Foot Blisters 2

This is the second 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. The first post was a discussion of blister formation and prevention, with expert advice from Dr. Grant S. Lipman of Stanford University. Now, we will learn more from Dr. Lipman about blister management:

Treating a blister as soon as possible reduces complications from further tissue damage or infection. As mentioned in the previous post, a sensation of warmth associated with a “hot spot” is a warning sign for an impending blister. Prompt attention and rapid intervention can halt the abrasive process to prevent progressive blister formation. Options for hot spot treatment include the preventive taping/lubricant measures mentioned or more expensive adhesive/gel pads, such as Band-Aid Blister Block or Blist-O-Ban (the latter scientifically proven to generate less friction than less expensive options such as adherent felt or moleskin).

Blisters deep to a callus should not be drained, as this is a painful and difficult process. These sub-callus blisters quickly refill with fluid after drainage, and the process can introduce bacteria that cause infection. Likewise, blood-filled blisters should be left intact, because of a similar concern for infection.

Any blister with murky fluid, that is draining pus, or which is associated with warm, red skin or red streaking towards the heart may be infected. The blister should be drained and have antibiotic ointment applied, and there should be consideration for the addition of an oral antibiotic.

The best protection for a blister is its own roof. Small intact blisters that are not causing significant discomfort should be left intact. To assist in protecting this roof, a small adhesive bandage or pad can be applied. Be certain to place a first layer of paper tape under any adhesive tape, so you do not inadvertently de-roof the blister when removing the tape.

The pain from a blister is due to pressure on the incompressible fluid trapped between skin layers. As the abrasion and pressure builds, there is further weakening and separation of skin layers and increased potential for rupturing the blister. When a blister opens, raw skin is exposed. If a blister is punctured with a needle and drained, it will often refill within a few hours. If a large hole is made that allows continuous fluid drainage, there is risk for tearing off the roof and leaving a large damaged area.

So, there is no one correct way to manage a blister. For every technique and product mentioned, there are at least several different options. The following blister treatments assume that you must continue on your feet, because resting and “staying off your feet” is not an option.

Basic Blister Treatment (for intact blisters):

1) Cut moleskin (or a basic blister care product) into a donut of diameter ½ inch to 1/3 inch around the blister. The blister should fit inside the hole in the donut.
2) Place a patch of Spenco 2nd Skin in the donut hole directly over the blister.
3) Cover the moleskin donut and patch with benzoin and tape.

Note that this “traditional” moleskin/donut treatment may cause further pressure points either directly under the moleskin or by transferring pressure and subsequent increased friction to the opposite side of the foot.

Basic Blister Draining:

1) Cleanse both the blister skin and a safety pin with an alcohol pad (the diameter of a safety pin is larger than that of a sewing needle to allow continuous drainage, yet not so large as to risk de-roofing the blister).
2) Puncture the blister with the pin at several points at the margin of the blister (generally on the outside of the foot), rather than via one large hole. This will allow natural foot pressure to continually squeeze out fluid, limiting the risk of de-roofing the blister.
3) Gently push out fluid with your fingers.
4) Blot away the expressed fluid.
5) Cover the drained blister with paper tape (protects the blister roof when any other overlying tape is removed).
6) Cover the paper tape with benzoin, then with shaped adhesive tape. All tape should have trimmed and rounded edges to minimize “dog ears” and peeling off.
7) Reaccumulated fluid can be drained through an intact bandage.

Open and Torn Blister Treatment:

1) Using small scissors or another sharp object, carefully de-roof the blister, completely trimming off the dead skin.
2) Place Spenco 2nd Skin on raw skin.
3) Cover the Spenco 2nd Skin with paper tape.
4) Apply a benzoin coating.
5) Cover with Elastikon or another tape product.

Toe Blister:

1) Drain the blister with an alcohol-cleansed safety pin.
2) Use one piece of Micropore tape to encircle the (leaving the torn
tape end at the dorsum of the foot to avoid irritating neighboring toes).
3) Pinch closed the tape.
4) Trim sharp edges or wrinkles in the tape. Avoid cloth tape or Elastikon on the toes, as the abrasive nature of these tape varieties may cause blisters on adjacent toes.

Advanced Blister Care Treatments:

1) One may advance a needle and thread through two sides of a blister, leaving ¼ inch of “tied tails.” The thread wicks away moisture and dries quickly. However, leaving an exit source and a wick in the wound may allow entry of bacteria.
2) De-roof the blister, then pour on Mercurichrome. This may be incredibly painful. This therapy is sometimes controversial, because of issues with pain and tissue toxicity.
3) Inject tincture of benzoin or New-Skin liquid bandage directly into the blister. This seals the blister, but may be incredibly painful.

