What is Acute Mountain Sickness (Altitude Illness; Altitude Sickness)?
As more and more people travel internationally for adventure and wilderness trips, doctors everywhere may need to advise and help prevent or treat various travel-related illnesses. One of the issues travelers can face relates to high altitudes. When we climb to high altitudes, the reduced oxygen can lead to different health problems, such as High Altitude Pulmonary Edema, High Altitude Cerebral Edema, and a common but milder condition called Acute Mountain Sickness, also known as Altitude Illness or Altitude Sickness.
Both High Altitude Pulmonary Edema and High Altitude Cerebral Edema are severe and potentially life-threatening conditions that demand instant treatment. The best response is to try and descend to a lower altitude or into an environment with increased pressure as safely and quickly as possible. On the other hand, the symptoms of Acute Mountain Sickness can usually be prevented or managed with medication taken orally, and it’s usually not necessary to descend or use supplemental oxygen.
Bear in mind that high altitude environments are those higher than 1,500 meters. The higher you go, the less oxygen there is in the air, which increases the risk of low oxygen levels in the body, a situation known as hypoxemia.
What Causes Acute Mountain Sickness (Altitude Illness; Altitude Sickness)?
Acute Mountain Sickness happens when your body reacts to lower amounts of oxygen in the air you breathe in, leading to a lack of oxygen in your tissues. At normal activity levels, the brain is the most sensitive part of the body to this lack of oxygen. So, the symptoms you might notice from Acute Mountain Sickness (which we’ll talk about later) are controlled by your central nervous system.
In many people who travel to high altitudes, their breathing patterns while asleep can become irregular, which could help to cause symptoms of Acute Mountain Sickness.
Risk Factors and Frequency for Acute Mountain Sickness (Altitude Illness; Altitude Sickness)
Acute Mountain Sickness is more common the higher up you go. It’s pretty rare below 2500 meters, but about 75% of travelers who aren’t used to the altitude might be affected at 3000 meters. If you’ve experienced this sickness before, you’re more likely to experience it again compared to those who’ve been fine on similar trips.
Existing health conditions can make Acute Mountain Sickness worse by making your body’s reaction to low oxygen levels more severe. Anemia and chronic obstructive pulmonary disease are examples of such conditions. Anemia can make it harder for your blood to carry oxygen, while chronic obstructive pulmonary disease can lower the amount of oxygen your lungs can take in.
- Before you go on your trip, it’s important to make several preparations:
- Screening to figure out how severe your disease is
- Extra treatment of your existing condition
- Considering taking measures to reduce the risk of low oxygen levels at a lower altitude
- Making sure you’re ready to treat the sickness during your trip
- Adjusting your travel plans as needed
Signs and Symptoms of Acute Mountain Sickness (Altitude Illness; Altitude Sickness)
Acute Mountain Sickness is a condition that can occur when someone travels to high altitudes too quickly. This can lead to uncomfortable symptoms such as a headache, nausea, vomiting, loss of appetite, feeling tired even when resting, trouble sleeping, and feeling dizzy or lightheaded. These symptoms usually start within the first day of being at a high altitude and can resolve on their own within one to three days as the body adapts to the lower oxygen levels.
It’s important to note that swelling in the face or extremities can also occur, even in the absence of other symptoms. This is seen as a sign that the body has not yet adjusted to the altitude. Severe cases can result in bleeding in the retina of the eye, affecting vision, but this is quite rare.
Testing for Acute Mountain Sickness (Altitude Illness; Altitude Sickness)
Acute mountain sickness is a health condition that’s identified based on certain symptoms in a specific situation. The main symptom to look out for is a headache. Some people may have other common symptoms too. There’s no particular lab test or other tests suggested for diagnosing this sickness.
Since the symptoms vary and can be general, showing unusual symptoms like diarrhea should prompt a check for other possible health issues. It’s also important to note that people may consume more alcohol while on vacation which can affect their health. Lastly, when someone has more severe symptoms related to the nervous system, it can indicate a potentially life-threatening condition known as High Altitude Cerebral Edema. Therefore, it’s essential to take this situation very seriously and seek immediate medical assistance.
Treatment Options for Acute Mountain Sickness (Altitude Illness; Altitude Sickness)
For travelers going to high-altitude locations, the most manageable risk factor is how quickly they ascend. Taking a slower, more gradual approach to getting to higher elevations allows the body to adjust to the lower levels of oxygen in the air. It’s the safest way to avoid altitude sickness and is the preferred method if the traveler’s schedule allows for it. The method helps mitigate the risk of aggravating any health conditions which can be triggered or worsened by low oxygen levels.
Also, the height at which a person sleeps is a more significant factor for altitude sickness than the highest height they reach during the day. If possible, for safe altitude acclimation, it’s advised to increase the sleeping altitude by no more than 500 meters per day, once above 2500 meters. It’s also suggested to set aside a day for acclimation when reaching 2500 meters and every 1000 meters of ascent afterward. For the first 48 hours upon reaching that height, it’s recommended to avoid exercise and alcohol until the body adjusts. If symptoms of altitude sickness appear, going higher should be avoided until they subside. If the symptoms persist, descending to a lower altitude is advised.
As for medication, acetazolamide is most commonly used for both prevention and treatment of altitude sickness. If you’re traveling above 9000 feet without time for your body to adjust, or if you’ve previously experienced altitude sickness, taking acetazolamide as a preventive measure can be helpful. The medication works by lowering the blood’s pH level, which in turn boosts the breathing rate. Generally, it’s well-tolerated, but it can cause a tingling sensation in the fingers and sometimes the lips.
Dexamethasone is less commonly used, primarily as a treatment and occasionally for prevention. Over-the-counter ibuprofen can also be effective, and might be a comfortable choice for some since they’re often familiar with its use. All three medications can cause stomach-related side effects, which can sometimes overlap with symptoms of altitude sickness. If these medications are well-tolerated, they should be continued until the traveler has had one to two days to acclimate at their highest altitude.
What else can Acute Mountain Sickness (Altitude Illness; Altitude Sickness) be?
There are a number of medical conditions that need to be ruled out when making a diagnosis. These conditions may have similar symptoms and could include:
- Low body temperature (Hypothermia)
- Stroke caused by blocked blood flow to the brain (Ischemic stroke)
- Inflammation of the protective membranes surrounding the brain and spinal cord (Meningitis)
- Intense headaches often accompanied by sensitivity to light and nausea (Migraine headache)
- Inflammation of the brain and spinal cord membranes, typically caused by a virus in children. This is not due to a bacterial infection (Pediatric aseptic meningitis)
- Bacterial infection causing inflammation of the protective membranes covering the brain and spinal cord in children (Pediatric bacterial meningitis)
- A dangerous reduction of body water in children (Pediatric dehydration)
- Headaches in children (Pediatric headache)
- A rare but serious condition that causes swelling in the liver and brain. This typically affects children and often follows a viral infection (Reye syndrome)
- Imaging tests done to diagnose inflammation or infections of the sinuses (Sinusitis imaging)
Accurately diagnosing the condition is crucial as the treatments for these illnesses can vary greatly. Doing so usually involves considering other possibilities and conducting necessary tests.
Possible Complications When Diagnosed with Acute Mountain Sickness (Altitude Illness; Altitude Sickness)
These are some severe conditions that a person may experience:
- Confusion
- Difficulty with movement (Ataxia)
- Unconsciousness or deep unresponsive state (Coma)
- Brain Herniation (a potentially deadly side effect of very high pressure within the skull that occurs when a part of the brain is squeezed across structures within the skull)
