Wilderness Medicine Magazine

Wilderness Medicine is the magazine published by the Wilderness Medical Society (WMS), which also publishes the journal Wilderness & Environmental Medicine. Over the past 25 years, Wilderness Medicine has evolved from a simple single color newsletter of a few pages with notes about WMS activities, to 4-color, glossy, 32-page magazine that has become a highly informative and entertaining publication. This most recent issue (Volume 25, #2, Spring 2008) takes the magazine to new heights.

There is a special section entitled Wilderness Reflections that features "North Appalachia November," "Our Big Patient" (environmental theme), "Generation 'W' - The Next Generation of Wilderness Adventurers and Wilderness Medical Experts," "The Joys and Challenges of Field Research in Remote Wilderness Areas," and "Education at 18,000 Feet."

It gets better from there, with articles about identifying poisonous plants, profiling certain past presidents of the WMS, food for the trail, advice about lower back pain encountered during scuba diving and swimming, wilderness medicine on top of the world, wilderness medicine at the Medical College of Georgia, and more.

The layout is attractive, the images sharp and colorful, and the commentaries extremely well written. I am very proud of the Editor, Chris Van Tilburg, M.D., and the editorial staff, headed by Jonna Barry. They continually strive to make Wilderness Medicine a "great read," and judging by this particular issue, are succeeding greatly. This is truly a great benefit to being a member of the WMS, so check it out.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

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Laceration Repair in the Wilderness

I'm delighted to present another guest post from Jeremy Joslin, M.D., entitled "Laceration Repair in the Wilderness":

The Scenario

It always happens by accident. You're using your new, lightweight pack saw to collect downed wood for an evening fire when the saw slips and slices into the back of your left thumb. Blood flows immediately, and you feel a rush of pain up your hand. You're four days' hike from civilization and the cut looks like it needs stitches.

Let the first aid begin. You apply pressure and the bleeding stops. After irrigating the wound with clean water, you reach into your pack to find your sewing kit and sutures. But should you really be stiching up this cut?

The answer doesn't necessarily hinge solely on your training. I've discussed this subject with emergency physicians who repair lacerations daily, as well as with first responders who learned from their grandmothers that if they could sew cloth, they could sew skin. My personal opinion is that people should take great pause before sewing a laceration outside of a medical exam room. In my mind, the decision about whether or not to sew a wound in the field is related to the issue of "wound appropriateness."

Wound appropriateness takes both wound size and cleanliness into account. A small wound that remains contaminated with dirt and debris shouldn't be closed because the closure would trap all the necessary ingredients for an infection. On the other hand, a small wound that's fairly clean probably doesn't need stitches anyway - perhaps not even in the Emergency Department! An article (1) reviewed this particular topic and came to the conclusion that uncomplicated lacerations less than 2 cm (just under an inch) didn't heal better or ultimately appear better when sutured (stitched) compared to when they were left unsutured. A small, debris-filled wound should be cleaned with water that is disinfected enough to drink, and then left open to heal or closed (e.g., skin edges brought together) with an adhesive bandage (strips).

My preferred technique for caring for small wounds is to clean them thoroughly, then use skin (tissue) glue to make the initial closure, after which I cover the entire wound with a piece of gauze and duct tape or with Tegaderm (a thin, clear, plastic adhesive covering) for protection. Some people have used "super glue" to close wounds, but this is not recommended for several reasons. Any laceration can be sutured by a physician in a delayed fashion upon your return, if such a repair is necessary for cosmetic or other reasons.

Any large wound needs to be examined with three things in mind:

How contaminated is the wound?
How much will the wound bleed?
Are there any other structures involved?

Every large wound will have different answers to these questions, which is where clinical acumen comes into play. Always prioritize control of blood loss, and consider closing the wound(s) loosely with stitches if this is the only way to staunch the bleeding. If the wound is deep, there may be damage to structures beneath the skin, such as tendons, ligaments, and/or nerves, any of which may require formal wound care not possible in the outdoors. Therefore, consider evacuation for all large wounds. While evacuating, the wound should be covered and compressed with a clean bandage.

