The Desert and Desert Survival 2

This is the fourth post based upon educational sessions and syllabus material presented at the Wilderness Medical Society Annual Meeting & 25th Anniversary held in Snowmass, Colorado from July 25-30, 2008. This post continues the discussion about the desert and desert survival, based upon the extensive knowledge of Dr. Edward J. (“Mel”) Otten, who is Professor of Emergency Medicine and Pediatrics, and Director of the Division of Toxinology at the University of Cincinnati.

All desert flora and fauna have one guiding principle for survival, which is to conserve water. The ground surface of the desert has the highest temperature because of the direct effect of solar heat and wind. Therefore, during the hottest times of the day, most animals are either below the surface, in underground burrows, or above the surface in available vegetation, cacti, trees, or shrubs. Most animals forage from dusk until dawn, when temperatures are cooler. Some mammals, such as kangaroo rats, never drink, but obtain necessary water through plant seeds. Plants have evolved a number of survival adaptations to maintain water, including stomata which are closed during the day and crassulacean acid metabolism (CAM) photosynthesis, which allows for accumulation of carbon compounds at night via the dark reaction . Other adaptations include stem photosynthesis in plants without leaves, thick cuticles, water storage tissues, and widespread shallow root systems. They also have evolved a variety of defense mechanisms, such as production of toxic compounds that act as herbicides to others plants and the formation of needles, spines and thorns that dissuade browsing animals. Obviously humans are not ,able to evolve these physiological changes, but must rely on behavior, technology andother adaptations to mimic the methods used by indigenous desert dwellers.

All things being equal, preparation improves the likelihood of survival. However, things are never equal so luck is probably the most important factor. The controllable factors are mental and physical conditioning, clothing, survival kit adequacy and survival skills. These may allow one to survive even in the most extreme conditions.

Mental preparation is key to any survival situation. The “will to survive” has been shown to be the most important factor in the outcome of a number of situations. Knowledge of the terrain features, weather, animal and plant life, and potential hazards should all be studied prior to travel to a desert area. Not only does this increase one’s chances for survival, but enhances enjoyment of the desert environment. Practical experience in finding water and food, navigation, and constructing shelters is more valuable than reading about it. Time spent in attending a course on survival in general or desert survival in particular may be invaluable if one is later in a true survival situation.

Physical conditioning and acclimatization are as important for desert travel as for mountaineering. Desert travel is difficult under most circumstances. The terrain is rough and may include sand dunes, sharp loose rock, flash floods, steep grades, and hot surfaces. Leg conditioning helps prevent the ankle and knee injuries that can force a survival situation in a harsh climate. Acclimatization involves three well described physiological adaptations and usually requires 10 to 14 days in a hot environment. These adaptations are an increase in the volume of sweat and number of active sweat glands; a decrease in concentration of electrolytes in sweat, and sweating at a lower body temperature. These can be induced before arriving in a hot climate by the use of a sauna or vigorous exercise to raise body temperature.

Clothing selection for desert travel is somewhat different than for most other wilderness activities. The less exposed skin, the better. While cotton is not good for most cold, wet climates, it is useful in the desert. Light colored clothing reflects sunlight and lessens skin temperature. Ripstop cotton (cotton material with nylon threads latticed within it) is best because it resists rips that are common in the desert. It is light enough to allow heat to escape, does not creagte a clammy feeling in low humidity, and protects against some ultraviolet radiation exposure and blowing sand. If ripstop cotton is not available, then any tight weave cotton is adequate. Long sleeves and long pants are a must to protect againstspines, thorns, splinters and insects. More importantly, they protect against solar radiation that causes sunburn and increases body temperature, and trap more cool air next to the skin. Sweat that is trapped may decrease water loss via evaporation. Trousers can be tucked into the tops of socks to protect from insects; sleeves should be not be rolled up to minimize the risks of sunburn and heat gain. Gaiters can be worn to protect lower legs and the inside of footwear from sand, rocks, and dust. In a survival situation, puttees (wraps that extend from the tops of the shoes to the knees, either over trousers or bare legs, can be made from strips of cloth, elastic bandages, or stockings to protect the lower legs. They can be incorporated into the socks and wrapped to above the knees in a fashion similar to that for gaiters.

