What is High Altitude Cardiopulmonary Diseases?
Every year, millions of people who love outdoor activities visit places with high altitudes. However, many of them are not aware, or not well prepared for the possible health risks that come with visiting such places. As a result, doctors and other healthcare workers need to know about these potential health problems to properly educate and treat their patients.
The so-called ‘high-altitude sicknesses’ are usually experienced by people visiting places that are over 8200 feet (or 2500 meters) above sea level. The more dangerous variants of this illness, like those affecting the brains and lungs, generally occur at moderately high heights. This mostly happens because places such as ski destinations, which are easy to reach and popular, involves rapid ascents. Identifying and treating these health problems quickly can greatly reduce the risks and improve the survival rates of patients.
One of the major concerns in high-altitude medicine is a condition called ‘high-altitude pulmonary edema’ or HAPE. This is actually the most frequent reason people die from high-altitude-related issues. The good news is, HAPE can mostly be prevented if the person gradually adjusts to the high altitude – a process known as ‘acclimatization’. If HAPE is detected early and treated timely, the prognosis is usually good, meaning that the patient would make a quick and full recovery. People with HAPE have difficulty breathing due to fluid accumulation in the lungs – caused by situations unrelated to heart problems. Worthy of notice is that, although people with existing health conditions are more likely to develop HAPE, many of those who get this illness are young and previously healthy individuals.
What Causes High Altitude Cardiopulmonary Diseases?
High-altitude pulmonary edema, or HAPE, is a condition that is typically linked with going to high altitudes too quickly, without allowing time to adjust to the changes in altitude. Factors such as personal health, environmental conditions, and existing health problems can all affect the likelihood of getting HAPE.
HAPE appears to be more frequent in males, and in people who use alcohol, sleeping pills, or other substances that can slow down breathing. If you’ve had HAPE before, the chances of getting it again are higher, with some studies showing rates of up to 60%.
Going up quickly to a high altitude is a strong risk factor in developing HAPE. This could happen if you travel by air to a high-altitude resort or if you go hiking or trekking to high altitudes. Also, being at higher altitudes, in colder environments, or doing more physically demanding activities can all increase the chances of getting HAPE.
Those with pre-existing medical conditions, such as pulmonary hypertension, lung diseases, and congenital heart defects, are also at a higher risk of developing HAPE. Interestingly, a condition known as patent foramen ovale (PFO), or a hole in the heart, seems to be more common in people with HAPE. Other heart defects that can lead to HAPE include holes or openings (atrial septal defects, ventricular septal defects, patent ductus arteriosus) in the heart. If a person is born without a right pulmonary artery, the risk of developing HAPE is very high.
Although it’s not entirely clear why, genetics can influence a person’s chances of developing HAPE. People at risk of HAPE have been found to have lower nitric oxide levels (a molecule that helps our blood vessels work properly) and higher endothelin (a molecule that constricts blood vessels) levels when they don’t get enough oxygen compared to people who are not as sensitive to HAPE. Those sensitive to HAPE also have trouble removing excess fluid from the air sacs in their lungs when they are oxygen-starved. This can hinder the body’s ability to regulate fluid buildup (or edema). Current research is focused on understanding the genetic factors that influence these pathways.
Risk Factors and Frequency for High Altitude Cardiopulmonary Diseases
The impact on the heart and brain due to high altitudes becomes more noticeable the higher you go. When we talk about high altitudes, we usually mean between 1500 to 3500 meters (4,921 to 11,483 feet). By very high, we mean from 3500 to 5500 meters (11,483 to 18,045 feet), and extreme altitude is anything above 5500 meters (18,045 feet).
Most altitude-related illnesses occur at altitudes greater than 2500 meters (8200 feet). Severe illness is not common below 3000 meters. Many factors can affect how common these illnesses are, such as how fast someone climbs and how much time they spend acclimatizing. For example, at high-altitude resorts in Colorado, one out of every 10,000 travelers might get sick. But for extreme altitudes like trying to reach the top of Denali (6200 meters), this rate goes up to 2 to 3% of climbers. Indian Army soldiers who were quickly sent to 5500 meters had a sickness rate of 15%.
The occurrence of HAPE (High Altitude Pulmonary Edema), a dangerous altitude-related illness, is closely linked to how quickly someone ascents. If the climb to 4500 meters is made over four days, the rate of HAPE is only 0.2%, but for a one to two-day ascent, the rate rises to 6%.
Signs and Symptoms of High Altitude Cardiopulmonary Diseases
In plain language, high-altitude pulmonary edema (HAPE) is a condition that affects people at high altitudes, usually within the first two to four days. It is often initially perceived as a simple reaction to increased physical effort. Early symptoms include a persistent cough, mild breathing difficulties during exercise, and longer recovery times after physical activity.
If the condition progresses without being addressed, the person may experience increased fatigue, bluish or purplish skin color (cyanosis), and faster heart and breathing rates. The defining sign of HAPE is difficulty breathing even when at rest, particularly noticeable at night. By this time, most people realize the seriousness of their condition and seek help. In severe stages, the person’s cough may bring up pink, frothy sputum (“spit”).
