High Altitude Oedema (HAPE and HACE): Symptoms, Prevention and UK Travel Advice

While most British travellers are familiar with the mild symptoms of Acute Mountain Sickness (AMS), such as headache and nausea, fewer are aware of its life-threatening complications: High Altitude Pulmonary Oedema (HAPE) and High Altitude Cerebral Oedema (HACE). These conditions occur when the body fails to adapt to the lower oxygen levels found at high altitudes, typically above 2,500 to 3,000 metres.

Oedema refers to an abnormal build-up of fluid in the body's tissues. In the context of high altitude, this fluid accumulates either in the lungs (HAPE) or the brain (HACE). Both are considered medical emergencies. According to NHS and NICE guidelines, early recognition and immediate action are the only ways to prevent permanent injury or death when these conditions manifest during a trek or climb.

HAPE is the most common cause of death related to high altitude. It occurs because the high-pressure environment in the lung's blood vessels causes fluid to leak into the air sacs, making it increasingly difficult to breathe.

Early Signs of HAPE

• Significant shortness of breath, even while sitting or resting.
• Extreme fatigue and weakness, often taking much longer to complete simple tasks.
• A persistent, dry cough.

Advanced Symptoms

As the condition worsens, the patient may develop a 'gurgling' sound in the chest and produce frothy sputum that may be tinged with blood. Their skin, lips, or fingernails may take on a blueish tint (cyanosis) due to a lack of oxygen in the blood. If you notice any of these signs, you must stop ascending immediately.

HACE is a rarer but equally dangerous condition where the brain swells with fluid. It is often considered the end-stage of untreated Acute Mountain Sickness. Because it affects the central nervous system, it can lead to coma within hours if ignored.

Key Indicators of HACE

• Ataxia: An inability to walk in a straight line or maintain balance (acting as if intoxicated).
• Confusion and Disorientation: Changes in personality, memory loss, or hallucinations.
• Drowsiness: Excessive lethargy that progresses to an inability to wake the person up.
• Severe Headache: A headache that does not respond to standard painkillers like paracetamol or ibuprofen.

Prevention is the bedrock of mountain safety. Most cases of HAPE and HACE occur in individuals who ascend too quickly without allowing their bodies time to acclimatise. UK health professionals and mountain medicine experts recommend the following 'Golden Rules':

• Fly to High, Sleep Low: If you fly into a high-altitude city (like Cusco or Leh), spend at least two to three days resting before climbing further.
• Monitor Ascent Rates: Above 3,000m, try not to increase your sleeping altitude by more than 300-500m per night.
• Rest Days: Schedule a rest day for every 1,000m of ascent.
• Hydration and Nutrition: Drink plenty of water and maintain a high-carbohydrate diet, while avoiding alcohol and sedatives.

In the UK, travellers may be prescribed Acetazolamide (often known by the brand name Diamox) to help prevent altitude illness. This medication works by acidifying the blood, which stimulates the brain to breathe faster, thereby increasing oxygen uptake. It is important to note that Acetazolamide is a preventative aid, not a cure for HAPE or HACE. It is usually started one to two days before you begin your ascent and continued until you have reached your peak altitude or started your descent.

A consultation with a UK doctor is required to ensure this medication is suitable for you, as it may interact with other health conditions or allergies (specifically sulphonamide allergies).

If you are planning an expedition to locations such as the Himalayas, the Andes, or Kilimanjaro, speaking to a GP online before you leave is highly recommended. A pre-travel consultation allows you to:

• Discuss your medical history and assess your risk of altitude-related illness.
• Review NICE-aligned guidance on acclimatisation schedules.
• Obtain private prescriptions for preventative medications like Acetazolamide.
• Learn how to distinguish between normal breathless and the early stages of pulmonary oedema.

An online doctor can provide factual, evidence-based advice tailored to your specific itinerary, ensuring you are medically prepared for the challenges of high-altitude environments.

If HAPE or HACE is suspected, the rule is absolute: immediate descent. You should not wait for morning or for symptoms to improve. A descent of even 500 to 1,000 metres can be life-saving. In trekking scenarios, oxygen cylinders or Portable Hyperbaric Chambers (Gamow bags) may be used to buy time, but these are temporary measures and not a substitute for reaching a lower altitude and seeking hospital care.