Advanced Textiles for Wound Care

S. Rajendran

• Publisher: Woodhead Publishing
• Year: 2009
• ISBN:
  9781845696306
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

An important and growing area of the textile industry is the medical sector. The extent of this growth is due to constant improvements in both textile technology and medical procedures. This collection provides a detailed review of how textiles are incorporated into wound care applications, explaining the importance and suitability of using textiles on different wound types.Part one of the book provides an overview of the use of textiles in particular aspects of wound care, providing details of wound management and the importance of laboratory testing in relation to wound care. Further chapters cover minor wounds, moist wound management and bioactive dressings to promote healing. Given their increasing importance, part two describes how advanced textiles, such as smart temperature controlled textiles and composites, can be used for wound care products. The final chapter gives an interesting insight into the use of fibrous scaffolds for tissue engineering.Advanced textiles for wound care is essential reading for any manufacturers, designers, scientists and producers of wound care materials. It is a valuable resource for professionals within the medical sector, as well as those in academia.

• Provides a comprehensive introduction to wound care from types of wound and wound healing mechanisms to the importance of testing in relation to wound care
• Analyses the application of textiles to wound healing covering minor wounds, burns, ulcers and other deep skin wounds
• Reviews the current use of smart textiles for wound care including drug delivery dressings and textile-based scaffolds for tissue engineering as well as future trends

Part I

The use of textiles in particular aspects of wound care

1

Wound management and dressings

S. Ather; K.G. Harding Cardiff University, UK

Abstract

The various types of wounds and their mechanisms of healing are described and factors affecting the management of wound healing are outlined. For chronic wounds, a number of factors when present in combination lead to the non-healing of wounds. Wound management should therefore be multifactorial and aim at correcting the underlying abnormalities. Options for treatment are described with no single treatment being universally effective owing to the multiple molecular and cellular events involved so that a combination of different therapies is required. Future trends include application of gene therapy and stem cell therapy.

Key words

wound healing

wound management

chronic wounds

1.1 Introduction

A wound is defined as a break in the epithelial integrity of the tissues. This disruption can be deeper and involve subepithelial tissues including dermis, fascia and muscle. They can be caused accidentally, intentionally or be a part of a disease process.¹ A wound is caused by physical trauma where the skin is torn, cut or punctured (an open wound), or where a blunt force trauma causes a contusion (a closed wound). The history of wound care spans from prehistory to modern medicine and has evolved from simple wound covers ranging from vinegar-soaked dressings, through topical antibiotics to topically applied growth factors.² Even during early historical periods several factors were noted that speeded up or assisted the process of healing. The necessity for hygiene, the prevention of bleeding and, later on, the germ theory of disease paved the way for modern wound management.

1.2 Types of wound

Wounds can be classified in many ways, by acute or chronic, by cause (e.g., pressure, trauma, venous leg ulcer, diabetic foot ulcer), by the depth of tissue involvement, or other characteristics such as closure (primary or secondary intention).

1.2.1 Acute wound

An acute wound is defined as a recent wound that has yet to progress through the sequential stages of wound healing.³ An acute wound is acquired as a result of an incision or trauma and heals in a timely and orderly manner. Surgically created wounds include all incisions, excisions, and wounds that are surgically debrided. Surgical wounds include all skin lesions that occur as a result of trauma (e.g. burns, falls), as a result of an underlying condition (e.g. leg ulcers), or as a combination of both.

1.2.2 Chronic wounds

Wounds that fail to heal in an anticipated time frame and orderly fashion and often recur are considered chronic.³ Venous leg ulcers, pressure ulcers and diabetic foot ulcers are some examples of chronic wounds.

1.2.3 Open and closed wounds

Wounds are also differentiated as open or closed wound types:

Open wounds: examples include incision or incised wounds, laceration, abrasions, punctured wounds and penetrating wounds,

Closed wounds: examples include contusions, haematoma and crush injuries.

1.3 Mechanism of wound healing

The aim of wound healing is homeostasis and restoration of tissue integrity. It is a well-orchestrated and complex process which is triggered by tissue injury and ends by regeneration or repair. Typically healing is divided into categories based on the anticipated nature of the repair process (Fig. 1.1).

