Altitude Sickness
SUMMARY: These are my notes on Altitude Sickness. Stresses of altitude include cold, low humidity, increased ultraviolet radiation and decreased air pressure. The main risk is hypoxia.
Risk
Inadequate acclimatisation may lead to altitude illness in any traveller going above 8000ft or 2500m.
Risk is unaffected by physical fitness or training.
Risk in children is equal to adults.
People >50 have a slightly lower risk.
Acute Mountain Sickness
Most common. Symptoms resemble a hangover - Headache, fatigue, loss of appetite, nausea, and vomiting.
Headache onset is 2 to 12 hours after ascent.
Resolves with descending in 24 to 72 hours.
Tips for Acclimatisation
Ascend gradually, increase the sleeping altitude by less than 500m per day, with an extra day for acclimatisation every 1000m
Consider Acetazolamide (Diamox) if the abrupt ascent is unavoidable
Avoid alcohol for the first 48 hours
Mild exercise for the first 48 hours
Having a high altitude exposure >2500m for 2 nights or more within 30 days of the trip will benefit
High Altitude Cerebral Oedema
Severe progression of AMS.
Rare.
Symptoms include profound lethargy, confusion, drowsiness, and ataxia.
Requires immediate descent.
Death within 24 hours of developing ataxia.
Risk Categories
Low - No prior history of altitude sickness. People taking >2 days to arrive at 2500m. No prophylaxis.
Intermediate - Prior history of AMS. Consider Prophylaxis.
High - History of AMS. Rapid ascent. History HACE / HAPE. Prophylaxis Strongly Recommended.
High Altitude Pulmonary Oedema
Occurs alone or with AMS / HACE.
Symptoms are exertional dyspnoea, then dyspnoea at rest.
Requires oxygen and descent immediately.
Diagnosis and Treatment
AMS / HACE - Clinical. Differentials include dehydration, exhaustion, hypoglycaemia, hypothermia, and hyponatremia. Treatment is descent >300m and symptoms will rapidly abate. Supplemental Oxygen 2L per minute. Antiemetics. Analgesia. Diamox.
HACE. Clinical. Descent. Oxygen. Portable hyperbaric chamber.
HAPE. Clinical. Differentials include Pneumonia, Bronchospasm, AMI, PE. Descent.
Pre-Existing Medical Conditions
Heart failure
Angina
Sickle cell disease
Medications
Acetazolamide / Diamox.
Acidifies the blood and increases respiration.
Side effects - Increased urination, paraesthesias on fingers and toes.
The dosage is 125mg every 12 hours beginning the day before ascent and continuing the first 2 days at altitude.
Longer if needed.
250mg BD if >100kg.
250mg BD is the treatment dose.
Alternatives - Dexamethasone. Nifedipine. Tadalafil. Sildenafil.