., high-altitude cerebral and pulmonary edema (1, 6).The exact mechanism causing AMS is unknown, although the prevailing hypothesis points to a process within the central nervous system (1), possibly an altered adaptation to the neurohumoral and hemodynamic adjustments during hypoxia (8). A marked increase in peripheral sympathetic activity is a common feature of mountain sickness (4, 11) and has also been suggested to contribute to the genesis of high-altitude pulmonary edema (4). Whether autonomic hyperactivation may play a role in the genesis of AMS is not known.The autonomic nervous system plays a role in the modulation of the oscillatory behavior of the cardiovascular system (23, 32a). Spectral analysis of variability in the R-R interval is a recognized tool that allows quantification of the oscillatory components, which in short-term recordings appear mainly organized...

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“…Acute mountain sickness (AMS) is a frequent medical disorder in travellers who rapidly ascend to altitudes >2,500 m [1]. When altitudes >4,000 m are reached within hours, only few do not have at least mild symptoms.…”

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confidence: 99%

Theophylline improves acute mountain sickness

et al. 2000

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A randomized two-part study was conducted in order to determine the efficacy of theophylline in the treatment of acute mountain sickness during fast ascent to altitudes >2,500 m.Fourteen healthy male subjects participated in a randomized single-blind placebocontrolled crossover study carried out in a decompression chamber (simulated altitude 4,500 m). A second randomized single-blind, placebo-controlled study was conducted at a high-altitude research laboratory (3,454 m) and included 21 healthy male subjects. The study medication was either 375 mg oral slow-release theophylline (250 mg if <70 kg) or a matched placebo tablet taken twice daily. The acute mountain sickness score (AMSS) was assessed three times a day, beginning 18 h prior to altitude exposure and continuing for 18 h after altitude exposure. In addition, measurements of respiratory frequency, pulse rate, oxygen saturation and arterial blood gas levels were performed.Acute mountain sickness was significantly reduced by theophylline during the decompression chamber study (mean SD 1.2 0.9) with placebo versus 3.6 0.8 with theophylline; p=0.03). During the high-altitude study, subjects with theophylline showed a significantly lower AMSS on arrival and after 18 h at altitude (0.6 versus 2.3, p=0.03). Oxygenation was improved in both parts of the study.In conclusion, oral slow-release theophylline improves acute mountain sickness. Eur Respir J 2000; 15: 123±127. This study was supported, in part, by Byk Gulden, Constance, Germany.Acute mountain sickness (AMS) is a frequent medical disorder in travellers who rapidly ascend to altitudes >2,500 m [1]. When altitudes >4,000 m are reached within hours, only few do not have at least mild symptoms. The symptoms of mild AMS include headache, dizziness, fatigue, gastrointestinal symptoms and sleep disturbance. During prolonged stay at high altitude, symptoms improve usually within 24±48 h.The pathogenesis of AMS is not fully understood, but it is generally agreed that the main underlying cause is hypoxia, which initiates the pathogenetic processes leading to AMS. Hypoxia is thought to cause water retention or a shift of water from intracellular to extracellular compartments [2], increase microvascular permeability [3] and increase cerebral blood flow [4]. All of these factors may contribute to AMS, although the role of enhanced cerebral blood flow remains controversial [5].AMS is normally best prevented by ascending slowly to high altitude. However, when rapid ascent is necessary (i.e. during rescue operations or passive transportation to high altitude), medical prophylaxis may be indicated. Acetazolamide at a dose of 250 mg twice daily and dexamethasone at doses of >4 mg twice daily have been reported effective in the preventive treatment of AMS [6,7].The effects of theophylline on AMS have not been studied, although its pharmacological profile would seem to predispose this substance to the treatment of AMS. The multiple pharmacological effects of theophylline (a phosphodiesterase inhibitor) are well cha...

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The Incidence, Importance, and Prophylaxis of Acute Mountain Sickness

Cited by 634 publications

References 8 publications

Acute high-altitude sickness

Acute high-altitude sickness

Autonomic cardiovascular regulation in subjects with acute mountain sickness

Theophylline improves acute mountain sickness

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