Read on to learn about high altitude pulmonary edema…
Have you planned a trip to somewhere decently above sea level for your next vacation? Well, in that case, there are a few things you need to know, even if you are a skilled hiker or a rookie, because medical science remains the same for everyone.
When you’re at a high altitude, the chances of your insides bursting due to low pressure are quite high. To prevent that, we’ll be going into detail about high-altitude pulmonary edema.
📌 Breaking Down the Term
The whole phrasing is intimidating. Hence, we can break it down into the following:-
An altitude is an elevation calculated above sea level. An area at least 2,400 meters (i.e., 8000 feet) above sea level is considered a “high altitude.” The peak of Mount Everest, which is in the Himalayan Mountain range, is at 8,850 meters (29,039 feet) and is considered the highest altitude on Earth.
Climbing to a peak as high as this one is a task because of the air pressure. When a person is at sea level, the air column above him is larger than at a higher elevation. Atmospheric pressure and altitude are inversely proportional; henceforth, when one continues moving higher, one may experience respiratory problems due to low pressure.
In earlier biology classes, we must have learned about the respiratory system, the different functions of blood, and various organs. The inhaled oxygen goes to the alveoli in the lungs and travels from there to the red blood cells, which have hemoglobin in them, which carry these oxygen molecules to the different organs in the body. This is one of the vital procedures in the human body.
Pulmonary edema is where the pressure inside the blood vessels increases due to a change in pressure outside the body, causing a constriction in the lungs and the vessels to dilate.
One thing leads to another, and it is eventually lethal. The leak fills the lung tissues and, eventually, the air sacs. This condition is also known as a ‘Wet Lung.’
📌 What Is High Altitude Pulmonary Edema (HAPE)?
After breaking down the term, you might have a vague idea of the said condition and what’s happening. But what is high altitude pulmonary edema in simple words? How fatal is it? When you decide to hike to such a place, you need to have a full and clear idea of what you’re dealing with. And luckily, you have a full guide ahead of you.
A high altitude comes with an extremely low atmospheric pressure value. As you continue climbing up, the pressure decreases. This change in air volume happens due to gravity.
Gravity pulls everything towards the center, including the air. So the air way above sea level tends to be pulled at a weaker force than the air at sea level, making you light on your feet and causing breathing problems, leading to high altitude illness (HAI).
Now, HAI includes different conditions, namely AMS (Acute Mountain Sickness), HACE (High Altitude Cerebral Edema) and HAPE (High Altitude Pulmonary Edema), our matter of concern.
A respiratory issue could be difficult to detect at an early stage. However, it also depends on how well a person can adapt to new altitudes. But you never know when nature is going to defy you. Quite alarming, right? Fret not; with all the safety protocols, you will be sure to sit back in peace. And to ensure that we take baby steps at a time.
📌 History Of HAPE
The first recognization of HAPE dates as far back as the 19th Century. Back in the day, it was originally attributed to pneumonia due to the cold or heart failure due to hypoxia. The first documented case of high altitude pulmonary edema is of Dr. Jacottet, who died in 1891 on Mont Blanc. He participated in a rescue on the mountain and refused to return early.
He extended his stay for 2 more days, staying at the height of 4,300 meters (14,100 feet), having obvious symptoms of AMS. He passed away on the second night there.
In 1960, Charles Houston, an internal medicine physician in Aspen, diagnosed 4 individuals with “edema of the lungs” and prepared a case report on the same.
Even then, these cases were considered as that pneumonia; Houston’s research proved it wrong, indicating that the cases were “acute pulmonary edema without heart disease.” Similar cases were noticed in rather healthy climbers who died after reaching a higher altitude.
📌 Who Are, and What Makes People More Susceptible to Hypoxia?
First things first, what is hypoxia?
An adequate amount of oxygen is needed for the body to function normally. Breathing air at lower atmospheric pressure causes low oxygen levels to be inhaled. The inhaled air goes straight to the lungs to the alveoli through airways. It is picked up by blood and carried to the rest of the body.
