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Acute Mountain Sickness: 

Acute Mountain Sickness John Glick M.D. Basics 2006


Goals Understand the physiology of high altitude illnesses Recognize high altitude syndromes Appropriately manage patients with high altitude illness

Why do I care?: 

Why do I care? Advise patients on travel to high altitude Prevention (self and patients) Treat all those patients Dr. Z will send you Prepare for rural (Leadville/Alamosa) and ortho (Crested Butte) rotations

Range of altitude illness: 

Range of altitude illness AMS HAPE HACE Retinopathy Periodic breathing (sleep disordered breathing) Snow blindness (Ultraviolet keratitis) Hypothermia and frostbite Sunburn


Epidimiology 25% of all travellers above 8500 ft 40-50% Everest Base Camp 1 70% Climbers on Mt. Rainier 50% Climbers on Denali More common >10,000’


Oxygen Oxygen is consistently 20.93% of the atmosphere Atmospheric pressure decreases with altitude Therefore PO2 decreases with altitude

Some typical PO2: 

Some typical PO2

Physiological response: 

Physiological response Hypoxia induced Ventilatory Response (chemoreceptors in carotid bodies) improved by resp. stimulants (Coca, Diamox, Caffeine, progesterone, almitrine) Increasing PO2 and decreasing PCO2 leads to respiratory alkalosis Kidneys respond by increasing bicarb excretion Increased Catecholamine release (increased HR, BP, venous tone)

Physiologic response: 

Physiologic response Hypoxic vasoconstriction in pulmonary vessels, initially improves V/Q mismatch but eventually causing pulm HTN Increased cerebral blood flow Increased red cell concentration by diuresis and concentration and increased epo levels Increased 2,3-DPG to increase release of O2 in tissues

Physiological response: 

Physiological response All of these responses are individual specific and cause the extremely variable response to high altitudes

Symptoms of Mild AMS First described in 37 BC “A man’s face turns pale, his head aches and he begins to vomit”: 

Symptoms of Mild AMS First described in 37 BC “A man’s face turns pale, his head aches and he begins to vomit” Frontal Headache Anorexia, insomnia Nausea, decreased appetite Malaise, fatigue

Name that peak: 

Name that peak

Symptoms of Moderate AMS: 

Symptoms of Moderate AMS Nausea progresses to vomiting. Headache persists Urine output decreases Resting pulse high, often >110

Symptoms of Severe AMS: 

Symptoms of Severe AMS Altered consciousness Localized Rales, SOB with exertion. (developing HAPE) Ataxia (developing HACE) Cyanosis Symptoms worsen unless aggressive tx. started.

HACE (high altitude cerebral edema): 

HACE (high altitude cerebral edema) Usually represents the end-stage of AMS. Typically occurs several days after the onset of AMS. Vasogenic edema from leaky blood brain barrier causes increased CSF, and increased intracranial pressure. Edema due to mechanical (increased pressures) and chemical (Vasc. Endothelial growth factor, NO) factors

HACE Symptoms: 

HACE Symptoms Impaired judgement Severe Headache nausea, vomiting Ataxia May progress to coma if not treated. failure of the tandem gait test is HACE by definition

HACE Risk factors: 

HACE Risk factors Rapid Ascent Altitude usually >12,000’ Small expansion volume in skull Males Obesity?

HAPE (high altitude pulmonary edema): 

HAPE (high altitude pulmonary edema) Dry cough, tachypnea, gurgling breathing, tachycardia. Fatigue, mental status changes Rales often present R mid lobe Late signs include cyanosis, extreme weakness, frothy cough. CXR Patchy infiltrates (due to regional differences in perfusion in lungs)



HAPE risk factors: 

HAPE risk factors Rapid Ascent Strenuous exercise on arrival Male gender Previous history of HAPE Respiratory depressants: EtOH, Barbs Male Re-entrant HAPE

Treatment Protocols : 

Treatment Protocols Mild AMS Moderate-Severe AMS HAPE HACE

Tx of Mild AMS: 

Tx of Mild AMS No further ascent until symptoms resolve (with or without treatment) Acetazolamide 125-250 mg orally, twice a day, to speed acclimatization Treat symptoms with analgesics such as aspirin or acetaminophen for headache, antiemetics such as prochlorperazine (Compazine, Stemetil) for nausea

Tx of developing moderate to severe AMS: 

Tx of developing moderate to severe AMS Descend until symptoms improve. (500 m) If symptoms are not resolving, consider adding: - Oxygen at 1-2 L/min - Hyperbaric therapy (Gamow bag, Chamberlite) - Dexamethasone 4 mg orally, intramuscularly, or intravenously every 6 h

Gamow Bag: 

Gamow Bag

Treatment of HACE: 

Treatment of HACE Immediate descent or evacuation 1000m Oxygen at 2-4 L/min Pox > 90% Dexamethasone 8 mg orally, then 4 mg q6 hintramuscularly, or intravenously Hyperbaric therapy if unable to descend. Avoid hypotension (watch out with the nifedipine!)

Treatment of HAPE: 

Treatment of HAPE Descend!!! (500-1000m) Wait for re-ascent. Oxygen Portable hyperbaric tx if unable to descend Nifedipine (long acting) 30mg q6 hours or (10-20 q8 hours) Consider Dexamethasone 4-8mg q6. Consider Acetazolamide. Long acting beta-agonists (serevent) EPAP/CPAP In clinic give O2 per pulse ox. Viagra

Tx of Mild skier’s HAPE (Club Med Syndrome): 

Tx of Mild skier’s HAPE (Club Med Syndrome) If stable may send back to condo with: Nifedipine (Procardia) O2 per nasal canula to keeps sats adequate. Sober friend/family who can watch pt. Recheck in morning.

Prevention of AMS: 

Prevention of AMS Slow or staged ascents Once over 8000 ft, no more than 500m per day “climb high, sleep low” (sleep 500m below activity) Maintain good fluid intake Be in shape! Do not over exert in first few days. Avoid EtOH Consider Acetazolamide prophylaxis 125mg BID. Gingko? (doesn’t seem so)


Pregnancy There are no studies or case reports of harm to a fetus if the mother travels briefly to high altitude during pregnancy. However, most authorities recommend that pregnant women stay below 3,658m (12,000ft) if possible.

Case 1: 

Case 1 Charlie, an 11 y/o resident of Philadelphia flies to Denver and immediately drives up to Breckenridge (9300’) and has an aggressive ski day. The next morning he is nauseous, fatigued and complains of a frontal headache. What is his dx? What would you recommend to him?

Case 2: 

Case 2 Tula, a 34 y/o experienced climber is on an expedition in the Himalaya. On day 8 he carries a very heavy pack from 17,000’ to 19,000 ft and returns. That evening he is fatigued, and develops a dry cough. The next morning he is so tired he cannot get out of bed, and now has pink frothy sputum, diffuse rales and has difficulty getting dressed. What is his dx? What can you do for him? (keep in mind he weighs 225lbs and the nearest road and phone are 8 miles away)

Don’t believe everything you read: 

Don’t believe everything you read Mountaineering parties traveling above 9,840 feet (3,000 meters) should carry an oxygen supply sufficient for several days. (Medline)



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