Tuberculosis

Is tuberculosis (TB) a problem for outdoor enthusiasts? Usually not, although if one travels abroad, there is an entirely different level of risk. There has been recent publicity about a man with a drug-resistant form of TB who exposed fellow airline passengers. Persons with diseases or taking medications that cause immunosuppression are more vulnerable to many germs, including the ones that cause TB.

TB is caused most commonly by the tubercle bacillus Mycobacterium tuberculosis; related species may also cause tuberculous disease. The germs are spread in tiny droplets and particles by the airborne route, namely, coughing and sneezing. When the bacilli take up residence in the human lung(s), they invade healthy tissue and cause infection. Lung tissue can be destroyed, sometimes to a great extent. Furthermore, the microbes can spread through the blood stream and lymph system to affect virtually every organ system, so a person may become extremely ill and die from the disease.

Typical symptoms of TB lung infection include cough with or without chest pain, fever, chills, sweating at night ("night sweats"), poor appetite and weight loss, and weakness. When TB is diagnosed by examination of sputum coughed up by the victim, sputum or tissue culture, x-rays, and skin testing, the victim is treated with many months of antibiotic therapy.

We live in an age of many drug-resistant germs, presumably because the use of antibiotics has allowed these germs to flourish. To make matters worse, there is a "dormant" form of TB, in which a person is infected but does not show any overt manifestation of the disease. Because so many cases of TB occur in countries other than the United States, the incidence of drug-resistant TB is higher outside North America than within its boundaries. We now even refer to "extensively drug resistant" TB, or EDR TB. So, as with many diseases to which Americans have become relatively unfamiliar, we should consider TB to be very high on the list of infectious concerns for foreign travelers.

Is there a way to limit exposure? In a hospital setting, this is done by isolating patients with known or suspected TB, using face masks, and keeping patients with TB or other communicable respiratory diseases in rooms with special ventilation, such that the air within the room can be removed and vented up to a dozen times a day. However, in the population and world at large, one might only be able to carry a face mask for use in a restricted environment and to avoid persons known or suspected to have TB. There is no particular geography that poses a special risk, but travelers are advised to wear a face mask, such as the N95, around persons with any illness that causes them to cough.

Tags: tuberculosis, TB, N95, health, wilderness medicine, outdoor medicine, healthline

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Running the Sahara

Allow me to introduce the first guest blogger at Medicine for the Outdoors. My good friend and colleague, Dr. Jeffrey S. Peterson, is an Assistant Professor of Surgery in the Division of Emergency Medicine at Stanford University Hospital. He is also the Founder and Sports Medicine Physician at Innovative Sports Medicine in Mountain View, California, and is a Medical Specialist Instructor of Urban Search and Rescue for the State of California Office of Emergency Services, as part of the Federal Emergency Management Agency. Jeff has long had a great interest in wilderness medicine, and in particular, athletic events conducted under challenging environmental conditions. In 2006 he served as a Race Physician for endurance races in the Atacama desert of Chile and the Gobi desert in China. An avid triathlete, he personally has completed two Ironman triathlons. Jeff was asked to serve as physician for the recent Running the Sahara event, in which three runners ran for 111 days through Senegal, Mauritania, Mali, Niger, Libya, and Egypt, covering more than 4,300 miles (6,920 kilometers). Jeff graciously agreed to share a bit of his diary with us, which will be presented here in six installments.

RUNNING THE SAHARA, by Jeffrey S. Peterson, MD

Part 1

ON November 2, 2006, a team of three runners stepped from the Atlantic Ocean and onto the beach at St. Louis, Senegal. Their intention was to run all the way across the Sahara desert and end at Suez, Egypt, in hopes of publicizing the water needs of the people of the Sahara to the larger world. Water in the region is running out - wells today have to be dug as much as 10 times as deep as in the past, due to a rising population and more industry depletion of the Sahara’s ancient and virtually un-recharging aquifers.

