When pressure sores develop from sustained positions, the damage occurs at two locations simultaneously – the superficial layers of skin next to the table, and the deep tissue next to the bony structure (e.g. lateral aspect of the femur) that the patient is lying on. What physics concept helps to explain this?
The physics concept that helps to explain the development of pressure sores is known as pressure distribution. When a person remains in a sustained position for prolonged periods, the body exerts pressure on the surface it is in contact with, such as a table or a bed. This pressure is distributed across the contact area.
The pressure exerted on the body is determined by the force being applied and the area over which that force is distributed. According to the formula P = F/A, where P represents pressure, F represents force, and A represents area, an increase in force or a decrease in contact area results in an increase in pressure.
In the case of pressure sores, the force applied by the body is primarily concentrated on the superficial layers of the skin and the deep tissues next to the bony structures. The bones provide less surface area for the force to be distributed over. Consequently, the pressure in these areas becomes significantly higher compared to the surrounding soft tissues.
As a result, the high pressure on the skin's superficial layers can cause damage to the skin itself, resulting in ulcers or sores. Simultaneously, the high pressure on the deep tissues next to the bony structures can restrict blood flow and impede nutrient delivery, leading to tissue damage and ultimately the formation of deep tissue injuries.
Understanding the concept of pressure distribution helps explain why pressure sores develop at both the superficial and deep tissue layers simultaneously when sustained positions are held for extended periods.