The Four-Stage Process of Wound Healing

The Four-Stage Process of Wound Healing

 

Wound healing is a natural restorative response to tissue injury. There are many types of wounds and they require different wound care products for proper recovery but most go through similar healing stages. It is essential to remember that wounds can progress both forward and back through the phases.

As the body engages in wound healing, a biochemical process takes place throughout body systems. It traditionally can be explained in terms of 4 classic phases:

Haemostasis Phase

This refers to the process that stops the actual bleeding. Haemostasis stage is a very quick process. It begins when blood starts leaking out of the body. In response body constricts to limit the blood flow. Blood platelets attach together to seal the break in the blood vessel. Later, clotting occurs and toughens the platelet with fibrin which is considered as molecular binding agent. The formation of a thrombus or clot keeps the platelets and blood cells trapped in the wound area. The thrombus is important in the process of wound healing but becomes a trouble if it detaches from the vessel wall and enters the circulatory system. This might lead to possibility of a stroke, pulmonary embolism or heart attack.

Most of the time, your body will attain this through a process called vasoconstriction, where the blood vessels are closed tight. Once homeostasis is achieved the blood vessels expand, that let white blood cells, antibodies, nutrients, enzymes and other elements flow properly into the affected area to advance wound healing and fight against infection. This is the time when someone would experience the physical changes in inflammation i.e., pain, swelling, redness and heat.

Inflammatory Phase

Inflammation is a way that body’s uses to alert you of an injury. It is vital in the wound care process, but if it goes on for too long, it can hinder regeneration. The process initiates right after the injury when the injured blood vessels leak transudate which is a fluid made of salt, protein and water that causes swelling. Inflammation controls bleeding as well as prevents the wounded area from infection. Meanwhile, the healing and repair cells rush to the site of the wound where fluid is accumulated.

In this stage, bacteria, damaged cells and pathogens are removed from the wounded area. The white blood cells, nutrients and enzymes create the swelling, pain, heat, and redness that are seen during this stage of healing.

Inflammation is only problematic if the phase is prolonged.

Proliferative Phase

In proliferative phase of wound healing, the wound is rebuilt with new granulation tissue made up of collagen and extracellular matrix. The proliferative phase contracts the wound as new tissues are built. Along with this, new blood vessels are also constructed to ensure granulation tissues stay healthy and get vital oxygen and nutrients.

Wound is contracted by Myofibroblasts that grips the wound edges and pulls them together. Granulation tissue generally stays pink or red and has uneven texture. Furthermore, granulation tissue does not bleed easily. Keep the check, as dark granulation tissue can be a sign of infection. In the last phase, the injury is covered with epithelial cells. It is important to remember that when wounds are kept moist the epithelialization happens faster than normal. Apply occlusive or semiocclusive dressings within 48 hours after injury; they will maintain optimum tissue moisture for effective epithelialization.

Maturation Phase

Maturation, also known as remodelling, is the last stage of the wound healing process and occurs after the wound is closed. It may take upto 2 years. The cells that had been used to repair the wound are no longer needed and are removed by apoptosis, or programmed cell death.

During the maturation phase, collagen aligns along tension lines and water is absorbed so the collagen fibers can lie closer together. Cross-linking of collagen reduces the thickness of scar and also makes the skin area of the wound stronger. It normally starts after about 20 days of an injury. The healed wound areas continue to be weaker and have lesser tensile strength than unwounded skin.