(1) Emergency Medicine Journal 2007;24:217-218; doi:10.1136/emj.2007.046813

image courtesy of St. David's Healthcare

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

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Automated External Defibrillators in the Wilderness

A friend of mine who manages a fishing camp in British Columbia recently asked me whether or not he should purchase an automated external debrillator (AED) for the camp. An AED is a device that is attached to a person in the event of an apparent cardiac arrest. Its circuitry automatically detects whether the victim is suffering from ventricular fibrillation (VF), in which the heart is not beating, but rather, is quivering and therefore not effectively pumping blood. If VF is detected, it delivers a shock designed to restore an instrinsic and effective cardiac rhythm. If it is successful in accomplishing this, the victim might survive. If an effective life-sustaining rhythm cannot be restored, the victim dies. My friend asked my advice because a fair number of fishermen who use the camp are senior citizens. The base camp is located a good two hours drive from the nearest medical assistance (including the arrival of an ambulance with paramedics or emergency medical technicians [EMTs]), and the remote fishing sites are even further out, adding at least an hour to any hypothesized response time.

The same question comes up from time to time with regard to expeditions, usually persons climbing mountains where they will be far from sophisticated medical care or on ocean-going vessels out at sea. My answer is more often related to the finances of the inquiring party than to any expectation that the device might actually save a life in a remote setting, where it couldn’t immediately be followed by advanced life support techniques (e.g., airway management, intravenous access, administration of anti-arrhythmic drugs) and other adjuncts to manage the primary cause of the cardiac arrest (specifically, ventricular fibrillation). But I usually conclude, as my grandmother was fond of saying, “It couldn’t hurt.”

In the New England Journal of Medicine, Volume 358, pages 1793-1804, April 1, 2008 (10.1056/NEJM0oa08011651), Gust Bardy, M.D. and colleagues published an article entitled “Home Use of Automated External Defibrillators for Sudden Cardiac Arrest,” in which 7001 patients residing at home with previous anterior-wall (of the heart) heart attacks (myocardial infarction) who were not candidates for an implantable cardioverter-defibrillator were assigned to two different response groups should they suffer a sudden cardiac arrest at home. The first group was assigned to call emergency medical services (EMS) and perform CPR, while the second group was assigned to use an AED, then call EMS and perform CPR. The conclusion of the study was that being in possession of an AED in a home setting did not improve overall survival, as compared with reliance on conventional resuscitation methods. Notably, of the group of patients who had access to AEDs, they were used in 32 patients, of which 14 received an appropriate shock. Of the persons who received a shock, 4 survived. The conclusion of the investigators was that access to a home AED did not significantly improve overall survival, as compared with reliance on conventional resuscitation measures.

So, what can we learn from this study of the use of AEDs in the home as it might relate to their use in a remote setting? Without question, the device sometimes works to convert VF to a life-sustaining heart rhythm. Prompt (generally accepted to be within 4 minutes of the onset of VF) deployment of an AED can save someone’s life. Therefore, the question now becomes, is it practical or cost-effective to have one with you on an expedition? The answer depends on your finances, ability to carry the device, which weighs pounds, keep it charged with electricity, have it withstand the environmental conditions in which you will travel, train participants how to promptly access the device and use it properly, rapidity with which it can be deployed, and so forth. Furthermore, you must be aware that even if one is able to convert VF to a stable heart rhythm, the victim may be suffering a heart attack or have other problems (such as congestive heart failure) that require advanced medical care. On the other hand, sometimes a person will suffer a single episode of VF that when terminated by an AED, results in no further deterioration and, thus, survival. So, would I carry an AED with me to fishing camp? I cannot offer a definitive answer, because it depends…

If you have thoughts about this matter, please feel free to share them.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

Tags: AED, automated external defibrillator, wilderness medicine, outdoor medicine, healthline

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Field Guide to Wilderness Medicine, 3rd Edition

The Field Guide to Wilderness Medicine, 3rd edition has just been published by Elsevier. The book is 919 pages, up from 709 pages in the 2nd edition, and 62 chapters with 17 appendices, up from 55 chapters and 16 appendices in the second edition. I'm very pleased with how the book turned out. This new edition is currently available at Amazon and other booksellers.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

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Acute Allergic Reactions Associated With CroFab

In the April 2008 issue of Annals of Emergency Medicine appears an article entitled "Acute Hypersensitivity Reactions Associated with Administration of Crotalidae Polyvalent Immune Fab Antivenom," by Robert Cannon, Anne-Michelle Ruha, and John Kashani. These doctors performed a chart review of all patients that had been admitted with the diagnosis of rattlesnake bite to Phoenix Children's Hospital and Banner Good Samaritan Medical Center in Phoenix, Arizona between July 2000 and June 2004.