Because of the wide temperature swings, a pile jacket or sweater is necessary at night. Layering of clothing, just as for cold climates, is the best means of preserving body warmth. In a survival situation, any insulating material, such as seat cushions, newspapers or dry grass, can be used to insulate whatever clothing is available. Even though wind is more of a problem than rain, a Gore-Tex jacket is also recommended, especially for “cold” deserts. A wide brim hat or kepi (a cap with a cloth extending from the back protecting the neck) is necessary to protect the head, face, neck, and ears. In a survival situation, a head covering can be made from whatever material is at hand. A cotton cravat, bandanna, or handkerchief can be used to keep the head and neck cool by soaking the material in water (if plenty of water is available; do not use precious drinking water) and then placing it on the head followed by a hat, or wrapping around the neck and shoulders under a shirt. Commercially produced neck wraps (Cooldanna, Climatech, Stacool) and vests that contain crystals that can be soaked in water and then become cool through a chemical reaction are also available, but probably do not add much in the way of total body cooling in extreme environments The cravat can also be used during dust storms to protect the nose and mouth. It can also be used as a towel and to absorb moisture from plants when obtaining water.

High (6 inches) top boots composed of leather or synthetic materials are necessary to prevent sand, rocks, burrs from entering the boots, support the ankles on rough terrain, insulate the feet from hot surfaces, and prevent the boots being pulled off in soft ground. Boots should be well broken-in prior to hiking. Military issue boots with metal spike protection can become extremely hot in desert conditions and should be avoided. Running shoes do not insulate the feet well and may become extremely hot.

Socks should not be cotton, because of the risk of blisters and lack of wicking and insulation. Polypropylene or a combination of polypropylene and wool is the best for socks because of less friction and thicker material. Foot care is extremely important, especially in a survival situation when walking is the only means of transportation. Feet should be inspected for blisters, foreign bodies, and abrasions on a regular basis while hiking. Socks should be changed frequently, at least twice a day, to allow them to dry out and to remove accumulated dust and sand. Leather gloves are very desirable to protect hands from hot objects, plant spines, thorns and splinters, insects, and blisters.

Abrasions and lacerations to the hands can quickly become infected in conditions where hand washing is difficult. Eye protection becomes very important in the desert, especially when traveling. Solar radiation, both direct and reflected, can cause keratitis similar to snow blindness. More commonly, blowing sand, dust and insects may cause corneal abrasions and conjunctivitis. Contact lenses are difficult to manage in the dry, dusty environment. Tinted goggles are best, just as with mountaineering, but glacier glasses or standard sunglasses can be used. Duct tape, adhesive bandages or other material can be used to fashion side shields for regular glasses to prevent sand and dust from entering through the sides. Insect head nets can be lifesaving, especially in African, Arabian and Australian deserts, where insects and insect borne diseases are a particular problem.

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Primitive Skills And Crafts

Primitive Skills And Crafts is "An Outdoorsman's Guide to Shelters, Tools, Weapons, Tracking, Survival, and More" compiled by Richard and Linda Jamison. The book is published by Skyhorse Publishing, Inc. and carries a retail price of $12.95 U.S.

The contributors to the book are Turkka Aaltonen, a survivalist and director of the Finnish Survival Guild; Donald Fisher, a historian of aboriginal lifestyles; Paul Hellweg, a wilderness survival expert and master of flintknapping (shaping flint, as for an arrowhead); the Jamisons; Peg Mathewson, an anthropologist; Larry Olsen, an outdoor survivalist; Jim Riggs, a primitive skills trainer; Steve Watts, an aboriginal skills expert; Dave Wescott, a pioneer in primitive outdoor education; Tamara Wilder and Steve Edholm, experts in primitive living skills; Ernest Wilkinson, an expert on animal behavior and winter survival techniques; and Margaret Wilson, a wild plant expert.

The book is written in essay format, rather than as an encyclopedia, so the writing style and level of detail vary from chapter to chapter. I found the historical explanations, such as that about the southeaster Indian rivercane blowgun, to be fascinating. So, as one peruses this book, he or she learns about how to make and/or use blowguns; hunting and fishing techniques with various spears, seines, improvised lines, traps, and the like; how to make primitive process pottery; stone survival tools; the many uses of the yucca plant, such as cordage, basketry, weaving, sandals, bags, mats, fire starter, and food; how to make hide glue; traditional basketry materials; tracking skills; primitive cooking methods; whole-shoot willow baskets; juniper-bark berry baskets; the nutritional value of a primitive diet; how to fashion a fire piston; throwing sticks; pine needle basketry; and the Paiute deadfall animal trap, to name a few.

There is no wilderness medicine in this book, but still much to commend it. It seems like it would be fun to attempt many of the skills described, so when your schedule permits, you might try to recreated some of these techniques, not so much to save your life, but to understand how incredibly easy we have it today. In listening to lectures by survivalists, I have come to appreciate that they certainly have their preferences for techniques, and opinions about the likelihood that any particular method will meet with success. So, you might wish to get a second opinion before you count on anything in particular that you read in a survival book.

If you are interested in the outdoors, and particularly in survival and history, this book is a fun read.

