​​Friction and pressure combine to create shear forces that stretch and irritate connective tissue within the epidermis initially creating a “hot spot.” Later, as the epidermis tears and plasma leaks into the torn tissue, a blister will form. As long as shear forces are present, the skin continues to delaminate and the blister grows until it breaks. More pressure—due to a heavy pack or persistent hiking downhill—will cause deeper damage and a more painful blister. Both the prevention & treatment of friction blisters require adding an external “sliding layer” to prevent shear forces from building within the skin.

​Friction Blister Prevention

• Wash skin, socks, etc. on a regular basis. Wear gaiters over boot tops and laces to keep dust & dirt out. Keep skin, socks, gloves, etc. dry. Change socks regularly. Sleep in clean, dry socks. An antiperspirant may help keep feet dry.
• Increase pack weight and distance slowly to allow the skin to adapt to new forces. Avoid continuous downhill hiking until skin has had time to strengthen.
• Make sure footwear, gloves, and clothing fit well.
• Anticipate blisters; treat hot spots immediately BEFORE they become blisters by adding an external sliding layer to reduce shear forces within the skin. Use tincture of benzoin and flexible medical tape to create a sliding layer between the skin and the inner sock. Add a friction patch (ENGO®) to footwear to create a sliding layer between the outer sock and footwear. [The use of Duct Tape® or Gorilla Tape® is not recommended to prevent or treat hot spots: the glue is very strong and often increases friction within the skin layers rather than reducing it.]

The Healing Process | Dressings | Antimicrobials | Summary | Bottom Line

Introduction
​Unfortunately, wounds are all too common on outdoor trips, with abrasions and full-thickness lacerations leading the list; that said, deeper wounds are not unheard of. The goal of wound care is to prevent infection and promote healing. Expedition settings bring challenges to wound management that are relatively rare in an urban environment and require a deeper understanding of the healing process and available dressing technology. Patients with a high risk for infection, especially with damage to tendons, ligaments, joints, or bones, should be evacuated for physician assessment and treatment. Clean wounds without damage to underlying structures can often be treated in the field with the right materials and constant monitoring.

The Healing Process
The wound healing process has five continuous and overlapping phases: ​

1. Hemostasis Phase [5-15 min]. When the skin is broken during the creation of a full-thickness wound, blood vessels constrict to minimize bleeding. Seconds later, platelets aggregate and adhere to the inside of the damaged vessels as specialized protean strands [fibrin] create a mesh designed to trap platelets, form a clot, and stop the leak. In a dry wound environment, the clot develops into a scab.
2. ​Inflammatory Phase [0-3 days]. Inflammation leads to local vasodilation and increased vascular permeability that, in turn, permit phagocytes and other supplies to seep into the tissue and, together with the clotting proteins, form an internal barrier and external scab that help contain and destroy bacteria. Excess fluid and debris (pus or slough) not picked up by the lymphatic system or ingested by phagocytes drains through the scab. Inflammation is a natural part of the wound-healing process and is only problematic if prolonged or excessive.
3. Proliferation Phase [3-24 days]. During the proliferation phase, new tissue made up of collagen—secreted by fibroblasts—and extracellular matrix gradually rebuild the damaged tissue: Myofibroblasts contract and pull the wound edges together, new capillaries form and grow into red granulation tissue, and pink/white epithelial tissue migrates from wound edges towards the center. Healthy granulation tissue is relatively tough, with little to no drainage [exudate]. 
4. Epithelialization Phase [3-24 days]. At the end of the epithelialization phase, skin cells entirely cover the the granulation tissue. Epithelial cells form faster when the wound is kept warm and moist. Occlusive or semi-occlusive dressings applied within 48 hours of the injury and used throughout the healing process help maintain the necessary humidity for optimal epithelialization.
5. Maturation Phase [24+ days]. The initial collagen laid down during the proliferative and epithelization phases is disorganized, and the wound is thick. During the maturation phase, collagen reorganizes along stress lines and increases the tensile strength of the remodeled skin. Cells used to repair the wound are no longer needed and die [apoptosis]. Fully healed wounds are roughly 20% weaker than uninjured skin.

