Travelling to high altitudes can cause an altitude-related illness.

Acute mountain sickness, accumulation of fluid in the lungs and swelling of the brain are potential problems.

Determining if you will be affected in advance, is impossible.

Being physically fit does not decrease your chances of developing a high-altitude illness. However certain groups are at increased risk, including people who:

• have a prior history of high-altitude illness;

• drink alcohol before adjusting to the change in altitude;

• ascend rapidly;

• have a heart or a lung problem that affects their breathing.

Preparing to travel

If you will be travelling above 2,500 metres, you should make an appointment with your healthcare provider before your trip. During this visit, you should discuss your travel plans, availability of medical care at your destination, and the potential need for medications to prevent and/or treat high-altitude illness.

In addition, people with certain medical conditions need to take special precautions when travelling at high altitudes:

• If you have had a heart problem in the past, check with your doctor to be sure that it is safe to travel to high altitudes. If you develop chest pain, shortness of breath, or dizziness while travelling, seek medical help immediately.

• If you use oxygen because of lung or heart disease, you will need a higher oxygen flow rate at high altitude.

• If you have diabetes and you check your blood sugar, be aware that blood glucose meters can give inaccurate results at high altitudes. Consult the manufacturer of the meter for recommendations.

• If you have sickle-cell disease, you will probably need oxygen if you travel above 2,000 metres.

• Asthma does not worsen at high altitudes.

Acute mountain sickness

It is the most common of the altitude diseases. It occurs in approximately 40 to 50 per cent of people who live at a low altitude and travel and stay at an altitude above 2,500 metres.

Symptoms

They usually occur within six to 12 hours of arrival at altitudes, though they can begin as soon as one hour or as long as 24 hours after arriving. AMS symptoms are similar to a hangover, and include:

• Headache

• Fatigue

• Lightheadedness

• Lack of appetite

• Difficulty staying asleep (waking frequently)

• Nausea, sometimes with vomiting.

AMS symptoms are often the worst after the first night and improve within one day if you do not ascend to a higher altitude. If you develop signs of acute mountain sickness, you should NOT climb higher until your symptoms have resolved. Climbing higher while you have symptoms of AMS can lead to serious complications like brain or lung swelling. Instead, you should rest and avoid drinking alcohol or taking sleeping pills as you recover.

Prevention

• If you live below 1,500 metres, avoid ascending rapidly. On the first night, avoid sleeping above 2,500 metres.

• After that, do not ascend more than 500 metres per day.

• Plan a day of rest for every 1,000 metres you ascend.

• Climb high and sleep low: Hike/ski to a higher altitude during the day and return to a lower elevation to sleep at night.

• If you drink caffeine (coffee, tea, soda) regularly, do not stop drinking it before or during your trip. Caffeine is safe at high altitudes, and stopping it suddenly can cause symptoms similar to AMS.

• If oxygen is needed, treatment with inhaled oxygen can reduce AMS symptoms. You can use oxygen for a period of time (example, one hour), only when you start having symptoms, or while sleeping. Many hotels in Colorado and the Alps have oxygen supplies in guest rooms for this purpose.

• A preventive medicine may be recommended if you have had high-altitude illness previously, or if you must ascend quickly. Treatment usually includes a medicine called Acetazolamide that you start taking the day before you ascend and continue for 48 hours or until you reach the highest point of your trip.

Acetazolamide side-effects can include frequent urination, hands and feet tingling, and blurred vision.

It is not recommended for pregnant women. Dexamethasone is a steroid that may be recommended as a preventive treatment if you are allergic to Acetazolamide.

In next week’s column, we will discuss the two more serious high-altitude illnesses: lung and brain swelling.

•Joe Yammine is a cardiologist at Bermuda Hospitals Board. He trained at the State University of New York, Brown University and Brigham and Women’s Hospital. He holds five American Board certifications. He was in academic practice between 2007 and 2014, when he joined BHB. During his career in the US, he was awarded multiple teaching and patients’ care recognition awards. The information herein is not intended as medical advice nor as a substitute for professional medical opinion. Always seek the advice of your physician. Never disregard medical advice or discontinue treatment because of information in this article.