The chart review yielded 93 patients who were treated with crotalidae polyvalent immune Fab (ovine [sheep]) antivenom (commercially known as CroFab; FabAV, Protherics, Inc., Brentwood, TN). This antivenom is made of "small" antibody fragments in a manner designed to make the antivenom more effective in humans at neutralizing snake venom, while resulting in fewer allergic (adverse) reactions. These 93 patients included 72 males and 21 females. Their mean age was 34.5 years (range 16 months to 91 years), and the mean dose of antivenom administered was 12 vials (range 4 to 32 vials). The incidence of acute hypersensitivity (allergic) reactions was 5 of 93, or 5.4%. In four of the cases, the reaction was mild and easily treated, such that the full course of antivenom could be administered. One patient developed a reaction that necessitated discontinuation of antivenom administration.

These data are even better than the previously reported data with respect to incidence of allergic reactions. Before CroFab came on the scene in 2001, doctors used Antivenin (Crotalidae) Polyvalent from Wyeth Laboratories, which is made from a different process, and was notorious for causing frequent serious allergic reactions. I can recall spending long hours working in the intensive care unit administering this older product to severely envenomed victims, essentially having to infuse a few drops of the antivenin alternated with intravenous epinephrine to counteract the allergic manifestations. It would take many hours to administer the requisite doses of antivenom, and many patients suffered both immediate and delayed allergic reactions. With CroFab, it has become much easier to manage snakebite victims.

As the authors explain, FabAV is produced by immunizing individual flocks of sheep with one of 4 poisonous snake venoms: Eastern Diamondback rattlesnake, Western Diamondback rattlesnake, Mojave rattlesnake, and cottonmouth. Because the sheep are immunized, they develop antibodies, which circulate in their bloodstreams. The serum from their blood is digested with papain, which breaks down the antibodies into fragments, from which the Fab fragments are isolated. Other fragments and extraneous proteins are discarded. The four different types of Fab fragments (one type from each flock of sheep) are combined to create a highly purified product that lacks the immunogenic larger antibody fragments and proteins fround in Antivenin (Crotalidae) Polyvalent. Thus, the final product is much less prone to induce an adverse allergic reaction.

Using the newer antivenom product, fewer patients should have allergic reactions necessitating therapies such as infusion of epinephrine, which will make their care easier and less dangerous.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

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Thank You to Musings of a Dinosaur for Grand Rounds

Thank you to Musings of a Dinosaur for including my post about exercise-associated hyponatremia in this week's edition of Grand Rounds. Grand Rounds is a weekly compilation of posts related to health care compiled by a host, who makes a great effort to compile an interesting collection for readers.

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Bear Spray

Since publishing my post that included advice for avoiding bear attack in the wilderness, I have had a few questions from people about how to defend against an attacking bear, and in particular, about the role of "bear spray."

Pepper spray marketed to repel bears definitely has a role, but should not be completely relied upon to deter an aggressive or charging bear. So avoidance of up-close bear encounters is the most important safety issue, and should never be forgotten.