This expedition was followed by a film crew, to be made into a documentary film. I was the physician for the runners, their support teams, and the film crew. Once acclimatized, all three runners planned to cover 75 to 80 kilometers (49 to 52 miles) each day. As their physician, I was part of a larger support team that allowed the runners to concentrate on the hard work of logging their daily mileage. For all involved, the task was prodigious, and I’m happy to report that all three runners -Charlie Engle (44 years old), Kevin Lin (31), and Ray Zahab (38) - succeeded in their 6,920 kilometer (or 4,300 mile) quest.

Prior to departure, everyone was properly vaccinated and immunized for hepatitis, typhoid, tetanus, diphtheria, pertussis, and yellow fever. Malaria prophylaxis was provided, in our case Malarone, as all four varieties of malaria exist in West and North Africa. Still, several of the Africans providing services for the expedition had to be treated for malaria during the trip, using a three-day protocol of 4 Malarone tablets taken orally. In every instance, the treatment was successful.

Beginning in Senegal, extremely unhygienic conditions on the starting beach (human excrement and dead animals littered the sand), plus a mid-autumn heat wave that the runners were slow to acknowledge, nearly ended the run before it even began. Multiple film-crew members were treated for heat exhaustion.

In order to protect the runners and the expedition from succumbing to the heat, after the fourth afternoon I issued a medical edict: No running from 11AM to 4PM. My pronouncement resulted in a near-mutiny from the runners. It was on that day that I looked at expedition leader Donovan Webster, and simultaneously we said, “Looks like we’ll be home for Thanksgiving.”

Yet, remarkably, the edict held, and within days the expedition began to find its rhythm. On Day 10 of the trip, the runners notched their first 80 kilometer stretch, following proper acclimatization and a new schedule: wake at 4 AM, eat breakfast, beginning running at 5AM for roughly 50 kilometers, break for lunch and a rest, and finish the day’s run in the late afternoon and evening.

By then, we had entered Mauritania, where I continued to treat heat-related illness, mostly for Kevin Lin of Taiwan, who was not accustomed to these scorching conditions. Eventually, I was forced to provide twice-daily intravenous drips of normal saline over three days to relieve cramping and severe dehydration.

More in Part 2…

Tags: Sahara,running,desert, Running the Sahara, Jeff Peterson, adventure Products, wilderness medicine, outdoor medicine, healthline

Labels: adventure, endurance, Jeff Peterson, running, Sahara, Sahara desert

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Adventures in Medicine in the Wall Street Journal

In the July 25, 2007 issue of the Wall Street Journal, Laura Landro wrote a terrific article entitled Adventures in Medicine as an installment of her regular feature The Informed Patient. It is an overview of wilderness medicine, and features information about the Wilderness Medical Society and a few of its members, such as Luanne Freer, M.D., Colin Grissom, M.D., and Eric Johnson, M.D. As part of the on-line feature, there is a link to a brief slide show depicting rescue situations.

I always enjoy reading Ms. Landro's articles, and of course, am especially delighted with this one. The wilderness medicine community welcomes her to the fold, and I'm hopeful that she'll apply her reporting expertise and enthusiasm to many more outdoor health-related topics in future columns.

photo by Mathias Schar

Tags: Wall Street Journal,Laura Landro,adventure, wilderness medicine, outdoor medicine, healthline

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Thank You to A Chronic Dose for Grand Rounds

Thank you to A Chronic Dose for including my post about a jellyfish sting in this week's Grand Rounds. Grand Rounds is a weekly compilation of interesting posts from medical bloggers, as chosen by the host.

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The 23rd Annual Meeting of the Wilderness Medical Society

"Come all who need rest and light, bending and breaking with over work, leave your profits and metallic dividends and come..." John Muir, 1874

I'm in Snowmass, Colorado at the 23rd Annual Meeting of the Wilderness Medical Society, an organization near and dear to my heart. Each summer, the WMS members and other health care providers come together to learn of new advances in the field, attend continuing education sessions, learn field techniques, and share a passion for wilderness medicine.

