Nepal’s breathtaking landscapes and high peaks attracts trekker from all around the world. However, trekking in Nepal often involves traversing through the high- altitude landscapes where the air gets thinner, oxygen levels drop that will require your body some time to adapt. So, you need to take care of yourself as that can lead to Acute Mountain Sickness (AMS)/ Altitude Sickness and can lead to more severe conditions. Understanding Altitude Sickness and the importance of Acclimatization is crucial to have a safe and enjoyable trekking experience in the lap of Himalayas.
What is Altitude Sickness?
Altitude Sickness or Acute Mountain Sickness (AMS) can be defined as a medical condition that happens when you ascend to a higher altitude quickly. The sickness occurs when the body fails to adjust to the reduced oxygen levels at high elevations. Altitude sickness is usually preventable and treatable. Recognizing the symptoms early is the key to prevent altitude Sickness. Following are some of the symptoms and causes of Altitude Sickness:
- Headache (most common early symptom)
- Nausea and Vomiting
- Dizziness and Lightheadedness
- Fatigue and unusual tiredness
- Loss of appetite
- Insomnia
- Shortness of breath
- Disturbed Sleep
- Malaise (a general feeling of discomfort, illness)
There are several factors that causes Altitude Sickness/ Acute Mountain Sickness (AMS) listed below:
- Rapid Ascent: Ascending faster arises higher risk of AMS. The body needs time to adapt to the decreasing oxygen level and ascending quickly does not allow for proper acclimatization/ body adjust.
- Reduced Oxygen Level: As altitude increases, the oxygen in the air remains content but the atmospheric pressure decreases. The low atmospheric pressure affects oxygen absorption in the lungs.
- Overexertion at high altitude: Trekking too fast, carrying heavy loads, or skipping rest days can strain the body, increasing oxygen demand and making it harder to adjust leading to worsen the AMS symptoms.
- Dehydration: High altitude environment causes high water loss due to rapid breathing and dry air. Drinking 3 – 4 liters of water daily helps maintaining oxygen circulation.
- Sleeping at higher altitude: As you sleep on the higher altitude, the oxygen intake is lower as the breathing gets slower. So, it increases the chance of AMS.
- Alcohol, Smoking or drug (medical or non- medical) use: Alcohol, Smoking or any sedative consumption during the trek leads to depress the respiratory system, reducing oxygen intake and increasing AMS risk.
- Individual Susceptibility: Regardless of fitness level, some people are prone to altitude sickness than other people. Genetics also plays a huge role in how well an individual can adapt to lower oxygen levels.
Forms of Altitude Sickness, their symptoms, causes and remedies:
Altitude Sickness is not fatal. However, if the symptoms are ignored or left untreated it can lead to severe life-threatening conditions like HACE or HAPE that requires immediate medical attention. The various forms of altitude sickness are listed as below:
Acute Mountain Sickness (AMS): Mild to Moderate
Acute Mountain Sickness (AMS) is the mildest and common form of altitude sickness that usually occurs at an elevation above 2,500 meters (8,200 ft) above sea level. This condition arises when the body struggles to adapt to lower oxygen level at high altitudes.
Symptoms: Headache, Nausea, Dizziness, Loss of appetite, Fatigue, Disturbed Sleep, Shortness of Breath etc.
Causes: Rapid ascent without proper acclimatization, dehydration and over exertion.
Remedies: Rest, Proper acclimatization, Staying Hydrated, Eating Light meals. If condition worsen, descend to a lower altitude.
High Altitude Pulmonary Edema (HAPE): Severe
High Altitude Pulmonary Edema (HAPE) is a serious and potentially fatal condition caused by fluid buildup in the lungs. It often occurs above 3,500 meters (11,500 ft) above sea level but can also occur in the lower altitude if the ascent is too rapid. Unlike AMS, HAPE affects the lungs severely and impacts breathing, making physical activity increasingly difficult.
Symptoms: Shortness of breath even at rest, persistent cough (sometimes with frothy sputum), chest tightness, bluish skin (cyanosis), and extreme weakness.
Causes: Rapid Ascent, lack of acclimatization, cold temperatures and genetic susceptibility.
Remedies: Oxygen Therapy and medications like Nifedipine can help but evacuation to a lower altitude remains the most effective treatment.
