Pressure sores (bedsores or decubitus ulcers) are injuries to the skin and underlying tissue caused by prolonged pressure. This continuous pressure limits blood flow, which starves the cells of oxygen and nutrients, eventually causing the tissue to break down and an open sore to appear. These injuries typically occur over bony areas like the tailbone, hips, and heels, where there is less muscle or fat padding to protect the skin. Pressure sores are also caused by shear forces, which is the stretching or friction that happens when a person slides down in a chair or bed, pulling the skin in one direction while the underlying tissue remains fixed. Pressure relief cushions are a primary tool in prevention and management, working to redistribute the body’s weight and decrease the high-pressure points that lead to this tissue damage.
Principles of Pressure Redistribution
Effective pressure relief is achieved through several biomechanical mechanisms that cushions employ to protect the skin and underlying soft tissues. One of the most important concepts is immersion, which describes the depth the body sinks into the support surface. Deeper immersion allows the weight concentrated beneath bony prominences, such as the ischial tuberosities, to be spread out over a larger contact area. This increased surface area ultimately lowers the pressure at any single point.
A related principle is envelopment, which is the cushion’s ability to conform precisely around the body’s contours. Greater envelopment ensures a more even distribution of weight, minimizing peak pressures under the most vulnerable bony areas. Cushion design must also actively work toward shear force reduction. Materials that allow the tissue to move along with the pelvis, or cushions with built-in contours, help prevent the sliding motion that causes damaging shear.
A Comparative Guide to Cushion Types
Air flotation cushions, often featuring interconnected air cells, offer one of the highest levels of pressure equalization by maximizing both immersion and envelopment. These cushions work by allowing air to flow between cells, constantly adjusting to the user’s shape and movements to reduce pressure away from high-risk spots. While providing superior skin protection, they require regular maintenance to ensure proper inflation, and an incorrectly inflated cushion can actually increase the risk of skin breakdown.
Foam cushions are a widely used and budget-friendly option, providing stability and being lightweight for easy handling. Standard foam offers less pressure relief and can compress over time, reducing its effectiveness. High-density or viscoelastic foam, commonly called memory foam, reacts to body heat and pressure, allowing it to mould to the body’s contours for improved pressure relief. However, foam can retain heat, and its effectiveness in pressure reduction is lower than air or gel options.
Gel cushions typically contain gel inserts or fluid bladders that help distribute weight evenly, combining moderate stability with good pressure relief. The gel material conforms well to the body, and some gel-infused foams also offer a cooling effect, which can help manage the microclimate of the skin. A drawback of gel cushions is their increased weight compared to foam, and the potential for the gel material to shift or for the cushion to “bottom out” if the fluid is not manually redistributed.
Hybrid and dynamic cushions combine the benefits of different materials or technologies to overcome individual limitations. Hybrid cushions often combine a stable foam base with gel inserts or air cells to offer balanced performance, such as stability for transfers and high pressure relief. Dynamic or alternating pressure systems are powered cushions that use a programmed cycle to inflate and deflate air cells, constantly shifting the pressure points to promote circulation, making them suitable for high-risk users.
Matching Cushion Technology to Patient Needs
The “best” cushion is entirely dependent on the individual user’s specific risk level, mobility, and lifestyle, meaning a professional consultation is frequently necessary. For active users or those assessed as low risk, a high-density contoured foam cushion or a basic gel-foam hybrid may be appropriate, as they prioritize stability and ease of transfer. These individuals often perform independent pressure shifts and need a cushion that supports their movement.
Patients categorized as moderate risk or those with limited mobility generally benefit from cushions that offer a better balance of pressure redistribution and stability. Gel-enhanced or specialized viscoelastic foam cushions are often recommended here, providing adequate immersion and envelopment without the high maintenance of air systems. This approach helps manage pressure during longer periods of sitting without requiring constant attention to cushion settings.
Individuals who are high risk, have existing pressure injuries, or are unable to perform independent weight shifts often require the maximum pressure equalization offered by air flotation systems. These systems provide the highest degree of immersion and are clinically proven to reduce peak pressures at bony prominences. However, the patient or caregiver must be capable of consistently checking the air cell inflation, and the reduced stability of air cushions can make transfers more difficult for some users.
Other factors, like the ability to clean the cushion and the user’s microclimate concerns, also play a role in selection. For users with incontinence, a cushion with a fluid-resistant, cleanable cover is necessary. Some materials like foam can retain heat, which is a consideration for individuals prone to sweating. Ultimately, a qualified healthcare professional, such as a physical therapist or wound care specialist, should conduct an assessment to ensure the chosen cushion is the correct size and meets the user’s unique needs.