Tags: blister, foot care, feet, wilderness medicine, outdoor medicine, healthline

Labels: blisters, feet, foot care, Lipman

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Foot Blisters 1

The Wilderness Medical Society Annual Meeting & 25th Anniversary held in Snowmass, Colorado from July 25-30, 2008 was fantastic in every aspect. The meeting was attending by more than 300 individuals, and included lectures, workshops, evening presentations and a celebration banquet complete with costume ball. I can’t imagine how the meeting might have been better, unless each and every one of you could have been in attendance.

In an extended series of posts, I am going to feature information adapted from the meeting presentations and syllabus, graciously contributed by speakers, all of whom are WMS members. They are all to be commended by the innumerable volunteer hours they contribute to wilderness medicine education, making the outdoors safer and a more enjoyable experience for all of us.

The first two posts from the meeting are about one aspect of backcountry foot care – blisters - based upon information provided by Dr. Grant S. Lipman, who is a Clinical Assistant Professor of Surgery in the Division of Emergency Medicine at Stanford University.

The cause of a friction blister is the repeated action of skin rubbing against another surface. As the external contact, such as a coarse, sweat- and dust-impregnated sock, moves across the skin, the opposing force is called the frictional force (Ff). The combination of the magnitude of the Ff and the frequency of the rubbing of the object across the skin determines the probability of a blister development. Therefore, the greater the Ff, the lower the number of rubbing cycles needed for blister development.

The outermost layer of the skin is known as the epidermis. The epidermal skin layers are, from superficial to deep, called the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. In terms of foot blister formation, shear forces extend horizontally between skin layers, between the skin and sock interface, between socks, and between socks and footwear. When the forces within a shoe or boot overcome resistance, sliding occurs. Repeated sliding at a friction point causes an initial sensation of heat – the so-called “hot spot.” Further friction on a hot spot causes blister formation. Skin cells in the stratum spinosum tear and separate. The superficial cells of the overlying layers remain relatively intact, forming a blister’s “roof.” The underlying skin layer, and associated interface between the epidermis and dermis, are usually unaffected. The separated space in the area under the blister roof quickly fills with fluid.

Thick skin like that found on the palms and soles is more likely to undergo blister formation. The epidermis in these areas is usually thick, tightly adhered to underlying structures, and relatively immobile, which causes greater friction than that induced in thinner, more supple skin, such as that found on the back of the forearm.

Blister healing is rapid if one can reduce further friction and worsening of the injury. In a mere 24 hours after blister formation, there is regenerative growth in the blister wound, and at 48 hours, evidence of healing in the basal layer. However, in the presence of continued friction and pressure, as is often the case in the backcountry, the body benefits from medical attention that provides healing assistance.

As in all of medicine, prevention is paramount. To prevent blisters, one must minimize friction generated by the normal biomechanical forces of walking and the contributors to friction. The force between the foot and the insole is determined by the weight of hiker as well as any weight being carried. Reducing the magnitude of the forces on the feet can be as simple as reducing the carried load, whether that means losing personal weight or shedding pounds from the backpack. Another way to minimize the force on the feet is to use a padded insole or arch support. This does not technically reduce the force, but it helps to evenly distribute pressure over the bottom surface of the foot, which thereby decreases the tendency for blister formation.

Either increasing or decreasing the ease with which two surfaces rub against each other can reduce frictional forces. If there is easy sliding, then coefficient of friction is small, reducing the chances for blister formation. At the opposite extreme, if there is no rubbing, then there is no movement at the skin-surface interface.

Shoes or boots should fit properly and comfortably. Shoes that are too tight can increase contact points of pressure on the foot. Those that are too loose can allow excess movement that allows generation of friction. Overly narrow shoes typically cause blisters on the large and small toes. Loose shoes can create blisters on the tips of toes from sliding and jamming the tips into the toe box. A toe box that is too shallow can cause blisters on the tops of the toes from repeated contact.

In general it is best to fit (size) shoes in the evening, because feet tend to swell throughout the day. When trying on shoes or boots, make sure to wear the same socks and/or insoles or orthotics that you will be using on the trails. Size boots to compensate for thicker socks. Allow for ample time to break in new footwear. This will stretch the material, sometimes loosen it and increase flexibility, and thereby reduce friction points against the foot. The breaking-in period also conditions the skin itself by causing epidermal thickening.