Individual characteristics that inhibit healing include:

• Age.
• Poor circulation, including vascular disease, diabetes, and obesity.
• Poor nutrition.
• Weakened immune response.
• Infection.
• Peripheral neuropathy.
• Stress.

Wound attributes that inhibit healing include:

• Infection. Wounds that are contaminated, dirty, deep, or have ragged edges are at high risk of infection. High-risk wounds often require thorough and ongoing cleaning and topical or systemic antimicrobials to prevent infection and heal. Signs and symptoms of a local infection include increased redness and heat around the wound site with pus and a foul odor. Signs and symptoms of a systemic infection include fever, chills, malaise, and red streaks extending from the wound site toward the trunk.
• Scab/dry healing environment. Wounds exposed to air dry out, and a scab [eschar] forms. Epithelial cells—formed during phase four—need moisture to migrate across the surface of the wound bed. If a scab is present, the cells form in the moist layer under the scab, dramatically slowing the healing process. Moist wounds heal 50% faster than dry wounds. The clear serous fluid that leaks from the surrounding tissue [exudate] during the inflammatory phase contains the nutrients, proteins, glucose, and white blood cells necessary for the wound to heal; however, too much exudate can cause the skin to soften and break down [macerate], left untreated, maceration can lead to a bacterial or fungal skin infection. Maintaining the correct moisture content in the wound bed is critical for rapid healing.
• Use of cytotoxic antiseptics. Chlorhexidine or povidine iodine are common topical antiseptics used to clean the skin around the wound to help prevent bacteria from migrating into the wound. If used directly on the wound, antiseptics destroy bacteria and healthy cells. While antiseptics may be warranted for an infected or high-risk wound, a risk/benefit analysis is required. Consider reducing the toxicity of a 10% Povidone iodine solution by diluting it with water; solutions less than 1% do little damage to healthy cells but are still toxic to bacteria. Leave in place for at least three minutes.
• Slough. Slough comprises dead white blood cells, tissue debris, bacteria, and fibrin. A small amount of slough is expected during the inflammatory phase of healing as the immune system works to kill bacteria within the wound; the amount of slough should decrease after the first day or two. Increasing slough indicates bacterial growth that will delay healing and may lead to a local infection. Slough is initially moist and soft but, over time, gradually dries into a leather-like consistency that may require surgical removal. Unlike purulent drainage [pus], slough has no odor.
• Biofilm growth. A biofilm is a microbial colony that can attach to a wound surface. The colony is encased in a thick, protective layer of sugars and proteins that shields the microorganisms from the patient’s immune system and many antimicrobial agents, including antibiotics and topical treatments, making them difficult to remove. Biofilm colonies are microscopic and must be confirmed by biopsy. To the naked eye, they appear as a shiny covering over the wound bed; they prolong inflammation, compromise skin integrity, and delay healing. 

Dressings
Characteristics of Ideal Expedition Dressings

• easy to use
• low cost
• works well for multiple wound types and across multiple healing phases
• hypoallergenic
• easy to remove
• conform to the wound bed and promote healing
• maintain a consistent moist environment to eliminate scab [eschar] formation, promote healing, and reduce scarring
• minimize micro-trash

Six categories of wound dressings are discussed below. Recommendations for field use are based on the ideal characteristics discussed above for healthy individuals with no local or systemic wound infection and appear in the highlighted boxes. Infected wounds and those slow to heal should be evacuated for assessment and treatment by a physician or wound care specialist.

