ALTITUDE SICKNESS
Altitude Sickness also known as acute mountain sickness (AMS), is a pathological effect of high altitude on humans caused by acute exposure to low partial pressure of oxygen at high altitude.
Although minor symptoms such as breathlessness may occur at altitudes of 1,500 metres (5,000 ft), AMS commonly occurs above 2,400 metres (8,000 ft). It presents as a collection of nonspecific symptoms acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover". It is hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can ascend to 2,400 metres (8,000 ft) without difficulty.
Acute mountain sickness (AMS) is the most common of the altitude diseases; it occurs in approximately 40 to 50 percent of people who live at a low altitude and sleep at an altitude above 10,000 feet (3000 meters), and in approximately 25 percent of those sleeping above 8000 feet (2400 meters).
Symptoms usually occur within 6 to 12 hours of arrival at altitudes above 8000 feet (2400 meters). Symptoms can begin as soon as one hour or as long as 24 hours after arriving. AMS does not occur after adjusting to a given altitude for three or more days.
AMS prevention -Ascend slowly — Ascending slowly is the best way to avoid AMS. A good idea is to make a graph of planned days versus altitude to see where the ascent profile may be abrupt and then adjust it according to the recommendations below. Some experts recommend the following:
●If you live below 5000 feet (1500 meters), avoid ascending rapidly. On the first night, avoid sleeping above 9000 feet (2800 meters).
●If you plan to travel above 9800 feet (3000 meters), do not increase your sleeping altitude more than 1600 feet (500 meters) per day as you go higher. Plan a day of rest for every 3200 feet (1000 meters) you ascend. On this rest day, do not over-exert yourself.
●Climb high and sleep low. Hike to a higher altitude during the day and return to a lower elevation to sleep at night. This will help you adjust to the altitude.
●If you plan to hike, or climb, do not over-exert yourself during the first few days at altitude. Pacing yourself is very important.
●Staying or hiking at elevations above 4900 feet (1500 meters) in the weeks before you ascend may allow you to ascend faster.
●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.
Consider taking a preventive medicine — Preventive treatment with a medicine may be recommended if you have had high altitude illness previously or if you must ascend quickly. If you have had high altitude illness before, you may be able to avoid taking preventive medicines by ascending slowly. You will need a prescription for these treatments.
●Prevention usually includes a medicine called acetazolamide, which you start taking the day before you ascend and continue for 48 hours or until you reach the highest point of your trip.
Acetazolamide can temporarily cause carbonated drinks to taste unpleasant. Other side effects can include the need to urinate more frequently, numbness or tingling in the hands or feet, nausea, drowsiness, or blurry vision. Acetazolamide is not recommended for pregnant women.Acetazolamide is a sulfa medicine, but many people with a sulfa allergy can take acetazolamide without a problem. If you are allergic to sulfa, talk to your doctor or nurse to determine if you should take a test dose before traveling .
●Dexamethasone is a steroid that may be recommended as a preventive treatment if you are allergic to acetazolamide.
●Taking aspirin or ibuprofen can help to prevent the headache that often occurs with AMS. If you will be ascending quickly, you can start taking aspirin or ibuprofen before you ascend. Otherwise, take it only if you develop a headache.
AMS symptoms — The symptoms of AMS are similar to a hangover, and include:
●Headache●Feeling tired●Lightheadedness●Lack of appetite●Difficulty staying asleep (waking frequently)●Nausea, sometimes with vomiting
These symptoms may be mild or severe. AMS symptoms are often the worst after the first night and improve within one day if you do not ascend to a higher altitude. Symptoms may return as you travel higher. However, symptoms can sometimes persist for days, even if you do not climb higher.
If you develop signs of AMS, you should NOT climb higher until your symptoms have resolved (usually within 24 hours). You should rest and avoid sleeping pills as you recover.
This may mean that you, as well as your fellow climbers, will be delayed or unable to climb as high or as far as you had hoped. However, climbing higher while you have symptoms of AMS can lead to serious complications.
AMS treatment — AMS treatment includes rest, descent, and may also include medicines to relieve symptoms. You should not exercise or climb higher until your symptoms have resolved. You should also know when and if you need to seek help.
●Headache – You can take non-prescription medicines for headache, such as aspirin, acetaminophen (brand name: Tylenol), or ibuprofen (sample brand names: Advil, Motrin).●Nausea or vomiting – If you have nausea or vomiting, a prescription medicine such as promethazine (brand name: Phenergan) or ondansetron (brand name: Zofran) may be helpful, if it is available.●Descent – If your symptoms do not improve or worsen over 24 to 48 hours, descend to an altitude where you feel better. Most people feel better after descending 1600 to 3300 feet (500 to 1000 meters).
