Altitude Myths Myth # 1 - Don't drink caffeine at altitude.
We don't know where this false assumption came from, but likely from the fact that caffeine is a mild diuretic (makes you pee). The concern is that it could dehydrate you and contribute to altitude sickness. This concern is unfounded unless you drink pots of black sludge coffee a day and little else. In reality, caffeine stimulates your brain, kidneys and breathing, all of which are helpful at altitude. And for those people who drink several caffeinated beverages a day, stopping abruptly can cause a profound headache. See Dr. Hackett's article on caffeine and altitude.
Myth #2 - Diamox masks symptoms of altitude sickness.
Taking Diamox to prevent AMS will not mask symptoms. It works on the same pathway that your own body uses to help you acclimatize. It is a carbonic anhydrase inhibitor which makes you urinate a base chemical called bicarbonate. This makes your blood more acidic and therefore stimulates breathing thereby taking in more oxygen. It speeds up your natural process of acclimatization and if you stop taking it you will not have rebound symptoms. It is one of the main medicines doctors use to prevent and treat acute mountain sickness (AMS).
Myth #3 - Physical fitness protects against altitude sickness.
Physical fitness offers no protection from altitude illness. In fact, many young fit athletes drive themselves too hard at altitude prior to acclimatizing thinking they can push through the discomfort. They ignore signs of altitude illness thinking it can't affect them because they are fit and healthy. Everyone, regardless of fitness, is susceptible to AMS.
Myth #4 - Drinking extra water will protect you from altitude illness.
Staying hydrated is important at altitude. Symptoms of dehydration are similar to AMS. In reality you only need an additional liter to a liter and a half of water at altitude. Too much water is harmful and can dilute your body's sodium levels (hyponatremia) causing weakness, confusion, seizures, and coma. A good rule of thumb to assess for hydration is to check your urine. Clear urine indicates adequate hydration, dark urine suggest dehydration and the need to drink more water.
Myth # 5 - Children are more susceptible to altitude illness.
Several studies have shown that children have similar rates of altitude illness as adults. No evidence exist that children are more susceptible to the altitude. If your child is otherwise healthy and the basic rules of acclimatization are followed they will likely do well at altitude. Children do get altitude illness and the main challenge in those very young is that they can't communicate their headache and other symptoms. Excessive crying in a baby the first 1-2 days at altitude could be altitude illness. Children with AMS bounce back quickly with treatment as do most adults.
Periodic breathing is a normal phenomenon at altitude, and is most prominent during sleep. It is characterized by periods of hyperpnea followed by apnea. Apneic duration is commonly 3-10 seconds, but may be up to 15 seconds. It occurs in everyone above their personal altitude "threshold". It may lessen slightly with acclimatization, but does not resolve until descent. It becomes more pronounced with ascent, but is not associated with altitude illness. It may result in panic in the trekker who wakes up either during the breath-holding phase ("I've stopped breathing!") or with the post-apneic gasp ("I'm short of breath, I've got pulmonary edema!"). Reassurance is helpful.
Acetazolamide (Diamox®) 125 mg po about one hour before bedtime reduces or eliminates periodic breathing. If needed, this should be continued until the patient has descended below the threshold elevation where periodic breathing became troublesome.
Insomnia at altitude is not necessarily caused by periodic breathing, but is thought to be secondary to cerebral hypoxia. Thus the respiratory stimulant acetazolamide is the sleeping tablet of choice.
Benzodiazepines are controversial; one small study has shown that temazepam improved sleep quality but caused a small decrease in mean oxygenation in unacclimatized healthy climbers; in well-acclimatized climbers the mean sleep oxygenation was slightly increased. I believe benzodiazepines should be avoided in persons with symptoms of AMS.
Edema of Altitude
Acute Mountain Sickness (AMS)
A spectrum of illness from mild to severe (HACE), AMS is common - the presence of moderate AMS (Lake Louise score of 4 or greater) is seen in approximately 25% of trekkers ascending to over 5000 m (16,500 ft) (personal study, unpublished). Under most circumstances, AMS is self-limiting, resolving in 24-48 hours.At altitudes over 2400m / 8000 ft, the diagnosis of AMS is based on a headache plus at least one of the following symptoms:
Diagnosis has been revolutionized by the advent of relatively inexpensive hand-held pulse oximeters: Sa02 will be inappropriately low. "Normal" is clearly going to be altitude-dependant. For example, Sa02 is 80-86% in healthy individuals at 4200 m; values as low as 75% may occur in asymptomatic non-acclimatized individuals. Values significantly below this at elevations below 5500 m are usually diagnostic of HAPE. Sa02s of 50-60% are common in HAPE at this elevation, and I have seen saturations in the low 30s.