The program for this meeting is one of the finest ever offered by the WMS, and has been focused to a certain degree on supporting the educational requirements of candidates for Fellowship in the Academy of Wilderness Medicine. In addition, there were two terrific pre-conference events - a "Toxicology in the Wilderness Symposium" and the Advanced Wilderness Life Support (AWLS) course. Workshops included "Core (fitness) Training in the Outback," "GPS Navigation," "Improvised Splinting," "Litters & Packaging," "Medical Volunteering in Developing Countries," and many others.

We learned from many of the masters: Peter Hackett on altitude medicine, Peter Kummerfeldt on survival, Eric Johnson on dive medicine, Luanne Freer on women in the wilderness, and Mel Otten on heat illness, to name a few. Dr. Hackett, who is Director for The Center for Altitude Medicine in Telluride, Colorado, offered his views on the latest on altitude medicine. He mentioned that current scoring systems used to grade acute mountain sickness (AMS), such as the Lake Louise Score and AMS Score, may not be any more useful than the simple observation by a victim that he or she “feels sick” or complains of a headache. The headache can be graded with a simple “1-10” grading system or an analog visual grading scale.

He also noted that in the Annapurna region of Nepal, awareness of AMS among the general population that travels to this region is increasing, as estimated by the increasing use of preventive drugs, such as acetazolamide (Diamox) and a decreasing incidence of AMS. Another observation is that susceptibility to AMS appears to be related to genetic predisposition, prior history of AMS, and rate of ascent (more rapid being worse). There are data to suggest that a brief (e.g., a few days) stay at altitude within two months of another, more prolonged stay, may aid in acclimatization. Interestingly, persons seem to have a lower threshold for pain at altitude. “Triptan” drugs, commonly used to treat migraine headache, are effective approximately 50% of the time for the headache associated with AMS. A very useful therapy for the headache of AMS is acetazolamide (Diamox) 125 mg by mouth twice a day.

Dr. Hackett explained that acetazolamide (Diamox) is very effective for prevention and treatment of AMS. It may be used in low doses for this purpose – 125 mg by mouth twice a day. A low dose (62.5 mg) may be used at dinnertime to improve sleep. Gingko biloba, which comes from the world’s oldest living tree species, has been touted as an effective agent for the prevention of AMS. It is essentially harmless to administer, but there are no definitive data to recommend its use. Sildenafil (Viagra) may be used to prevent and treat high altitude pulmonary edema (HAPE) because of their effect to lower pulmonary artery pressure, which is felt to contribute to the vascular leak that generates fluid in the lungs. Dr. Hackett will be studying the use of tadalafil (Cialis) to prevent and treat HAPE.

This evening's special presentation will be "Maps, Midwives, and Medicine Men: Using GIS and Ancient Healing Wisdom to Save the Amazon in Six Dimensions," delivered by Mark Plotkin, Ph.D., one of the world's foremost ethnobotanists and President of the Amazon Conservation Team.

This morning, I completed the "Run for Research" on mountain trails. Despite being nearly a "running relic," I crossed the finish line in first place for the men's division for the short course of 1.7 miles. I was pretty impressed with myself until I discovered that I was the only male entrant in the short course. Everyone else toughed it out on the big hills, but at least I was there at the finish line to offer my congratulations.

Tags: WMS, Wilderness Medical Society, wilderness medicine, outdoor medicine, healthline

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A Jellyfish Tale

In May, I enjoyed a few days' diving in the Baja at La Paz, Mexico. At that time of year, the water is relatively cool and the visibility isn't perfect, but there is still much to see underwater as the nutrients arrive in the currents prior to the return of the big animals, such as hammerhead sharks and whale sharks. The dive operation at the Cantamar Resort was superb, so we were treated to swift and smooth boat rides to the dive sites, excellent dive guides, and wonderful lunches.

