Acute mountain sickness is a type of altitude sickness which develops within a few hours of an unacclimatized individual ascending rapidly to a high altitude. It is characterized by sudden onset of a bitemporal headache, nausea, fatigue, dizziness and can be life-threatening with the development of cerebral or pulmonary edema.
Presentation
Acute mountain sickness (AMS) is a common form of altitude sickness which affects between 10 to 80% of individuals climbing to high altitudes [1] [2] [3] [4] [5]. Symptoms are variable and usually commence within 24 hours of an unacclimatized individual ascending rapidly to altitudes > 8000 feet. Common symptoms include headaches, dizziness, vomiting, anorexia, fatigue, and insomnia [6] and they are due to the hypoxic and hypobaric environment at high altitudes [7]. Other symptoms like loss of appetite, light-headedness, lassitude, dyspnea and delirium may also be present. Some patients experience worsening of symptoms with the development of either cerebral edema (HACE - high altitude cerebral edema) and/or high altitude pulmonary edema (HAPE). But in a majority of the cases, the symptoms of AMS usually improve after a day unless the patient ascends again to a higher altitude, in which case the symptoms can worsen.
Entire Body System
- Fatigue
On ascent to 5085 m, ratings of perceived exertion (RPE ascent ), fatigue by Brunel Mood Scale, and AMS were recorded daily. [ncbi.nlm.nih.gov]
[…] and weakness : Not tired or weak = 0 Mild fatigue/weakness = 1 Moderate fatigue/weakness = 2 Severe fatigue/weakness = 3 Dizziness and lightheadedness: Not dizzy = 0 Mild dizziness = 1 Moderate dizziness = 2 Severe dizziness, incapacitating = 3 Difficulty [ultimatekilimanjaro.com]
The symptoms of acute mountain sickness include headache, fever, fatigue, nausea, dizziness, anorexia, and sleep disturbances. This article describes the management of acute mountain sickness. [medlink.com]
[…] sickness : altitude sickness that is experienced usually within several hours to one day of ascending above 8000 to 10,000 feet (about 2500 to 3000 meters) and that is marked by headache, nausea, loss of appetite, vomiting, insomnia, dizziness, and fatigue [merriam-webster.com]
- Malaise
A 32-year-old Japanese woman with headache, anorexia and malaise, just after travelling cities of the altitude of over 4,000 m by a long-distance coach is described. [ncbi.nlm.nih.gov]
Symptoms of mild AMS include mild headaches, increased breathing, rapid pulse, nausea, loss of appetite, lack of energy, and general malaise. These are warning signs not to go any higher than you already are. [nps.gov]
Symptoms usually start 12-24 hours after arrival at altitude and include headache, dizziness, fatigue, shortness of breath, loss of appetite, nausea, disturbed sleep, and a general feeling of malaise. [medicinenet.com]
Respiratoric
- Dyspnea
What are the initial manifestations of acute mountain sickness (1) Headache (Severe and persistent) (2) Lassitude (3) Drowsiness/Dizziness (4) Chilliness/Nausea and vomiting (5) Facial pallor/Dyspnea and cyanosis What are the late symptoms of acute mountain [quizlet.com]
Other symptoms like loss of appetite, light-headedness, lassitude, dyspnea and delirium may also be present. [symptoma.com]
Subjective benefits include improvement in sleep habits, tolerance to cold; decreased dyspnea, anginal symptoms and tachycardia and improved appetite, all of which are symptoms associated with high altitude illness. [clinicaltrials.gov]
Initially, patients have dyspnea on exertion, decreased exertion tolerance, and dry cough. Later, dyspnea is present at rest. Pink or bloody sputum and respiratory distress are late findings. [merckmanuals.com]
High-altitude pulmonary edema (HAPE) occurs most commonly two to three days after arrival at altitude and consists of dyspnea (difficulty breathing) with exercise, progressing to dyspnea at rest, a dry cough, weakness, chest tightness or congestion, and [hprc-online.org]
- Periodic Breathing
