Medical Essentials for High Altitude Adventures
Whether in the rolling high steppes of Tibet, the looming snowy ranges of the Himalayas and Pakistan, or the numerous hot, humid jungles and savannahs in Eastern and Central Africa, trekkers have choices. Many trekkers - and not only alpinists - are becoming increasingly interested in climbing high mountains, with the sunlight on snow and the icy cold attraction of the mountains acting as an irresistible force in equal measure. The number of people likely to once again fuel a short alpine summer has begun to increase once more.
If we have a good understanding of the potential health risks at altitude, then we can control them by taking preventive measures. At high altitudes, our bodies undergo several physiological improvements that must occur to allow organs to receive sufficient oxygen from the air we breathe for typical metabolism.
There is a big debate around the question of whether or not altitude affects everyone. It is thought that some people are predisposed to becoming acutely mountain sick by any of the factors that add to acclimatization. A lack of sufficient acclimatization, thereby leading to being genuinely unwell at high altitude, is avoided by many of those people who have no prior experience. Good knowledge and the right gear are not only the keys to a safe high-altitude experience, but they also contribute to many levels of enjoyment in the mountains!
Understanding High Altitude Physiology
At sea level, or 700 to 1,500 feet above, the oxygen pressure is 129 to 132 mm of Hg or 21%; it is only 41 to 47 mm of Hg, or 6.6% at 30,000 feet. To maintain the oxygen supply due to the low oxygen concentration available, the human body shows various physiological adjustments or responses. Oxygen from the lungs is transported to the tissues by attaching it to haemoglobin, which increases almost twice during hypoxia at high altitudes. Though there is a modest increase or hyperventilation of minute ventilation at high altitudes, the lung volume remains the same or the ERV falls due to the diaphragm's reduced excursion, vital for gas exchange.
Due to hypoxic vasoconstriction or pressure-mediated vasoconstriction as a rapid pulmonary vasoconstrictor response, the PAO2 is almost equal to the PIO2 of 90 to 100 mm of Hg in the systemic arterial blood. It is an acute response that prevents any part of the lung or body from collapsing. There is a quick cardiovascular adjustment or acceleration of heart rate by both the sympathetic and parasympathetic stimulation to pump blood to other parts.
A series of adjustments in the human body include changes in minute ventilation (hyperventilation with a lesser ERV), oxygen exchange, haemoglobin increase, cardiac and stroke volume increase, oxygen delivery increase, and kidney response to EPO-RBC increase. The central nervous system is mainly affected by high altitudes, releasing cortisol from the adrenal gland and producing free radicals, which cause lipid peroxidation. This age-accelerated irreversible change occurs primarily in the frontal lobe related to mood and cognition.
Knowing the above essentials about various parts of the human body, any adventure lover or trekker can readily understand the supra-physiological condition of high altitude while suffering from Acute Mountain Sickness symptoms. An adventure lover should go through the essence and concept of high-altitude medicine to improve safety and enhance the adventure.
Common High Altitude Illnesses
There is a range of illnesses you can develop as a result of being at a higher altitude. Many of these are preventable, but recognizing the signs and symptoms can be the key to successful treatment.
Acute Mountain Sickness (AMS) is most common at elevations above 2500 m. The cause is a relative lack of oxygen due to our environment. Symptoms occur with increased altitude and typically begin 6 to 96 hours after arrival. The main symptoms include headache, dizziness, and difficulty sleeping. In some cases, when timely and appropriate medical treatment is not received, AMS can worsen.
High Altitude Pulmonary Edema (HAPE) is less common than AMS and can be more severe. It can occur at elevations above 2500 m as well. The cause is also a relative lack of oxygen due to the environment. Symptoms occur with increased altitude and typically begin 6 to 96 hours after arrival. The main symptom of HAPE is shortness of breath at rest.
High Altitude Cerebral Edema (HACE) is caused by a relative lack of oxygen due to high altitude. This typically occurs at elevations above 3000 m, but it can exist at lower elevations. Symptoms can increase from early AMS symptoms. Usually, the person affected may complain of tiredness and weakness of the body, despite adequate rest. They may also have difficulty walking and an unsteady gait. The main symptom is usually a severe headache that does not respond to medication and may be accompanied by vomiting. The appearance of at least one of the above symptoms may indicate HACE.
