How do pressure sores come about?

Recently, I saw some netizens discussing the issue of pressure sores. Someone said that pressure sores can occur in two hours, so why is it okay to sit for so long while studying or taking exams? Is sitting for two hours while studying or taking exams really the same as a patient getting a pressure sore for two hours?

Today, let’s share with you some knowledge about pressure ulcers!

01. What is a pressure ulcer?

In fact, what we call "sitting for 2 hours to study and take exams" is very different from the patient's 2 hours of pressure sores. First, let's talk about the problem of pressure sores. Pressure sores, generally called pressure injuries, are defined as:

“Localized injury to the skin and/or underlying soft tissue, usually over bony prominences or where the skin contacts a medical device. This ulcer may present as localized tissue damage with intact epidermis or as an open ulcer and may be painful. Severe and/or prolonged pressure or pressure combined with shear may lead to pressure ulcers. The tolerance of the subcutaneous soft tissue to pressure and shear is affected by the environment, nutrition, perfusion, comorbidities, and soft tissue condition.”

From this definition, we can see that pressure sores often occur at bone protrusions. In fact, this has been confirmed by clinical studies. For example, the picture below shows that pressure sores are prone to occur when the human body is in the supine or lateral position.

Basically, they are those places that are prone to bulging. For example, when lying on your side, the auricle will be pressed under the head, which can easily lead to pressure sores on the auricle. This is probably the case for many people who suffer from ear pain after sleeping on their side for a long time. Of course, although many people feel that they sleep very soundly and do not move, in fact, if you are willing to do a study and use a monitor to watch your own sleeping process, you will find that your body is actually making fine adjustments during your sleep to avoid maintaining a posture for too long.

Next, let’s talk about the studying and exam postures that netizens are discussing.

02. What we thought was a quiet state

Let’s first talk about what you think your quiet state is: you think this is how you sit for 2 hours while studying or taking an exam, like a wooden man, motionless.

In fact, your action is like this

When monitoring your behavior, it can be said that it is very diverse. Are you surprised by your diverse behavior?

Bigger movements include playing with mobile phone, sleeping, and stretching.

Slightly smaller movements, whispering, looking around.

Even some subtle movements, such as raising or lowering the head, adjusting the direction of the head according to the teacher's movements, or making slight adjustments to the body.

These are all things that happen repeatedly in reality, but you just think you are not moving at all. However, if the teacher at the podium is willing to observe, he or she will find that you are actually moving all the time.

03. What about the patients?

How do people in hospital beds get their pressure sores? In fact, patients are really different from what we think they can do when they sit still. They can really stay still.

For example, the incidence of pressure sores in ICUs is relatively high. Many people are studying the need to consider the issue of pressure sores in ICU treatment. Why? Because many people who enter the ICU have basically lost many vital signs, and many have basically no autonomy, so pressure sores may occur.

For example, researchers once compared the incidence of pressure ulcers in the ICUs of the nephrology, general surgery, cardiovascular and neurology departments, and found that the incidence of pressure ulcers in the neurology ICU was the highest, reaching 55.4%, which means that more than half of the patients had pressure ulcers.

Why is this so? Because nerves are the basic components responsible for human reflexes. Once a serious problem occurs with the nerves, or even if one loses consciousness, it will lead to serious problems, such as coma. In this case, because of the problem with the nerves, even basic reflexes may be lost. How can one move?

Other actions that interfere with the nerves, such as anesthesia, are also prone to pressure ulcers during surgery.

To sum up, what we think is a "non-moving" state is actually not completely still, and the quiet state of many patients is the real still state. That is why pressure sores occur in patients, while normal people will be fine even if they sit still for 2 hours!

[1] Tang Guofang. Abnormal behavior detection system for students under classroom monitoring[D]. Chongqing University of Technology, 2021.

[2] Lun Qinglong, Su Peng, Lu Da, Li Shuo, Li Jian. Biomechanical modeling and experimental study of pressure ulcer-prone areas during assisted supine rollover[J]. Chinese Journal of Biomedical Engineering, 2022, 41(03): 310-319.