Eventually, the low levels of O₂ in the stream means not an adequate amount in the tissues, thus, causing hypoxia. And since the oxygen goes through the blood, for it to be in a lower amount in the bloodstream means it is hypoxemia.
Hypoxia is when enough oxygen has not been inhaled and cannot be carried by the blood to various tissues sufficiently. The factors leading to this can be both internal and external.
The external causes could be high-altitude climbing, inhalation of toxicants, air traveling, drowning, etc. Hypoxia at high altitudes is common due to the reduced atmospheric pressure, which also comes with low oxygen levels. This type of hypoxia is called hypobaric hypoxia (HH).
People with a heart or lung condition, like asthma, are more susceptible to hypoxia. Other factors which increase the risk of hypoxia include COVID-19, pneumonia, influenza, anemia, etc.
📌 Early Symptoms Of High Altitude Pulmonary Edema (HAPE)
The extent of the altitude involved causes physiological and symptomatic changes variations. The initial manifestations of HAPE include:-
- Exercise tolerance: All human bodies have an exercise tolerance rate, meaning the capacity to endure or endurance to tolerate exercising the body for some time. At a high altitude, this capacity reduces gradually as one keeps moving higher. Simply put, you may experience fatigue way easier than you usually do.
- Coughing: Although dry and persistent coughing, (maybe) followed by a pink-tinged, or in worse cases, bloody sputum can indicate HAPE.
- Breathing: You may experience unusual breathing or respiratory problems, even when simply resting.
- Cyanosis: While up there, the appearance of your skin might change. You will notice that parts of your skin have changed into a bluish, almost purple, tinge. This skin tinting due to low oxygen and cold exposure is called cyanosis. The prime sites of this discoloration are hands, feet, lips, and even the mucous membrane lining inside your mouth.
- Crackles: HAPE may even cause one or both lungs to make a crackling noise upon inhalation. Crackles are sometimes hard to detect. They are heard only with a stethoscope (auscultation).
- High Altitude Pulmonary Edema (HAPE) is also accompanied by signs of High Altitude Cerebral Edema (HACE), in which the brain swells with fluid because of the effects of high altitude. HACE is the last stage of acute mountain sickness (AMS). However, dexamethasone is the choice of medicine for treating AMS and HACE.
Symptoms of the said condition start developing as early as 2-4 days from arrival. It is highly unlikely to develop at the same altitude after the 4th and 5th days, maybe because the body has already remodeled and adapted to the atmospheric pressure outside. Thus, making the pulmonary vasculature less prone to the effects of hypoxia.
Reading till here, you must have figured out that the diagnosis is not easy for this condition. It solely depends on the symptoms. But this becomes a challenge when these symptoms overlap with other conditions. Like, how HAPE was considered to be pneumonia before it was discovered, leading to an inappropriate diagnosis.
HAPE commonly occurs in the first 2-4 days of climbing at altitudes higher than 2,500 meters (8,200 feet). These symptoms typically tend to worsen at night. The symptoms mentioned above are usually common and must be treated immediately.
While examining these, rapid breathing, heart rates, and a fever of 38.5° C (101.3° F) are quite common. A distinct feature of this condition would be that oxygen saturation levels (SpO2) are comparatively lower than usual. Giving extra oxygen rapidly improves symptoms and SpO2 levels.
📌 When Is It Severe?
Like every sickness in medical science, HAPE is also graded between mild, moderate, or severe. These grades are assigned based on the severity of the symptoms, clinical signs, and chest x-rays. Now the question arises, which symptoms are considered as severe?
- Difficulty breathing even while exerting or resting.
- The level of fatigue.
- The presence and quality of the cough.
📌 Risk Factors
Several different factors contribute to the development of HAPE. Sex (usually, men are more at risk for HAPE compared to women), genetic factors, rapid ascent rate, a history of HAPE, respiratory tract infections, etc. are some factors that put one at risk for the condition. People with underlying cardiopulmonary circulation abnormalities leading to pulmonary hypertension are at risk of HAPE, even at average altitudes.
For example, individuals with patent foramen ovale are 4 times more common on the list of HAPE susceptibles than the general population.
Such scary situations should not stop you from having fun. Following are some recommended safety guidelines or precautions one must follow while hiking to the hills.