Patients with evolving HAPE may have normal saturations at rest. Always try to provoke desaturation in patients suspected of having HAPE, but who have a normal Sa02, with a simple exercise test: have them walk about 100 m on level ground, at a reasonable pace (enough to get out of breath). Persons with simple fatigue or High Altitude Bronchitis will not desaturate.
Patients will often be breathless, with rattling/gurgling respirations; they may be coughing up white or pink foamy sputum; they are frequently unable to lie flat. Crackles are heard first in the right middle lobe, but may be absent in up to 30% of cases of HAPE. Note that crackles may be present in up to 30% of cases of simple AMS, so they are not diagnostic. The onset of HAPE is frequently at night. Fever is common, and resolves with treatment. In part because of the fever, there have been many deaths due to HAPE being misdiagnosed and mistreated as pneumonia.
1 - Mild
Dyspnea on exertion
fatigue while moving uphill
HR (rest) < 90-100
RR (rest) <20
dusky nailbeds or
localized crackles,if any
Minor exudate involving less than 25% of one lung field
2 - Moderate
Dyspnea at rest
fatigue on level walking
cyanotic nail beds
Some infiltrate involving 50% of one lung or smaller area of both lungs
3 - Severe
Dyspnea at rest
HR > 110
RR > 30
facial & nailbed cyanosis
Bilateral infiltrates > 50% of each lung
It is not uncommon in the Himalaya to be consulted on a trekker who is found in the morning in a comatose state. Clearly the history will be limited to the ascent profile and second-hand information on whether the patient appeared ill the day prior. Evaluate respiratory status, measure arterial oxygen saturation with a pulse oximeter, and perform a quick neurological exam for any obvious focal deficits.
It may be clear whether or not the patient has HAPE, but often HACE cannot be ruled out as a cause of the coma. HACE is commonly seen with severe HAPE, presumably due to the severely decreased PaO2 (equivalent to an ascent to a much higher altitude). The patient is treated for both HACE and HAPE as follows: Dexamethasone 8 mg IM, nifedipine 10-20 mg sublingual, oxygen at 4 l/m, and hyperbaric treatment for 1 hour. Usually, at the end of this hour the patient is alert and a more thorough history and exam are obtained. Further treatment is then carried out according to the protocols previously described. Consider non-altitude causes of coma in patients with focal neurologic deficits, or who don't get better with the above treatment. Stroke is uncommon but can occur in persons who seem to have little in the way of risk factors. Clinically unsuspected brain tumors may also present at altitude with neurological signs.
Prevention is the key to avoiding frostbite. Here are some important reminders:
- Stay well hydrated and well fed to enable your body to generate heat!
- Avoid alcohol, which can impair your sensation (and judgment!)
- Avoid smoking, which will constrict your blood flow
- Don’t climb/trek under extreme weather conditions (wind, very cold)
- Avoid tight fitted clothing, no wrinkles in the socks
- If your clothing/socks/gloves get wet from snow/rain or perspiration, DRY them quickly – including boot insoles
- Wear mittens rather than gloves in extreme cold and a liner glove underneath if you need quick temporary access to fingers (e.g. photography)
- Never ignore numbness – as an old professor once told me – “if you feel your fingers and toes getting numb and you ignore it, that numbness might be the last thing you ever feel!” Numbness is a sign that you may be getting into trouble. If it doesn’t resolve by increasing activity, you need to get somewhere to take off your gloves/boots and rewarm yourself.
- Avoid rubbing frostbitten areas – beating on them only increases the chance of injury and doesn’t help them rewarm faster.
- IF you or your buddy has frostbite, get somewhere warm, but only rewarm the injured area if there is no chance it will refreeze
– keep the area padded and protected against further heat loss. The quickest way to rewarm is to submerge in warm water (~104F, or the warmth of a hot tub, test the water first with a thermometer or an uninjured body part – a frozen hand can’t determine if the water is too hot!)
Hypothermia can kill in mere minutes. Cold temperature, but also strong wind causes the body to rapidly lose heat. You start to shiver in order to maintain body heat from the rapid muscular shaking. If your body temperature drops to 35C/95F, you may get dizzy and disoriented, then the shivering stops. The body now maintains temperature only around the important organs; heart, brain and lungs and shuts down blood circulation to the arms and legs. Your pulse becomes weak and slow. Your blood vessels widen. Now, you feel hot and want to remove your clothes, finally slipping into unconsciousness. Eventually, your heartbeat stops.
Full blown Hypothermia will not be improved by additional clothing since clothing doesn’t generate heat. In difficult climbing situations, you need to put hot water bottles in your armpits, to your crotch and/or stomach – or you can strip and get into a sleeping bag - together with another undressed person, to warm up by the others body heat (yeah, yeah - keep your dirty imagination to yourself!).