The surface of the water was generally flat, and our entries into the water were relatively easy, because there was little current and our group of divers worked well together. We played with sea lions underwater and saw countless pufferfishes, scorpionfishes, multi-colored moray eels, magnificent nudibranchs, bright starfish, barracuda, and stingrays, including a small manta and the bullseye electric ray Diplobatis ommata. As is my habit, I urged everyone to be careful and to avoid touching animals, sharp corals, or anything with which they were unfamiliar.

The sun was very hot, so it was important to use sunscreen and lip balm. I shared my supply of Safe Sea with everyone. This is a combination sunscreen-jellyfish sting inhibitor product that has been tested and found effective against many species of stinging creatures. When applied properly, it stays on the skin for 45 minutes to one hour underwater and is formulated to diminish or prevent stings from jellyfish or other similar creatures equipped with microscopic stinging cells. I never (well, almost never, as you will soon learn...) enter the ocean without covering my exposed skin with this product, because why not take every advantage to not be stung? Jellyfishes and other marine stingers are often effectively camouflaged, way too small to be noticed, or are slightly submerged under the surface, which renders them virtually invisible to the naked eye.

On one particular dive, we were anchored close to a lighthouse upon a rock outcropping that served as a resting place for about 20 sea lions. The water surface showed a slight chop due to the wind, so it was difficult to visualize anything translucent on the surface. I donned my full wet suit, buoyancy compensator, and mask, but did not "smear up" with Safe Sea for this water entry, so my hands, neck, and face were exposed. and jumped feet first off the boat into the water. Someone then handed me my underwater camera, and I kicked gently to the anchor line to meet up with the other divers. In a flash, I experienced incredibly intense burning pain over both of my hands and wrists. The top of my left hand was on fire, while the underside of my right wrist hurt as if it had suddenly been lanced with 1000 needles. I stuck my facemask in the water and saw the purple "sails" of two small Portuguese man-of-war "jellyfish" (colonial siphonophores actually, but that's not critical to the discussion), with long trailing dark tentacles that terminated in their attachment to my body. The tentacles stuck to my skin like the webs emitted by Spiderman, so I shook my hands and forearms as hard as I could to pull them loose, to no avail.

I held my camera in my left hand, and while shaking it, the muscles in my hand and wrist went into a brief intense spasm from the sting, so I dropped the camera, which spiraled down into the depths below me. Fortunately, it came to rest in clear view 60 feet below me. Another diver thoughtfully dove down and retrieved it. Meanwhile, the friend of my son, who was diving with us, caught a tentacle across the throat, and was stunned and frightened. He exited the water and went back up on the boat to sit out the dive. I didn't see or hear him become injured, so I had no idea that he had been stung or was now suffering back on deck.

I pulled and rubbed the tentacles off my hands while I was in the ocean, waited a few moments, decided that I could tolerate the pain, and continued my dive. While I was underwater, my son's friend attempted to treat his sting by rubbing it with an ice cube, which is not the correct thing to do. When I ended my dive and returned to the boat, I learned of his sting, and treated him with an effective therapy - application of a mixture of rubbing alcohol and vinegar to the skin, which immediately ended the stinging pain.

Shame on me for not using Safe Sea before I entered the water. Had I followed my own advice, I would either have not been stung or had a much less severe reaction to the man-of-war. I've warned so many thousands of people of the hazards of getting stung that you would think I'd be a bit smarter. I can assure you that from this point forward, I won't be diving without taking proper precautions. Four days after the original sting, the skin reaction resembled a bad poison oak rash, with red, raised, and itchy bumps that perfectly define the attachment of the tentacles to my skin. It required a full four weeks for the rash to resolve.

