What is High Altitude?

High altitude refers to any location that is 3,500 metres or more above sea level.

What is Altitude Sickness?

Altitude sickness occurs when your body struggles to adapt to the reduced oxygen pressure at high altitudes. Even though the air still contains the same percentage of oxygen, the lower pressure makes it difficult for your lungs to supply your body with enough oxygen. Your body attempts to compensate through various processes, such as hyperventilation, to increase oxygen intake.

However, hyperventilation leads to an increase in carbon dioxide (CO2) levels in the blood. An enzyme called carbonic anhydrase converts this CO2 into bicarbonate, causing the blood to become more acidic. This acidity can result in breathing apnoea, which decreases oxygen intake further. The cycle continues as the body tries to adjust, increasing cardiac output and haemoglobin levels to help transport oxygen.

Types of Altitude Sickness

Acute Mountain Sickness (AMS) – This is the most common type of altitude illness, affecting around 65% of travellers at high altitudes.

High Altitude Cerebral Edema (HACE) – A severe form of altitude sickness, affecting 10% of people who don’t treat AMS. This is a life-threatening condition.

High Altitude Pulmonary Edema (HAPE) – Can be fatal and doesn’t always begin with AMS.

Symptoms

AMS – The initial signs include headaches, along with other symptoms like fatigue, nausea, dizziness, shortness of breath, disturbed sleep, and loss of appetite. Symptoms usually appear 6-10 hours after reaching a high altitude and may resolve in 1-3 days if ascent is delayed.

HACE – In addition to AMS symptoms, people with HACE may experience lethargy, confusion, and coordination issues (ataxia). It typically occurs at least two days after reaching a high altitude.

HAPE – Along with the symptoms of HACE, HAPE presents shortness of breath that worsens with exertion, a dry cough, and eventually difficulty breathing, even at rest. In severe cases, the cough becomes productive, with blood-tinged sputum. It usually develops after two or more days at high altitude.

Prevention

To prevent sickness, it is essential to ascend gradually, allowing time to acclimatise. Plan rest days every three days and avoid sleeping more than 300 metres higher than the previous night if symptoms are present. Stay hydrated and minimise physical exertion. If symptoms worsen or become severe, always descend immediately.

Altitude sickness tablets, such as Diamox, can help with acclimatisation by aiding the body’s adjustment to high altitudes. It’s important to note that if you have previously experienced AMS, you’re more likely to suffer from it again during future high-altitude trips. Conversely, just because you didn’t experience AMS before doesn’t mean you’re immune on subsequent visits.

Treatment

Insurance – Make sure your travel insurance includes emergency evacuation by helicopter if you plan to reach high altitudes.

AMS Treatment – If you experience symptoms of AMS, the best course of action is to rest. Most symptoms will disappear after one or two days. Painkillers can help with headaches, and antiemetics may relieve nausea. If symptoms worsen, descend by 500 to 1,000 metres immediately.

HACE and HAPE Treatment – Immediate descent is critical. Administer oxygen, and use medications like Nifedipine and Dexamethasone for HAPE, and Dexamethasone for HACE.

Availability

Visit your local pharmacy to learn more about altitude sickness tablets, or feel free to pop in when it’s convenient to enquire further.