●Oxygen – If needed, treatment with inhaled oxygen can reduce the symptoms of AMS. You can use oxygen for a period of time (eg, one hour), only when you have symptoms, or while sleeping. Home oxygen companies are present in most high-altitude resort areas and your doctor should be able to call in a prescription for oxygen in advance.
●Acetazolamide – Acetazolamide is a prescription medicine that you can take to treat and prevent AMS.
●Dexamethasone – Dexamethasone is a steroid that can reduce symptoms of AMS. You can take dexamethasone with acetazolamide, if needed. Dexamethasone increases blood sugar levels in people with diabetes.
When to seek help — AMS symptoms should improve as you adjust to the altitude, usually within 24 to 48 hours. If your symptoms worsen at any point, you should descend and seek help.
HIGH ALTITUDE CEREBRAL EDEMA
High altitude cerebral edema (HACE) is a rare life-threatening altitude disease, and is a severe form of acute mountain sickness (AMS). It is caused by leaky capillaries in the brain, which causes swelling.
HACE prevention — HACE can be prevented with the measures discussed above. (See 'AMS prevention' above.)
HACE symptoms —
HACE usually occurs within one to three days after traveling above 9800 feet (3000 meters). Symptoms may include:
●Exhaustion, drowsiness, and severe weakness
●Difficulty walking straight
●Confusion and irritability
●Acting drunk
HACE treatment — HACE is a medical emergency and you should descend to a lower altitude as soon as possible. Waiting to descend can be disastrous; symptoms can worsen quickly and you may not be able to walk. Delaying descent increases the risk of life-threatening complications, or even death.
Besides descent, other HACE treatments include:
●Several hours in a portable hyperbaric chamber. This can be a useful and life-saving treatment until descent is possible.
●Dexamethasone. This is an important medicine to have on hand if you plan to sleep above 9800 feet (3000 meters). You should take it immediately if you develop signs of HACE, with the recommended dose being 8 to 10 mg by mouth. You should take 4 mg every six hours thereafter until you have descended. You should take dexamethasone before entering a hyperbaric chamber.
●You should use oxygen if it is available. You can use oxygen inside a hyperbaric chamber.Portable hyperbaric chamber — Portable hyperbaric chambers are inflatable pressure bags that can be used to treat people with AMS, HACE, or high altitude pulmonary edema (HAPE). You are zipped into the chamber and the device is inflated with a foot pump.
When inflated, the air inside the chamber is more like the air you breathe at lower altitudes. This increases the amount of oxygen in your blood, relieving symptoms of high altitude illness quickly. You can remain in the chamber for several hours.
HIGH ALTITUDE PULMONARY EDEMA
High altitude pulmonary edema (HAPE) is a potentially fatal condition in which lung capillaries leak and fluid accumulates in the lungs. HAPE is uncommon, but can occur in people who rapidly ascend to altitudes above 8200 feet (2500 meters).
HAPE prevention —
As with other high altitude illnesses, the best way to prevent HAPE is to ascend slowly. This is especially true if you have a previous history of HAPE.Preventive medicines are not usually recommended unless you have a history of HAPE and you must ascend quickly to altitudes above 8200 feet (2500 meters). Preventive medicines may include nifedipine (commonly used to treat high blood pressure), tadalafil, dexamethasone, or acetazolamide.
HAPE symptoms —
Symptoms of HAPE include cough, breathlessness at rest or with activity, and difficulty walking uphill. These symptoms usually begin two to four days after arriving at altitude. You may or may not also have symptoms of acute mountain sickness (AMS).
Symptoms can worsen, and you may feel more short of breath, even while resting. You may also begin to cough up pink, frothy sputum (spit).
HAPE treatment —
HAPE is a medical emergency. You should seek medical care or descend as soon as possible if you develop symptoms. Waiting to descend can be disastrous; symptoms can worsen quickly and you may not be able to walk. Waiting also increases the risk of developing life-threatening complications, or even death.
Treatments for HAPE include:
●Descend or seek medical care at the first sign of HAPE.
●Supplemental oxygen; this is the most effective treatment and should be started as soon as possible. It should be continued until symptoms resolve. Oxygen may be life-saving if descent is not possible.
●Hyperbaric treatment may be used as an alternative to descent, if it is available. You can use oxygen inside a hyperbaric chamber.
●Nifedipine or other medicines may be helpful if oxygen is not available and descent is not possible.●Stay warm and avoid cold temperatures.
●Rest; this includes not carrying a pack while descending.
OXYGEN IN YOUR BODY
ALTITUDE O2 (%)
1350 MTR AROUND 90-95%
2800 MTR AROUND 92-93%
3400 MTR AROUND 85-90%
4000 MTR AROUND 80-83%
5000 MTR AROUND 75-80%
5500 MTR AROUND 70-75%