I hope that none of you ever has the need for the following advice, but just in case you are in the ocean and are stung by a Portuguese man-of-war, jellyfish, or other similar stinging creature, here is what you should do:

1. Exit the water if possible.
2. Immediately rinse the wound with seawater, not with freshwater. Do not rub the wound with a towel or clothing to remove adherent tentacles. Nonforceful freshwater rinsing or a rubbing variety of abrasion is felt to stimulate any microscopic stinging cells that have not already fired. Surf life savers (lifeguards) in the United States and Hawaii have reported that a freshwater hot shower applied with a forceful stream may decrease the pain of an sting.
3. Remove any visible tentacles with forceps or a well gloved hand. In an emergency, the palm of the hand is relatively protected, but take care not to become stung.
4. Commercial (chemical) cold or ice packs applied over a thin dry cloth or plastic bag have been shown to be effective when applied to mild or moderate stings. Whether the melt water from ice applied directly to the skin can stimulate the discharge of stinging cells has not been determined.
5. Acetic acid 5% (vinegar) is the treatment of choice to inactivate most jellyfish toxins. The vinegar should be applied continuously for at least 30 minutes or until the pain is relieved. This may be done by soaking a napkin or cloth and placing it on the affected skin.
6. Different species respond better or worse to different topical decontaminants. There are substances that may be more specific and therefore more effective. Depending on the species, these include isopropyl (rubbing) alcohol (40% to 70%), dilute ammonium hydroxide, sodium bicarbonate (baking soda), lemon or lime juice, olive oil, sugar, urine, and papain (papaya latex [juice] or unseasoned meat tenderizer powdered or in solution).
7. Perfume, aftershave lotion, and high proof liquor are not particularly useful and may be detrimental. Other substances mentioned to be effective at one time or another, but which are to be condemned on the basis of toxicity, are organic solvents such as formalin, ether, and gasoline.

Immersing the area in hot water has generally not been recommended, on the premise that the fresh water solution causes stinging cells to discharge. However, one study compared hot (40 to 41 degrees Centigrade [104 to 105.8 degrees Fahrenheit]) water immersion to papain meat tenderizer or vinegar for treatment of a single-tentacle Carybdea alata (Hawaiian box) jellyfish sting to the forearm, and found the hot water immersion to be the most beneficial.

Once the wound has been soaked with a decontaminant (e.g., vinegar), remaining (and often “invisible”) stinging cells must be removed. The easiest way to do this is to apply shaving cream or a paste of baking soda, flour, or talc and to shave the area with a razor or similar tool. If sophisticated facilities are not available, the stinging cells should be removed by making a sand or mud paste with seawater and using this to help scrape the victim’s skin with a sharp edged shell or piece of wood. The rescuer must take care not to become stung; bare hands must be rinsed frequently.

Tags: Portuguese man-of-war, jellyfish, marine sting, medical, physician, health, wilderness medicine, outdoor medicine, healthline

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A New Water Filter

Sawyer Products, Inc. has released a new hollow fiber membrane water microfilter that will filter out bacteria, protozoa, and viruses, because it filters out particles down to the 0.2 micron size. It is rated to perform for up to 3,000 gallons before the filtration unit should be replaced, and can handle a pressure of up to 40 pounds per square inch (PSI). This product (Sawyer® Water Purifier) comes packaged with a polycarbonate bottle and faucet adapter. A water bag for attachment may be purchased. Upon request, the company will provide literature that describes a virus removal test of the Sawyer®7/6BV filter, which is incorporated into the unit.

Another product (Sawyer® Water Filter) has a larger-pored filter, so is recommended for bacteria and protozoa, but not for viruses. It is rated to perform for up to 500 gallons. They both have reasonable flow rates, so that arduous pumping is not necessary to achieve reasonable volumes of filtered water in a brief period of time.

