Wounds are classified by mechanism and physiological disturbance. Whilst differing classifications are used they commonly fit into seven broad categories (excluding burns – discussed later in this chapter). It is important that the practitioner can describe a wound for documentation and referral purposes, especially in today’s increasingly litigious society.

Incised wound

An injury to the skin that may be superficial or deep. Incisions are caused by sharp objects such as a knife or broken glass. Incisions are typically clean wounds (unless the object is dirty), with neat edges.

Lacerations

Lacerations are a tearing or splitting of the skin caused by blunt trauma. Commonly lacerations are caused by either direct or indirect blow to the skin by a heavy or fixed object such as furniture or the floor.

Puncture/penetrating wounds

These wounds have a small opening where the object has penetrated the skin causing potential underlying damage. It can be very difficult to assess these wounds as the damage may not be indicated by the entry wound. Careful assessment of the wound is required in a controlled environment by a competent and experienced practitioner; this is usually undertaken in an operating theatre or Emergency Department. The investigation of depth and underlying damage is not recommended in the prehospital environment. A concise history is paramount in providing a level of suspicion of underlying injury. Common causes of these wounds range from stab wounds to standing on a nail.

Abrasion

An abrasion (often referred to as a graze) is a superficial removal of the skin by rubbing or friction. This can be painful due to the exposed nerve endings and may have embedded dirt in the skin. These wounds may range from carpet burns from a fall to severe ‘gravel rash’ following a fall from a moving motorcycle.

Crush Injury

These are caused by severe crushing pressures causing the skin to split. Crush wounds are often associated with underlying injury to bone or organs due to the forces involved.

Bite wounds

These wounds are naturally caused by the teeth which may be human or animal. Bite wounds are often ragged edged and involve bruising from the crushing forces involved. Bite wounds are associated with a high risk of infection due to the natural bacteria in the mouth of the human or animal.

Contusions

Also referred to as bruising, a contusion is bleeding from damaged blood vessels beneath the skin that result in a bluish/purple discoloration beneath the skin. These are typically caused by blunt trauma, although contusions may form around the site of other wounds.

Other wounds

These include amputation which is the complete detachment of a part of the body that may be cut or torn away. This may result in significant bleeding due to the damage to arteries, veins and bone. If tissue still connects the amputated body part then it is termed as partial amputation. Avulsion injuries are a flap of skin and underlying tissue that is partially torn or cut away, one such injury is the tearing away of the scalp in blunt head trauma.

Wound healing is a dynamic process involving physiological processes in a series of stages whereby damaged or destroyed tissues are restored to normal function.³

Phases of wound healing

Wound healing is a complex process that occur s in a predictable order. The processes of wound healing are generally described in four stages ⁴:

• Haemostasis
  
• Inflammatory stage
  
• Proliferation or reconstructive stage
  
• Maturation or re-modelling stage.

Whilst these stages are not distinct and may overlap, for simplicity they will be discussed individually, due to the complex nature of wound healing only brief discussion will be provided, further reading suggestions are provided at the end of this chapter that will provide more information.

Haemostasis

This occurs within seconds and minutes of injury. Blood vessels constrict to reduce blood loss. When platelets come into contact with collagen from damaged blood vessels chemical mediators are released that promote coagulation.⁴ Platelets adhere to vessel walls and damaged edges where they are stabilised by fibrin threads to form a clot.

Inflammatory stage

Neutrophils, monocytes and keratinocytes (white blood cells) migrate to the damaged area over the first 2–3 days following injury. Histamine release causes vasodilatation and increased permeability of capillary walls to cause leucocytes, antibodies, proteins and electrolytes to exude into the surrounding tissues. This causes the wound to be red, swollen and hot.⁴ White blood cells (neutrophils and macrophages) begin the process of repair by destroying and ingesting bacteria and devitalised tissue. This increases the oxygen demand in the tissues through the increase in cellular activity; therefore hypoxic wounds are more susceptible to infection and poor healing.

Proliferation or reconstructive stage

This stage lasts from about 3–24 days. As macrophages accumulate at the site of injury chemical mediators are released that attract fibroblasts to the site. Fibroblasts produce proteins such as collagen and elastin that leads to the formation of new connective tissue that increases the strength of the wound.⁵ New blood vessel formation is also stimulated and will begin to grow in the matrix of connective tissue. The new tissue at the site of injury is referred to as granulation tissue; this is generally pink/red in appearance and is very fragile. Wound contraction also occurs, with specialised fibroblasts pulling the wound edges together to reduce the surface area of the wound. During this time re-epithelialisation occurs as epithelial tissue migrates across the surface of the wound to eventually cover the wound.