High Altitude Cerebral Edema (HACE) – Severe and Life Threatening
High Altitude Cerebral Edema (HACE) is the most dangerous form of altitude sickness occurring when fluid accumulates in the brain. This condition typically develops above 4,500 meters (14,800 ft) and can be fatal if not treated immediately. HACE often starts with severe AMS symptoms and gets rapidly worsen, that will ultimately affect the cognitive function and coordination.
Symptoms: Severe Headache, Confusion, Ataxia (Difficulty Walking), Hallucinations, Slurred Speech, Altered Mental State, and unconsciousness.
Causes: Prolonged exposure to high altitude, rapid ascent and ignoring
Remedies: Immediate descent is the only life saving action. Oxygen Therapy, Dexamethasone can help reducing brain swelling, but descent is the best action.
Importance of Acclimatization
Acclimatization is the physiological process letting your body adapt to reduced oxygen level at high altitude by producing more red blood cells, increasing breathing rate, and making other adjustments to optimize oxygen delivery to tissues. Acclimatization is the most effective way to prevent altitude sickness. Proper acclimatization reduces the risk of AMS and enhances the overall trekking experience.
How the body Acclimatizes?
The human body undergoes several physiological processes during acclimatization:
- Hyperventilation: Hyperventilation is the increased breathing rate. At higher altitude, the body naturally starts breathing faster and deeper to intake more oxygen.
- Higher Red Blood Cell Production: The primary adaptation to high altitude is the body's production of more red blood cells, which are responsible for carrying oxygen throughout the body. This helps to improve oxygen transportation in the blood, enhancing overall endurance.
- Improved Oxygen Utilization: The muscles and tissues adjust and functions efficiently with less oxygen, making physical exertion more manageable at altitude.
- Changes in Blood Chemistry: The kidneys help regulate blood acidity by excreting bicarbonate, which balances the effects of increased respiration.
Best Practices for Acclimatization
To enjoy trekking at the high-altitude region, you can follow these practices of acclimatization to minimize the risk of altitude sickness.
Gradual Ascent
The golden rule of acclimatization is to ascend slowly. Slower ascend at a higher altitude gives your body time to adjust to the lower oxygen levels. It is better to ascend only 300 – 500 meters (1,000 – 1,600 feet) per day after reaching 3,000 meters of altitude.
Acclimatization Day
Incorporating rest days during trek allows the body to adjust before ascending further. For treks above 3,500 meters, it would be better to include one acclimatization day every 1,000 meters of gain.
Follow the "Climb High, Sleep Low" Rule
This technique involves trekking to the higher altitude during the day and returning back to lower elevation for sleep. It helps accelerate acclimatization and helps adjusting your body.
Hydration is the key
Staying hydrated is one of the best ways to prevent AMS. You should drink at least 3 – 4 liters of water daily to prevent dehydration. Dehydration is the prime reasons for AMS. So, hydration is the key.
Proper Nutrition
A rich diet in carbohydrates provides required energy for trekking in high altitude. You should avoid heavy proteins, greasy meals, alcohol consumption and smoking, that can strain the body.
Medications (if necessary)
Use of Acetazolamide (Diamox) helps to speed up acclimatization by stimulating breathing and aiding oxygen absorption. However, it should be only taken under medical advice.
Monitor Symptoms
You should always listen to your body. Ignoring the early signs of altitude sickness can be dangerous. If any symptoms of Acute Mountain Sickness appear, it is important to rest, hydrate, and allowing your body some time to adjust.
Use Supplemental Oxygen (if necessary)
For severe cases, oxygen cylinders or portable altitude chambers (Gamow bags) can be lifesaving.
Medications for Altitude Sickness
- Acetazolamide (Diamox): Helps prevent AMS by increasing breathing rate and improving oxygenation.
- Dosage: 125-250 mg twice daily, starting 1-2 days before ascent.
- Dexamethasone: Used for severe AMS, HACE prevention, or emergency treatment.
- Nifedipine: Used to treat HAPE by reducing pulmonary pressure.
*Note: These medications should be used under medical supervision.*
Altitude sickness is preventable with proper acclimatization, hydration, and awareness. Trekkers should always prioritize safety over reaching their destination. By understanding AMS and following acclimatization guidelines, you can enjoy Nepal’s breathtaking high-altitude landscapes without risking your health.