Periodic breathing is a common breathing pattern during sleep at high altitude. More than 100 years ago, Mosso [33] described this periodic breathing pattern, which consists of a series of 3-5 breaths followed by a short respiratory pause, or apnea. [emedicine.medscape.com]
The fraction of TIB spent with periodic breathing was determined as the sum of all cycle times of periodic breathing divided by TIB. Counts of oxygen saturation dips ≥4% and histograms of oxygen saturation averaged over 1 s periods were obtained 26. [erj.ersjournals.com]
Periods of sleeplessness The need for more sleep than normal, often 10 hours or more Occasional loss of appetite Vivid, wild dreams at around 2500-3800m in altitude Unexpected momentary shortness of breath, day and night Periodic breathing that wakes [explorehimalaya.com]
- Dyspnea at Rest
[…] at rest, and chest tightness. [quizlet.com]
(fluid in the alveoli, with a dry cough that gets worse, fever and dyspnea at rest) and / or high altitude cerebral edema (HACE) (swelling of the brains, with headaches that no longer respond to analgesics, unsteady walk, increased vomiting and gradual [climbeverest.jimdo.com]
High-altitude pulmonary edema (HAPE) occurs most commonly two to three days after arrival at altitude and consists of dyspnea (difficulty breathing) with exercise, progressing to dyspnea at rest, a dry cough, weakness, chest tightness or congestion, and [hprc-online.org]
High-altitude pulmonary oedema dyspnea at rest, moist cough, severe weakness, drowsiness, cyanosis, tachycardia, tachypnea rales. [ncbi.nlm.nih.gov]
Gastrointestinal
- Nausea
Symptoms of mild AMS include: mild to severe headache; nausea; vomiting; lack of appetite; lack of energy; altered balance and coordination; dizziness. [bigislandhikes.com]
Mild symptoms include headache, loss of appetite, nausea, fatigue, insomnia and dizziness. These symptoms are usually resolved by spending one or two extra nights at the same altitude. If symptoms worsen, descent to lower altitudes is warranted. [mallatreknepal.com]
Whereas headache scores up to 6 hours in hypoxia were not correlated with other AMS symptoms, nausea was correlated with dizziness and fatigue (r=0.45 and 0.56, p [ncbi.nlm.nih.gov]
- Vomiting
Stop it once below 2500m/8200ft AND after at least 3 days of treatment by tailing off the dose slowly (give the last 3 doses 12-hourly) ii) Diamox 250 mg 8 to12-hourly iii) Treat persistent vomiting with anti-vomiting medication Prop the victim up in [mountainmonarch.com]
More serious symptoms of AMS include increased tiredness, severe headaches, vomiting, loss of coordination, shortness of breath and coughing fits. These extremely dangerous symptoms are called high altitude cerebral edema (or HACE). [mallatreknepal.com]
A 55-year-old female Nepali pilgrim presented to the Himalayan Rescue Association Temporary Health Camp near the sacred Gosainkund Lake (4380 m) north of Kathmandu, Nepal, with a complaint of severe headache, vomiting and light-headedness. [ncbi.nlm.nih.gov]
Definition of acute mountain sickness : altitude sickness that is experienced usually within several hours to one day of ascending above 8000 to 10,000 feet (about 2500 to 3000 meters) and that is marked by headache, nausea, loss of appetite, vomiting [merriam-webster.com]
- Loss of Appetite
Definition of acute mountain sickness : altitude sickness that is experienced usually within several hours to one day of ascending above 8000 to 10,000 feet (about 2500 to 3000 meters) and that is marked by headache, nausea, loss of appetite, vomiting [merriam-webster.com]
For trekkers to Nepal the death rate from all causes was 0.014% and from altitude illness 0.0036% soldiers posted to altitude had an altitude related death rate of 0.16% Clinical features of mild altitude sickness are (1): headache loss of appetite nausea [gpnotebook.co.uk]
Signs of mountain sickness Early signs of acute mountain sickness include headache, nausea, loss of appetite and insomnia. If vertigo, vomiting, apathy, staggering and breathlessness occur, immediate accompanied descent is essential. [kalcounty.com]
