What is High Altitude Pulmonary Edema?
High Altitude Pulmonary Edema (HAPE) is a life-threatening condition that can happen when you are at high altitudes. This condition causes fluid to build up in your lungs due to low levels of oxygen (a condition called hypoxia), and it is not linked to heart disease. Symptoms of HAPE can include fatigue, difficulty breathing, and a dry cough, especially when you’re physically active. If it’s not treated, these symptoms can get worse, leading to difficulty breathing even when resting, abnormal lung sounds, a bluish color of the skin or lips (known as cyanosis), and it can be fatal in up to 50% of cases.
What Causes High Altitude Pulmonary Edema?
High Altitude Pulmonary Edema (HAPE) is a sickness that can happen when you’re in places higher than 2500 meters above sea level, but it can also occur as low as 2000 meters. Things that increase your chances of getting HAPE include your body’s individual response to low oxygen levels (hypoxic ventilatory response or HVR), how high you go, how quickly you ascend, being male, taking sleep medication, eating too much salt, cold weather, and heavy physical activity.
People who already have certain health conditions that affect blood flow in the lungs, blood pressure in the lungs, response of lung blood vessels, or have a hole between the two upper chambers of their heart (patent foramen ovale), might be more likely to develop HAPE.
Risk Factors and Frequency for High Altitude Pulmonary Edema
The seriousness of High Altitude Pulmonary Edema (HAPE) can vary based on several factors such as how high up you are, how quickly the situation is recognized and handled, and the availability of medical care. Statistics show a link between the likelihood of experiencing HAPE and the altitude; for example, at heights of 4500 meters, the chance of getting HAPE ranges from 0.6% to 6%, and at 5500 meters, it increases to between 2% and 15%. What’s more, climbing quickly also raises the chances of getting HAPE. If you’ve had HAPE before, the chances of it happening again can be as high as 60%. Interestingly, being in good physical shape does not necessarily protect you from HAPE. If treated, the death rate could reach 11%, but if left untreated, it could shoot up to 50%. It’s also common for people with HAPE to experience Acute Mountain Sickness (50% of cases) or High Altitude Cerebral Edema (14% of cases).
Signs and Symptoms of High Altitude Pulmonary Edema
High Altitude Pulmonary Edema (HAPE) usually sets in 2 to 5 days after one reaches a high altitude. It starts subtly with symptoms such as a dry cough, difficulty with physical activity, chest pain, and shortness of breath during exertion. If it’s not treated, these symptoms can worsen, leading to shortness of breath even at rest and severe breathlessness during physical activity. The individual could start to cough up pink frothy mucus or even blood. Additional signs could include a rapid heartbeat, quick breathing, and bluish skin, lips or fingernails. It’s common for oxygen levels in the blood to be lower than normal for the given altitude, often between 40% to 70%. Despite the low oxygen levels, the person may seem healthier than expected.
- Symptoms start 2 to 5 days after reaching a high altitude
- Dry cough
- Difficulty with physical activity
- Chest pain
- Shortness of breath during exertion
- Progression to shortness of breath even at rest and severe breathlessness during physical activity without treatment
- Coughing up pink frothy mucus or blood in severe cases
- Rapid heartbeat and quick breathing
- Bluish skin, lips or fingernails
- Lower than normal oxygen levels in the blood – typically between 40% to 70%
- Appearing healthier than expected despite low oxygen levels
Testing for High Altitude Pulmonary Edema
If you might have high altitude pulmonary edema (HAPE), it means your lungs may have filled with fluid because of high altitude. The doctor would look for at least two of these symptoms: chest tightness or pain, cough, difficulty breathing when resting, or being unable to do as much exercise as usual.
They would also check for two of the following signs during a physical examination: central cyanosis (where your skin or lips appear blueish due to low oxygen), unusual sounds in your lungs, a faster than normal heartbeat, or rapid breathing.
If it’s possible, they might do a chest X-ray or ultrasound. This could show patches of fluid in your lungs – called ‘alveolar infiltrates’. The scans should show that the middle part of your chest (mediastinum/heart) are normal size. The ultrasound might show lines (called ‘B-lines’) that represent fluid in your lungs, which comes with this condition.
They may also do an EKG, which could show signs that the right side of your heart is working harder than it should be, and/or experiencing abnormal heart rhythms, which could be a sign of low oxygen.
If you have this condition and receive extra oxygen, doctors would expect to see a quick improvement in your oxygen levels (measured by a SpO2 monitor) and how you feel.
Even though lab tests might be available, they don’t often contribute much to the diagnosis. The doctor should also consider whether you might have acute mountain sickness (AMS) and/or high altitude cerebral edema (HACE), which are other conditions related to high altitude.
Treatment Options for High Altitude Pulmonary Edema
If you’re experiencing symptoms related to high altitude, the best treatment is usually to move to a lower altitude. In other words, you should go down at least 1000 meters or keep going until your symptoms begin to improve. It’s also important to try to avoid heavy physical activity while you do this, as exerting yourself can make your symptoms worse by increasing the body’s oxygen needs.
Along with going to a lower altitude, using extra oxygen might help to ease your symptoms. If moving to a lower altitude isn’t easy or possible due to certain conditions, oxygen can be a good short-term solution, although the long-term solution would still be to go to a lower altitude when it’s possible. Oxygen can be given through a special type of nose tube or face mask that allows a high flow of oxygen, and it is generally adjusted until your oxygen saturation (SpO2) rises above 90%.
Another option when it’s not possible to descend is using a portable hyperbaric chamber. This is a special container where the air pressure can be increased to mimic being at a lower altitude. However, some people may find this challenging if they are feeling sick, nauseated, claustrophobic, or are experiencing changes in their mental state. There’s also the risk of your symptoms coming back after you leave the chamber.
There are also some medications that can help with the symptoms. Nifedipine can help by relaxing the blood vessels in the lungs, but it’s not meant to be the only treatment if oxygen or descending are options. There are also other medications known as phosphodiesterase inhibitors that work by relaxing and opening up the blood vessels leading to your lungs, helping to lower the blood pressure within these vessels.
However, medical research hasn’t shown benefits with some other treatments like the medication acetazolamide, the use of beta-agonist drugs, or diuretics, which are medicines used to help your body eliminate salt and water.
What else can High Altitude Pulmonary Edema be?
Some health conditions that might be mistaken for one another because they share similar symptoms include:
- Asthma
- Bronchitis
- A blockage in the airways caused by mucus, also known as mucous plugging
- Heart attack, or myocardial infarction
- Pneumonia
- Pneumothorax, or a collapsed lung
- Pulmonary embolism, which is a blockage in the lung’s blood vessels
- An infection in the upper airways, commonly known as an upper respiratory tract infection