Cost estimates based upon useful filter life and retail cost of the filters indicates that the Water Filter achieves filtration at a cost of 7 cents per gallon, and the Water Purifier achieves filtration at a cost of 4 cents per gallon. Both filters can have their effective lives extended by filtering “pre-filtered” water (which has had large particulates removed), filtering water that has “settled” in order to isolate less contaminated water, and pulling water from below the surface of a fresh water body, but not from sediment-laden bottom water.

As for many other products on the outdoor retail market, the consumer must rely upon manufacturer’s claims and literature from independent testing agencies to have confidence in the capabilities of the products.

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Thank You to Vitum Medicinus for The Official Grand Rounds, Volume 3, Number 43

Thank you to Vitum Medicinus for including my post about an unexpected trap in this week's Grand Rounds. Grand Rounds is a weekly compilation of interesting posts from medical bloggers, as chosen by the host. This week's host went the extra mile to comment upon each post.

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An Unexpected Trap

I just returned from a few days fishing in central British Columbia, near the city of Williams Lake. Being an avid and traditional secretive fisherman, I can't reveal the exact location where I caught a 14- to 20-inch trout on every single cast. On one day, after catching approximately 100 fish (it was catch-and-release fishing, as is our usual habit), I was forced to retire in order to rest my arm, sit in an easy chair by the campfire, and swat mosquitoes.

The biters were present in abundance. This past winter created a substantial snowmelt, and the terrain is still moist and green where it is usually brown and dry by this time of year. The mosquitoes thrive on these conditions, so they were out in force. Fortunately, they weren't the large insects that can carry a man off, like the big bugs in Alaska, but they were persistent and voracious. Our insect repellent was precious. We carried all varieties of solutions, creams, and wipes. It was the latter that proved to be a near-disaster for one of our party.

Repel® Sportsmen Formula® Insect Repellent comes in a variety of preparations, one of which is 30% DEET wipes. These are supplied in a plastic cannister from which the wipes are removed, one at a time. They come out the top through an opening that is surrounded by inward-directed rigid plastic triangles designed to provide enough friction and resistance to allow a wipe to be pulled through, torn from the following wipe, then hold the remaining wipe in place to be pulled out in turn.

Our teenage fisherman encountered the cannister with no wipe poking out through the opening, because someone had torn off a wipe and allowed the remainder to fall back into the cannister. So, the victim stuck his index finger through the opening to try to snag one of the wipes. What he didn't appreciate was that the way the opening is designed, it flexes enough to allow a finger to enter, but is rigid enough so that the (sharp) points do not allow the finger to be removed if it has been jammed sufficiently through the opening.

I responded to a cry of distress. My young friend's finger was caught in the mosquito repellent cannister opening so tightly that the circulation to the tip of his finger was severely diminished, and the points of the plastic triangles were very painfully poking into his skin. We gently tried to pull his finger back in the direction from whence it had entered, but this hurt way too much and would have perhaps severely cut his skin. I suppose it is possible that we could have yanked hard and hope for small punctures and a reverse flex-and-release of the plastic, but the poor boy was in agony and not in a mood for an experiment.

Fortunately, we always bring a well-supplied toolbox with us. I grabbed a pair of cutting pliers and cut successively larger wedges out of the plastic until I was able to spread the opening of the finger trap and set the finger free. In a pinch, I could have used any sufficiently sharp cutting instrument, but this was the best solution.

The moral of the story, and a good rule for life in general, is don't poke your fingers where they don't belong.

Tags: Repel, insect repellent, DEET, fishing, finger trap, wilderness medicine, outdoor medicine, healthline

Labels: DEET, finger trap, fishing, insect repellent, Repel

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Dehydration

In the June 6 edition of the San Francisco Chronicle, I wrote a column entitled "The Well-Watered Athlete." The column was derived from a longer piece that needed to be condensed a bit in order to meet the publication guidelines for the newspaper. For the sake of those who wish to have a bit more explanation, here is the longer version.