Transparent Micro-thin Film Dressings
Transparent micro-thin film dressings are permeable to water vapor but not liquids. They help maintain a moist environment for full-thickness wounds with little exudate and abrasions. Because they are transparent, you can watch the wound heal through them. If clear fluid [serious exudide] builds under the film, switch to a foam dressing to prevent skin maceration. Alternatively, add a non-adherent gauze dressing ± additional gauze under the film to absorb excess fluid. You can also add a antimicrobial directly to the wound bed or dressing if the wound is at risk for infection. Transparent film dressings are often the best choice for wet expedition environments and can be layered with other dressings to manage exudate. Paint the surrounding skin with Tincture of Benzoin to aid in adhesion.

​Foam Dressings
​Foam dressings are effective for all wound types. They adhere to the wound’s surface and absorb excess exudate while maintaining a warm, moist wound bed; they can be left in place for multiple days. Generally, the thicker the foam, the more exudate it can absorb and hold. Some foam dressings come with a perimeter adhesive, while others require fixation. Foam dressings without perimeter adhesive can be cut to size but need a transparent film dressing or flexible medical tape [we carry Mefix®] to hold them in place. If the wound is at risk for a local infection, you can apply an antibacterial ointment under the foam. Foam dressings can also degrade moist slough on the wound surface.

Dry Gauze Dressings
​While dry gauze dressings should never be used directly on a wound bed before the wound has completely closed, they can be impregnated with medical honey or Vaseline to create a moist environment to promote healing. Dry gauze can added as a secondary dressing to hold excess exudate or provide protective padding. Vaseline-impregnated gauze dressings are inexpensive and work well for dry or low exudate wounds; they can be held in place using a non-adhering bandage, flexible medical tape, or a transparent film dressing. For maximum flexibility and to minimize micro trash, carry roller gauze instead of individually wrapped gauze pads.

​Hydrogel Dressings
​Hydrogel dressings are primarily used for dry wounds or wounds with minimal exudate. They reduce pain, promote healing, and can be used with infected wounds. Once the lid has been removed, they are commonly used to relieve pain and promote healing with friction blisters. They can also degrade slough on the wound surface.

​
​Hydrocolloid Dressings
​Hydrocolloid dressings use gel to create an impenetrable protective barrier that prevents bacteria from entering the wound bed and maintains a moist environment. Like hydrogel dressings, they are used with dry wounds or wounds with minimal exudate; however, they should not be used with infected wounds or wounds at risk of infection because they are occlusive and can trap bacteria.

​​Calcium Alginate Dressing​s
Calcium alginate dressings are used with wounds with substantial exudate. They form a soft gel when in contact with exudate and conform to the contours of the wound to provide a micro-environment that helps break down dead tissue and encourage new skin cell growth. They can be used to pack deep wounds. They require a secondary dressing and fixation.

​Antimicrobials
Recommendations for antimicrobials used in treating wounds in a remote setting are for healthy individuals and designed to prevent a local or systemic wound infection. Infected wounds and those slow to heal should be evacuated for assessment and treatment by a physician or wound care specialist.

​Povidone-iodine Solution & Chlorhexidine
Use soap and water to gently wash the wound bed and surrounding skin and pat dry at each dressing change. Apply chlorhexidine or povidone-iodine solution to the skin surrounding the wound to reduce the chance of bacteria reaching the wound bed. If the risk or consequences of local infection are high, dilute a 10% povidone-iodine solution to less than 1% and wash the wound before applying the primary dressing.

​Medical Honey
Medical honey has proven more effective than antibacterial ointments in preventing infection and promoting healing. It can be used to fill a deep wound, applied to the wound’s surface, or impregnated into a gauze dressing. It can be left in or on a wound for up to seven days.

​Antibacterial Ointments & Creams
Antibacterial ointments & creams — e.g., Bacitracin, Neosporin, Polysporin, or mupirocin — to prevent wound infection are controversial.

Refer to the graphic on the below for a summary of wound care guidelines throughout the healing process. Download a pdf copy 

Bottom Line

There's a ton of information in this post. Bottom line, here's what you need to know:

Severe bleeding is rare in an expedition environment; partial- and full-thickness wounds are not. Barring a life-threatening bleed, you need to be able to clean, dress, bandage, and care for a wound until it heals or you have successfully evacuated the patient to more advanced care.

