Altitude sickness is a medical condition when you rush to walk at a higher altitude. It increases higher as you go because the atmosphere gets thinner and our body finds difficulty in adjusting. This means there will be less amount of oxygen and our body will find it difficult to breathe at higher altitudes.
It is also considered the mildest form of Acute mountain sickness. Different individuals react differently to altitude sickness, some show signs of headaches, vomiting, tiredness, confusion, trouble sleeping, and dizziness. If these symptoms are not addressed properly, then they become severe like high-altitude pulmonary edema (HAPE) with associated shortness of breath or high-altitude cerebral edema (HACE) with associated confusion and chronic mountain sickness.
Some people start experiencing altitude sickness at an altitude of 2,500 m while some experience it at a lower region. The high degree of elevation gain and activity is the main risk factor for altitude sickness. More than 20 percent of people suffer from AMS at an altitude of 2500m while 40% of people contract it at 3,000m.
The confirmation is usually based on minor symptoms like headache, nausea, shortness of breath, and vomiting which normally occur after contracting it. The minimization of symptoms is done by ascending gradually by covering only 300 m of distance daily. Altitude sickness may occur in those who are physically fit. The regular intake of fluid and descending downward helps to treat the symptoms. Medicine like Ibuprofen, acetazolamide, or dexamethasone helps to cure minor cases while oxygen therapy and a portable hyperbaric bag are used in severe cases.
Male trekkers and mountaineers suffer from HAPE while AMS and HACE are experienced both by male and female adventurers. The Chinese text which dates back to 30 BCE, describes the altitude sickness as “Big Headache Mountains” which refer to the Karakoram Mountains of KIlik Pass.
Other Names
Acute Mountain sickness is also known as High-altitude cerebral edema, altitude anoxia, altitude sickness, mountain sickness, and high-altitude pulmonary edema.
Cause
Altitude sickness is experienced at an elevation of 1,500m which gradually changes to severe at extreme altitudes. When you encounter this sickness above 6,000m, you may require supplemental oxygen otherwise your condition may worsen. The decrease in available oxygen with an increase in altitude reduces mental and physical alertness. The loss of water from the lungs due to dehydration also causes altitude sickness. High altitude sickness can be classified as:
- High altitude (1,500–3,500 m / 4,900–11,500 ft)
The elevation of 1500 m to 3500m is characterized as a high altitude. Then, the reduction of oxygen level and air pressure will reduce your physical power along with an increase in ventilation walls. This results in slight damage of the arterial oxygen transport which causes its saturation above 90 %. Most of teh people ascend rapidly in the altitude range of 2400 to 4000 m, then they will suffer from altitude sickness commonly.
- Very High altitude (3,500–5,500 m / 11,500–18,000 ft)
The very altitude range is characterized by a distance of 3500 m to 5500 m. Here, the Saturated oxygen level falls below 90% and the arterial partial pressure of oxygen falls less than 60mmHg. Severe altitude sickness occurs in this range and there will be less amount of oxygen in your blood whether you are exercising, sleeping, or suffering from high altitude pulmonary edema.
- Extreme altitude (above 5,500 m / 18,000 ft)
The elevation above 5,500 m is known as extreme altitude. It is also known as hypoxemia, hypocapnia, and alkalosis. The physical capabilities start to decline so you need to have a proper acclimatization to climb higher.
Some of the possible reasons behind the altitude sickness:
- Altitude sickness begins when there is a reduction of air pressure and deficiency of oxygen level at the higher elevation.
- The fast climbing rate at a higher altitude.
- Living near or at the seal level and traveling to higher regions.
- Previous illness.
- Use of intoxicants like alcohol and smoking.
- Medical problems related to the heart, nervous system, or lungs.
- Anemia patients.
- Lack of proper acclimatization at higher altitudes.
Symptoms
Every individual reacts differently in the high-altitude region. Healthy people experience it at around 2000 m above sea level after ten hours of ascent. You will begin symptoms like headache, confusion, fatigue, stomach illness, dizziness, and sleep disturbance.
- Primary symptoms
The first thing you will experience if you contract altitude sickness is a headache. Headache may also occur due to dehydration. Headache with other disorders causes the following symptoms:
- Gastrointestinal: Loss of appetite, nausea, vomiting, excessive flatulation
- Nervous: Fatigue or weakness, headache with or without dizziness or lightheadedness, insomnia, "pins and needles" sensation
- Locomotory: Peripheral edema (swelling of hands, feet, and face)
- Respiratory: Nose bleeding, shortness of breath upon exertion
- Cardiovascular: Persistent rapid pulse
- Other: General malaise
2. Severe symptoms
- Pulmonary edema (fluid in the lungs): Similar signs like that of bronchitis, continuous dry cough, fever, and shortness of breath while resting.
- Cerebral edema (swelling of the brain): Headache that doesn't go away even after the introduction of analgesics, irregular rate, continuous fainting, nausea, vomiting, and retinal hemorrhage.
The severe case of altitude sickness appears as a fluid accumulation in the tissues which is known as edema. People suffer from High-Altitude Pulmonary Edema (HAPE) or High-Altitude Cerebral Edema (HACE). HACE occurs by vasodilation of cerebral blood vessels as a result of hypoxia followed by a higher flow of blood exerting high pressure on the capillary walls.
It leads to life-threatening conditions like coma or death. Headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, half-body side paralysis, coordination loss, and confusion. Moving downwards helps to reduce these symptoms. Dexamethasone is taken in the case of HACE.
