Bed sores: why they develop, how they manifest and heal

Bed sores, also known as pressure ulcer or decubitus, are damage to the skin and subcutaneous (underlying) tissue. Pressure ulcers arise due to the interaction of risk factors, especially as a result of long-term pressure and shear to the surface of the body, skin and over a bony prominence under the skin. In most cases, these areas are under pressure due to body weight.

Common pressure sore sites include:

• back of the head
• the process of the 7th vertebra of the cervical spine
• shoulder blades
• elbows
• the sacral area, the sacrum
• ischial tuberosity, a.k.a.sit bones (buttocks)
• heels
• in side-lying position, the main sites are hips and the trochanter area, leg, shoulder, wrist, temples
• in prone position, the main sites are the knees, toes, palm, area of the head under weight
• in sitting postions, affected sites include the lower leg area and the heels

Pressure ulcers are demarcated areas of skin damage, a more severe case being damage to subcutaneous tissues affecting a smaller layer of underlying fat. Fat has a protective effect, so it functions as a shock absorber or a heat insulation. The injury arises due to long-term exposure already within a few days.

If the conditions are worse, it can take just a few hours.

FAQ:

Why and when do pressure ulcers develop?

How do they manifest, and what do they look like?

What can we do to alleviate or treat the condition?

There are various definitions in the literature with a uniform explanation. A pressure ulcer is a chronic wound that results in a disorder of the microcirculation (small blood supply). The result is insufficient blood supply, oxygenation and nutrient supply.

Insufficient blood supply, i.e. ischemia, results in damage to the tissue, and therefore to the skin, subcutaneous tissue, and muscles. An ulcer develops, a process known as ulceration. In the worst case, the tissue dies (necrosis). The origin of bed sores is a result of external as well as internal factors.

The following facts are known about pressure ulcers:
70% of all bed sores occur in people over 70 years of age
60% of pressure ulcers occur during the first two weeks
17% of sufferers are long-term patients requiring care
34% of bedsores occur in the sacral region
nd 26 % on the heel

Bed sores, especially those in the advanced stage, present a risk for complications. The wound is prone to get infected, sionce it provides easy entrance for bacteria. This complication worsens the healing of the wound and the overall health condition of the patient. Sepsis, also known as blood poisoning, and death are possible.

Other complications include bleeding, cyst formation, even relapses (a recurrence of a past condition after healing) and chronic bed sores. So, timely treatment, especially the prevention of bed sores in immobile and high-risk patients, should be considered as a major requirement as part of treatment and home care.

Pressure ulcers arise as an interplay of external and internal factors, especially for people in high-risk groups, including those who have limited mobility, whether partial or complete impairment, in supine position or sitting for a long time, e.g. in a wheelchair.

The cause of bed sores is either the pressure, friction or shear force. These forces act on sites with the highest body pressure can be applied to the skin and subcutaneous tissues due to the patients's weight. The riskiest sites are the ones with the least subcutaneous fat because the pressure is greater on the bone.

This is the case, for example, in the sacral region when lying in supine position. When lying in lateral recumbent position, the affected sites incude the temples, shoulder, elbow, tailbone, knee, but also the leg. When the patient is in sitting position, the most affected site is the lower legs (where they rest against the chair) and the heels.

The mechanism of how bed sores gradually arise might be summarised as follows:

1. pressue
2. limited microcirculation or blood supply
3. lack of oxygen
4. tissue damage
5. tissue death
6. infection

Pressure can be the result of several types of forces. Pressure is a vertical force that arises due to gravity. The skin, subcutaneous tissue, and muscle are compressed between the outside surface and the bone. Blood supply is compromised, followed by tissue damage and the emergence of pressure ulcers.

Shear, or shearing forces, for example, arises in Fowler's or semi-sitting position as a result of the patient slipping or being pulled to a higher position. The opposite force on the skin and lower structures with repeated and prolonged exposure can result in impaired blood supply and lymph microcirculation. Shear will damage the small blood vessels as well as the lymphatic vessels.

Friction is an example of another mechanism. Repeated friction or rubbing damages the surface of the skin. If there is increased humidity and frictional forces, the formation of bedsores is very likely. People with fecal and urinary incontinence (the involuntary excretion of bowel contents and urine) are most at risk. Therefore, moisture-absorbing materials that do not breathe are unsuitable for bedridden patients.

