Fundamentals - Practice & Skills, part 13: Wound Healing
by Meris Shuwarger BSN, RN, CEN, TCRN August 02, 2021 Updated: June 16, 2022 11 min read
This article focuses on wound healing. You can follow along with our Fundamentals of Nursing flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.
Phases of wound healing
There are four phases of wound healing. These apply no matter the size of the wound. The phases of wound healing are: hemostasis, inflammatory, proliferation, and maturation. The duration of each phase may differ, depending on the type of wound, but all wounds have these phases in common.
The first phase is hemostasis. “Hemo” means blood. “Stasis” means stop. So, the goal of hemostasis is to stop the bleeding.
This is accomplished through the process of vasoconstriction, which is when the muscles around the blood vessels tighten to make the space inside smaller, and by activating the platelets in the blood, which trigger the “clotting cascade” (a series of clotting factors that activate one after the other) to stop the bleeding.
Hemostasis is followed by the inflammatory phase. The goal of this phase is a clean wound. This phase may last several days.
Inflammation allows for the influx of white blood cells (neutrophils and macrophages) to eliminate bacteria and prevent infection. This is achieved through a process called diapedesis, the passage of blood cells through the capillary walls. Diapedesis is accomplished by vasodilating the capillaries, the opposite of vasoconstriction. So in this process, the capillaries are rendered “leaky,” which allows the neutrophils to seep through the capillary walls to do their work.
Inflammation is a normal part of the wound healing process — to an extent. Diapedesis will cause swelling, edema, and pain. It will be important to monitor the patient in the event remediation is required for any of these symptoms during this phase of wound healing.
The next phase of wound healing is the proliferation phase, whose goal is to fill and cover the wound. This phase introduces fibroblasts, which form granulation (or new) tissue. A fibroblast is a common type of cell found in connective tissue that plays a key role in healing wounds. With granulation, new blood vessels develop (known as angiogenesis). The wound contracts, and epithelial cells migrate to cover the wound bed.
The last phase is known as maturation. The goal of maturation is to remodel the scar tissue. This can take a long time, up to a year or more.
In this phase, one type of collagen (type 3) is replaced by stronger collagen (type 1). Collagen is a structural protein that plays an essential protective role in the human body.
When discussing the healing process, we talk about healing by intention — primary, secondary, and tertiary intention. Literally, this means the first, second, and third way of doing something.
When a wound is healed by primary intention, the edges of the wound are approximated, which means they are brought together — they touch. Following a surgical incision, for example, the edges of the incision are approximated. That is, they are brought together using surgical sutures or staples. A paper cut heals by primary intention (we use a Band-Aid to approximate the edges of the cut).
When a wound is healed by secondary intention, it is left open to heal through granulation, contraction, and epithelialization. This is “healing from the inside out” and takes longer than wound healed by primary intention.
An example of a wound healed by secondary intention is a pressure injury — an injury where the edges cannot be approximated and that must heal from the inside out.
Note that there is a higher risk of infection when healing times are longer.
Tertiary intention is when the closure of a wound is delayed — the wound is left open in order to irrigate, debride (thoroughly clean), and observe it (usually for about a week), before closing it surgically once the risk of infection is lower.
Complications of wound healing
Complications of wound healing may include:
- Hemorrhage: bleeding from a damaged blood vessel
- Dehiscence: the total or partial separation of wound layers, that is, when a previously closed wound opens again
- Evisceration: dehiscence with organs protruding
Evisceration is a true medical emergency and the patient requires immediate surgical intervention.
In the event of evisceration, do not try to reinsert the organs. Place a saline-moistened gauze over the open area, lower the head of the bed (possibly put the patient in the Trendelenburg position), notify the provider immediately, and maintain patient NPO (null per os, i.e., the patient should fast) in anticipation of surgical repair.
Barriers to healing
There are many barriers to healing, including chronic illnesses (e.g., diabetes, which can impede circulation), smoking, malnutrition (especially insufficient protein), older age, impaired circulation (e.g., peripheral arterial disease), immunosuppression (having a weakened immune system), and corticosteroids (which can cause immune suppression).