Soft and supple feet are better able to withstand frictional stress than are cracked and horny feet. Many podiatrists recommend preparing feet with Bag balm, a moisturizer, petrolatum, or other softening agent. Calluses should be filed down to prevent them from tearing off or contributing to the development of deep blisters underneath that are extremely painful and difficult to drain. Toe nails should be kept trimmed short and beveled downwards to reduce the development of bleeding underneath the nails (subungal hematomas).

It is possible to reduce shear forces in the footwear system by deliberately creating a weak shear layer using two pairs of socks. The goal is to have friction occur between the two layers of socks, not between the skin and the socks. A smooth, thin, snug fitting synthetic sock worn as an inner layer against the foot will move with the foot, while a thick, woven sock worn as an outer layer tends to move with the footwear and cushion against shocks. The thinner synthetic liner sock will also assist in moisture control by wicking moisture and perspiration away from the skin surface.

A preventive barrier between the footwear and a potential point of blister formation can save many an outing. Barriers are best utilized as preventive measures before blisters form, either at the beginning of the day or as soon as a hot spot develops. The barrier needs to be adhesive so it can remain fixed to skin, despite the action of friction, warmth and/or moisture. Micropore paper tape, cloth tape, Elastikon elastic tape, moleskin, Spenco Blister Pads, Blist-O-Ban, and duct tape are methods to prevent blister development. Using an adhesive such as tincture of benzoin or Pedi-Pre Tape Spray will help keep the barrier adherent to the skin.

A cardinal rule of taping is to smooth out any wrinkles, and cut off “dog ears” that may lead to further pressure points. ENGO Blister Prevention Patches are slick fabric-film composite patches that are placed on the inside of the shoe or insole. Silicon gel toecaps and sheaths reduce friction between the toes and therefore blister formation in this common and frustrating location to.

Keep the skin clean and dry to minimize friction. Skin hydration leads to increasing contact area and friction, so moist skin results in more frequent blisters. However very wet skin has a low incidence of blister formation, likely due to the lubricating effects of water on the skin surface.

High-technology oversocks combine waterproof materials with traditional socks to help keep feet dry when repeatedly exposed to water. Combining GORE-TEX oversocks with wicking liner socks and foot antiperspirant is a method to reduce foot moisture. Consider the addition of gaiters to help eliminate dirt, gravel, sand, and rocks from entering the sock-shoe system. If your feet are often moist or sweaty, then try to change socks frequently.

Drying powders decrease moisture for short periods of time and are useful in the evening to dry out feet, but after about one hour may actually increase the friction between surfaces. Lubricants have been developed that are more advanced than traditional Vaseline, which is greasy and tends to trap grit particles, which are irritating and may increase friction and blister production. Advanced lubricants that combine silicone and petrolatum have a silky feel, prevent friction, and repel moisture from the skin. Lubricants can be applied preemptively, or over tape when hot spots develop. However, after about 3 hours, friction is increased as the lubricants are absorbed into the skin and socks. Lubricants should be tested before use on the trail to assess for allergic reaction, and if used, reapplied frequently.

Antiperspirants irritate and block sweat ducts, reducing the amount of perspiration. People who suffer from a condition called hyperhidrosis experience excessive foot perspiration and subsequently have extremely moist feet. These people may benefit the most from antiperspirants.

The next post in this series will be about blister treatment.

Tags: blister, foot care, feet, wilderness medicine, outdoor medicine, healthline

Labels: blisters, feet, foot care, Lipman

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Summer Tips

I was recently invited by Revolution Health to offer their readers a few summer safety tips to beat the "silent summer spoilers." The following is a modified version of what was presented, with the notation that these afflictions are not so silent, and can certainly ruin your vacation or outdoor adventure.

Sunburn can be brutal. The best way to avoid sunburn is to stay out of direct sunlight. If possible, stay in the shade, and wear sun-protective clothing. Use a sunblock that is effective against both ultraviolet A (UVA) and UVB rays. It is an increasingly prevailing opinion that UVA is more damaging than previously thought.

Be certain to obtain a good application (at least an ounce or two for a "normal" sized adult), and reapply the sunscreen often, particularly if you are sweating or spending time in the water (scuba diving, surfing, swimming, etc.). If you are taking medication, know if it might make your skin more sensitive to sunlight.