If you are working with or around machinery, chainsaws, axes, other cutting tools, etc., we recommend carrying:

• An extremity tourniquet.
• Hemostatic gauze [preferred], trauma dressing/maxi-pad, or roller gauze.
• Elastic bandageElastic Bandages.

To clean a wound, we recommend carrying:

• An irrigation syringe. The larger the syringe, the easier the process is.
• A 10% povidone iodine solution in a Nalgene® bottle [to purify water, clean the skin around the wound, dilute to less than 1% for flushing a deep wound or wound bed prone to infection].

To dress a clean, low to moderate risk wound during the inflammatory phase:

• Roller gauze.
• ± non-adherent gauze dressings
• Scissors to cut the gauze or dressings or to trim wound edges.
• Vaseline. Dress with a Vaseline-impregnated dressing to seal the wound.
• Cover with a self-adhering bandage.

​
To pack and dress a deep wound, we recommend carrying:

• Roller gauze.
• Tweezers or forceps.
• Scissors to cut the gauze or dressings or to trim wound edges.
• A A 10% povidone iodine solution in a Nalgene® bottle. Use the 10% solution around the wound; dilute to less than 1% and completely saturate the gauze.
• Vaseline. Dress with a Vaseline-impregnated dressing to seal the wound.
• Cover with a self-adhering bandage.

​If you are on an afternoon, day, weekend, or even a long-weekend trip and get a partial or full-thickness wound, you're not out long enough to get past the inflammatory phase of wound healing, and will not need to carry a foam dressing; for longer trips you will. To dress a wound with low to moderate exudate, a wound at risk of infection, or a wound with increasing slough in the proliferation and epithelialization phases, we recommend carrying:

• Borderless foam dressings.
• Flexible medical tape.
• Medical honey.

To protect a wound in a wet expedition environment, we recommend carrying:

• Transparent micro-thin film dressings.

Looking for a reliable field reference? Consider consider purchasing one of our print or digital handbooks; our digital handbook apps are available in English, Spanish, and Japanese. Updates are free for life. A digital SOAP note app is also available.​

While mountain biking down a steep single track your friend catches his front wheel and is thrown forward with his bike. During the fall the handlebars smash into the left side of his chest. Asa has difficulty sitting up and catching his breath, and appears to have injured his left wrist. After assisting him to a sitting position and coaching him to breathe with his abdomen, his respiratory distress appears to resolve. During your physical exam, he reports a sharp pain (7) in the ribs on his lower left chest when he tries to take a deep breath. While his left wrist hurts (4) and has a slightly decreased ROM with good distal CSM, it appears weak: Asa is unable to easily hold and lift a full 1-liter water bottle. His helmet is cracked, he reports feeling a bit woozy, and has a headache (4); the remainder of his physical exam is unremarkable. With abdominal breathing, the pain in his ribs is manageable (3). 20 minutes after his accident his pulse is 94 and regular and his respiratory rate is 22 and remarkably easy; he reports his normal pulse rate is in the mid-60's and he doesn't know his normal respiratory rate. While awake, he still feels a bit "out of it." A focused spine assessment reveals cervical pain and tenderness at C-7 with no shooting pain and normal motor and sensory exams.

What is wrong with Asa and what should you do? Click here to find out.

You are a Forest Service wildland firefighter supervisor and trainer. You have a strenuous field exercise planned for tomorrow for a new cadre. Unfortunately, an unseasonable heat wave is in place and the high temperature predicted for the day is in excess of 110 degrees F.

What are your concerns and how should you address them? Click here to find out.

You and your partner are planning a two or three day backpacking trip near your home in Boone, NC with your seven year-old daughter and six year-old son. They have been car camping with you for the past three years, taken short day hikes, and enjoyed both. Your daughter is severely allergic to wasps and poison oak; she was hospitalized at four after being stung by a yellow jacket in your backyard.

How should you plan your trip? Click here to find out.