Prolonged pressure on the skin and underlying tissues caused by extended periods of immobility is the primary factor leading to the development of pressure ulcers, commonly known as bedsores. These injuries occur when constant external pressure starves the tissue of oxygen and nutrients, initiating a breakdown process. For patients confined to a bed or chair, a standard mattress cannot adequately mitigate this risk. Specialized therapeutic support surfaces, often called pressure mattresses, have been developed as a medical intervention to manage and prevent this health complication.
Defining the Therapeutic Mattress
A pressure mattress is a specialized medical device designed to provide a support surface that actively manages the interface between the patient’s body and the bed. Its fundamental purpose is to prevent the concentration of pressure on bony prominences, such as the hips, sacrum, and heels. Unlike conventional bedding, a therapeutic mattress is engineered to redistribute the patient’s weight evenly. This redistribution maintains blood flow and tissue viability for individuals who cannot frequently reposition themselves, aiding in the clinical prevention and treatment of pressure-related skin damage.
The Mechanism of Pressure Redistribution
The core function of a pressure mattress is reducing interface pressure, the force exerted between the body and the support surface. This is primarily achieved through immersion and envelopment. Immersion refers to the depth the patient sinks into the mattress, while envelopment describes how closely the mattress contours around the patient’s shape. By allowing the body to sink and conform, weight is spread over a larger area, lowering the pressure at any single point.
Another element is the reduction of shear forces. Shear occurs when layers of tissue slide across each other, such as when a patient is pulled up in bed or when the head of the bed is elevated, which can damage blood vessels and deeper tissues. Therapeutic surfaces minimize this internal tissue distortion. Furthermore, many advanced systems incorporate microclimate control, which manages the temperature and moisture levels immediately next to the skin. Regulating this environment is important because excess heat and moisture increase the skin’s susceptibility to breakdown.
Categorization of Pressure Support Surfaces
Therapeutic mattresses are broadly categorized based on their mechanism of operation: static or dynamic. Static, or reactive, support surfaces are non-powered and redistribute pressure by conforming to the patient’s body shape. These often use high-specification foam, gel bladders, or non-powered air chambers that provide continuous, low-pressure support. The weight of the individual causes the material to deform, which increases the contact area and lowers the peak pressure on vulnerable sites.
Dynamic, or active, support surfaces require an external power source, typically an electric pump, to actively change the pressure points beneath the patient. The most common type is the alternating pressure mattress, which uses a series of interconnected air cells that cyclically inflate and deflate. This systematic cycling ensures that pressure is periodically removed from different areas of the body, effectively mimicking the natural repositioning performed by a mobile person. Other dynamic systems include low air loss mattresses, which circulate a large volume of air to manage the skin’s microclimate, and hybrid systems that combine foam and powered air cells.
When is a Pressure Mattress Necessary?
The necessity of a pressure mattress is determined by a clinical risk assessment that evaluates a patient’s susceptibility to developing a pressure ulcer. Patients with severely limited mobility, those who are bedridden, or individuals unable to reposition themselves independently are considered at high risk. Medical conditions that compromise skin integrity or circulation, such as spinal cord injuries, diabetes, or severe malnutrition, also increase the risk profile. The use of a specialized surface is a standard part of care for these individuals.
The choice of mattress type is guided by the patient’s level of risk and the stage of any existing pressure ulcers. A static mattress may be appropriate for individuals at a lower risk or those with early-stage injuries. Conversely, a dynamic alternating pressure system is indicated for patients at a high or very high risk, or for those who already have more severe, established pressure ulcers. In these cases, the active tissue offloading provided by the powered system aids in the healing process and prevents further deterioration.