If you are going to carry bear spray, here is some important information assembled from the writings and lectures of experts (including Steve French, M.D., Luanne Freer, M.D., Timothy Floyd, M.D., and Stephen Herrero). I also gleaned excellent information from the UDAP Industries site:

1. Purchase a product advertised to repel bears. Some authorities indicate that the spray distance must be at least 25 feet with a minimum duration of 6 seconds, while others argue that duration is not as important as rapid, intensely concentrated coverage of the attack area.
2. Product names include UDAP Pepper Power,
3. The product should contain at least 1% capsaicin and/or capsaicinoids. Most products from reputable companies contain significantly more.
4. Carry the spray where it is obvious and can be immediately deployed. It should be in a holster on your waist or chest. If it is hidden in the bottom of your pack, it will not be of any use to you during a sudden attack. Show your companions the location, so they can grab it if necessary.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

Tags: bear, capsaicin, pepper spray, bear spray, wilderness medicine, outdoor medicine, healthline

photo courtesy of UDAP Industries

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Exercise-Associated Hyponatremia

An excellent case report, entitled "Severe Exercise-Associated Hyponatremia on the Kokoda Trail, Papua New Guinea," appears in the first issue of Volume 19 of the journal Wilderness & Environmental Medicine. Sean Rothwell and his co-authors describe the plight of a 43 year old man who collapsed and had a seizure in the afternoon of the third day of a guided trek. The amount of sodium in his blood was found to be dangerously low, and was attributed to (presumed) fluid replacement with water without sufficient electrolyte supplementation.

Exercise-associated hyponatremia (low serum [in the blood] sodium) is a common complication of "ultradistance" exercise and other situations (e.g., heavy sweating) in which there are large fluid losses without adequate sodium replacement. When someone becomes hyponatremic (e.g., suffers from low serum sodium) to the extent that symptoms appear, the following are noted: nausea, vomiting, headache, weakness, fatigue, muscle weakness, difficulty with balance and walking, confusion, fluid in the lungs (shortness of breath and coughing, sometimes productive of frothy and/or blood-tinged sputum), and seizures. The condition can be fatal. Other conditions, such as dehydration, can cause the same symptoms. If the person is known to have ingested a large amount of plain water without any electrolyte supplementation, then hyponatremia should be suspected.

According to the authors, risk factors for the development of exercise-associated hyponatremia are low body weight, female gender, greater than 4 hours of continuous exercise, slow performance pace, inexperience with the activity, excessive water drinking, kidney dysfunction, and hot environmental conditions.

If someone is felt to suffer from exercise-associated hyponatremia, he or she should be prevented from making the situation worse. In other words, any ingested fluid must be high in sodium content. If the victim is in a very bad condition, such as suffering from seizures, then it will be necessary to have a medical provider initiate an intravenous line in order to administer fluid with high sodium content. If the victim is short of breath and supplemental oxygen is available, it should be given.

The best way to prevent exercise-associated hyponatremia is to be certain that fluid replacement during times of heavy exertion and sweating takes into account fluid losses. There is no absolute prescription for success with regard to prevention. Some experts believe that in an endurance situation (e.g., adventure race), fluid replacement should be guided by thirst, while other experts believe that thirst alone underestimates fluid requirements. The ingestion of electrolyte-containing beverages (e.g., "sports drinks") has not been shown to prevent the development of exercise-associated hyponatremia in athletes who drink "to excess." The precise definition of "to excess" remains to be determined. In general, it is prudent to drink enough liquids to keep one's urine copious and light-colored, but now so much that excessive urination or bloating are the results of personal oral hydration efforts.

image of the Kokoda track (trail) courtesy of www.peregrineadventures.com

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

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Thank You to Health Business Blog for Grand Rounds

Thank you to David E. Williams of Health Business Blog for including my post about ozone and the outdoors in this week's edition of Grand Rounds. Grand Rounds is a weekly compilation of posts related to health care compiled by a host, who makes a great effort to compile an interesting collection for readers.

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Ozone and the Outdoors

Here's an interesting news item (within the quotation marks) that was recently brought to my attention:

"Content provided by Reuters on April 22, 2008
WASHINGTON (Reuters) - Even breathing in a little ozone at levels found in many areas is likely to kill some people prematurely, the National Research Council reported. The report recommends that the U.S. Environmental Protection Agency consider ozone-related mortality in any future ozone standards, and said local health authorities should keep this in mind when advising people to stay indoors on polluted days.

The report looks at ground-level ozone, a component of smog, as opposed to the ozone found in the high atmosphere, which protects the earth from ultraviolet rays. Ozone is a form of oxygen formed by the reaction of sunlight on air containing other pollutants such as hydrocarbons and nitrogen oxide. It is a powerful oxidizer, meaning it can damage cells in a process akin to rusting.