Table: Combined external and internal risk factors

The visible process of bedsores is mostly from the outside. When reddened skin is present. However, if pressure ulcer results from a cleavage mechanism, it is invisible for a long time. The reason is that the deeper structures are damaged first and a deep wound, an ulcer, is created.

Table: Bedsores are divided into stages

Some sources present a 5-stage classification, where stage 4 is described as affected muscle fascia (sheet), swelling, and inflammation, and stage 5 as the onset of necrosis and deep tissue destruction affecting the bone and joints.

Of course, pressure ulcer itself is not just a local problem. Its advanced stages affect the body as a whole. They worsen the underlying diseases, while long-term diseases will have a negative effect on the emergence and healing of bedsores.

Infection of injured skin and deeper structures is a serious complication. It worsens the healing of pressure ulcers, but also the overall condition of the individual. Sepsis is dangerous and its severe form is life-threatening. As a result, bed sores are a source of protein loss. Decreased protein levels make healing difficult and exacerbates malnutrition.

Complications of pressure ulcers include:

• eczema caused by a skin infection in response to bacteria
• spread of the infection into the blood, ie bacteria, and subsequent involvement of the heart, brain, arthritis
• cellulite, either superficial or deep inflammation of the surrounding area
• sepsis as a result of inflammation of the pressure ulcer and the surrounding area
• osteomyelitis as a consequence of stage 4 bed sores
• pain, pain relief prior to repositioning, rehabilitation, or wound treatment

Cellulitis, i.e. as an infection involving the inner layers of the skin, not as cellulite, colloquially orange peel syndrome, which is especially an aesthetic issue for some women.

Bed sores can be identified by their external symptoms. The GP or medical staff (nurse, nurse) can visually determine whether a pressure ulcer is suspected to be developing. As mentioned earlier, if there are external, surface manifestations due to searing, it might be too late, as a larger extent of damage will be suspected in the deeper layers.

The condition of superficial skin and clinical manifestations or pain are helpful in determining the stage of bed sores. In stage 3 or 4 bedsores, it is also necessary to determine the presence of infection. A swab will be taken for a microbial examination and to check antibiotic susceptibility. The most common aim is to verify the presence of various bacteria.

An additional test done to determine CRP in order to confirm the spread of the infection. Body temperature is measured. The determination of plasma proteins (albumin) is one of the important laboratory examinations.

Subsequently, a vascular examination can be performed using duplex sonography. Taking pictures of pressure ulcers can help the treatment because the photographs will allow the doctor to compare the damage or evaluate healing.

It is possible to assess the risk of bed sores in high-risk patients by using the Norton Scale. The evaluation is performed by counting the individual score. If the final score is less than 25, the person is at risk for bed sores. In other words, the lower the score, the higher the risk of a bed sore.

Table: Norton pressure sore risk evaluation scale

Pressure ulcers arise due to long-term pressure. However, under certain conditions and risk factors, they may arise within a few hours. Most pressure ulcers develop during the first two weeks, for example, after the person is immobilised.

In immobile patients, a pressure ulcer is the result of insufficient or inappropriate care and neglected repositioning. This occurs not only in the hospital environment, nursing care, but also in the home.

Initially, a delimited red area of the skin is visible, but it is not damaged. People with darker skin may have white patches. Local swelling may be associated. Later on in the second stage, blisters or superficial skin damage are formed.

Stage 3 is a more serious condition because the ulcer has damaged the deeper layers. However, it only affects the fascia. In stage 4, the deep layer is damaged. Muscles and tendons are visible, and the bone or the joint maybe damaged.

Bed sores are dangerous due to complications that manifest depending on the type, for example cellulitis which is an inflammation of the deep subcutaneous layers around the pressure ulcer. This is a subsequent risk for the spread of bacteria throughout the body.

Bacteria can get to the heart, brain or joints inside the blood. Sepsis is a severe condition that can result in death. Other general symptoms may include fever, pain (including general body pain). If the pressure ulcer affects the bone, it causes osteomyelitis, an inflammatory disease of the bone.