Mild symptoms include headache, loss of appetite, nausea, fatigue, insomnia and dizziness. These symptoms are usually resolved by spending one or two extra nights at the same altitude. If symptoms worsen, descent to lower altitudes is warranted. [mallatreknepal.com]
Cardiovascular
- Tachycardia
Electrocardiography demonstrates sinus tachycardia and often, right ventricular strain. [ncbi.nlm.nih.gov]
What are the late symptoms of acute mountain sickness (1) Facial flushing/Irritability (2) Difficulty concentrating/Vertigo (3) Tinnitus/Visual and Auditory disturbances (4) Anorexia/Insomnia (5) Increased dyspnea/Weakness on exertion (6) Palpitations/Tachycardia [quizlet.com]
History will reveal recent ascent to high altitude by the unacclimatized patient while physical examination may reveal tachycardia, tachypnea, and pulmonary rales if the patient is developing pulmonary edema. [symptoma.com]
Subjective benefits include improvement in sleep habits, tolerance to cold; decreased dyspnea, anginal symptoms and tachycardia and improved appetite, all of which are symptoms associated with high altitude illness. [clinicaltrials.gov]
On examination, cyanosis, tachycardia, tachypnea, and low-grade fever (< 38.5° C) are common. Focal or diffuse crackles (sometimes audible without a stethoscope) are usually present. [merckmanuals.com]
Eyes
- Retinal Hemorrhage
To see what retinal hemorrhages look like, check out NEJM Clinical Images: Retinal Hemorrhages Associated with High Altitude. [lifeinthefastlane.com]
High-altitude retinal hemorrhages occur in up to 30% of people at 13,999 ft (4,267 m), 50 to 60% at 17,998 ft (5,486 m), and probably in 100% above 22,309 ft (6,800 m). High-altitude retinal hemorrhages may be more common in those with AMS. [hprc-online.org]
Blurred vision is the main symptom of high-altitude retinal hemorrhage. [drugs.com]
Delayed appearance of high altitude retinal hemorrhages. PLoS One. 2011 Feb 17. 6(2):e11532. [Medline]. [Full Text]. Frayser R, Houston CS, Bryan AC, Rennie ID, Gray G. Retinal hemorrhage at high altitude. N Engl J Med. 1970 May 21. 282(21):1183-4. [emedicine.medscape.com]
- Visual Impairment
Symptoms include headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower altitudes may save those afflicted with HACE. [en.wikipedia.org]
- Visual Impairment
Symptoms include headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower altitudes may save those afflicted with HACE. [en.wikipedia.org]
Skin
- Pruritus
Table 4 Adverse events in groups receiving prophylactic agents for AMS Difficulty in falling asleep 1 (0.98) 1 (0.98) Light sleep 3 (2.94) 1 (0.98) Dizziness 2 (1.96) 0 (0.00) Drowsiness 2 (1.96) 0 (0.00) Pruritus 1 (0.98) 1 (0.98) Dry hand 1 (0.98) 0 [bmccomplementalternmed.biomedcentral.com]
Neurologic
- Headache
In AMS-, nitrate did not alter headache or sense of effort. [ncbi.nlm.nih.gov]
He described headache and vomiting and gave names such as "the Great Headache Mountain" and "the Little Headache Mountain" to the mountains on his route. [medlink.com]
- Dizziness
Mild symptoms include headache, loss of appetite, nausea, fatigue, insomnia and dizziness. These symptoms are usually resolved by spending one or two extra nights at the same altitude. If symptoms worsen, descent to lower altitudes is warranted. [mallatreknepal.com]
[…] and lightheadedness: Not dizzy = 0 Mild dizziness = 1 Moderate dizziness = 2 Severe dizziness, incapacitating = 3 Difficulty sleeping: Slept as well as usual = 0 Did not sleep as well as usual = 1 Woke many times, poor sleep = 2 Could not sleep at all [ultimatekilimanjaro.com]
The symptoms of acute mountain sickness include headache, fever, fatigue, nausea, dizziness, anorexia, and sleep disturbances. This article describes the management of acute mountain sickness. [medlink.com]
[…] acute mountain sickness : altitude sickness that is experienced usually within several hours to one day of ascending above 8000 to 10,000 feet (about 2500 to 3000 meters) and that is marked by headache, nausea, loss of appetite, vomiting, insomnia, dizziness [merriam-webster.com]