Ozone is known to cause respiratory problems and worsen heart disease. Children and the elderly are at special risk. The EPA asked the National Research Council, part of the advisory National Academies of Science, to analyze the link between ozone and early death.

A committee appointed by the council found that deaths related to ozone exposure are more likely among people with pre-existing diseases and other factors that could increase their susceptibility. But they said premature deaths are not limited to people who are already within a few days of dying. They looked at studies that linked deaths directly with variations in ozone levels, as well as animal studies that examined whether there was a biological explanation for ozone causing death.

The committee looked at studies done in several cities across the United States as well as in Canada and Europe. They took into account differences in temperature and humidity that may affect the ozone level. The EPA toughened standards for ozone pollution in March but outside experts complained its new requirements were more lax than the EPA's own scientists recommended. The new standards are 75 parts per billion in ambient air in the United States. The previous standard was 80 parts per billion. The EPA's Clean Air Scientific Advisory Committee recommended a standard of 60 to 70 parts per billion."

As it is difficult to conceive of wilderness medicine without the wilderness, I absolutely believe that environmental issues should be featured from time to time within this "Medicine for the Outdoors" blog. Indeed, it is well accepted that the outdoors is in need of the equivalent of medical attention. Certainly, for those of us who venture outdoors frequently, and who choose to exercise in urban locales in preparation for our wilderness excursions, air quality is a very high priority. It appears that accumulations of ozone at low altitude are increasing, and that they will have a deleterious effect upon human lungs, even in the absence of our immediate appreciation of pain, shortness of breath, or decreased exercise tolerance.

I was asked recently by Dr. Val Jones of Revolution Health to comment upon the ozone situation, and was happy to do so. John Briley, who is an excellent writer, prepared a report that featured useful information, and I provided elements of the following commentary in response to Mr. Briley's questions:

Knowledge about air quality on a day-to-day basis is becoming a necessity for persons who live, work, and play in the outdoors. It is crucial that these people, and those responsible for them, know what published ozone levels mean. The Environmental Protection Agency posts these data daily, with a U.S. map showing elevated-ozone areas, via http://airnow.gov/; these reports are also published on the weather pages of many daily newspapers. But how many of us look at them, and with what intensity are they reported? If people have access to this information, they can make informed choices about whether and how hard to exercise, how much time to spend outdoors, etc. Just as the heat index is a very useful guide for people to avoid being afflicted by heat illness during heat waves, the Air Quality Index (AQI) is essential for determining when it is safe to be exposed to atmospheric air. It is a sad fact of life, but a fact nonetheless, that AQI should be known and advertised to promote good health, and to avoid bad health.

EPA’s Air Quality Index runs from zero to 500; this covers a range of pollutants, but ozone is a leading factor in determining the AQI. Air pollutant levels above a value of 100 could be a concern for people with pre-existing respiratory conditions, and levels above 150 indicate potential for adverse health effects in anyone breathing that air. An air-quality from 201 to 300 is “very unhealthy” and anything above 300 is “hazardous.”

On days with unhealthy ozone levels, one should try to limit exposure by staying in environments that are protected from the ozone-laden air. This might be indoors in a location with central air conditioning. If the air is toxic, you should avoid outdoor exercise, unless you are willing to suffer a burning sensation in your throat and eyes, difficulty breathing, triggering of incipient reactive airway disease (such as asthma), a general ill feeling, and the potential for lung irritation and inflammation that may contribute to permanent lung injury. Even casual exposure to high ozone levels is toxic. That toxicity rises when you exercise because you’re breathing more rapidly and deeply, thus assaulting your lungs and your immune system, and likely shuttling more of the atmospheric pollutants into your bloodstream and your tissues. So, if you walk outside and there’s a visible haze and your eyes burn and your throat is irritated, something’s not right. If you’re exercising in those conditions, you should cease the activity immediately.