- Mild cough
- Shortness of breath during exercise
- Longer recovery time after physical activity
- Increased fatigue
- Bluish or purplish skin color
- Faster heart and breathing rates
- Difficulty breathing at rest
- Pink, frothy sputum in severe cases
About half of HAPE cases come with symptoms of acute mountain sickness, which include headaches, nausea, vomiting, sleep problems, and dizziness. A minority of HAPE cases (14%) also have high-altitude cerebral edema (HACE), causing psychological changes like confusion and, in extreme cases, coma. Patients with HAPE may have low oxygen levels in their blood, leading to rapid breathing, a fast heart rate, and bluish or purplish skin tones. Some patients may experience mild fever. It’s important to consider HAPE as a cause of illness in anyone at high altitudes presenting with low blood oxygen levels and mental changes, regardless of whether they report breathing difficulties or not.
Testing for High Altitude Cardiopulmonary Diseases
To diagnose high-altitude pulmonary edema, a condition in which the lungs fill up with fluid due to being at high elevations, your doctor will take your medical history, examine you, and measure vital signs like your heart rate or blood pressure. They don’t always need special lab tests or images for this diagnosis, but sometimes these can provide extra insights.
For instance, your doctor might perform an X-ray to look at your lungs. If you have high-altitude pulmonary edema, the X-ray might show spots on your lungs where fluid has built up. These spots can be scattered rather than evenly spaced, and might appear on one or both lungs. As you get better, your doctor can use X-rays to track your progress and see if the spots are reducing in size or disappearing completely.
Your doctor might also use a tool called a pulmonary ultrasound, which lets them see the inside of your lungs. If you have high-altitude pulmonary edema they might find a pattern called comet tails or B-lines. This pattern is created because the fluid in your lungs interferes with the ultrasound signals.
Additionally, other tests like an echocardiogram, which is an ultrasound of the heart, can show whether your heart is reacting to the extra strain caused by fluid in the lungs.
There’s no specific blood test to diagnose high-altitude pulmonary edema. However, some blood tests can clue your doctor into this condition. For instance, a test called an arterial blood gas can show if your lungs are getting enough oxygen. Your doctor might also check your white blood cell count since it can be slightly higher in people with this condition. Other tests can check for substances in your blood called brain natriuretic peptide and troponin, which might be higher if your heart is trying to cope with fluid in your lungs.
Treatment Options for High Altitude Cardiopulmonary Diseases
If you suffer from high-altitude pulmonary edema (a condition that causes fluid to build up in your lungs when you’re at high altitudes), the treatment you receive will depend on how severe your illness is, what resources are available, and what rescue operations can be performed in potentially harsh environments. Two main treatments are moving to a lower altitude and supplying extra oxygen.
Patients with mild to moderate symptoms tend to feel better quickly when they descend even 500-1000 meters. However, wild, rugged conditions can sometimes make descending difficult, particularly if the patient’s ability to move around has been affected.
Providing extra oxygen should start as soon as there’s any suspicion of high-altitude pulmonary edema. Additional oxygen helps ease the low oxygen levels in the blood, decreases the body’s response of narrowing the arteries in the lungs which occurs under low oxygen conditions, and provides relief from symptoms. The goal is to get oxygen levels in the blood to 90% or more. If it’s available, a treatment called hyperbaric oxygen therapy could also be considered – some rescue units even carry portable inflatable chambers to provide this therapy on the spot if immediate descent isn’t possible. As colder temperatures and further physical exertion could make the condition worse, efforts should be made to keep patients warm and resting unless they are making efforts to descend.
In a hospital setting, supplying extra oxygen is the most effective treatment. It immediately improves low oxygen levels in the blood, reduces the narrowing of the arteries in the lungs, relieves a mismatch in blood and air flow in the lungs, and alleviates symptoms by improving the patient’s strenuous breathing, rapid breathing, and rapid heart rate. In severe cases, patients may benefit from therapies called continuous positive airway pressure (CPAP) or expiratory positive airway pressures (EPAP), which involve the use of a machine to help them breathe.
While oxygen therapy and descending to a lower altitude are definitely the most effective treatments, medications can have a role in managing high-altitude pulmonary edema in situations where neither of these options are feasible, or as additional treatments in severe cases to reduce the pressure in the arteries in the lungs. For example, a drug called Nifedipine, which is a calcium channel blocker, can slightly reduce the pressure and resistance in the pulmonary arteries. Other drugs such as sildenafil and tadalafil, which are Phosphodiesterase-5 inhibitors, may also help by increasing the amount of nitric oxide, a substance that widens the vessels in the lungs. Dexamethasone, a type of steroid, might be used to treat something called high-altitude cerebral edema, a severe condition where the brain swells because of high altitude, but isn’t typically used just for high-altitude pulmonary edema. Other medications, like diuretics, nitrates, and morphine, were once studied as treatments but are no longer recommended, as their benefits are far less than oxygen therapy and descending.