- Confusion
These similarities can lead to confusion in the diagnosis of hypoglycemia versus AMS, particularly for diabetics ascending to altitude. [ncbi.nlm.nih.gov]
[…] disturbances with flickering vision and problems judging distance Pressure in the chest, rapid breathing and pulse rate, crackles in breathing and shortness of breath Swelling beneath the skin (edema), typically around the eyes Swollen ankles and hands Confusion [mallatreknepal.com]
If you have HACE you may: Have a severe headache Feel very confused Lose co-ordination Have blurred or double vision Notice changes in your behaviour – for example, you may feel irritable or be unhelpful Lose consciousness Hallucinate (see, hear, feel [trekthehimalayas.com]
- Insomnia
RESULTS: Results showed that, at 500 m, AISS and insomnia prevalence were higher in older individuals. After acute exposure to altitude, the HR, AISS, and insomnia prevalence increased sharply, and the increase in older individuals was more marked. [ncbi.nlm.nih.gov]
Definition of acute mountain sickness : altitude sickness that is experienced usually within several hours to one day of ascending above 8000 to 10,000 feet (about 2500 to 3000 meters) and that is marked by headache, nausea, loss of appetite, vomiting, insomnia [merriam-webster.com]
[…] the death rate from all causes was 0.014% and from altitude illness 0.0036% soldiers posted to altitude had an altitude related death rate of 0.16% Clinical features of mild altitude sickness are (1): headache loss of appetite nausea fatigue dizziness insomnia [gpnotebook.co.uk]
- Sleep Disturbance
Sleep disturbance is the most common symptom, and the lower prevalence of headache on Day 3 may be due to the effects of medication and/or acclimatization. [ncbi.nlm.nih.gov]
In subjects reporting severe headache, 40% did not report sleep disturbance. Sleep disturbance correlates poorly with other symptoms of AMS (Mean Spearman correlation 0.25). [journals.plos.org]
The symptoms of acute mountain sickness include headache, fever, fatigue, nausea, dizziness, anorexia, and sleep disturbances. This article describes the management of acute mountain sickness. [medlink.com]
Workup
The clinician can diagnose AMS on the basis of the patient's clinical presentation, history, and physical examination findings. History will reveal recent ascent to high altitude by the unacclimatized patient while physical examination may reveal tachycardia, tachypnea, and pulmonary rales if the patient is developing pulmonary edema. Laboratory tests like complete blood count may be abnormal with elevated hematocrit, and erythrocytosis while arterial blood gas analysis will reveal respiratory alkalosis. Pulse oximetry values do not usually indicate the severity of AMS and are therefore not useful in either detecting or in the management of the condition although they may help to detect HAPE. An electrocardiogram may show variable features like right axis deviation, non-specific ST-T changes, sinus arrhythmias, and P wave abnormalities. Chest radiography is indicated only in patients suspected clinically to have HAPE.
The diagnosis and severity of AMS can be assessed using the Lake Louise score (LLS) [8] as well as the Environmental Symptoms Questionnaire (ESQ) [9] [10]. The LLS was developed by a consensus conference on Hypoxia and Mountain Medicine in 1991 and consists of a self-reported score which is the sum of responses to five questions [8] and can be verified by a clinician during an interview. The ESQ consists of an inventory of expected physiological and psychological symptoms and was developed by the United States army. A part of this inventory containing symptoms indicative of cerebral hypoxia (AMS-C) is used to assess AMS [11]. However, the two questionnaires do not corroborate to provide an identical diagnosis [12] and as yet there is no gold standard tool for the assessment of AMS [13] [14].
