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
- Headache
- Dizziness
- Nausea
- Vomiting
- 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:
- Confusion
- Shortness of breath even at rest
- Inability to walk
- A cough that produces a white or pink frothy substance
- Coma
How to prevent or minimize the effects of altitude sickness:
Proper acclimatization:
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:
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)
Reference: Thorax
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.
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.
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.
Recommended medication dosing to prevent & treat altitude illness (Ref: Center for Disease Control)
| MEDICATION | INDICATION | ROUTE | DOSE |
|---|---|---|---|
| Acetazolamide | AMS, HACE prevention | PO | 125 mg twice a day; 250 mg twice a day if >100 kg body weight
Pediatric: 2.5 mg/kg every 12 hours, up to 125 mg |
| AMS treatment | PO | 250 mg twice a day1 | |
| Dexamethasone | AMS, HACE prevention | PO | 2 mg every 6 hours or 4 mg every 12 hours
Pediatric: do not use for prophylaxis |
| AMS, HACE treatment | PO, IV, IM | AMS: 4 mg every 6 hours
HACE: 8 mg once, then 4 mg every 6 hours Pediatric: 0.15 mg/kg/dose every 6 hours up to 4 mg |
|
| Nifedipine | HAPE prevention | PO | 30 mg SR version every 12 hours or 20 mg SR version every 8 hours |
| HAPE treatment | PO | 30 mg SR version every 12 hours or 20 mg SR version every 8 hours | |
| Salmeterol2 | HAPE prevention | Inhaled | 125 µg twice a day |
| Sildenafil | HAPE prevention | PO | 50 mg every 8 hours |
| Tadalafil | HAPE prevention | PO | 10 mg twice a day |
Acetazolamide
Mechanism of Action
When taken preventively, acetazolamide hastens acclimatization to high-elevation hypoxia, thereby reducing occurrence and severity of AMS. It also enhances recovery if taken after symptoms have developed. The drug works primarily by inducing a bicarbonate diuresis and metabolic acidosis, which stimulates ventilation and increases alveolar and arterial oxygenation. By using acetazolamide, high-elevation ventilatory acclimatization that normally takes 3–5 days takes only 1 day. Acetazolamide also eliminates central sleep apnea, or periodic breathing, which is common at high elevations, even in those without a history of sleep disorder breathing.
Dose
An effective dose for prophylaxis that minimizes the common side effects of increased urination and paresthesia of the fingers and toes is 125 mg every 12 hours, beginning the day before ascent and continuing the first 2 days at elevation, and longer if ascent continues. Acetazolamide can also be taken episodically for symptoms of AMS, as needed. To date, the only dose studied for treatment is 250 mg (2 doses taken 8 hours apart), although the lower dosage used for prevention has anecdotally been successful. The pediatric dose is 5 mg/kg/day in divided doses, up to 125 mg, twice a day.
Adverse & Allergic Reactions
Allergic reactions to acetazolamide are uncommon. Since acetazolamide is a sulfonamide derivative, cross-sensitivity between acetazolamide, sulfonamides, and other sulfonamide derivatives is possible.
Dexamethasone
Dexamethasone is effective for preventing and treating AMS and HACE and might prevent HAPE as well. Unlike acetazolamide, if the drug is discontinued at elevation before acclimatization, mild rebound can occur. Acetazolamide is preferable to prevent AMS while ascending, and dexamethasone generally should be reserved for treatment, usually as an adjunct to descent. The adult dose is 4 mg every 6 hours; rarely is it needed for more than 1–2 days. An increasing trend is to use dexamethasone for “summit day” on high peaks (e.g., Aconcagua and Kilimanjaro) to prevent abrupt altitude illness.
Ibuprofen
Recent studies have shown that taking ibuprofen 600 mg every 8 hours helps prevent AMS, although not quite as effectively as acetazolamide. Ibuprofen is, however, available over the counter, inexpensive, and well tolerated.
Nifedipine
Nifedipine both prevents and ameliorates HAPE. For prevention, nifedipine is generally reserved for people who are particularly susceptible to the condition. The adult dose for prevention or treatment is 30 mg of extended release every 12 hours, or 20 mg every 8 hours.
Phosphodiesterase-5 Inhibitors
Phosphodiesterase-5 inhibitors selectively lower pulmonary artery pressure, with less effect on systemic blood pressure than nifedipine. Tadalafil, 10 mg taken twice a day during ascent, can prevent HAPE. It is also being studied as a possible treatment.
CONCLUSION:
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
It stood out to me when you talked about how it is a good idea to descend down the mountain if your symptoms of altitude sickness get worse. Would it be a good idea to go to an oxygen clinic if you have really bad altitude sickness symptoms? I would think that you would be able to recover faster at an oxygen clinic.