High Altitude Sickness:
Altitude sickness occurs if you ascend too quickly without allowing your body to adjust properly to the rarefied air. Understanding high-altitude sickness is very important if your trek involves hiking over 9,100 feet/2,800 meters. While the percentage of oxygen remains constant atmospheric pressure decreases as one goes higher; hence as one ascends the amount of oxygen available in the atmosphere decreases.
As one ascends, it is quite common to experience heavy breathing, fatigue, increased urination, sleep disturbances and a slight headache. But if your headache persists and worsens along with one or more of the symptoms listed, you should understand that it is the early onset of altitude sickness. It is important to remember that everyone regardless of age, sex and physical fitness levels is susceptible to altitude sickness.
There are three levels of altitude sickness:
Acute mountain sickness (AMS) is the mildest form and is very common of altitude sickness. The symptoms can feel like a hangover — dizziness, headache, muscle aches, nausea.
High-altitude pulmonary edema (HAPE) is a buildup of fluid in the lungs that can be very dangerous and even life-threatening. This is the most common cause of death from altitude sickness.
High-altitude cerebral edema (HACE) is the most severe form of altitude sickness and happens when there’s fluid in the brain. It, too, is life-threatening, and you need to seek immediate medical attention.
Altitude Sickness Symptoms
- Fatigue and loss of energy
- Shortness of breath
- Problems with sleep
- Lossof appetite
- Loss of coordination and trouble walking
- A severe headache that doesn’t get better with medication
- A tightening in your chest
Symptoms usually come on within 12 to 24 hours of reaching a higher elevation and then gets better within a day or two as your body adjusts to the change in altitude.
If you have a more moderate case of altitude sickness, your symptoms might feel more intense and not improve. Instead of feeling better as time goes on, you’ll start to feel worse. You’ll have more shortness of breath and fatigue. If symptoms don’t improve, NEVER ascend. Instead descend if possible.
If you develop a severe form of altitude sickness like HAPE or HACE, you might have:
- Shortness of breath even at rest
- Inability to walk
- A cough that produces a white or pink frothy substance
How to prevent or minimize the effects of altitude sickness:
For proper acclimatization, ascent per day should be limited to 300m/1000ft. though this may not always be possible. The mantra for trekking at high altitude is “climb high, sleep low”. You can trek higher than 1,000 feet in the day but should descend and sleep low. Ensure that you have some acclimatization days where you sleep at the same altitude for a couple nights before ascending.
On the Everest Base Camp Trek, it is important to spend a couple nights at Namche and Dingboche. Most trekkers forego sleeping at Dughla and will proceed directly from Dingboche to Lobuche. Stopping at Dughla can prove to be a significant factor in enabling proper acclimatization and ensuring that you reach Everest Base Camp. Similary, on the Manaslu Circuit Trek, it is important to spend a couple nights both at Sama Gaon and Samdo before proceeding towards the Larkyala pass. Some guides and trekking companies may push for a quicker ascent. Be aware of this and do NOT put your life in danger.
Pulse Oximeters though not 100% accurate, is useful in predicting acute mountain sickness. It is natural for oxygen saturation to decrease as one gains altitude. But if the decrease is substantial and if there are symptoms of altitude sickness, the trekker must descend immediately. Below are normal oxygen saturation levels as you ascend on the Everest Base Camp Trek.
99% at 154 meters
97% to 99% at 1,400 meters (Kathmandu)
95% at 2,220 meters
92% to 95% at 3,250 meters (Namche)
92% at 3,600 meters (Tengboche)
90% at 3,950 meters (Pangboche)
85% to 89% at 4,400 meters (Dingboche)
83% to 88% at 4,715 meters (Lobuche)
78% to 84% at 5,100 meters (Gorakshep)
Gamow Bags and Supplemental Oxygen:
The Gamow Bag is a portable hyperbaric chamber used for the treatment of acute mountain sickness (AMS) also known as altitude illness. By increasing air pressure around the patient, the Gamow Bag simulates descent of as much as 7,000 feet, thus relieving AMS symptoms. If descent is not feasible because of logistical issues, supplemental oxygen or a portable hyperbaric chamber in addition to dexamethasone can be lifesaving.
At Crystal Mountain Treks, we provide a Gamow Bag along with Supplemental Oxygen on treks that involve trekking for multiple days at high altitude such as the Upper Dolpo Trek. On other high-altitude treks such as the Everest Base Camp Trek we provide supplemental oxygen. There is NO additional charge to our clients for use.
Medications to Prevent High Altitude Sickness
Acetazolamide commonly sold as Diamox is the most popular medication used to both prevent and treat high altitude sickness. It can be purchased over the counter in Kathmandu. The recommended dosage is 125 mg every 12 hours. If taking prophylactically begin at least 48 hours prior to arriving at altitude.
Dexamethasone and Nifedipine are used to treat HACE and HAPE respectively. But these require a prescription.
Alcohol and Coffee
Alcohol should be avoided at altitudes above 10,000 feet. It suppresses breathing and lowers blood oxygen levels. Basically, it hampers the acclimatization processes and can also disturb sleep. If you must, it is OK to drink a beer or two on the return from Base Camp but only after you arrive at Namche (11,000 feet or lower). It’s OK to drink a cup or two of coffee especially if you drink coffee regularly. But it’s recommended to avoid coffee in the evening as it could hamper sleep.
There is NO reason for anyone to die from altitude sickness. One should be aware that mild illness is a possibility but severe illness and death can always be avoided. Travelers who adhere to 3 principles can prevent death or serious consequences from altitude illness:
- Know the early symptoms of altitude illness and be willing to acknowledge when they are present.
- Never ascend to sleep at a higher elevation when experiencing symptoms of altitude illness, no matter how minor they seem.
- Descend if the symptoms become worse while resting at the same elevation.
Reference: Center for Disease Control