1.4 Acute Mountain Sickness and HAPE

• What can happen to people who ascend rapidly to high altitudes?

  They can become acutely sick or die
• When does acute mountain sickness typically begin after ascent?

  From a few hours up to about 2 days
• What are the two main events that occur with acute mountain sickness?

  1. Acute cerebral edema
  2. Acute pulmonary edema
• What causes acute cerebral edema in high altitude sickness?

  Local vasodilation of cerebral blood vessels
• How does vasodilation affect capillary pressure in acute cerebral edema?

  It increases capillary pressure, causing fluid leakage
• What are the effects of cerebral edema on a person?

  Severe disorientation and cerebral dysfunction
• What is the cause of acute pulmonary edema in high altitude sickness?

  The cause is still unknown
• How does severe hypoxia contribute to acute pulmonary edema?

  It causes pulmonary arterioles to constrict
• What happens to pulmonary blood flow during acute pulmonary edema?

  It is forced through fewer unconstricted vessels
• What is the result of high capillary pressure in the lungs?

  Local edema occurs in the lungs
• What can happen if pulmonary edema spreads in the lungs?

  It leads to severe pulmonary dysfunction
• How can breathing O2 affect acute pulmonary edema?

  It usually reverses the process within hours
• What are the effects of chronic mountain sickness?

  1. High red blood cell mass and hematocrit
  2. Elevated pulmonary arterial pressure
  3. Enlarged right side of the heart
  4. Falling peripheral arterial pressure
  5. Congestive heart failure
  6. Possible death without descent
• What causes increased blood viscosity in chronic mountain sickness?

  High red blood cell mass
• How does hypoxia affect pulmonary arterioles in chronic mountain sickness?

  It causes them to become vasoconstricted
• What happens to pulmonary arterial pressure due to vasoconstriction in chronic mountain sickness?

  It rises excessively, leading to heart failure
• What is the consequence of blood flow being diverted through nonalveolar vessels?

  It causes poorly oxygenated blood flow
• How long does it typically take for most people with chronic mountain sickness to recover?

  Days or weeks after moving to lower altitude