Patients with mild symptoms that get better fully when they descend can consider slowly moving back up to high altitudes after resting for 2 or 3 days at a lower altitude. For those who get the condition at moderately high-altitude resorts, they might only need rest and low flow extra oxygen for 2-3 days if they choose not to descend, provided the healthcare team is comfortable with their management.
What else can High Altitude Cardiopulmonary Diseases be?
While mountain sickness is often a common issue for people at high altitudes, it’s also important to remember that other chronic conditions can become worse. Issues like lung-related high blood pressure, heart failure, swelling in the limbs, heart valve diseases, irregular heart rhythms, and sudden lung infections could occur at any altitude. These should be considered especially if a person is lacking oxygen or has breathing problems.
Mountain-related illnesses such as High Altitude Pulmonary Edema (HAPE), might occur alone or alongside other altitude illnesses. Doctors should conduct a thorough medical history and examination to check for other high-altitude diseases such as:
- High-altitude brain swelling (HACE)
- Acute mountain sickness
- High-altitude headache
- High-altitude fainting (syncope)
- High-altitude lung infection or cough
It’s important to note that people are more prone to blood clots at high altitudes, which could lead to stroke or pulmonary emboli (blockage in the lungs). Also, being at high altitudes might weaken the immune system, increasing the risk of infections and delayed healing in otherwise healthy individuals.
What to expect with High Altitude Cardiopulmonary Diseases
High-altitude pulmonary edema (HAPE) is a condition that can occur when someone ascends to high altitudes too quickly. This can cause fluid to build up in the lungs, making it hard to breathe. Despite being the primary cause of death related to high altitude, the outlook for most people with HAPE is very good.
Spotting early symptoms and starting treatment quickly is crucial to lessen the severity of the condition. If a person tries to continue going higher or exerting themselves after they start showing symptoms, the disease can get worse. However, even moderate to severe cases of HAPE can get a lot better with oxygen therapy and descending to a lower altitude.
If a person with HAPE gets to a hospital, they usually just need extra oxygen. People with mild cases can often manage their symptoms by stopping their ascent, resting, and waiting until their body has adjusted to the altitude and their symptoms have completely gone away. After that, they may choose to continue climbing, but they should take it slow and watch out for symptoms.
Even though people who’ve had HAPE before are more likely to get it again, many can go to high altitudes again if they take their time and allow their body to acclimatize. Long-term complications from HAPE are rare.
Possible Complications When Diagnosed with High Altitude Cardiopulmonary Diseases
People who get quick treatment for high-altitude pulmonary edema (shortness of breath or other lung issues caused by high altitudes) usually recover well and avoid complications. However, at high altitudes, there are increased risks of blood clots and a weakened immune system. So, doctors need to check for other conditions like lung clots or pneumonia in these patients.
It’s also common for patients with high-altitude pulmonary edema to experience acute mountain sickness or high-altitude cerebral edema (swelling in the brain due to high altitudes), which may need additional treatments. But there’s no data suggesting that problems like chronic high blood pressure in the lungs, congestive heart failure, recurring pneumonia, or obstructive lung disease are long-term complications.
Common Conditions with High-Altitude Pulmonary Edema:
- Pulmonary emboli (lung clots)
- Pneumonia
- Acute mountain sickness
- High-altitude cerebral edema (swelling in the brain)
Though these conditions can occur, evidence does not suggest the development of chronic lung or heart-related complications.
Preventing High Altitude Cardiopulmonary Diseases
Doctors and health professionals should explain to patients the importance of ascending at a slow and steady pace when going to higher altitudes. They should also stress the importance of allowing the body time to adjust to new heights. It’s crucial to recognize early signs of High Altitude Pulmonary Edema (HAPE), a condition that can occur if you ascend too fast and your lungs start to take in fluid. If these signs start to appear, you should stop going up to let your body acclimatize. If symptoms become worse, it’s important to go back down to a lower altitude and seek medical help.
Education about seeking medical attention if symptoms appear should be also provided. People should also make themselves aware of local medical facilities before going on trips to high altitudes.
People who have had HAPE or think they might have had it should know that they could get it again if they go to higher altitudes in the future. Taking preventative medicine and increasing altitude slowly (climbing no more than 300 meters a day when you’re above 2500 meters) can help your body adjust to the new height more easily which is very important. These preventive measures are not usually suggested for everyone going to higher altitudes, but for those who are sensitive and have a history of getting HAPE.
Nifedipine is a medicine that has been studied a lot for preventing HAPE and is usually taken as a 30mg dose every 12 hours. Usually, this medicine is started the day before going to higher altitudes and is continued for five days after reaching the highest point in your trip.
Other medicines like sildenafil and tadalafil might also help prevent HAPE. Preventive doses can vary, but a common dose is 50 mg of sildenafil every 8 hours or 10 mg of tadalafil every 12 hours.
Dexamethasone is a medicine that can certainly help prevent Acute Mountain Sickness (AMS) and High Altitude Cerebral Edema (HACE), conditions that can happen at high altitude due to a decrease in oxygen. A small study also showed that it could be promising in preventing HAPE with a dose of 8 mg every 12 hours.