1. GRADUAL Ascension
If you are someone who lives at a lower altitude, it is a must for you to climb slowly. The low atmospheric pressure, extremely cold weather, and low oxygen levels might be foreign to your body. The human body needs much time to adapt to a place decently.
The Wilderness Medical Society (WMS) recommends a gradual ascension of 500 meters (1,600 feet) daily and not pushing yourself more than recommended. You should also rest every 3-4 days, i.e., no climbing.
Proper diet maintenance also plays a crucial role in keeping a healthy system from encountering the adversities of high altitudes. It is recommended to include a good amount of carbs in your diet. The extra calories help in keeping your body fully prepared at all times. Plenty of whole-grain snacks go a long way.
Full hydration is recommended for the body at all times at such a height. So make sure you pack a lot of water bottles for your adventure!
4. Say no to alcohol
Any intoxication, not just alcohol, should not be consumed while you’re still climbing every day. Even medications like sleeping pills can make acute mountain sickness (AMS) worse if you have got it. You should not be drinking while your body is still trying to adapt. But if you want to, wait until you have finished the 48 hours mark after arriving to let your body adapt to the new environment.
5. Slow and steady
Earlier, we talked about a person’s exercise tolerance. Keep in mind that take it easy with your body. Start climbing slowly and maintain that pace. If you start feeling fatigued, slow it down or take a rest.
Typically taking medication ahead of time isn’t recommended. But it is when you are climbing a high altitude. Nifedipine (30 mg) is known to prevent AMS effectively.
This is recommended mostly to people with a prior case of HAPE. Research shows that the medication is most effective if taken one day before the climb and continued for the next four to five days.
There are additional medications as well. These medicines still require further research and determined treatment guidelines. Acetazolamide, salmeterol, dexamethasone, etc. are to name a few.
7. The Engine Needs to Cool Down
The human body needs to slow down all its vital functions when it sleeps, including the retardation of its heart rate. Since the heart rate is slowed down, it will become naturally difficult to breathe deeply, quickly becoming a problem at a high altitude.
There is also less oxygen being circulated at night since photosynthesis requires sunlight. Keeping these things in mind, one should plan ahead of time when hiking.
There are some checks one can make ahead of time, like, estimating the total time duration of the hike. This will ensure you can get to the highest altitude while there is still some sunlight. Ideally, one should not decide on setting up their sleeping bags at an altitude over 305 meters (1000 feet). So, it is best practice to climb down a little while you’re still left with some light in your hands.
First-line treatments, like, descent to a lower altitude as quickly as possible, are recommended for mild symptoms of HAPE. Improvements with this type of treatment are seen in as few as 500 to 1000 meters (1,640 feet to 3,281 feet).
However, the descent is not necessary for people caught on mild HAPE. It could further be treated through warming techniques, rest, and even the provision of supplemental oxygen. A situation may arise where you cannot provide supplemental oxygen to the person, and descent is no longer an option. What to do, then? In such cases, a portable hyperbaric chamber comes in handy and helps simulate the descent.
Again, nifedipine (30 mg) is a standard medication for climbers who have developed HAPE. However, it is best to back it up with decent and not use it as a substitute for the descent, hyperbaric therapy, or oxygen therapy.
Early recognition of symptoms is vital in treating HAPE, especially when accompanied by AMS symptoms like headache and nausea.
Descent, use of supplemental oxygen (i.e., to bring the saturation levels back to 90%), and maybe some medications are the most therapeutic options available to one at the earliest. Exertion is advised to be kept to a minimum, and it should be made sure that the patient is kept warm at all times.
In acute mountain sickness (AMS), if the prevailing symptoms start getting less intense, the patient can reascend gradually to a higher altitude like before. This fact has allowed many people with HAPE to continue ascending slowly after a good while of rest and descent.
Hoping that this article gave you the confidence boost you needed. Prevention has always been better than cure. Many people are unaware of such adversities awaiting them, but ensuring you have the right knowledge is paramount in a journey. Hopefully, this little guide cleared the fog of doubt you probably had.
Wishing you a fun and safe trip!