Support Surface Overlay With Inflatable Pivoting Elements for Shear Control
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Solution Overview
Problem
Conventional support surface overlays fail to effectively manage shear forces and contact pressure, leading to potential decubitus ulcers, especially when inclined, due to uncontrolled application and release of shear forces, which can cause lateral displacement and occlusion of capillary blood flow.
Innovation Solution
A support surface overlay with selectively inflatable compartments and pivoting elements that apply and release shear forces in a controlled manner, combined with body retention features like straps and a deformable layer to enhance perfusion and prevent lateral displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If frictional engagement is used to prevent lateral displacement on inclined surfaces, then user retention is improved, but shear force application to the skin increases causing capillary blood flow occlusion
Solution Approach 1:
The support surface is divided into multiple independently controllable inflatable segments or zones. By selectively inflating and deflating specific segments, the system creates localized frictional engagement to prevent lateral displacement while allowing other areas to remain low-shear, thus resolving the contradiction between user retention and shear force reduction.
Solution Approach 2:
The support surface transitions from a static configuration to a dynamic one where inflatable elements can be selectively activated and deactivated. This dynamic adjustment allows the system to apply frictional forces only when and where needed for user retention, minimizing overall shear force application to the skin while maintaining stability on inclined surfaces.
2Stress or pressure
If traditional redistribution surfaces are used to distribute weight, then contact pressure is reduced, but the system becomes thick and complex
Solution Approach 1:
The patent employs inflatable elements (pneumatic system) to create a thin yet effective pressure redistribution surface. The air-filled segments can be inflated to provide pressure relief and deflated to reduce thickness, offering a compact solution that maintains low contact pressure without requiring the substantial thickness of traditional foam or cushioning materials.
Solution Approach 2:
The system dynamically changes the inflation parameters (pressure and volume) of the inflatable elements to optimize both pressure redistribution and thickness. By adjusting these parameters, the surface can transition between different states - providing maximum pressure relief when inflated and minimizing thickness when deflated, thus resolving the contradiction between pressure reduction and thickness control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances perfusion by alternatingly applying and releasing shear forces, reducing the risk of decubitus ulcers by maintaining capillary blood flow and preventing lateral movement, even on inclined surfaces.
Implementation Method 1
frictional engagement of the skin with the support surface counteracts the parallel force component and prevents the user from sliding off of the support surface. In doing so, the frictional engagement force pulls the user's skin in a direction generally parallel to the skin, and thus contributes to occlusion of capillary blood flow in the frictionally-engaged region of the skin.
Implementation Method 2
Another factor that contributes to occlusion of capillary blood flow is application of shear force to the skin (sometimes referred to as skin shear).
Implementation Method 3
One factor that contributes to occlusion of capillary blood flow is application of contact pressure to human skin (sometimes referred to as interface pressure) in excess of the vascular occlusion threshold, which commonly is regarded to be about 28-32 mm Hg.
Implementation Method 4
Such contact pressure may be applied to the skin, for example, in a direction having a component normal to the skin in response to the force of gravity applied to a human lying on a support surface
Data Source
AI summary
A support surface overlay includes a selectively inflatable compartment including a plurality of selectively inflatable pivoting elements configured to pivot with respect to adjacent portions of the overlay when the selectively inflatable compartment is inflated and deflated. The pivoting elements are configured and operable to selectively apply and release shear forces to and from the skin of a user lying upon the overlay when the selectively inflatable compartment is inflated and deflated. The support surface overlay may include a body retention feature configured to hinder lateral displacement along or across a body-supporting surface of the support surface overlay in response to inflation and deflation of the selectively inflatable compartment or otherwise. The body retention feature may be a body retention strap including a selectively inflatable pivoting element configured to pivot with respect to an adjacent portion of the body retention strap when the selectively inflatable pivoting element is inflated and deflated. The body retention feature may be a deformable layer or inflatable bolster that envelopes a portion of a user lying on the support surface overlay and thereby resists slippage of the user.