Pay attention to your surroundings. High altitude, wind, and sun reflecting off the surface of water, sand, or gravel add to UV exposure. Don't forget to protect your eyes with sunglasses rated to block nearly 100% of UV radiation. If you decide to use insect repellent containing DEET (N,N-diethyl-m-toluamide) as well as a sunscreen, be advised that the combination might reduce the effectiveness of the sunscreen. If you are using two separate products (sunscreen and insect repellen), in general, it is best to apply the sunscreen first, allow it to absorb into the skin for 20 to 30 minutes, then apply the insect repellent, in order to maximize the effect of the repellent. If you are going to be in water where you might come in contact with stinging jellyfish, consider using Safe Sea sunblock with jellyfish sting protective lotion incorporated into the product.

A mild sunburn without blistering can be treated with cool compresses, showers or baths, a non-sensitizing skin moisturizer lotion, and aspirin or a nonsteroidal anti-inflammatory drug (e.g., ibuprofen) to decrease inflammation. A sunburn, even first degree, that is so extensive that it causes the victim to suffer chills, nausea and vomiting, weakness, and diarrhea, may require oral rehydration and bedrest. If blisters are present, this indicates second-degree burns, which sometimes must be treated with topical antiseptic ointment, bandages, and more extensive medical care. You certainly wish to avoid this situation. The skin bubbling and peeling that follow a first degree sunburn are superficial and do not result in fluid loss, and rarely lead to infection, but the skin should be kept clean and moisturized to prevent any complications. Anyone with a severe sunburn of any sort should be examined for dehydration.

Blisters are the bane of hikers and trekkers, and often of persons wearing new sandals, particularly if the feet are dirty and dusty, as the grit and grime serve as agents of abrasion. Break in andy new shoes, boots, flip-flops and sandals before walking any distance in them. Keep your feet clean and dry. When walking in boots, wear a thin pair of liner socks under your regular socks, so that the friction is between the socks, not between the boots and your feet. Cushion any reddened "hot spot" or cover it with a BlistOBan® bandage before a fluid-filled blister appears. If you do get a blister:

Fasten a "donut"-shaped foam pad to the perimeter of the affected area. Cover the affected area ("donut hole") with a fitted hydrogel (e.g., Spenco 2nd Skin®) pad, and then place tape over the foam and hydrogel. Watch for signs of infection, which include cloudy fluid or pus within the blister, or red streaks emanating from the edges of the blister into the surrounding skin. If the blister appears infected, use a disinfected or carefully cleaned needle to create a small puncture at the edge of the blister, and drain it. Cover the open wound with antiseptic ointment, and apply a sterile dressing.

Sprains and strains are common ailments in the summertime due to increased outdoor activity. The most common sprain involves the ankle. In the event of a sprain, use the "RICE" technique. RICE stands for "rest, ice, compression, elevation." Try to rest the joint. Elevate the affected body part and apply ice packs intermittently (e.g., 15 minutes on, 15 minutes off) as much as is practical for the next 24 hours. If the skin becomes reddened and painful from the application of ice, ease off to avoid a cold injury (e.g., frostbite) to the tissues. Mild compression with a wrap may provide some pain relief. If you need to keep walking, tape, bandage or splint the joint for support.

Once a joint is weakened by a strain or sprain, re-injury is common. Take precautions by using a mechanical ankle support (e.g., brace and high-top shoes or boots) and/or a walking stick over rocky terrain. It takes a full 6 to 8 weeks to recover from a mild ankle sprain, and 3 to 6 months to recover from a severe sprain.

Gastroenteric problems are common in the summer. Traveler's diarrhea, commonly caused by the bacteria E. coli, is often due to water or food contamination. Failure to wash or "gel" hands or to properly prepare food are likely the most common errors that lead to diarrhea. Water disinfection techniques include heating, addition of chemicals, filtration, or application of UV light. It is important to carry redundant water disinfection systems, so that if a unit (e.g., filter) is lost or damaged, you have backup. Avoid drinking beverages with ice, unless you can be absolutely certain that the ice was prepared from properly disinfected water.

Tick and mosquito bites can result in serious, even fatal, infections. So, be certain to protect yourself. If circumstances permit, wear light-colored pants tucked into socks and paired with a long sleeve shirt. Wear a head net or use a bed net when needed. Use insect repellent(s). Permethrin is applied to clothing, while DEET or picaridin is applied to exposed skin. Perform regular "tick checks" of the entire body (especially the scalp, groin and armpits), and immediately remove ticks. When attempting to remove a tick, do not twist it, touch it with a hot object such as a hot match head, or attempt to suffocate or kill it with petrolatum (petroleum jelly), mineral oil, kerosene, stove fuel, etc. These techniques might cause the tick to struggle and regurgitate potentially infectious agents into your bloodstream.

