blog O výškovej chorobe (AMS)

Altitude mountain sickness

AMS it is one of the most prominent risk factors when trekking in the Himalayas. It occurs as a result of hypoxia (simply put, a lack of oxygen) when ascending to higher altitudes. Its presence should not be underestimated, and special attention should be given, especially to its prevention.

What is AMS (altitude mountain sickness)

Acute mountain sickness (AMS) occurs as a result of hypoxia (lack of oxygen) in the vast majority of cases above 2500 meters above sea level. Risk factors mainly include previous issues with altitude sickness or rapid ascents to higher altitudes. It affects most people above 4000 meters above sea level. This relatively mild form manifests itself with symptoms such as headaches, loss of appetite, nausea, or insomnia. With gradual acclimatization, it usually subsides on its own and does not require treatment. More severe manifestations of altitude sickness include the development of pulmonary or cerebral edema; however, these are much rarer and typically occur at higher altitudes, around 7000 to 8000 meters. Tolerance to altitude is highly individual and does not strongly correlate with physical fitness. It is more influenced by age, the level of physical exertion, and the quality of acclimatization. Interestingly, pulmonary edema tends to occur primarily in younger individuals, with susceptibility decreasing as age increases.

Prevention

The basic principle is slow acclimatization to altitude. Up to 3000 meters above sea level, it is recommended to ascend 300-500 meters in altitude per day. If the situation allows, it is advisable to sleep at lower altitudes. After finishing the daily stage, a short acclimatization walk to a higher altitude followed by a descent is recommended. Around 3500 meters above sea level, it is usual to take a rest day for acclimatization, dedicating it to a walk around the area. Physical inactivity in bed during acclimatization is not advisable. Above 4000 meters, it is ideal to slow down the daily ascent to 200-300 meters per day. The key here is not so much how many meters we ascend daily, or the final altitude we reach, but the altitude of the next overnight stop. Acclimatization is also influenced by adequate hydration, which requires an increased intake of fluids.

Acclimatization can be supported even before the trek, at home. A crucial factor for the body is iron. It is essential for the production of hemoglobin and red blood cells, which are the primary distributors of oxygen in the body. Without it, acclimatization won't go too smoothly. Therefore, try to eat foods rich in iron, such as red meat, seafood, quinoa, tofu, legumes, or pumpkin seeds. Other vitamins and minerals also have a positive effect on the acclimatization process. In the professional literature, Vitamin A, C, D, B vitamins, and zinc are often mentioned.

Another way to prepare for a high-altitude trek (or expedition) is to go on an acclimatization hike before flying to Nepal. A very rewarding, beautiful, and not technically demanding option is the hike to Monte Rosa from the Italian side, where we can spend a night (ideally two) at the highest hut in the Alps - Margherita Hut (4554 meters above sea level).

Alternatively, you can undergo basic acclimatization training in a hypobaric chamber, which faithfully simulates low pressure and thus high altitude. One such chamber is located in Topoľčany, Slovakia, and was built by our friend and enthusiast, Milo. I personally used it before an expedition to the Pamirs, where a helicopter dropped us at the base camp at 4200 meters above sea level within half an hour. Feel free to contact him, and he can tell you how he could help. You can find the link to the chamber at https://hypobar.webnode.sk/

Symptoms of AMS

At the first signs of AMS (acute mountain sickness), we don't need to panic immediately. It is mainly characterized by headaches, loss of appetite, nausea, or insomnia. Usually, it will resolve on its own as the body adapts to the decreasing pressure and, consequently, the lower oxygen levels by producing red blood cells and hemoglobin. In cases of beginning pulmonary edema, a dry cough and shortness of breath occur, even without physical exertion. Sometimes, a sensation of "bubbling in the lungs" is described. It can progress into apathy or delirium. For cerebral edema, the symptoms start more subtly, but can escalate quickly. It begins with behavioral changes, increased headache, vomiting, disorientation, hallucinations, numbness, and even unconsciousness. There have been cases where brain centers shut down, and the affected person loses functions such as speech. As a general rule, any change in health status during altitude gain should be assumed to be altitude sickness.

Treatment of AMS

Treatment for mild AMS (acute mountain sickness) is not necessary, and those with stronger constitutions usually handle it quite well. Increasing fluid intake, ibuprofen, or other analgesics may help. A supportive supplement could be Ginkgo. However, we don’t overdo medication and monitor the patient’s condition to avoid worsening the illness. Suppressing symptoms is not entirely desirable. We prefer light movement over lying down in a sleeping bag. Masking the illness or excessive use of painkillers and continuing the ascent can be very dangerous. This increases the risk of sudden deterioration, which can lead to an inability to cooperate and lower the chances of effective assistance. For symptoms of pulmonary edema, sildenafil (Viagra) or tadalafil may help. Caffeine can also be useful. Inhalation of supplemental oxygen, if available, is another option. At this stage of the illness, immediate descent to lower altitudes is crucial, as it increases pressure and the amount of oxygen the body receives. After descent, the illness usually subsides, and the patient’s condition improves rapidly. For cerebral edema, dexamethasone is typically effective. The patient’s condition usually improves quickly after taking the medication, but it has a limited duration, which should be used for immediate descent to lower altitudes. In both severe forms of altitude sickness, it is advisable to consider evacuating the patient from the mountain environment and handing them over to medical care. In Nepal, our local partners can arrange this, and we stay in contact with them via satellite phone. This rescue is usually fully covered by your mountain insurance (e.g., Alpenverein). However, this typically means the end of the trek, so the first priority is not to neglect the problem and to communicate openly about your condition before it’s too late. Altitude sickness should never be underestimated, although excessive fear is also not warranted. As the saying goes, it’s okay to get altitude sickness, but it’s not okay to die from it. I believe that we will always handle it successfully on our treks, and return from all our beloved mountains healthy and full of experiences.

Mišo Gabriž