Wound drainage is a normal part of the healing process, though some types of drainage may indicate an infection. When changing the dressing of a wound and assessing its drainage, keep in mind the question, “Is what I’m seeing normal?”
Types of drainage
The different types of drainage include:
- Serous drainage: clear, watery drainage, which is normal
- Serosanguineous: serous fluid mixed with blood, which appears light pink and/or blood-tinged
- Sanguineous: bloody drainage that is bright red
- Purulent: looking like pus. This wound’s drainage is cloudy and could be white, yellow, or beige. It is malodorous (bad smelling). This indicates an infection is present.
Amount of drainage
Another thing to observe is the amount of drainage, which may be described as scant, small, moderate, large, or copious. Scant indicates a slightly moist wound with no exudate (pus) and, at the other end of the scale, copious, where the wound tissue is filled with fluid, and more than 75% of the bandage is covered in exudate.
In addition to the amount and type of drainage of a wound, a wound’s appearance can indicate how it is healing.
A wound that appears red indicates healthy tissue and good circulation. The wound has a “beefy” red color. Continue to protect the wound site and maintain a moist wound healing environment.
A wound that appears yellow indicates the wound needs cleaning. The wound contains slough (necrotic tissue, which may look like “chicken fat”) and/or has purulent drainage (pus). This wound must be irrigated and cleaned.
A wound that appears black indicates a wound that requires debridement. The wound contains eschar (hard or rubbery black/brown necrotic tissue) and needs autolytic debridement (using the body’s enzymes and natural fluids to soften bad tissue for its removal), enzymatic debridement (the application of a prescribed topical agent that chemically liquefies necrotic tissues with enzymes), chemical debridement (using enzymatic chemicals on the wound to cause lysis (breaking down) of the necrotic tissue in the wound), or sharp debridement (the use of scalpels, scissors, sharp curettes, or forceps to excise the necrosis from a wound bed).
Hi, I'm Meris, and in this video, we're going to be talking about wound healing. I'm going to be following along using our Fundamentals of Nursing flashcards. These are available for purchase on our website, leveluprn.com, along with a lot of other amazing flashcards. If you're following along with me using your own set, I am starting on card number 81. Let's get started.
Okay. So first off, we're going to start talking about the phases of wound healing. Keep in mind, this applies for small wounds and big ones, but they all have the same phases in common. It just may take more or less time, depending on the type of wound. So first we have hemostasis. The goal of hemostasis is to stop bleeding. Hemo means blood. Stasis means stop. So that's going to be through the process of vasoconstriction and using our clotting cascade and activating platelets so that we can actively stop that bleeding. We're going to move on to the inflammatory stage after that. I want you to pay careful attention to this because inflammation is a normal part of wound healing, to an extent. So inflammation is important because this is what allows for the neutrophils, the first responders, to get to the injured area so that they can start gobbling up the pathogens and trying to prevent infection. If you remember way back to A&P, they do this through a process called diapedesis. Diapedesis is done by vasodilating those capillaries to make them leaky. Leaky capillaries allow neutrophils out, but they can also cause swelling, and this is why we see swelling and edema and pain with inflammation. After that point in time, we are at the proliferation phase of wound healing. Proliferate means to make more of. So in this phase, we are generating new skin cells that are going to actually fill and cover the wound to help to regenerate the tissue that was lost because of that injury. And then we are at the maturation phase. And the phase here is going to be remodeling that scar tissue, which can take a long time. It can take a year or more to rebuild that collagen and get that nice strong scar tissue in there. So those are the phases of wound healing.
Next up, we're going to be talking about healing by intention, and you will hear this referred to, healing by primary, secondary, or tertiary intention, literally means, first, second, and third way of doing something. So if you'll see here on our card, we have some bold red text to really let you know that something's important, so pay careful attention to that. When we heal something by primary intention, this means that the edges of the wound are well approximated. Well approximated means that they are brought together well. So they are touching. I think of this surgery that I just had right here. This is healing by primary intention. I had a surgical incision made. The edges were approximated, brought together with surgical sutures, and then that's how the wound is healing. That is going to be very common with surgery. Things like paper cuts, that sort of thing, is going to heal by primary intention.