HAPE is a condition where there is a vasoconstriction in the pulmonary circulation which results in an increased cardiac output followed by an increase of capillary pressure. It is fata and it progresses rapidly. The symptoms like fatigue, severe dyspnea, and dry cough which changes to pink and frothy sputum can be seen. You need to descend to cure these symptoms.
Exam and Test
When you suffer from altitude sickness, the medical assistant will examine your chest area via a stethoscope. If you have fluid accumulation in the lung, then it sounds like crackles (rales) in the lung. Here are a few tests that should be done in these cases:
- Blood tests
- Brain CT scan
- Chest x-ray
- Electrocardiogram (ECG)
Treatment
Acute mountain sickness should be treated in the early stages otherwise it could be life-threatening. The primitive treatment starts if you climb down to a lower altitude as soon as you suffer from it. An extra oxygen tank helps your condition. In case of severe condition, you should be admitted to the hospital. However, acetazolamide also known as Diamox helps you to breathe and reduce symptoms.
It causes frequent urination so increase the water intake and avoid any sort of intoxication. Likewise, pulmonary edema, a condition of accumulation of fluid in the lungs can be treated by:
- Oxygen
- A high blood pressure medicine called nifedipine
- Beta agonist inhalers to open the airways
- Breathing machine in severe cases
- Medicine to increase blood flow to the lungs called phosphodiesterase inhibitor (such as sildenafil)
The symptoms of altitude sickness and brain swelling (Cerebral edema) are reduced by Dexamethasone(Decadron) consumption. Portable hyperbaric chambers help to stimulate conditions of higher altitude at lower altitude which helps the detect bad weather to mountaineers.
Outlook (Prognosis)
In altitude mountain sickness, mild cases improve if you climb down to a lower altitude. If it is not taken care of in the early stage, it becomes severe and results in brain swelling (cerebral edema), lung problems, and death. Most of the trekking locations are in remote regions where emergency evacuation and treatment will be difficult, so it depends on your physical willpower and how fast you will move downwards.
Possible Complication
The possible complications of acute mountain sickness results:
- Coma (unresponsiveness)
- Fluid in the lungs (pulmonary edema)
- Swelling of the brain (cerebral edema), which can lead to seizures, mental changes, or permanent damage to the nervous system
- Death
When to seek a medical professional
You must contact a medical professional if your symptoms don't reduce even though you decline to a lower altitude region. Make sure to contact your leader by dialing the local emergency number. When you or your teammate experience severe symptoms like coughing up blood, or severe problems while breathing, you must seek medical help. Climbing down the mountain is the first thing to do.
Prevention
The first step to reducing altitude sickness is to ascend down slowly. You should avoid hike and skiing in the first 24 hours at high altitudes. Avoid consuming alcohol and sleeping pills because they reduce the acclimatization process. Alcohol causes dehydration and worsens altitude sickness so avoid consuming it before 2 days of the actual trekking or mountaineering.
- Pre acclimatization
Pre-acclimation helps the body to adapt where oxygen concentration is low. You will spend less time in the mountains, and make sure to consume less amount of food and other dietary supplies. Some examples of pre-acclimatization include remote ischaemic preconditioning, using hypobaric air breathing in order to simulate altitude and positive end-expiratory pressure.
- Altitude acclimatization
The process of adapting to the decreased oxygen level at a higher altitude to avoid acute mountain sickness is called altitude acclimatization. Climbers and trekkers start applying the phenomenon of “climb high, sleep low” as soon as they are above 3,000m. Many climbers stay a few days at a base camp and then climb to a high camp followed by returning slowly to the base camp.
They stay overnight at a higher camp for a few times while extending the time spent at a higher altitude which helps the body to adapt to increased altitude. This process helps increase the production of red blood cells. After that, the climber will continue this process until he reaches the destination camps without any sickness. It is very essential for those trekkers who move very rapidly from lower altitudes to higher altitudes.
- Medication
Altitude sickness can be cured in mild cases by medication. Certain medicines like acetazolamide or nifedipine and phosphodiesterase (PDE) inhibitors like sildenafil and tadalafil help prevent altitude sickness.
- Over-the-counter herbal supplements and traditional medicines
The use of herbal supplements and traditional medicine also helps to reduce or prevent altitude sickness. Supplements like ginkgo biloba, and R crenulata, minerals such as iron, antacids, and hormonal-based supplements such as medroxyprogesterone and erythropoietin reduce the susceptibility to acute mountain sickness. There is not enough research which support that these herbal supplements remove altitude mountain sickness.
- Oxygen enrichment
Altitude sickness in higher regions can also be prevented by introducing a small amount of supplemental oxygen in climate-controlled rooms. When you are at 3400m, only a 5 % rise in oxygen concentration via an oxygen concentrator helps you to feel the atmosphere of 3,000m which will ease your difficulty. Oxygen is provided either via nasal cannula or mask from liquid containers or gas bottles.
Electricity is also used to generate oxygen concentrators like Pressure Swing Adsorption (PSA), VSA, or vacuum-pressure swing adsorption (VPSA). PSA technology when used for stationary oxygen concentrators, degrades the performance at high altitudes with low barometric pressures. This can be compensated by using a concentrator that has maximum flowing capacity.
Other methods
The altitude sickness can be prevented by increasing water intake. When walking at higher altitudes, thin dry air causes fluid loss via breathing so make sure to hydrate yourself throughout the trek.
