High Altitude Sickness Terminology for High Altitude Sickness

High Altitude Sickness

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 O 2 in ambient air due to altitude

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

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

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

Progression • Hyperventilation begins to alter the acid base balancee • Decreased CO 2 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

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

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

Initial Presentation of Acute Mountain Sickness (AMS) • Headache in a recently arrived person at altitudes greater than 2500 m • GI distress common • Insominia, dizziness, fatigue is the progression

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

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

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 2500 m drop in altitude

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