Course Content
Introduction to Wound Management
Chapter 1 Wound Introduction Enable fullscreen INTRODUCTION The skin is the largest organ in the human body, comprising approximately 15% of total adult body weight. The skin maintains our internal environment while protecting us from the external environment. It allows us to experience a wide range of stimuli, from pleasure to pain. A break in the continuity of the skin surface is the first step in the formation of a wound and provides a potential portal of entry for infection. A wound can be as simple as a surface abrasion, or it can be an extensive, life-threatening destruction of tissue that reaches down to and includes the internal organs of the body. While the healing process is basically the same for all wounds, there are many extenuating factors that will either expedite or impede healing. Wound care does not belong to anyone healthcare profession. Successful outcomes are achieved when an interdisciplinary team approach is used, calling on the expertise of many different clinicians and employing many different treatment modalities—from simple dressings to advanced treatments such as negative-pressure wound therapy and hyperbaric oxygen therapy. Clinicians encounter wounds in every healthcare setting, from the penetrating gunshot wound that is rushed to the ER, to acute and chronic wounds that need to be treated in the acute care hospital setting, outpatient clinics, nursing homes, hospice care, and in-home care. Over 7.5 million people in the United States currently have a chronic wound, and as the population ages with a concurrent increase in chronic health conditions, this number is set to increase (Krasner, 2014). For instance, in the United States diabetes is the number one cause of nontraumatic lower-extremity amputations, accounting for approximately 80,000 cases each year, and nearly 85% of all lower extremity amputations in patients with diabetes are preceded by a foot ulcer. Aggressive wound care is a critical part of limb salvage programs (Armstrong & Lavery, 2010). Overall, it is estimated that chronic wound care costs run at around $20 billion annually, and healthcare clinicians are called upon to provide cost-effective, state-of-the-art care to increasingly complex wounds.
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Introduction to Wound Management
Chapter 2 Skin and the External Barrier
Wound Management Introduction

Chapter 2 Skin and the External Barrier
SKIN—THE EXTERNAL BARRIER
To properly understand the occurrence, continuation, and healing of wounds, it is necessary to first look at the skin.

 

The skin is comprised of two layers: the epidermis, made up of four to five thin layers stacked on top of each other, and the dermis (often referred to as the “true skin”), a layer of connective tissue directly below the epidermis. Beneath the dermis is the subcutaneous tissue, which separates the skin from the underlying muscles, tendons, joints, and bones. Skin varies in thickness from less than one millimeter in the eyelids to greater than four millimeters on the soles of the feet.

 

Epidermis
The deepest layer of the epidermis is known as the stratum basale or stratum germinativum. It is a layer of dividing, reproducing cells that migrate upward. As they travel, they differentiate and become filled with keratin, a tough, fibrous protein. The mature cells are pushed to the surface, where they die; thus, the outermost layer of the epidermis is made of flat, dead keratinocytes. The stratum basale also contains melanocytes, the cells responsible for producing melanin, the pigment that adds color to the skin and also protects against the damaging effects of ultraviolet light.

Shallow wounds to the epidermis usually heal rapidly and without complications. Usual skin thickness is reestablished, and there is no scar formation.

 

Dermis
The layer of skin directly beneath the epidermis is the dermis. A basement membrane separates these two layers. The dermis is mainly connective tissue and is therefore much stronger than the epidermis. The dermis varies in thickness across the surface of the body, but everywhere it is significantly thicker than the overlying epidermis.

The dermis is itself made up of two layers: the papillary layer is directly beneath the epidermis, and the reticular layer is below that. The primary function of the papillary dermis is to supply nutrients to the epidermis. The reticular dermis contains fibroblasts cells, which synthesize the connective tissue proteins, collagen, and elastin. These cells are responsible for the strength and elasticity of the skin. The reticular layer of the dermis also contains macrophages, which are essential for wound healing, and mast cells, a key component of our immune system.

 

The tissue of the dermis also contains small blood vessels, lymph vessels, nerves with their endings, and the smooth muscle fibers of hair follicles. Hair, nails, sweat glands, and sebaceous glands are sunken epidermal appendages that lie in deep valleys in the dermis surrounded by a row of germinative epidermal cells.

 

Subcutaneous Tissue
Beneath the dermis is a layer of subcutaneous tissue containing fat. The thickness of the subcutaneous layer varies throughout the body. It is thickest along the anterior thigh and thinnest on the back of the hands.

Besides s fat cells, subcutaneous tissue contains blood vessels, lymph vessels, and nerves. The subcutaneous layer is held together by a continuous sheet of fibrous membrane that runs parallel to the surface of the skin. This membrane is called the superficial fascia.

 

The subcutaneous tissue provides insulation to the body, and it is also important in pressure redistribution. Individuals with a thin layer of subcutaneous tissue and limited mobility are at high risk for the development of pressure ulcers. Those with excess subcutaneous tissue can have a harder time with wound healing since subcutaneous tissue is not well profused, and this, in turn, decreases the blood supply to the dermis and epidermis (Tortora & Derrickson, 2012).

The subcutaneous tissue is a loosely organized compartment. When skin wounds extend deeper than the dermis, dirt is easily pushed into and spread within the subcutaneous tissue. This increases the risk of infection and requires that deep wounds be cleaned thoroughly.

 

Beneath the subcutaneous tissue layer, structures (such as muscles and organs) are enclosed in their own separate connective tissue sheaths. The generic name for these sheaths is deep fasciae. Deep fasciae generally look off-white in fresh wounds. When treating a wound, tears in the deep fasciae are repaired whenever possible.

 

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