Acute Mountain Sickness
Acute Mountain Sickness (AMS) is the foremost cause of traveller morbidity at high altitudes. It is a three-dimensional syndrome encompassing physiological, psychological, and cognitive impairments but is particularly characterized by the development of the more common symptoms of headache, lassitude, sleep disturbances, anorexia, nausea, intolerance to activity, and fatigue during continued stay at high altitude. The severity of the illness is mild to moderate and it is self-limiting, generally occurring after a rapid ascent. The symptoms develop more commonly a few hours after reaching higher altitudes and are generally reduced overnight.
The diagnosis of AMS is difficult to establish as it is subjective to the individual. Effective verbal communication is essential, and after excluding other commonly seen conditions at altitude such as exhaustion, hypothermia, dehydration, or low atmospheric pressures, a high correlation between subjective and objective symptoms may establish the diagnosis.
Following rapid exposure to altitudes above 2500 m, the development of AMS has been associated with other factors: individual susceptibility, rapid altitude gain, and more than ordinary physical exertion. Reduced fluid intake or dehydration may serve as a conditional risk factor to those persons affected due to increased plasma osmolality, hemoconcentration, and ventilatory stimuli. Ample evidence illustrates that the best management of AMS generally involves prevention rather than treatment post-development of this condition.
Rest, acclimatization to lower altitudes, or medications are treatment options. Ideally, the person should remain at the same altitude until recovery ensues, subsequently restricting altitude gain. Unwillingness to rest or 'acclimatize' will result in decreased performance, exhaustion, and a high risk of developing more severe forms of altitude illness. Briefly, the more rapid ascents are made, the greater the likelihood of AMS developing. Exposure to lower barometric pressures at night may worsen symptoms.
High Altitude Pulmonary Oedema
High altitude pulmonary oedema (HAPE) begins to occur from about 2500 m while people with pre-existing conditions are at increased risk. The lungs develop an excess of fluid, or "oedema," in the smallest blood vessels in the lungs when ascent to altitude exceeds a person’s rate of acclimatization. It can occur in isolation or following the symptoms of acute mountain sickness (AMS) or high altitude cerebral oedema (HACE). HAPE can sometimes be confused with pneumonia, aspiration of food, or another high-altitude condition called high-altitude cough. If left untreated, HAPE can lead to death.
Acute mountain sickness (AMS) is the most common sickness at high altitudes, whereas HAPE has been described as the cause of most high-altitude deaths. Mild symptoms of HAPE include breathlessness and a persistent cough. A high heart rate is a good indicator of lung problems, and this can be checked at rest and after ascent by feeling the pulse. More advanced signs include the production of frothy, white foam. When victims of HAPE present with blue lips, they may go into comas. For concerned family and friends, broken speech, chest tightness, or an extremely fast breathing rate should be considered advanced at high altitudes – all representing emergency signs.
Symptoms occurring at altitude should not be exaggerated. Symptoms of AMS and/or HACE may also be signs of developing HAPE. If your symptoms do not improve, worsen, or are severe, it is advisable to descend quickly. Ascending while experiencing HAPE can result in more severe illness. It is important to seek medical attention for any illness occurring at a high altitude if descent is not immediately possible. If descent is not possible, the individual should be monitored closely and supported as much as possible.
It is also vital to reconsider the safety of other individuals exposed to such high altitudes. In the unlikely chance that it is impossible to descend immediately or access emergency inhaled bronchodilator oxygen should be given, if available, and continued until descent is possible. Known as “acclimatization,” the speed of ascent and the maximum altitude reached, standard risk factors, plus a genetic disposition are all associated with the development of HAPE.
Unfortunately, acclimatization practices do not provide complete protection against this potentially life-threatening condition. Whether these neurotransmitters go on to promote high-altitude symptoms, cardiac output, or pulmonary capillary pressure to a dangerous extent has not been proven. In reality, HAPE has been found many times in individuals who ascend quickly after flying. To reduce side effects and symptoms of HAPE or other altitude conditions, travelling faster than the body’s ability to acclimatize is not recommended.
High Altitude Cerebral Oedema
Introduction: During high altitude exposure, a condition called high altitude cerebral oedema (HACE) may occur as a potentially life-threatening event. HACE is characterized by the swelling of the brain due to the accumulation of fluid in it. It manifests as clumsiness, coordination loss, confusion, and severe headache. The most rapid onset with frequently escalating symptoms develops as a sequela of acute mountain sickness (AMS).
HACE deserves special emphasis because of its sudden appearance and the subacute or acute diseases it carries. People on high mountains watch the weather; HACE is referred to as 'one-brain syndrome.' It is good to know that HACE can happen if you do not ascend according to guidelines. HACE can emerge if your climbing plan makes a severe deviation from your acclimatized state. This is why it is worth monitoring such conditions, and it is good to know their early symptoms. It is essential to know this if you are planning to go to very high mountains. Additionally, people with a previous high-altitude history or underlying diseases will have a say in this regard.