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Thank You to "monash medical student" for Grand Rounds

Thank you to Jeffrey Leow of monash medical student for including my post about poison oak allergic contact dermatitis in this week's edition of Grand Rounds. This week's Grand Rounds, which is a weekly compilation of posts related to health care compiled by a host, was created by Jeff Leow, who is a medical student in Melbourne, Australia. He has done a terrific job tying together a diverse set of posts under the common theme of armed conflict.

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Poison Oak Allergic Contact Dermatitis

Case Reviews in Clinical Dermatology, Volume 1 Issue 3, had an interesting discussion about certain aspects of poison oak/ivy dermatitis. The following are some of the points made by the authors, with additional comments by me:

"Contact dermatitis" (CD) is a broad term used to describe inflammation of the skin caused by direct contact with an irritating substance or allergen (a substance that induces an allergic reaction/response). Allergic contact dermatitis is a hypersensitivity reaction to a substance exposed to the skin to which a person has become allergic.

Sensitization to a substance can develop at any time, including adulthood. It may develop for substances that have been used repeatedly without any difficulty by an individual in the past. Poison oak/ivy allergic contact dermatitis is quite common. It is most likely to occur in persons with significant outdoor exposure, such as forest firefighters and backpackers. Sometimes a person may unknowingly encounter the allergen. For instance, urushiol in poison oak can persist on items such as clothes and gardening tools for years, and may be transmitted to a person from the fur of a pet, in the smoke of a campfire, or from a casual brush with plant that intrudes on a hiking path.

In general, a contact dermatitis eruption due to poison oak appears as itchy blisters, both large and small, on a reddened base in a linear (patterned in lines) distribution. Despite common belief, the fluid contained in the blisters does not spread the rash; only the urushiol resin itself can spread the rash. The resin in the is composed of a mixture of catechols and causes the hypersensitivity reaction when it comes in direct contact with the skin.

Urushiol is a water-soluble substance that can only be removed in significant amounts if washed immediately. Only 50% can be removed after ten minutes of contact, 25% after 15 minutes, and no resin can be removed after one hour of contact with the skin. Prevention of exposure to these plants is the most sensible, but not always the most practical solution. Many attempts have been made to prevent contact with the resin by applying topical skin protectants.

To make some treatment recommendations, the authors of the article offered a clinical case:

A 28-year-old, otherwise healthy man presented with a one-week history of a rash that began as small, itchy blisters on his inner arms a few days after camping in the Sierra Nevada Mountains. A few days later, he started to develop new large, red areas on his back. He felt somewhat fatigued but denied having fever or other symptoms. On physical examination, small blisters and black streaks were apparent in a cluster on his inner arm. There were other large reddened areas on his back. Based on his presentation, the diagnosis was "black spot poison oak contact dermatitis with systematization (spread to other parts of the body)."

The patient was treated with oral prednisone, starting at 60 mg per day and tapered by 10 mg per oral dose every 3 days. His symptoms resolved completely within two weeks.

According to the authors, this case illustrated an unusual presentation of poison oak contact dermatitis and the importance of rapid diagnosis and treatment. "Rhus dermatitis," commonly known as "poison ivy, poison oak, or poison sumac," and currently referred to as "toxicodendron dermatitis," is one of the most common forms of contact dermatitis (CD) in the U.S. It is characterized by itchy blisters on a reddened base in the setting of a history of exposure to an offending plant or some other vehicle (such as a dog's fur) that is carrying the resin.

Poison ivy grows in all states in North America with the exception of Alaska. Poison oak is separated into two categories: Western Poison Oak, which only grows on the Pacific coast of North America, and Atlantic Poison Oak, which is found mostly in sandy soils in the eastern part of the U.S. Poison ivy and poison oak are grouped with other toxicodendron dermatitis agents, including Japanese lacquer tree, cashew nut tree, poison sumac, and other members of the Anacardiaceae family of plants. Marked pruritus is typically the first symptom of toxicodendron dermatitis, beginning between the fingers, and on the eyelids, wrists, and top (opposite the palm) aspects of the fingers within 48 hours of exposure.

Itching is generally followed by inflammation and the characteristic appearance of a linear bumpy (raised) rash with blisters. As long as the plant oil remains on the skin, it can be transferred from the hands to other body parts. However, once the offending agent has been washed off, there is generally no further expansion of the rash, except in areas that have come in contact with the resin. In some cases, CD can become severe, covering over 20% of the body in adults and 10% of the body in children or manifesting systemically with fevers, fatigue (tiredness), and other symptoms.

The offending urushiol is an oleoresin that is both an allergen (causes an allergic response) and a primary irritant. It is a very resilient substance, and can persist for weeks to months on clothes, furniture, and animal fur. Typically, the allergic reaction to urushiol occurs within 24 to 72 hours, but it can be seen as quickly as six hours after exposure, particularly in highly sensitive individuals.