On high-ozone days, exercising in the early morning or after dusk should not be relied upon to necessarily reduce exposure to ozone to an acceptable level. Ozone levels do not automatically correspond to temperature, so just because it is cooler outside doesn’t mean the ozone level is safe. Even though the EPA notes that ozone levels tend to peak in late afternoon and early evening, because levels build throughout the day on hot, sunny days, they still could be unsafe before dawn or after dusk. That’s why awareness of the levels via something like the AQI is key.

The press release above confirms that low level, chronic exposure to ozone can cause long-term damage. Even if the acute exposures are undetectable, the cumulative toxicity can lead to increased morbidity – and perhaps even mortality. This is not an alarmist perspective, as studies looking at ozone exposure and lung disorders confirm the links.

Many reversible conditions can become irreversible over time. Whether it’s cigarette smoking, or ozone, or toxicity from contaminated food products, the body can often repair itself to a certain extent, but in the case of ozone, chronic exposure may eventually cause sufficient persistent inflammation to lead to permanent scarring and inflammation of tissue.

Precisely when that permanent damage might occurs varies from person to person, so we can’t say definitively that, for example, someone who jogged three times a week at noon all summer long in a high-ozone area will develop lung disease. But we can say that, generally, chronic exposure to ozone will eventually become a contributor to lung irritation and injury.

I harken back to my youth in the summer of 1968, when the summer Olympics were held in Mexico City. There were ahtletes seeking to perform well who trained by running at altitude and by exercising behind buses, in order to acclimatize themselves, or so they thought, to the polluted air they expected to encounter during competition. They wanted to adapt to toxic particulate matter, vehicle exhaust, and ozone, but undoubtedly had no idea that in the process, they were assaulting their lungs. Today, from an ozone perspective, if you live in the following cities, you had best be careful:

25 Most Ozone-Polluted Cities (2007)

1 Los Angeles-Long Beach-Riverside, CA
2 Bakersfield, CA
3 Visalia-Porterville, CA
4 Fresno-Madera, CA
5 Houston-Baytown-Huntsville, TX
6 Merced, CA
7 Dallas-Fort Worth, TX
8 Sacramento--Arden-Arcade--Truckee, CA-NV
9 Baton Rouge-Pierre Part, LA
10 New York-Newark-Bridgeport, NY-NJ-CT-PA
11 Washington-Baltimore-Northern Virginia, DC-MD-VA-WV
12 Philadelphia-Camden-Vineland, PA-NJ-DE-MD
13 Hanford-Corcoran, CA
13 Modesto, CA
15 Phoenix-Mesa-Scottsdale, AZ
16 Charlotte-Gastonia-Salisbury, NC-SC
17 Las Vegas-Paradise-Pahrump, NV
17 Milwaukee-Racine-Waukesha, WI
19 St. Louis-St. Charles-Farmington, MO-IL
20 El Centro, CA
20 Kansas City-Overland Park-Kansas City, MO-KS
20 Beaumont-Port Arthur, TX
20 Chicago-Naperville-Michigan City, IL-IN-WI
24 Grand Rapids-Muskegon-Holland, MI
25 Atlanta-Sandy Springs-Gainesville, GA-AL
25 Cleveland-Akron-Elyria, OH

We are running out of time to mend our environmental ways. Air quality would be a reasonable place to begin.

opening image courtesy of the U.S. Environmental Protection Agency

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

Tags: ozone, air pollution, wilderness medicine, outdoor medicine, healthline

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Hydration Question

A reader writes: “I have been told that under most circumstances a properly hydrated person should be urinating every 1 and 1/2 to 2 hours. Is this accurate?”

This is probably a reasonable statement, although there is no absolute correlation of time interval between episodes of spontaneous (e.g., associated with the urge to urinate) urination and state of hydration. For instance, a person might be well hydrated and exercising, so not appreciate an urge to urinate. Exercise is also the reason why a person may not appreciate thirst, so until someone takes a break from the exercise and attempts to urinate, it may be difficult to tell exactly where someone is from a hydration perspective.

The general rule is to drink enough liquid so that the urine is light-colored and copious, no matter what the interval between episodes of urination. If the urine is dark-colored, this may indicate that it is concentrated (with waste products), which occurs when the kidneys (and body) are working to conserve fluid. “Cloudy” (not clear) urine may be caused by excess protein in the urine, a urinary tract infection, or some other reason. Using the urine hydration chart depicted above, urine should not be darker in color than #4.

