1. High Altitude Sickness

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. Management 1.Stop further ascent 2.Descend as soon as practical at 1 st signs of severe symptoms

12. 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

13. 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!