Altitude Sickness: Types, Causes, Symptoms, Risk Factors, Diagnosis, Treatment And Prevention

Ever felt nauseous or had a throbbing headache during a hike? A sudden rise in your heart rate? Then you may have been experiencing something called altitude sickness. Altitude sickness occurs at altitudes of 8,000 feet and above and should not be neglected.

Altitude sickness is caused due to a lack of oxygen. It occurs while doing activities at a high altitude, such as hiking, driving, climbing etc where your body does not get the right amount of oxygen. For individuals who are used to high altitudes, the problem would not be prominent like that for the ones who are not accustomed to it ^[1] .

Altitude sickness is severe and should not be ignored as the condition is dangerous for your body. One study suggested that younger people (18-19) and older people (60-87) might be at higher risk. The risk of developing altitude sickness between the genders is believed to be equal, but some observational studies have shown that women have a slightly higher risk than men ^[1] .

Types Of Altitude Sickness

The condition is classified into three types and they are as follows ^[2] :

Acute mountain sickness (AMS): It is the mildest form of altitude sickness and is very common.

High altitude pulmonary oedema (HAPE): This type is caused when there is a build-up of fluid in the lungs. HAPE is dangerous and life-threatening if left untreated.

High altitude cerebral oedema (HACE): This is the most severe form of altitude sickness and develops when there is fluid retention in the brain. HACE causes the brain to swell up and stop functioning.

Causes Of Altitude Sickness

The condition develops when your body fails to get acclimatised to the high elevations. When you are climbing to higher altitudes, the air becomes thinner and has low levels of oxygen.

A majority faces altitude sickness at elevations above 8,000 feet. According to a study, 20 per cent of hikers experiences altitude sickness between 8,000 and 18,000 feet and almost 50 per cent of hikers and trekkers experience it above 18,000 feet ^{[3] [4]} .

Symptoms Of Altitude Sickness

The signs usually develop within 12 to 24 hours of reaching a higher elevation. The symptoms of altitude sickness are as follows ^[5] :

• Headache
• Nausea
• Dizziness
• Vomiting
• Shortness of breath
• Fatigue
• Loss of energy
• Loss of appetite
• Disturbed sleep or insomnia

Severe symptoms of altitude sickness are as follows ^[6] :

• Confusion
• Coughing
• Skin discolouration
• Shortness of breath even while resting
• Chest tightness
• Bloody mucus
• Decreased consciousness
• Inability to walk in a straight line

Specific symptoms of HACE are extreme drowsiness, confusion and irritability and trouble walking. The symptoms of HAPE are increased breathlessness, weakness and severe coughing.

If the symptoms get too severe and worsen over time, you will require immediate medical attention, which otherwise can cause coma or death ^[7] .

Risk Factors Of Altitude Sickness

The following actions can trigger altitude sickness ^[8] :

• Ascending too rapidly
• Inadequate fluid intake
• Hypothermia
• Overexertion within 24 hours of ascent
• Consumption of alcohol

Complications Of Altitude Sickness

In the event of a lack of timely medical attention, the condition can cause the following complications ^[9] :

• Brain swelling
• Pulmonary oedema
• Coma
• Death

Diagnosis Of Altitude Sickness

The doctor will carry out the examination based on the individual's signs and symptoms. Using a stethoscope, the doctor will check for shortness of breath.

Any rattling or crackling sounds in your lungs indicate the presence of fluid. The doctor may suggest for a chest X-ray as well ^[9] .

Treatment For Altitude Sickness

The most important treatment for any level of altitude sickness is to go down to a lower elevation as soon as possible while remaining safe.

However, for severe cases medical attention is necessary. Medications such as acetazolamide are prescribed for reducing the symptoms of altitude sickness ^[10] .

Lung inhaler, high blood pressure medication and a phosphodiesterase inhibitor medication are also prescribed, for reducing the pressure on the arteries in your lungs.

Prevention Of Altitude Sickness

Acclimatisation is the best way to prevent getting altitude sickness. It is the process of slowly letting your body gets used to the changes in air pressure as you travel to higher elevations ^{[11] [12]} .

• Start your journey below 10,000 feet.
• If you walk, hike, or climb over 10,000 feet, only go up an additional 1,000 feet per day.
• Drink 3-4 quarts of water every day.
• Do not use medications such as sleeping pills.
• Make sure about 70 per cent of your calories are coming from carbohydrate-rich foods.

FAQs On Altitude Sickness

Q. What are the first signs of altitude sickness?

Ans: Dizziness, fatigue, headache and difficulty sleeping.

Q. How long does altitude sickness last?

Ans: Most people can recover from a mild case of acute mountain sickness quickly after returning to lower altitudes. Symptoms typically subside within hours but may last up to 2 days.

Q. Can altitude sickness kill you?

Ans: Altitude sickness can make you dizzy, nauseous, and, in extreme cases, can even kill you.

Arya KrishnanEmergency Medicine

MBBS

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