Dehydration, or depletion of body fluids, can swiftly debilitate athletes and outdoor enthusiasts. Anyone who ventures to high altitude, exercises in extremes of environmental temperature (hot or cold), or performs heavy exertion is at greater risk for dehydration. Staying well hydrated should be a top priority for participants and spectators alike.

When a person must rely on oral consumption of fluids, the limiting factor is how quickly liquids can be absorbed from the gastrointestinal (GI) tract. Since the maximum rate of stomach emptying (a surrogate for fluid absorption) is only 1.2 quarts per hour, it’s easy to understand how a person can become dehydrated when fluid losses exceed this amount. Most people are able to tolerate a 1 quart per hour sweat rate and manage rehydration with oral fluids. The same principle holds true if fluid losses are from diarrheal illnesses, which are common in adventure travelers.

Recall that world-class distance runners who are acclimated to heat can sweat in excess of 3 quarts per hour! However, only evaporated sweat contributes to efficient heat loss. Sweat that drips from the skin does not contribute to the cooling process, but certainly contributes to dehydration .

Dehydration is roughly estimated as follows:

Mild dehydration – thirst, dry mucous membranes (mouth, eyes), dry armpits, dark-colored urine, decreased sweating, normal pulse rate

Moderate dehydration – the above plus sunken eyes, doughy skin, weakness, scant darkened urine, rapid and weak pulse rate

Severe dehydration – the above plus altered mental status (confusion, delirium, fainting), elevated body temperature (if it’s hot outside), no urine, no tears, no sweating, collapse, dangerously low blood pressure

Most people underestimate their fluid requirements, so it is very important to replace liquids as soon as you can.

If fluid losses are expected, then hydrate prior to the situation. If exercising in an endurance event, assume that you will constantly be mildly dehydrated. Many sports beverages contain too much sugar for an optimal rate of GI absorption. If the beverage contains more than 2 to 2.5% glucose, dilute it with water to achieve approximately half that concentration. If you are in the wilderness and don’t have access to sports beverages or dry mix, you can prepare a homemade solution (1 quart of disinfected water plus ½ to 1 teaspoon of sodium chloride [table salt], and glucose [6 to 8 teaspoons of table sugar or 1 to 2 tablespoons of honey]). Each quart of this concoction should be alternated with ½ to 1 quart of plain disinfected water. Estimation techniques to measure powdered ingredients (such as a “pinch” of table salt) are notoriously inaccurate, which can be dangerous if you add excessive amounts. Use a proper measuring implement.

Oral Rehydration Salts (ORS) that meet World Health Organization standards are available in a dry mix; Cera Lyte 70 oral rehydration salts create a rice-based solution. One packet of either is mixed with a quart of water. After the solution is prepared, it should be consumed or discarded within 12 hours if kept at room temperature or 24 hours if refrigerated. Other choices that are quite palatable include Gatorade or CeraSport electrolyte-containing sports beverage.

If only fruit juice is available, remember to cut it to half strength with water. Coffee, tea, and alcohol-containing beverages cause increased fluid loss through excessive urination (diuretic effect) and should be avoided.

To limit dehydration, encourage frequent rest stops and water breaks. Try to ingest a quart per hour until the frequency of urination begins to increase the the urine color turns light or clear. The best indicators of adequate dehydration are clear, light-colored urine and absence of thirst. If the urine remains darkened or scant, then fluid requirements are not being met. Never rely upon thirst alone to guide fluid replacement.

Adequate water ingested during exercise is not harmful, does not cause cramps, and will prevent a large percentage of cases of dehydration and heat illness. The temperature of the fluid ingested should be cool, to promote transit through the stomach. It is a myth that ingesting cold fluid causes abdominal cramps, so long as the amount ingested is prudent. If large quantities of electrolytes are lost and not replaced (e.g., if large quantities of water are consumed without salt), a person can become quite ill.