Now, when we heal by secondary intention, a wound is intentionally left open to heal through granulation. So this is going to be granulation, contraction, and epithelialization. This is going to happen when we heal basically from the inside out is how you can think about it. This is going to have a higher risk of infection but longer healing times. A good example of this would be a pressure injury. It's not something where we can really approximate the edges. They're eroded so far out from one another they can't be brought together, so it's going to heal from the inside out. It's going to take longer and higher risk of infection. And then tertiary intention is when the closure of a wound is intentionally delayed. So this might mean that it has become open or it is left open, and we delay the closure so that can irrigate the wound, debride the wound, and observe it usually for about a week, and then we're going to close it surgically when the risk for infection is lower.
Okay. Now moving onto complications and barriers of healing. This is a big one because you need to know who is most at risk for poor wound healing. If you see here, there's a ton of bold, red information on these cards here, so I would say definitely make sure you feel comfortable with all of it. Let's talk about it. So one of the complications of wound healing is going to be dehiscence. Dehiscence is when a previously closed wound opens back up. This could be for a lot of reasons, but the point here being, dehiscence refers to a closed wound separating and opening. Now evisceration is dehiscence with organs protruding. So for instance, if this wound here on my elbow were to dehisce, these layers would pop open and separate but nothing is going to eviscerate, right? It's not in a location where it can. But when I had abdominal surgery, if I had dehiscence in that area, it's possible that it could go deep enough. It could open all the way potentially and cause evisceration where my bowels, my organs are actively exposed and on the outside of my body, right? When that happens, it's a true medical emergency, and this is going to be one of the times where you need to know what to do. So we need to put saline moistened gauze. Not water, right? We do not want bacteria, and we need the right isotonicity. We need it to be the same tonicity as our body fluids. So saline moistened gauze over the open area. I'm going to lower the head of the bed, maybe even put them in Trendelenburg. And then I'm going to notify the provider immediately. After I put saline-moistened gauze on and lower the head of the bed, there's nothing else that me can do-- that I can do as the nurse, right? The only thing I can do after that point is call the provider. They need surgical intervention immediately.
Now, barriers to healing, there are a lot. In general, chronic illnesses are going to complicate wound healing almost all the time, right? A big one we think of would be diabetes mellitus. That's going to be a problem with circulation. We're going to have poor circulation, and that can cause impaired healing, as well as any time we have fluctuating blood glucose levels, we can impact our healing as well. So very important that we keep tight glycemic control on diabetics, meaning that we keep their blood glucose level in a good range very closely when we're trying to have them heal from some kind of an injury or wound or surgery. Other things would be immunosuppression. Corticosteroid can cause immune suppression, so things like that to be aware of.
Lastly, we're going to talk about drainage and wound appearance. You need to know, when you're doing a dressing change or assessing a wound, "Is what I'm seeing normal?" So we can have different types of drainage. Serous is going to be that watery, kind of clear, maybe has a little hint of a tan color-- not tan. It's not thick, but it's just kind of maybe a little off-white, I would say. Serous draining, that's normal. It's nothing crazy going on there. Serosanguineous, so serous fluid mixed with blood, sanguineous, is going to be kind of pink tinged. So it's going to be maybe a light pink. Then we have sanguineous. Sanguineous means bloody, so this is going to be bright red discharge here, drainage, and then purulent. When we have something that is purulent, it means it is looking like pus. This is going to be thick, cloudy. It might be white, yellow, or beige. It's going to smell bad. Any time discharge smells foul, we need to be concerned about that. Malodorous, mal meaning bad, odor meaning smell, right? A bad smell. It's not good. That indicates infection. And then when we talk about what the wound itself looks like, know that a red wound that has a beefy appearance, that's a healthy looking wound. We like that. That means that there is good circulation happening. If we have a yellow wound, that probably means that it needs to be cleaned. And if it is black, it means we need debridement. We need to actually remove the dead necrotic skin or tissue from that area so that it can heal in a good way.
Okay. I hope that review was helpful. If it is, please go ahead and like this video. That would mean so much to us. If you have a great way to remember something, I definitely want to hear it in the comments below. And be sure to subscribe to the channel, because you want to be the first to know when our next video posts, which is going to be talking about diabetic foot care and wound care. Thanks so much, and happy studying.
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