Finally, learn to recognize poison ivy, oak, and sumac. If you become exposed to their resin, immediately wash it off with soap and water or with a specialized scrub (e.g., Tecnu or Zanfel) within 30 minutes if possible. To treat a rash from poison ivy, oak or sumac, you may soothe the affected skin with calamine lotion and also consider the following measures: apply a topical anesthetic, such as praxomine HCl 1%; soak in a tepid (not hot) bath supplemented with baking soda or Aveeno (contains oatmeal proteins); consider taking an antihistamine medication, which helps control itching and acts as a sedative. Consult a physician if the reaction is severe. Prescription treatment (such as corticosteroid therapy) may be required.

The resins from plants can remain on clothes, fabrics, backpacks, tents, pet fur and elsewhere for long periods of time, so be certain to wash these carefully to prevent further exposure to the resin. Once the rash appears, you are not contagious, and you cannot spread the rash by scratching. However, you can open up blisters and make the affected skin vulnerable to secondary infection.

image courtesy of w3.ouhsc.edu

Tags: sunburn, poison oak, insect+repellent, wilderness medicine, outdoor medicine, healthline

Labels: blisters, insect repellent, poison ivy, poison oak, sprain, strain, sunburn

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Blisters

Blisters are the bane of hikers. These clear fluid- or blood-filled vesicles have probably ended more outings than all major illnesses combined. They can be prevented by keeping feet dry, wearing adequate and properly fitting socks, wearing thin liner socks (polypropylene or polyester) under heavier wool-blend hiking socks, breaking in footgear prior to the expedition, and padding all rough edges within hiking boots. If an area is known to rub, prevent a blister by applying a nonwrinkled layer of moleskin, Molefoam, or athletic tape over the skin before a “hot spot” develops. A terrific method to prevent a potential hot spot (e.g., area that will be rubbed, such as one's heel within a boot) or cover a non-blistered (prior to the appearance of a blister) hot spot is the Blist-O-Ban "bandage" from SAM Medical Products.

If a blister is caused by pressure (ill-fitting boots), you have a couple of choices. As mentioned above, prior to actual blister formation, you can protect or pad the area. Once a blister forms, the blister site can be padded with moleskin or other adhesive foam, so that rubbing no longer occurs, the blister should be ringed with a doughnut of padding and left intact. For a better cushion, a piece of Spenco 2nd Skin (an inert gel consisting of polyethylene oxide and water) can be laid into the doughnut hole and the entire area covered with a second layer of moleskin or an absorbent bandage, such as a Spenco adhesive knit bandage. If no such padding is available, if continued rubbing will rupture the blister, or if the blister interferes with walking, then you can drain it of fluid by using a “sterile” needle (heat a sewing needle to red hot and allow it to cool) to punch a small hole at its edge. If an antiseptic ointment, such as mupirocin or bacitracin, is available, it should be applied to the open wound underneath a sterile (or clean, if "sterile" is not available) dressing or bandage. If the blister appears infected, it should be unroofed entirely, an appropriate dressing and ointment applied, and the victim treated with dicloxacillin, erythromycin, or cephalexin for 5 days or until the skin appears normal. If the dressing (such as Curad Hydro Heal) keeps the blister slightly moist, it may be less prone to drying out and cracking.

Blisters or reddened skin may also be caused by an allergic (“contact”) reaction to chemicals such as formaldehyde or rubber. If a rash is confined to the soles of the feet (shoe inserts) or top of the feet (shoe tongue dye), suspect this problem. In this case, the footgear must be changed.

If a blister is caused by a thermal burn, it should be immediately immersed in cool or cold water (do not apply ice directly to the burn) for 10 to 15 minutes, in order to relieve pain and lessen the ultimate injury. Then dry the wound and apply a soft, sterile dressing. Unless there is a reason to suspect infection (cloudy fluid or pus, fever, redness and swelling beyond the blister edges, swollen lymph glands), burn blisters should be left intact. Opening an uninfected blister or sticking a needle into it risks introducing bacteria that can cause an infection. A topical antibacterial cream, such as silver sulfadiazine or mupirocin, or ointment such as mupirocin or bacitracin, should be applied if the blister is broken, or to prevent the dressing from sticking to the wound. Alternatively, apply a layer of Spenco 2nd Skin or Aquaphor gauze underneath a sterile gauze dressing.

photo of reddened foot courtesy of www.planet-x-bikes.com

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

Tags: blister, wilderness medicine, outdoor medicine, healthline

Labels: blisters, hikers, hiking

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