Despite the presence of AMS symptoms, magnetic resonance imaging does not detect brain edema or an increase in brain volume for up to 12 hours after hypoxia and is therefore not helpful in the diagnosis and management of AMS [14].
Axis
- Right Axis Deviation
An electrocardiogram may show variable features like right axis deviation, non-specific ST-T changes, sinus arrhythmias, and P wave abnormalities. Chest radiography is indicated only in patients suspected clinically to have HAPE. [symptoma.com]
Serum
- Hypocapnia
The current data revealed that on going to high altitude, the subjects experienced not only hypoxia but also developed hypocapnia, therefore, both hypoxia and hypocapnia may be the factors in genesis of AMS. [jpma.org.pk]
The hypoxic ventilatory drive causes hypocapnia and a reduction in respiratory drive [11]. [journals.plos.org]
Severe altitude illness occurs most commonly in this range. [10] Extreme altitude [ edit ] Above 5,500 metres (18,000 ft), marked hypoxemia, hypocapnia, and alkalosis are characteristic of extreme altitudes. [en.wikipedia.org]
QT, RR, ST Intervals
- Non Specific ST-T Changes
An electrocardiogram may show variable features like right axis deviation, non-specific ST-T changes, sinus arrhythmias, and P wave abnormalities. Chest radiography is indicated only in patients suspected clinically to have HAPE. [symptoma.com]
Rhythm
- Sinus Arrhythmia
An electrocardiogram may show variable features like right axis deviation, non-specific ST-T changes, sinus arrhythmias, and P wave abnormalities. Chest radiography is indicated only in patients suspected clinically to have HAPE. [symptoma.com]
Treatment
Treatment of AMS 250 mg PO BD until symptoms resolve. [ncbi.nlm.nih.gov]
BMJ 2003;326:915-919 Links: physiology of altitude clinical features treatment of mountain sickness prophylactic (preventative) measures against development of mountain sickness acclimatization to altitude [gpnotebook.co.uk]
Major Treatment Modalities for High-Altitude Illnesses (Open Table in a new window) Treatment Indication Dose Mechanisms of action and Comments Acetazolamide Treatment and prophylaxis of AMS Treatment: 250 mg PO q8h Prophylaxis: 125-250 mg PO bid starting [emedicine.medscape.com]
Prognosis
What is the prognosis for HAPE? HAPE tends to get better quickly on descent and outlook (prognosis) is that there is usually complete recovery. [patient.info]
(Outcomes/Resolutions) Early diagnosis and immediate management of Acute Mountain Sickness does not pose any adverse long term effects on the patients Overall, the prognosis of AMS is good with early intervention Additional and Relevant Useful Information [dovemed.com]
The prognosis for a person that gets altitude sickness depends on the severity of the sickness. [emedicinehealth.com]
Etiology
(Etiology) Acute Mountain Sickness primarily develops due to low level of oxygen and lowered air pressure at high altitudes The faster one’s ascent to high altitudes, the higher is the risk of developing AMS. [dovemed.com]
A hemangiogenic and lymphangiogenic origin of this angiosarcoma has been documented. [16] Etiology The most important single causative agent in Stewart-Treves syndrome is prolonged chronic lymphedema. [emedicine.medscape.com]
Cerebral etiology of acute mountain sickness MRI findings. Wilderness Environ Med 6: 229–230, 1995. Google Scholar Copyright information © Springer Science+Business Media New York 1999 Authors and Affiliations Peter H. Hackett 1 1. St. [link.springer.com]
