Acute altitude illness

Acute altitude illness encompasses  acute mountain sickness, high altitude pulmonary oedema and high altitude cerebral oedema.

1) Acute mountain sickness (AMS)

Acute mountain sickness is generally a self-limiting condition that occurs at altitudes >2500m. It develops gradually over 6 to 24 hours. 

Features include: 

• Headache 
• Worse on moving/lying down
• Improves after vomiting 
• Vomiting
• Dizziness
• Fatigue 
• Insomnia 
• Anorexia 

Fitter, younger individuals tend to suffer from AMS most. 

Prevention:

• Gain height at no more than 500m per day 
• Medications:
• ?Acetazolamide (carbonic anhydrase inhibitor) 
• Risk of Stevens-Johnson syndrome, renal failure and toxic epidermal necrolysis 
• ?sidenafil/tadalafil  

Treatment: 

• Descent
• Oxygen 
• ?Acetazolamide
• ?Dexamethasone

2) High-altitude pulmonary oedema (HAPE)

Presents like pulmonary oedema 

Treatment

• Descent 
• Oxygen 
• Acetazolamide 
• Dexamethasone 
• Nifedipine 
• Sildenafil/tadalafil 

3) High-altitude cerebral oedema (HACE) 

Presentation includes ataxia, confusion, altered mental status and papilloedema. 

Treatment

• Descent 
• Oxygen 
• Dexamethasone 
• Acetazolamide 

References:

Clarke, C. Acute mountain sickness: medical problems associated with acute and subacute exposure to hypobaric hypoxia. Postgrad Med J. 2006; 82(973): 748-753.

Luks, A. et al. Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness. Wilderness and Environmental Medicine. 2010; 21(2): 146-155. 

Raytheon Polar Services Company. HAPE treatment guidelines. 2006. Available at http://search.nsf.gov/search?access=p&output=xml_no_dtd&sort=date%3AD%3AL%3Ad1&ie=UTF-8&btnG=Google+Search&client=NSF&oe=UTF-8&proxystylesheet=NSF2&site=NSF&q=HAPE