Highlighting Health Issues at High Altitudes (Episode 3)

Death on the Peak: A Mountaineer's Demise at High Altitude

Acute Mountain Sickness, High Altitude Pulmonary Edema, High Altitude Cerebral Edema

Highlighting Health Issues at High Altitudes (Episode 3)

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In the scorching heat of early August, 2017, a troop of Boy Scouts was venturing through the Uinta Mountain Range in Utah. A plucky seventeen-year-old Scout complained of a crushing headache and nausea. His situation worsened over the next day. Realizing the gravity of his condition, they decided to evacuate the scout the following morning. As the scout settled for the night, he was still plagued by his headache and displayed a deterioration in muscle control.

The Scouts woke up early to carry out their evacuation, while a Scout Master embarked on a grueling 6-10 mile trek to get within reach of cellular signal, calling for a helicopter medical evacuation. Upon arrival, the medics discovered the lifeless body of the scout. Reports from the Scouts suggested that he managed to take a few steps before collapsing unresponsive, and CPR was attempted. The young, fit teenager had no significant medical history, and the elevation in the crater where he perished ranged between 10,000' in the valley to 13,500'. If such a promising teenager could succumb to altitude sickness at these altitudes, common across the Rockies, then we must take these conditions very seriously and familiarize ourselves with their signs, treatments, and when evacuation is necessary.

The most common myth regarding altitude sickness is that it is caused by the low concentration of oxygen in the atmosphere. While the atmosphere typically consists of about 21% oxygen, which remains constant up to an altitude of around 21,000 feet (900 feet higher than the summit of Denali and 9,000 feet below the summit of Everest), the partial pressure of this oxygen within the lungs can be dramatically lower. This partial pressure is integral to "push" oxygen into the bloodstream. It might be challenging to comprehend the concept of air-pressure, but picturing air as a fluid can make it more accessible. At sea level, we are submerged beneath a colossal amount of "fluid" above us, pulled down by gravity, intensifying the pressure of these gases in our lungs. As we climb higher, there's less "fluid" above us, which causes a decrease in pressure and leads to what's known as "Acute Mountain Sickness" (AMS). The hemoglobin, which carries oxygen in the blood, fails to pick up oxygen molecules leading to decreased oxygen levels (hypoxia) at the organs.

Elevation can be divided into three principal categories: high altitude (4,900' to 11,500'), very high altitude (11,500' to 18,000'), and lastly, extreme high altitude (above 18,000'). At around 7,000', the partial pressure of oxygen drops sufficiently that the saturation of oxygen in hemoglobin decreases, causing it to become detectable through the use of pulse oximetry. Most individuals at these elevations will have a "pulse ox" of over 90%. As we ascend above 11,500', people will exhibit a pulse ox less than 90%, and their symptoms will worsen with exertion or attempting sleep. The majority of altitude illness occurs in this range. Elevations surpassing 18,000' are, for the majority, unsustainable for any substantial duration without proper acclimatization, and could potentially be fatal.

It's not merely the altitude that triggers altitude sickness; the speed at which you ascend plays a significant role as well. Hikers who take the time to adequately acclimatize and follow the established axioms ("sleep low, climb high") experience the least troubles from AMS, while those who undergo a sudden change in elevation exhibit the most pronounced symptoms.

Higher altitudes are often colder than lower altitudes and have much drier air. People at altitude tend to breathe faster to compensate for the decreased oxygen levels, and their urinary production increases to cope with the metabolic byproducts. Combining these factors frequently leads to dehydration, which can be further aggravated, particularly in ski and tourist destinations, by alcohol consumption. This is why we stress the importance of maintaining proper hydration in the backcountry and especially at elevation.

To summarize our findings; altitude sickness arises from a lower partial pressure of oxygen in the lungs, which results in fewer oxygen molecules crossing into the blood through the capillary beds. Dehydration and rapid ascent can exacerbate these processes. These disease processes are predictable, and it is our responsibility to recognize the signs and symptoms for early treatment, as well as understanding when the patient's situation is critical and requires immediate evacuation.

In the early 90's, a conference was held at Lake Louise called the International Hypoxia Conference. The physicians there developed a scoring system to ascertain the prevalence and severity of AMS. This scoring system, known as the Lake Louise Consensus on Altitude Illness, defines the three identifiable conditions caused by altitude; AMS, High Altitude Pulmonary Edema (HAPE), and High Altitude Cerebral Edema (HACE).

In the presence of a recent gain of altitude:

Acute Mountain Sickness (AMS)

Headache accompanied by one of the following:
Loss of appetite, nausea, or vomiting
Fatigue or weakness
Dizziness or lightheadedness
Difficulty sleeping

Note: The signs for AMS can be subtle, particularly in the absence of clinical context. Many travelers from low altitude levels to ski resorts may experience a headache and sleep problems, but only a fraction of these people actually present for medical treatment.