Evid Based Complement Alternat Med. 2013, 2013: 718739- PubMed PubMed Central Google Scholar Swenson ER, Maggiorini M, Mongovin S, Gibbs JSR, Greve I, Mairbäurl H, Bärtsch P: Pathogenesis of high-altitude pulmonary edema: inflammation is not an etiologic [bmccomplementalternmed.biomedcentral.com]
Epidemiology
Aims: Previous epidemiological investigations of the relationship between smoking and acute mountain sickness (AMS) risk yielded inconsistent findings. [ncbi.nlm.nih.gov]
Like the previous study these trekkers completed the LLS together with an epidemiological questionnaire. Then at 4,730m another set of trekkers, this time 189 were recruited (demographics: male = 108, female = 68, mean age 33, range 18-71). [climbkilimanjaroguide.com]
Epidemiology: Prevalence Colorado ski resort: 25% of travelers Himalayas: 50% of travelers III. [fpnotebook.com]
Pathophysiology
AIMS: Despite extensive research on acute mountain sickness (AMS), the underlying pathophysiology remains unclear. [ncbi.nlm.nih.gov]
Pathophysiology of AMS/HACE The exact pathophysiology of AMS/HACE is unknown. [emedicine.medscape.com]
The blood-brain barrier and intracranial hemodynamics are the two key elements in the pathophysiology of HACE and AMS. [link.springer.com]
Prevention
They can easily be prevented by gradual ascent to promote acclimatization. Early detection is the key in preventing deaths. [ncbi.nlm.nih.gov]
The Prevention of High-Altitude Illness Study in 2003, comparing Ginkgo to acetazolamide and placebo, demonstrated that Ginkgo does not prevent altitude sickness ( 13 ). [journals.lww.com]
References
- Gertsch JH, Seto TB, Mor J, Onopa J. Ginkgo biloba for the prevention of severe acute mountain sickness (AMS) starting one day before rapid ascent. High altitude medicine & biology. 2002;3(1):29–37.
- Honigman B, Theis MK, Koziol-McLain J, et al. Acute mountain sickness in a general tourist population at moderate altitudes. Ann Intern Med. 1993;118(8):587–92.
- Karinen H, Peltonen J, Tikkanen H. Prevalence of acute mountain sickness among Finnish trekkers on Mount Kilimanjaro, Tanzania: an observational study. High altitude medicine & biology. 2008;9(4):301–6.
- Maggiorini M, Buhler B, Walter M, Oelz O. Prevalence of acute mountain sickness in the Swiss Alps. BMJ. 1990;301(6756):853–5.
- Murdoch DR. Altitude Illness Among Tourists Flying to 3740 Meters Elevation in the Nepal Himalayas. J Travel Med. 1995;2(4):255–6.
- Barry PW, Pollard AJ. Altitude illness. BMJ. 2003;326(7395):915–9.
- Gallagher SA, Hackett PH. High-altitude illness. Emerg Med Clin North Am. 2004;22(2):329–55.
- Roach RC, Bartsch P, Hackett PH, Oelz O. The Lake Louise acute mountain sickness scoring system, in Hypoxia and Molecular Medicine. Queens City Press, Burlington, Va, USA, 1993; pp. 272–274.
- Kobrick JL, Sampson JB. New inventory for the assessment of symptom occurrence and severity at high altitude. Aviation Space and Environmental Medicine. 1979; 50: 9: 925–929
- Sampson JB, Kobrick JL. The environmental symptoms questionnaire: revisions and new filed data. Aviation Space and Environmental Medicine. 1980; 51: 9 (1): 872–877
- Beidleman BA, Muza SR, Fulco CS, Rock PB, Cymerman A. Validation of a shortened electronic version of the environmental symptoms questionnaire. High Altitude Medicine and Biology, 2007; 8 (3): 192–199.
- Wagner DR, Teramoto M, Knott JR, Fry JP. Comparison of scoring systems for assessment of acute mountain sickness. High Altitude Medicine and Biology. 2012; 13 (4): 245–251.
- Roach RC, Kayser B. Measuring mountain maladies. High Altitude Medicine and Biology. 2007; 8 (3): 171–172
- Bartsch P, Bailey DM, Berger MM, Knauth M, Baumgartner RW. Acute mountain sickness: controversies and advances. High Altitude Medicine & Biology. 2004; 5: (2): 110–124.