Some prominent predisposing conditions for HACE are infection, dehydration, exhaustion, or traumatic brain injury. Patients with HACE usually wish to lie down and seem less anxious. Ensure the person remains at a lower altitude and gets immediate evacuation. These measures can prevent or reduce the ensuing suffering. Management: Descent is the single most effective treatment for HACE. Descent apparatus or modes should be ready.
Additional oxygen can be started promptly at an adequate flow rate, and the patient can make use of this oxygen during the descent. The patient should be evacuated as soon as possible after the initiation of the treatment. In cases when immediate descent is not feasible, strong medications may be started in consultation with a medical professional.
A HACE awareness program is essential for climbers and crews going above 5,500 meters. The increasing number of trekkers climbing above 6,000 meters will be given a clear perspective about the way of ascent, fluids, and rest, and those who cannot adhere to climbing ethics are at risk of AMS (HACE). HACE could happen to a person who ascends more than 240 land meters per day and to dehydrated individuals. Therefore, it is important to remain adequately hydrated.
Preventative Measures and Acclimatization Techniques
There are several preventative measures that an individual can take to minimize the occurrence of high-altitude illnesses. Kitting oneself out with the right gear is an essential start, but preparing the body physiologically is also crucial. Ensuring one can ascend gradually is important, even if one cannot partake in an initiated acclimatization program. No less vital is maintaining hydration and proper nutrition. Acclimatization is the process of the body adjusting to the decrease in oxygen at high altitudes.
This primarily involves increasing the rate and depth of breathing and increasing the heart rate. Altitude-related illnesses such as acute mountain sickness or pulmonary/cerebral oedema occur when an individual has not acclimatized to a certain altitude in time or has not acclimatized properly and has more than likely occurred inadvertently. If one does have the luxury of time, then there is no downside to acclimatizing. Spending extra days at intermediary altitudes will invariably enhance acclimatization for everyone irrespective of fitness.
Physical fitness can assist in both the symptoms and time spent to acclimatize to high altitude. Those who are more aerobically fit have a higher lung capacity, which allows for greater oxygen uptake. A good cardiovascular system also avoids excess strain on the heart when dealing with elevated elevation. Regardless of fitness level, it is still not possible for an individual to train for altitude before arrival, as acclimatization is a gradual process.
The goal of acclimatization in a pre-acclimatization or non-pre-acclimatization scenario is to recognize whether you are acclimatizing. If you are prepared, are taking preventative medication, and are aware of and keep an eye on the symptoms of altitude-induced illness, high altitude illnesses may bypass you.
Medical Supplies and First Aid Kits for High Altitude Travel
Pre-made medical supplies and first aid kits are available for travel to altitude. The first aid kit should typically contain many items like antiseptics, bandages, medical tape, gauze, and scissors. To these, items specifically targeted for altitude travel can be added. Medications commonly used for headache, respiratory issues, antihistamines, congestion relief sprays, fever, diarrhoea, motion sickness, anti-nausea medicines, and general first aid for muscle strain, sprain, and sunburn should complete the first aid inventory.
A personalized medicine pack is always better, taking into account every individual's specific health and potential allergies or contraindications. Medicines and first aid supplies are of no use if placed at a location that is inaccessible during emergencies. So the ability to carry and retrieve a kit from the bag is important.
When packing medicine or first aid items, they should be chosen with care. The medications that are known to be taken without personal contraindications and allergies should be carried. This includes packaged over-the-counter, individually packed, high-altitude relevant medications, and properly evaluated pre-existing prescriptions. Reading the label is a vital step before using medicines from the kit.
As far as the timing is concerned, it is important to consider the consumption of a packaged medication. The route and the timing for over-the-counter liquid and tablet medications should be understood. The medicine pack should always be preceded by an inspection and inventory check. During an emergency, any incomplete inventory may stand as a hurdle.
Hence, prior intimate knowledge of the medicine pack, including the look and feel of the contents, is vital for the journey's success. Our choice of medical essentials can directly impact the safety of the journey, and in case of an emergency, it can dramatically alter health and psychological standings.
Conclusion
With the knowledge and understanding of the potential health risks at altitude, we can control them by taking preventive measures. To learn more about High-Altitude medicine, download our eBook Summit Survival: Medical Essentials for High Altitude Adventures.