1.1 Differential wound healing.

1.3.1 Healing by primary intention

Wound edges are approximated with sutures, staples or adhesive within hours of its creation with no defect. This enables closure to occur quickly with minimal tissue needed to repair the defect and minimal scarring.

1.3.2 Healing by secondary intention

The wound is left open and no formal closure is done. Healing occurs by epithelialisation and contraction, e.g. healing associated with a large and/or deep wound in which the tissue edges cannot be approximated. The size of the gap determines the degree of new tissue matrix and epidermal surface needed for complete closure.⁴

1.3.3 Delayed primary/tertiary healing

Wound closure is delayed for several days; this is usually employed for infected wounds.

Irrespective of the cause, wounds heal in a very similar fashion. Studying this process and how to optimise this remains the central focus of attention for the clinicians. It is a dynamic and interactive process that involves a variety of blood and parenchymal cells, extracellular matrices and soluble mediators. During this process, wound healing passes through four phases of haemostasis, inflammation, proliferation and remodelling. These phases are clinically indistinct and overlap in time. Tissue injury sets in motion a cascade of cellular and biochemical activities which leads to healing of the wound. In the following sections, stages in the process of wound healing are described (Fig. 1.2).

1.2 Biology of wound healing.

1.3.4 Haemostasis

The first step in the process (immediate up to 2–4 h) of inflammation is haemostasis, which is characterised by vasoconstriction and coagulation. It starts soon after injury and is usually completed within the first few hours. Injury to the tissues causes disruption of blood vessels and lymphatics exposing the platelets to fibrin and collagen. This activates the platelets and complement cascade. Platelets also interact with the injured tissue, causing the release of thrombin, which converts soluble, circulating fibrinogen to fibrin, which in turn traps, and activates platelets and forms the physical entity of the hemostatic ‘plug’.⁵

The activated platelet releases cytokines and growth factors including thromboxane A-2 and serotonin which are important inflammatory mediators and also cause vasoconstriction The clot also serves to concentrate the elaborated cytokines and growth factors including platelet-derived growth factor (PDGF) and transforming growth factor (TGF) β1.⁶ Coagulation leads to hemostasis, which initiates healing by leaving behind messengers that bring on an inflammatory process. Deficiency of clotting factors (Factor VII. IX, XII) leads to impaired wound healing.⁷

1.3.5 Inflammation

The stage of inflammation starts soon after haemostasis (immediate up to 2–5 days) and is usually completed within the first 48 to 72 h but it may last as long as 5 to 7 days.⁸ The initial vasoconstriction is followed by vasodilatation and increased vascular permeability in response to histamine and other vasoactive mediators.

Role of neutrophils

The net result of this change in vascular permeability is an influx of polymorphonuclear cells (PMN) and monocytes in the injured area in a protein-rich fluid. Neutrophils phagocytise debris and bacteria, they also kill bacteria by releasing caustic proteolytic enzymes and free radicals in a process called ‘respiratory burst’.⁹ The surrounding tissue matrix in unwounded tissue is protected by protease inhibitors which can be overwhelmed and penetrated if the inflammatory response is extremely robust leading to damage to normal tissue. Unless stimuli for neutrophil recruitment persist at the wound site, the neutrophil infiltration ceases after a few days, they undergo apoptosis and are engulfed and degraded by macrophages.¹⁰

1.3 Wound biology: phases of wound repair.

Macrophages

Macrophages start appearing in the wound two days after the injury and dominate the wound cell population over the next few days. Beside resident macrophages, the majority of macrophages at the wound site are recruited from the blood. Monocytes extravasate from the blood vessel, become activated and differentiate into mature tissue macrophages. Macrophages are crucial to wound healing and perform a number of functions.

They act as antigen-presenting cells...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright page
• Contributor contact details
• Woodhead Publishing in Textiles
• Preface
• Part I: The use of textiles in particular aspects of wound care
• Part II: Types of advanced textiles for wound care
• Index