Otherwise - keep moving until at safety. In 1998, a climber died of hypothermia on the North Side. All that was found left of him was his clothing neatly folded below the summit. This is quite typical of the condition. Confused, the brain tries to bring some order in the situation, thus folding the clothes.
Again, prevention is key! Here are some tips:
- Stay well nourished to help your body produce heat and shiver effectively when needed.
- Stay well hydrated and well rested.
- Change wet inner garments promptly
- INSULATE! (head and neck are key!) – great materials include Gore-Tex, Thinsulate, Flectalon
- Follow the C-O-L-D clothing principle:
- Open – when exercising to reduce sweating/wetness
- Loose/Layers – to retain heat
- Dry – to limit conductive heat loss
Snow blindness, or solar/ultraviolet keratitis is an excruciatingly painful state that comes from the sun burning the covering of your eye -- the cornea. And it happens, very commonly if you don’t wear sunglasses, or if you don’t wear appropriate sunglasses in any bright light situation – especially easy to encounter at altitude.
A sunny day on fresh snow can be beautiful, but incapacitating if you’re not protected. Keep in mind that the brightness can exceed 10-15 times the amount of light that is safe and comfortable for your eyes to accommodate.
Sometimes, when climbing on oxygen, the warm and moist breathing air will escape your oxygen mask upwards and sometimes clog up your goggles, especially upon climbing down. Your choice will then be to climb "blindfolded" or remove the glasses. You might choose to pull your glasses a bit out from your face, allowing the warm air to pass them. The suns rays will now be able to burn your eyes at the unprotected sides. An anti-fog lens cleaner may help in this situation.
If the weather is overcast you might be tempted to remove the glasses altogether. Yet the rays are just as harmful when cloudy, and the following morning you’ll be sorry. After 8 years of climbing it finally happened to us. It took only a short time without goggles at our summit descent (shooting film), we noticed nothing, and in the morning we were a mess.
Here are some guidelines to use when choosing a good trekking/mountaineering pair of sunglasses:
- 99-100% UV absorption
- Polycarbonate or CR-39 lens (lighter, more comfortable than glass)
- 5-10% visible light transmittance
- Large lenses that fit close to the face
- Wraparound or side shielded to prevent incidental light exposure
Diarrhea is the number one medical complaint of travelers in the first 2 weeks away from home. It is prevalent in countries with underdeveloped water purification and sanitation systems, and it attacks nearly everyone who visits the Khumbu for any amount of time. BUT it is preventable if you are careful and practice good hygiene.
When you're sliding into first and you feel a something burst
Bacterial infection is only one cause of diarrhea. Viruses, protozoa, certain medications, food intolerances, allergies are among the myriad other causes of this ailment. This important to remember, because there is no one pill that takes care of all of them. And if you indiscriminately take antibiotics (which only work on bacteria), you can actually make any of the other causes of diarrhea even worse by knocking out all of your body’s natural “good” bacteria. Diarrhea is a complicated problem, and if it persists for days or is associated with bleeding, fainting, severe dehydration, high fevers, severe pain, you should see a doctor for professional evaluation and treatment.
When you're sliding into second and you feel something beckon
Some people take prophylactic (preventative) medication to prevent diarrhea, but this may be a very risky practice. The potential side effects from some of these medications range from slightly annoying to deadly, not to mention the alteration of your natural bacterial flora and potential development of antibiotic resistance. You should make the decision to take prophylactic medications with your personal physician. I don’t advise it in most situations.
When you're sliding into third and you and you feel a little. . .
For climbers with diarrhea on Everest, higher camps provide even more hostile situations; stripping in the icefall or while roped at the Lhotse wall is inevitable at times, and memorable always. In 1997, a climber fell and was killed while doing his thing at C3. Always be carefully roped when leaving tent at C3, even for very short distances!
Diarrhea causes dehydration and disturbance of the mineral balance in your body. Drink plenty and add electrolyte supplement (ORS packets are widely available in Nepal.)
When you're sliding into home and you feel a burst of . . .
Since diarrhea is such a pain on Everest, sometimes you will have to take aids like Imodium to halt it. You should be careful with these aids though. If you have a bacterial infection, diarrhea is your body’s way of getting rid of the bad bacteria. Use Imodium or the equivalent only when you really have to.
Again, prevention is key:
- WASH YOUR HANDS after using the toilet and before eating.
- Treat your water with a good filter or by boiling or by using iodine – and don’t slip up!
- Avoid raw food. Boil first or wash and peel before eating.
- Avoid unpasteurized dairy products.
- Avoid drinking products with ice that is made from untreated water.
For more up to date information about treatment of diarrhea in Nepal, follow the link to diarrhea discussion on the CIVEC website, www.ciwec-clinic.com
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