High altitude refers to any destination situated above 3500 metres. While these elevated locations offer breathtaking vistas, they also pose unique health challenges.
What is Altitude Sickness?
Altitude sickness occurs when individuals fail to acclimatise properly, leading to insufficient oxygen intake. Despite the same oxygen levels in the air at high altitudes, the decreased air pressure makes it challenging for the lungs to absorb the adequate amount of oxygen required for normal bodily functions. To adapt, the body initiates various processes. Initially, it triggers hyperventilation in an attempt to increase oxygen intake, leading to elevated CO2 levels in the blood. Carbonic Anhydrase then converts this excess CO2 into bicarbonate, causing blood acidosis and apnea (breathing cessation), which ultimately reduces oxygen intake. Diamox (acetazolamide) can help prevent carbonic anhydrase activity, preventing blood acidosis and maintaining breathing without apnoea. Additionally, the body increases cardiac output and haemoglobin levels to facilitate oxygen transport.
Types
- Acute Mountain Sickness (AMS): The most common, affecting approximately 65% of travellers.
- High Altitude Cerebral Edema (HACE): A life-threatening condition that may develop if AMS is left untreated, occurring in 10% of cases.
- High Altitude Pulmonary Edema (HAPE): This condition is not necessarily preceded by AMS and can be life-threatening.
Symptoms
- AMS: Symptoms include a headache along with fatigue, loss of appetite, nausea, sleep disturbance, shortness of breath and dizziness. Typically occurs 6-10 hours after ascent and usually resolves in 1-3 days if further ascent is delayed.
- HACE: Symptoms are similar to AMS but also include lethargy, confusion and ataxia. Typically occurs at least 2 days after ascent.
- HAPE: Symptoms include those of HACE along with shortness of breath during exertion, a dry cough and, in some cases, blood-stained sputum. Typically occurs at least 2 days after ascent.
Prevention
- Be aware of altitude symptoms
- Acclimatise slowly
- Include rest days every 3 days
- Avoid sleeping more than 300 metres higher than the previous night and/or in the presence of AMS symptoms
- Stay hydrated and minimise exertion
- Always descend if symptoms worsen or are severe
- Consider Diamox to aid acclimatisation
- Past experiences at high altitudes may influence future experiences with altitude sickness
Treatment and Insurance
- Disclose your planned maximum altitude for proper insurance coverage, including emergency evacuation by helicopter.
- For AMS: Rest, analgesia for headaches and anti-emetics for nausea may help. If symptoms worsen, descend immediately by at least 500-1000 meters.
- For HACE/HAPE: Immediate descent is critical. Oxygen, nifedipine and dexamethasone are options for HAPE, while dexamethasone is suitable for HACE.
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