High Altitude Cerebral Edema (HACE)

Change in mental status and/or ataxia (unsteady gait) with AMS
Both a change in mental status and ataxia in a patient without AMS

High Altitude Pulmonary Edema (HAPE)

At least two of the following -
Shortness of breath at rest
Cough, especially productive of pink frothy sputum
Weakness or decreased performance with exertion
Chest tightness or pain, new onset

AND

At least two of the following -
"Wet" lung sounds in at least one field
Central cyanosis (bluing of the lips or skin)
Increased heart rate (typically >100 bpm)
Increased respiratory rate (typically >20 resp/minute)

The signs for AMS can be subtle, especially in the absence of clinical context. Many travelers from low altitude levels to ski resorts may experience a headache and sleep problems, but only a fraction of these people actually present for medical treatment. Still, a study in the New England Journal of Medicine in June 2001 (High Altitude Illness, Dr P Hackett) states that 22% of people coming to Summit County in Colorado (home to Breckenridge, Arapahoe Basin, Keystone, Loveland, and Copper Mountain) met the criteria for AMS, and this figure rose to around 42% above 10,000'; a focused history should include questions about how quickly they ascended, any acclimatization they attempted, fluid intake, appetite, and urine production, and these details should be documented for monitoring purposes. A presentation suggestive of altitude sickness should always be treated seriously, and treatment should be initiated.

The best medicine is always prevention, and this is especially true in environmental hazards. It's crucial to plan acclimatization days into your adventure. If you're engaging in mountaineering at extreme elevation, consult with your guide to ensure that you'll be following the best practices of "sleep low, climb high" including acclimatization climbs with a return to base camp. Ascend at a rate less than 1,000 feet per day. Stay well-hydrated and monitor your urine production, particularly its frequency and color. If necessary, a physician can prescribe Acetazolamide (Diamox) as a prophylaxis (preventative) or as a treatment in higher doses. Refrain from alcohol, especially the first night after an ascent.

If our methods of preventing AMS fail, and our strategies for mitigating AMS prove ineffective, then aggressive treatment is necessary. Dr. Peter Hackett, from the aforementioned NEJOM study, recommends three things for HAPE/HACE; descend, descend, descend. The use of supplemental oxygen can be beneficial, and so can the use of steroids, specifically Dexamethasone, but they should be used in conjunction with a plan that facilitates rapid evacuation to lower elevation. Portable hyperbaric chambers, such as the Gamow bag, can be carried by expeditions in the danger zone and pressurized to simulate lower altitudes, but these are very costly and not indicated for routine travel in the lower 48 states. The patient should be taken to an elevation where the symptoms begin to resolve. These patients who are symptom-free for three days may be cleared to attempt a summit/ascent again, but a recurrence of symptoms should trigger the termination of the expedition and rapid evacuation, including helicopter rescue if available.

In conclusion, as we ascend, we experience reduced air pressure which leads to decreased oxygen levels and other physiological changes. The faster we ascend, the more pronounced these effects. Multiple systems can be affected. Proper acclimatization, a gradual ascent, and proper hydration are the most effective means of prevention. If our assessment indicates "headache plus one" (symptom), it suggests Acute Mountain Sickness, and we should be vigilant for potential deterioration into life-threatening conditions (HAPE/HACE). After we've determined that someone likely has AMS, we need to carefully monitor them for any change in motor function, which we like to call the "-umbles", the "mumbles", the "stumbles", and the "grumbles". Shortness of breath with exertion progressing to shortness of breath at rest, especially in the presence of "wet" sounds lungs or a cough productive of pink frothy sputum, is a critical finding indicative of pulmonary edema. These patients need to be rapidly descended to a safe altitude where symptoms disappear and they should remain asymptomatic for three days before attempting another ascent. If they cannot tolerate this, evacuation is necessary.

We hope that this information has been useful and has added some new skills to your toolbox. As always, it's important to consult a medical professional before you venture to high altitudes, especially if you have your sights set on big peaks in Asia, South America, or Alaska. Altitude sickness is just one of the many conditions we discuss in both our Wilderness First Aid and Wilderness First Responder courses, so if you're interested in learning more, be sure to check out our schedule and join us for a class!

Stay safe and bon voyage!

ADDITIONAL RESOURCES:

https://www.high-altitude-medicine.com/AMS-worksheet.html - AMS Worksheet designed for the facilitation of assessment of altitude sickness. Professional guides should be aware of this worksheet and conduct assessments of their clients twice daily at elevation.
The Boy Scout's demise at high altitude serves as a grim reminder of the seriousness of altitude sickness, especially in the wilderness.
Proper understanding of conditions like Acute Mountain Sickness (AMS), High Altitude Pulmonary Edema (HAPE), and High Altitude Cerebral Edema (HACE) is crucial for one's health and wellness in mountainous regions.
The scout's tragic incident occurred at elevations common across the Rockies, highlighting the need for interpretable signs, treatments, and evacuation strategies for such altitude-related illnesses.
Higher altitudes often bring cooler temperatures, dry air, and dehydration, which could further aggravate the effects of altitude sickness if proper health and fitness measures are not taken.
Fitness and exercise, coupled with maintaining hydration levels and following recommended acclimatization practices, can help mitigate the risks of altitude sickness in mountaineering situations.
The rapid onset of neurological disorders, respiratory conditions, chronic diseases, or even ordinary medical-conditions at high altitude could escalate quickly, necessitating immediate medical attention and potential evacuation.