High Altitude Sickness

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High Altitude Sickness
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Terminology for High Altitude Sickness

• AMS acute mountain sickness
• Apnea cessation of breathing
• Edema local or systemic excesive accumulation
  of body fluids
• HACE high altitude cerebral edema
• HAPE high altitude pulmonary edeme
• Hypobaric hypoxia dec level of O2 in ambient
  air due to altitude

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Altitudes greater than 10,00 feet place operators
at risk

• Sx listed as immediate and long term in exposure
  and display
• Initial immediate response to altitude is
  hyperventilation triggered by hypoxia
• Over a period of time the chemical stimulation
  causing hyperventilation will reverse this may
  take from 10-14 days

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60-80 of respiratory symptoms occur within 7-10
days of exposure

• Acclimation to high altitude is effective in
  reducing this
• Acclimation cannot be achieved in less than 10
  days

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Is your unit going above sea level?

• Medical threat assessment for terrain
• Paskistan army performs well above 4,000m due to
  prolonged acclimation
• Acclimate your personnel as/when possible

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Progression

• Hyperventilation begins to alter the acid base
  balancee
• Decreased CO2 can seriously alter the
  effectiveness of the cardio vascular system
• Cellular walls begin to break down and fluid
  accumulation begins

• Initial Sx of headache occur for this increased
  intercranial pressure related headache
• Recognition of this early onset Sx and descending
  will abate serious condition later

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Despite Acclimation Sx may still occur

• Sx vary from mild to life threat
• All are mission limiting for the soldier and
  cannot be ignored
• HAPE HACE are life threats without ALS
  intervention

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Risk Factors

• Degree of acclimation
• Ascent rate
• Height achieved
• Altitude soldier sleeps at
• Fitness level of soldier population is not
  commonly a protective measure ensuring protection
  from Altitude Sickness

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Initial Presentation of Acute Mountain Sickness
(AMS)

• Headache in a recently arrived person at
  altitudes greater than 2500m
• GI distress common
• Insominia, dizziness, fatigue is the progression

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HACE / HAPE

• Clinical Dx made after severe symptoms to include
  respiratory distress and marked decreased level
  of consciousness
• Evidence of retinal hemorrhage is evidentiary to
  above
• Drowsiness to stupor is a common patient
  presentation

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Management

• Stop further ascent
• Descend as soon as practical at 1st signs of
  severe symptoms

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Medical Therapy

• Somestimes descending a few hundred meters is
  enough to reverse symptoms

• Use of a portable HBO chamber will improve the
  condition
• 2 PSI over ambient will simulate a 2500m drop in
  altitude

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Summary

• Medical threat assessment when about to operate
  above 2500 m
• Acclimate early
• Expose slowly over a period of 2wks
• Descend or seek ALS before Sxs progress
• Mild AMS can still affect mission effectiveness
• HACE/HAPE are life threats descend!