Maturation or re-modelling stage

This stage commences at about 21 days after the injury and may continue for over a year. There is a gradual reduction in the vascularity of the wound and collagen fibres are re-modelled to a more organised structure that strengthens the wound. During this time stronger avascular tissue may replace the highly vascular granulation tissue, this may lead to scarring.⁴

Complications in wound healing

There are a variety of complications that can affect wound healing; this section will briefly discuss some of the key issues that may affect wound healing.

Factors that affect wound healing

Whilst wounds may present in a variety of forms as previously discussed the principles of wound management can be generalised to deal with each situation with little adaptation.

Control of bleeding (no foreign body)

Control of bleeding (foreign body present)

In the presence of a retained foreign body in a wound, it is important that the object is not removed from the wound as this may cause further tissue damage, dislodge blood clots or unseal blood vessels causing an increase of bleeding. The following principles apply to the management of bleeding with a retained foreign body:

• Do not remove the object, unless small and sitting on top of the wound as opposed as embedded in the wound. If debris is sitting upon the wound it may be brushed away gently using a sterile pad.
  
• Do not apply pressure upon the object as this may cause further damage.
  
• Pressure should be applied to the sides of the wound, holding the wound together.
  
• Pad around the object to apply pressure to the sides of the wound and to ensure the object is not dislodged. When padded a bandage can be applied over the top to secure the padding.
  
• Consider primary principles of wound management, such as elevation.
  
• In the event of failure to stem bleeding then indirect pressure may be required.

Indirect pressure

If bleeding is not controlled by initial first aid measures then application of indirect pressure should be considered. This requires pressure to be placed upon the artery that supplies the area of bleeding. Applying pressure will reduce blood flow to the area and subsequent blood loss during which time more substantial or definitive bandaging can be applied.

Common sites for indirect pressure include:

• The brachial artery for arm wounds
  
• The femoral artery for leg wounds
  
• The temporal artery for scalp wounds.

The carotid artery should not be compressed when dealing with head or scalp wounds.

In the presence of severe haemorrhage that is uncontrolled by direct and indirect pressure (for example amputation) there are few options available for wound control; in such occasions it is suggested that a tourniquet could be used. The tourniquet was initially used by battlefield surgeons in ancient Rome to control bleeding during amputations; subsequently the use of the tourniquet has undergone fluctuations in popularity with a recent resurgence in military settings.⁷ Arterial tourniquets work by compressing muscle and other tissues surrounding extremity arteries, therefore compressing the lumen of the artery and reducing distal blood flow.⁷ The tension required to achieve this is dependent upon the size of the extremity⁸ and the width of the tourniquet.⁹ Wider tourniquets are more effective at stopping arterial flow at a given tension than a narrow tourniquet due to an increased area of vasculature being compressed.⁹

Complications of tourniquet use

There are a variety of potential complications associated with the application of a tourniquet. The time a tourniquet is applied for has often been a concern over its’ use, even application for a matter of minutes leads to changes in muscle and nerve physiology. In an early study by Heppenstall et al. (1979)¹⁰ found that after 1 hour there was no evidence of muscle damage, however at 2 hours of ischaemia elevated levels of lactic acid and creatinine phosphokinase were found (these are linked to skeletal muscle damage or injury). Surgical guidelines and studies support no more than 60–90 minutes of use, with a suggested upper limit of 2 hours.¹¹ However these studies are not prehospital based, so there is little guidance upon a safe duration of application.

There has been documented evidence of post-tourniquet complications known as post-tourniquet syndrome (weakness/parasthesia/pallor/stiffness) in the distal limb. This has been related to the damage caused to muscle, nerves and blood vessels during tourniquet use of over 1.5 hours in surgical intervention. This syndrome appears common but the effects are limited to approximately 3 weeks.¹² There are further concerns over issues such as worsened venous bleeding with an incorrectly applied tourniquet that allows for arterial flow to continue but venous return to be stemmed.⁷ Compartment syndrome is a further complication that may occur with prolonged use, however little evidence surrounds this area and it is suggested the it may be the injury itself, not the tourniquet, which causes the presence of compartment syndrome.¹³ Whilst there are numerous concerns and potential complications of tourniquet use the evidence surrounding these issues is unclear.^14,15

Can they be used safely?

Recent military experience supports the safety of short-term tourniquet use in prehospital care^16,17,18 with a small-scale study finding limb salvage with arterial injury in 11 of 14 patients despite tourniquet times averaging 2 hours.¹⁹