Student Presentations

Can affect anyone who ascends to more than 8000 feet (2438m). Several factors are important in adaptation to altitude: how long the ascent takes, how high, and length of stay.

The physiology of altitude sickness is not completely understood. The fundamental problem lies with the fact that with increasing altitude there is a progressive decrease in barometric pressure and a corresponding lower partial pressure of oxygen in inspired air, resulting in less oxygen delivery to the body.

Acute mountain sickness:

• Begins 4-6 hours after arrival at altitude, rare below 8000 feet and affects most above 10,000 (3048m).
• Signs and symptoms:
  • Mild: headache, lack of energy, nausea, dizziness, weakness, insomnia
  • Severe: severe headache, irritability, nausea, vomiting, SOB with exercise, marked fatigue, irregular or periodic breathing, apnea
• Treatment: Definitive treatment is descent to a lower altitude, though this is rarely needed for mountain sickness. Fluids, light diet, and curtail activity

High Altitude Pulmonary Edema (HAPE):

• Abnormal accumulation of fluid in the lungs. Begins 24-96 hours after arrival at altitude. Rare below 8000 feet,but affects 10% of individuals above 14,500 feet (4420m).
• Signs and Symptoms:
  • excessive SOB on exertion
  • gurgling breathing
  • severe respiratory distress
  • frothy cough
  • SOB with rest
  • bibasilar crackles
  • dry cough/wheezing
  • confusion
  • increased respiratory and heart rate
  • coma
  • marked periodic breathing at night

• Indicates swelling of the brain. It is the least common, but most severe form of altitude sickness since it can result in permanent injury or death.
• Occurs 48-72 hours after arrival at altitude.
• Rare below 12,000 feet (3656m).
• Signs and Symptoms:
  • progressive headache, unrelieved with medication
  • lack of coordination, unable to heel to toe walk
  • confusion and bizarre behavior
  • unconsciousness
  • symptoms of moderate acute mountain sickness present
• Treatment for HAPE and HACE:
  • Immediate descent to lower altitude. If able because of weather, or transportation then oxygen and bed rest may help.
  • Hyperbaric therapy is effective and practical if descent not possible. A portable hyperbaric chamber, the Gamow Bag can be inflated to 2 pounds per square inch using a foot pump. This is equivalent to a 5000 feet (1524m) drop in altitude. Improvement is usually immediate.
  • Acetazolamide 1.0 g/day
  • Dexamethasone 4mg q 6 hours
• Prevention:
  • Staging ascent: remain at altitude of 6600-9800 feet (2012-2988m) for a few days. Allow one day ascent and acclimatizefor each 1000 feet from elevations 10,000-14,000 feet (3048-4267m). Allow two days for each 1000 feet above 14,000 feet.
  • Maintain adequate hydration-dehydration increases likelihood and makes symptoms worse.
  • Carry oxygen
  • Acetazolamide 250 mg bid, 24 hours before ascent and continue for 2-3 days while at altitude. Prophylaxis given only if patient has a history of altitude sickness or plans on rapid ascent to altitudes above 8000 feet.
  • Dexamethasone 2-4 mg q6 hours, begun the day of descent and continued for three days at higher altitude may significantly reduce incidence and severity.

References:

• Bezruchka S: High Altitude Medicine. Med-Clin-North-Am. 1992 Nov 76(6):1481-97.
• Coote J: Medicine and mechanism in altitude sickness. Sports-Med. 1995 Sep; 20(3): 148-159.
• Johnson T. and Rock P: Current concepts, acute mountain sickness. New Engl J Med. 1988; 319:841.
• Zafren K: High Altitude Medicine. Emerg-Med-Clin-North-Am. 1997 Feb; 115(1): 191-222.