Black spot contact dermatitis is usually caused by poison ivy and poison oak, but can also be caused by sap from the Japanese lacquer tree, because the chemical structures of the oils in both plants are quite similar. When the resin from the Japanese lacquer tree comes into contact with skin, it turns black and attains a shiny appearance that becomes especially noticeable within the first 72 hours after exposure.

Black spot poison oak as a diagnosis can be challenging when the presentation consists of only asymptomatic black spots. Patients become concerned when these black spots, appearing as marker or ink spots, do not wipe off, and they sometimes confuse the lesions with melanoma. The ability of the resin to persist on clothes, fur, and tools for years can also complicate the picture since patients may deny a history of exposure because they are unaware of their contact with the resin. This pigment develops not only on the skin but on clothing as well. The black lesions cannot be washed off the skin and are followed by itchy blisters. They eventually peel off, and the skin heals without scarring.

This presentation is not commonly observed, probably because for the black lesions to occur, the skin needs to come into contact with a much higher concentration of plant sap. In most cases, persons experience only brief contact with the offending plant and then further dilute the concentration of oleoresin via perspiration or bathing so the appearance of black spots does not occur.

Regardless of whether or not black coloration occurs, after suspected exposure to the resin, the first step should be to wash the skin with soap to remove the urushiol and prevent further spread of the agent. This is most effective if done within 15 minutes of exposure. All clothes and any other items that came into contact with the offending plant should also be washed. Many patients find cool tub baths helpful in relieving the itching and edema associated with the rash, and oral antihistamines provide nighttime relief from itching. During the acute blistering stage, cool, wet dressings applied for approximately 20 minutes several times a day may help with swelling, especially around the eyes and on the face.

The decision to use topical or oral steroid medication(s) depends on a number of factors, including but not limited to age of the patient, severity of symptoms, amount of body surface area involved, and presence or history of a medical condition in which administration of an oral steroid could cause an adverse reaction.

The American Academy of Dermatology recommends topical steroid treatment only for mild cases. Typically, medium potency topical steroids are used, except on (delicate) skin around the eyes, which requires a less potent steroid. In general, the steroid preparations are liberally applied to the affected areas twice daily for 7 days. Oral steroids are used in more severe cases and in sufferers who have systemic involvement.

In severe cases, oral steroid courses (typically prednisone) are given at 0.75 to 1 mg/kg/day every morning, and this dose is tapered over a three-week period. Generally, oral steroids are tapered by approximately 10 mg every 2 to 3 days. For these severe, generalized cases, short (e.g., a few days) courses of low-dose oral corticosteroids have proven inadequate.

image of black spot reaction courtesy of Professional Education Services Group

Tags: contact dermatitis, rhus dermatitis, poison oak, black spot dermatitis, wilderness medicine, outdoor medicine, healthline

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Sea Salt

Sea Salt is a compilation of memories and essays by underwater cinematographer extraordinaire, Stan Waterman. Stan Waterman is an icon in the scuba diving community. He is a pioneer in the field of underwater cinematography, best known for his pioneering 1971 documentary feature film entitled Blue Water, White Death. I have come to know him a bit this past year through the Academy of Underwater Arts and Sciences, and can vouch for his unbridled enthusiasm, infectious smile, sense of humor, and generosity. When the man enters a room, all eyes are upon him as the swashbuckler lights it up.

The book is a collection of memoirs first and then essays, many of which appeared over the years in other publications, predominantly dive magazines. Therefore, the first part of the book hangs together better than the second, because there is a sequence in the narrative that comprises Stan’s personal history. It is a life of adventure interspersed with glimpses of personal experiences and development that provided the motivations for his eventual migration to become an explorer, both personally and in his profession. The glimpses into the adolescent psychology that motivated a young man to forego the option of privilege for one of self-achievement are telling. I know doctors born with silver spoons who proved themselves in analogous fashion. To a greater or lesser extent, we are all products of our upbringing, and Stan Waterman is no different.

Having dived in many of the waters described by Waterman, I must admit to feeling a bit of kinship in the experiences, even though he usually arrived to these locations many years before me. The emotions of encountering a shark face-to-face, having a close call with a predator, or being exhilarated after a phenomenal dive are the cherished moments in diving. Dive boats, rocky mounds covered with bird excrement in the Galapagos, and magical moments underwater with manta rays are the common ground upon which the conversational ice is broken. Waterman has done as much as any man to successfully capture these moments in visual media, and now he has done much of the same on the written page, which is a rare double talent. Furthermore, having heard him speak in public, I would consider him a true triple threat.

More than anything, Sea Salt is one man’s tale of how a person can combine his or her profession with their passion, which after all, is the mantra of wilderness medicine. I admire the man for what he has accomplished, how he shares with others, and for the role model he has become for a population of senior adventurers that are grey eagles, silver dolphins, and white-maned lions.

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