High Altitude Illnesses

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The body can experience many changes while at high altitude. These changes are all a response to declining oxygen pressure. While the percentage of oxygen at high altitude is equal to that at lower levels, atmospheric pressure is decreased. Atmospheric pressure measures how many oxygen molecules are available per a given volume (per breath, for example). In response to the lower levels of available oxygen, the body increases heartbeat rate, breathing rate, and the production of red blood cells, allowing more oxygen to be received from every breath. As the available oxygen falls and the air thins, the body responds in many ways that may result in a variety of altitude-induced sicknesses.

Cerebral Edema (HACE):
In response to decreasing atmospheric pressure the body will respond by increasing blood flow to the brain. However, the body can overcompensate, resulting in blood vessels' leaking fluid into the brain, causing it to swell. This is the foundation for the symptoms presented by Acute Mountain Sickness as well.

Cerebral Edema Symptoms:
• Ataxia (loss of balance and muscle coordination)
• Decreased mental functioning
• Severe headache
• Nausea and vomiting
• Hallucinations or stroke-like symptoms of impaired speech

Acute Mountain Sickness (AMS):
Acute Mountain Sickness is still a very poorly understood illness. LIke all forms of altitude sickness, this condition is brought about by low levels of oxygen. It is believed that AMS is brought about by swelling of the brain tissue as a result of hypoxic stress.

Acute Mountain Sickness (AMS) Symptoms
• Nausea & vomiting - blood directed away from gastrointestinal tract compromises its function, resulting in nausea
• Headache - increased blood flow to the brain to maintain mental function causes the brain to increase in volume, leading to headaches
• Shortness of breath - low oxygen levels
• Exhaustion that doesn't fade with rest - low oxygen levels
• Ataxia (loss of balance and muscle coordination)

Note: These are just a couple of the altitude illnesses that afflict mountain climbers. HAPE will be further explored as you continue to read the patient's story.

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