It’s easy to become dehydrated outdoors, as most people underestimate their fluid requirements. Situations of particularly high risk include cold, dry weather (respiratory fluid loss from breathing, particularly if it is rapid), high altitude (loss of thirst and breathing cold, dry air), extreme heat (nausea, inadequate thirst), during times of great exertion, and with any intercurrent illness (particularly if it involves nausea and vomiting). These are times when it is important to drink a minimum of two liters (quarts) of water when there is no significant fluid loss (e.g., at rest in a non-stressful environment), and more if conditions warrant. So long as alcohol is not ingested and one avoids any beverage with a diuretic effect, it doesn’t make much difference what beverage is chosen. Drink what you like, and drink enough.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

Tags: hydration, dehydration, wilderness medicine, outdoor medicine, healthline

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Thank You to Suture for a Living for Grand Rounds

Thank you to Suture for a Living for including my post about seabather's eruption in this week's edition of Grand Rounds. Grand Rounds is a weekly compilation of posts related to health care compiled by a host, who makes a great effort to compile an interesting collection for readers.

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Sea Bather’s Eruption

From the month of May through September, oceangoers along the U.S. Gulf coast need to be concerned about a particular form of skin rash caused by tiny jellyfish. As the summer season progresses, this can also become a problem along the entire eastern seaboard. I've been afflicted while scuba diving in Cozumel, Mexico, and the episodes can be much more than a minor annoyance. Indeed, the intensity with which some people react to these particular stings was an impetus for the development of Safe Sea, a jellyfish sting inhibitor product for which I participated in the design of clinical trials.

Sea bather’s eruption, often misnamed "sea lice" (which are true crustacean parasites upon fish), occurs in seawater and more often involves bathing-suit-covered areas of the skin, rather than exposed areas. The skin rash distribution is very similar to that from seaweed dermatitis, but no seaweed is found on the skin. The cause is stings from the nematocysts (stinging cells) of thimble jellyfish, such as Linuche unguiculata, and the larval forms of certain anemones. The victim may notice a tingling sensation under the bathing suit (breasts, groin, cuffs of wet suits) while still in the water, which is made much worse if he takes a freshwater rinse (shower) while still wearing the suit. The rash usually consists of red bumps, which may become dense and confluent. Itching is severe and may become painful.

Treatment is often not optimal, because application of vinegar or rubbing alcohol to stop the envenomation may not be very effective. An agent that may work better is a solution of papain (such as unseasoned meat tenderizer), which may be applied using a mildly abrasive pad, although a good outcome is not guaranteed. After the decontamination with any agent and a thorough freshwater rinse, apply hydrocortisone lotion 1% twice a day to treat the inflammatory component of the skin reaction. If the reaction is severe, the victim may suffer from headache, fever, chills, weakness, vomiting, itchy eyes, and burning on urination, and should be treated with oral prednisone as if he suffered from poison oak. Topical calamine lotion with 1% menthol may be soothing.

Prevention is obviously quite important. If you are able to obtain the product, cover exposed skin areas with Safe Sea. This includes at least a few inches underneath the cuffs of wet suits or Lycra-type "stinger suits" that are equipped with elastic cuffs at the wrists and ankles, and sometimes around the neck. If you only wear a normal bathing suit, which does not have tight cuffs, the tiny creatures can easily wash onto your skin underneath the suit, where they can wreak havoc. So, if you are concerned about the possibility of seabather's eruption, you must also apply the Safe Sea underneath your bathing suit. If there are "thimbles" (jellyfish) visible in the water, it is best to stay out. If you are swimming in apparently uninfested water and begin to feel a tingling sensation on your skin, then the "swarm" may be moving into your location and you should exit the ocean.

Preview the 25th Anniversary & Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 25-30, 2008.

Tags: sea bather's eruption, sea lice, Safe Sea, marine, wilderness medicine, outdoor medicine, healthline

Labels: marine sting, sea bather's eruption, sea lice

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