Condition yourself for the environment. To acclimatize, gradually increase exercise in a hot environment for a minimum of an hour a day for 8 to 10 days. Children require 10 to 14 days. Acclimatization is manifested as increased sweat volume with decreased electrolyte concentration (more efficient sweating), greater peripheral blood vessel dilation (more efficient heat loss), lowered heart rate, decreased skin and core temperatures during exercise, increased water and salt conservation by the kidneys, and enhanced metabolism of energy supplies.

Tags: oral rehydration, dehydration, heat, acclimatization, physician, health, wilderness medicine, outdoor medicine, healthline

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What's In Your Medical Kit?

Wilderness Medicine is the official newsletter of the Wilderness Medical Society. Over the past 24 years, it has evolved from a one-page mimeographed announcement sheet to a four-color, glossy quarterly magazine supported by an editorial staff and numerous contributors. I always look forward to receiving my copy, because the publication is full of interesting stories and useful advice.

The Spring 2007 issue is no exception. One article that stands out for its practicality is in the section Backcountry Medicine and is entitled “What’s in Your Kit?” The author, Dr. Timothy Platts-Mills, is a rising star in this area of expertise. I suggest that you read what he has written, but in the meantime, here are a few “pearls” excerpted from his excellent advice:

Preparation, Organization, and Communication: Carry a cell phone in the U.S. backcountry; consider a satellite phone outside the U.S. Carry a waterproof paper and pencil for critical notes to be transmitted in rugged environments.

Foot Care and Skin Care: One way to manage a blister is to drain it with a small incision, then cover it with a cyanoacrylate tissue adhesive (“tissue glue”), cover the dried adhesive with moleskin, then cover the moleskin with duct tape, and then grease the duct tape with Vaseline.

Respiratory Problems: Always carry epinephrine for injection in an allergy kit or as an EpiPen to treat a serious allergic reaction. Oxymetazoline nasal spray (Afrin) applied to a small piece of cotton wool may be held in the nose to help control a nosebleed.

Altitude Illnesses: Acetazolamide (Diamox) is used to both prevent and treat acute mountain sickness.

Wounds: Clean wounds first with clear, flowing water, then irrigate thoroughly with clean, disinfected water. Attempt to apply a significant irrigation pressure by using a plastic water bottle with a hole or a syringe attached to a needle or catheter of approximately 18-gauge. (Remember, the solution to pollution is dilution!)

Abdominal Complaints: If a pregnant patient develops abdominal pain in the backcountry, she should be evacuated for evaluation. Therefore, women of childbearing age should carry a urine pregnancy test.

Analgesia and Central Nervous System Treatments: If you are responsible for the care of persons on an expedition, carry adequate pain medications.

Miscellaneous: Cavit is useful to fill cavities. Insect repellent containing DEET or picaridin should be carried to avoid mosquito bites, which can transmit significant diseases, such as malaria and West Nile virus infection.

photo courtesy of www.kidsdomain.com

Tags: medical kit, backcountry, expedition, medical, physician, health, wilderness medicine, outdoor medicine, healthline

Labels: first aid, first aid kit, Wilderness Medical Society, wilderness medicine

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Thank You to OVER!MY!MED!BODY! for Grand Rounds

Thank you to OVER!MY!MED!BODY! for including my post about the book Three Cups of Tea in this week's Grand Rounds. Grand Rounds is a weekly compilation of interesting posts from medical bloggers, as chosen by the host. This week's host, a medical student at Stanford, has done a terrific job. Keep up the good work!

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Answering Questions from Readers

A fair number of comments from readers of this blog come in the form of clinical questions, in which someone asks for a response to a personal medical question. While I would like to be able to answer most of these, it is difficult to do that without more complete information, and in the absence of being able to examine the patient(s).

When a question or comment raises an issue or point of interest that is important for everyone, then I will try to address the topic in a separate post, rather than as an isolated answer to a question. In this way, more people can benefit.

Thanks for being a reader, and for your understanding.

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