High-Altitude Pulmonary Edema (HAPE)

What is high-altitude pulmonary edema (HAPE)?

High-altitude pulmonary edema (HAPE) is when fluid collects in your lungs at high altitudes. It’s a severe form of altitude sickness (mountain sickness). It can make it hard to breathe, cause fluid to build up in your lungs, and, in serious cases, cause bleeding in your lungs. This can prevent your tissues and organs from getting enough oxygen.

HAPE happens when you go from low altitudes (at or near sea level) to high altitudes without giving your body time to adjust to the lower amount of oxygen. It usually starts the second to fourth night after being at a high altitude.

HAPE happens at or above 8,200 feet (2,500 meters). You don’t need to summit Everest to get this high up — many ski resorts in the U.S. and Canada have base elevations at or higher than 8,200 feet. There are even a few large-population cities around the world at high elevations.

High-altitude pulmonary edema can be fatal. Seek immediate medical attention and move to a lower altitude if you have symptoms of HAPE.

Types of this high-altitude pulmonary edema

There are two types of HAPE:

• Classic HAPE. Classic HAPE happens when someone who usually lives at a lower altitude ascends to an altitude above 8,200 feet too rapidly.
• Re-entry HAPE. Re-entry HAPE happens when someone who normally lives at a high altitude stays at a lower altitude. When they re-ascend to their typical, higher altitude without taking the time to reacclimate, they can experience HAPE the same way someone living at a lower altitude would.

How common is HAPE?

According to studies, about 6% of people who ascend 14,800 feet (4,500 meters) over one to two days experience high-altitude pulmonary edema. If you have a history of HAPE, the likelihood of it happening again is high. With the same rate of ascent (4,500 meters over one to two days), about 60% of people experience HAPE again.

What are the symptoms of high-altitude pulmonary edema (HAPE)?

Symptoms of high-altitude pulmonary edema include:

• Cough. This can progress from a dry cough to coughing up pink, frothy mucus.
• Shortness of breath (dyspnea). This may start as getting tired or winded easily during activity. You’ll eventually start getting breathless even at rest.
• High heart rate (tachycardia).
• Fast breathing (tachypnea).
• Low fever.
• Blue skin, lips or nails (cyanosis).

You may also have symptoms of other forms of altitude sickness, like high-altitude cerebral edema.

What causes HAPE?

As you get higher in altitude, the air pressure and oxygen levels are lower than at or near sea level. Your body can eventually adjust to the lower oxygen level, but it takes time. If you increase your altitude too quickly, not enough oxygen will get into your bloodstream and out to your tissues and organs. This can make you sick and eventually be fatal.

If part of your lungs isn’t getting enough oxygen, the blood vessels in your lungs will narrow. This is an effort to push blood to other parts of your lungs that are working better. It increases the pressure on the vessels, causing them to leak fluid. The fluid will sit in your lungs and make it hard to breathe. Eventually, blood may leak into your lungs, causing you to cough up blood-tinged mucus.

What are the risk factors for HAPE?

Being physically fit doesn’t protect you from HAPE. The biggest risk factor is ascending too quickly, regardless of how healthy or in shape you are. It’s more common in people assigned male at birth (AMAB).

Other risk factors for HAPE include:

• Having a history of HAPE.
• Preexisting pulmonary hypertension.
• Differences in the structures of your heart, including intracardiac shunts and blood vessel abnormalities.
• Cold temperatures.
• Respiratory infections.

How is high-altitude pulmonary edema diagnosed?

A healthcare provider diagnoses HAPE based on your symptoms. They’ll check your breathing, blood pressure, blood oxygen level and heart rate. If they take you to a medical facility, a chest X-ray can confirm fluid in your lungs. They may also perform other imaging and tests to rule out other conditions.

How is high-altitude pulmonary edema treated?

Supplemental oxygen is the first treatment for HAPE. You should also move to a lower altitude as soon as possible. This usually means descending at least 1,000 feet (300 meters) and as much as 3,300 feet (1,000 meters). You might need emergency medical personnel to evacuate you. Stay warm and keep hydrated.

Once at a lower altitude or while you’re waiting to be moved, a provider might treat you with hyperbaric therapy. This might be in the form of a portable hyperbaric chamber (Gamow Bag®). Providers sometimes use medications like nifedipine or phosphodiesterase (PDE) inhibitors (like sildenafil or tadalafil). But they’re not typically used if oxygen and descent options are available.

Can high-altitude pulmonary edema be prevented?

Ascending to high altitudes gradually is the best way to prevent altitude sickness, including HAPE. If you start to feel symptoms of altitude sickness, stop and acclimate before ascending further, or descend until you feel better. Don’t wait until your symptoms get worse.

Other guidelines to reduce your risk of HAPE while traveling to high altitudes include:

• Plan your trip carefully, following guidance on how much you should increase your altitude each day.
• Remember to factor in air travel that might quickly take you to higher altitudes. You still need to acclimate, even if you didn’t get there on foot.
• Plan for rest days to acclimate. About one to two days of rest every three days is recommended.
• Talk to your healthcare provider about any health conditions you have that might impact you at higher altitudes.
• If you might be at risk for HAPE, ask your provider if you should take preventive medications (prophylaxis). Providers sometimes prescribe the same medications that treat HAPE to help prevent it.

What can I expect if I have HAPE?

Without immediate treatment, HAPE can quickly be fatal. You should seek emergency medical attention and expect to be evacuated to a lower elevation for medical treatment. Your provider can tell you if it’s safe to complete your ascent when you feel better. It’s usually not recommended right away since the recurrence rate is high.

How long do HAPE symptoms last?

High-altitude pulmonary edema can take up to two weeks to fully resolve.

What’s the mortality rate for high-altitude pulmonary edema?

Without treatment, HAPE is fatal in 50% of cases.

When should I seek medical attention?

You should seek medical attention at the first signs of altitude sickness. Tell someone you’re traveling with about your symptoms in case you aren’t able to communicate them later. If you’re experiencing symptoms of HAPE, get help immediately.

What questions should I ask my doctor?

It might be helpful to ask your healthcare provider:

• How long will it take to feel better?
• How can I safely ascend to higher altitudes in the future?
• Can I continue my trip?
• When should I follow up with you?