Pivoting Inflatable Support Overlay for Shear-Controlled Perfusion
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Solution Overview
Problem
Existing support surfaces fail to adequately address the issues of vascular occlusion and shear force-induced capillary blood flow occlusion, leading to decubitus ulcers, despite efforts to redistribute pressure and mitigate shear forces.
Innovation Solution
A support surface overlay with selectively inflatable compartments that include pivoting elements, which apply and release shear forces to enhance perfusion by alternatingly applying and releasing interface pressure and shear forces on the skin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If traditional redistribution surfaces with large air cells are used, then weight distribution is improved, but interface pressure remains insufficient to enhance perfusion
Solution Approach 1:
The support surface overlay is divided into multiple discrete inflatable nodes or cells, each capable of independent pressure application. This segmentation allows localized high-pressure zones to form at specific contact points, enabling interface pressure to exceed the vascular occlusion threshold for perfusion enhancement while maintaining overall weight distribution through the distributed node array.
Solution Approach 2:
The system dynamically changes the pressure parameter within inflatable nodes, transitioning between low-pressure states for weight distribution and high-pressure states for perfusion enhancement. This parameter modulation allows the same structure to serve dual functions: redistributing weight across large areas while periodically applying concentrated pressure pulses to enhance blood flow.
2Force
If frictional engagement is used to prevent sliding, then shear force is applied to skin, but capillary blood flow is occluded
Solution Approach 1:
The inflatable nodes apply shear force periodically through cyclic inflation and deflation, rather than maintaining continuous frictional engagement. This periodic action creates alternating phases of high shear force (during inflation/deflation) and low shear force (during stable states), allowing capillary blood flow to recover during low-shear intervals while still achieving perfusion enhancement during high-shear phases.
Solution Approach 2:
The system transitions from static frictional engagement to dynamic, controlled shear force application. The inflatable nodes move and deform in a controlled manner, applying shear force only when necessary for perfusion enhancement, then releasing it to allow blood flow recovery. This dynamic approach replaces continuous harmful friction with intermittent, beneficial shear stress.
3Reliability
If thinner overlay with smaller air cells is used, then perfusion is enhanced through higher pressure, but user walks along the surface when inclined
Solution Approach 1:
The segmented node structure provides discrete contact points that can independently adjust to user position and surface inclination. This segmentation creates a stable, adaptive interface where nodes can maintain contact without requiring the entire surface to be rigid, preventing user sliding while preserving the high-pressure perfusion enhancement capability of individual nodes.
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 overlay enhances perfusion by controlling the application and release of shear forces, thereby improving blood flow and reducing the risk of decubitus ulcers.
Implementation Method 1
Another factor that contributes to occlusion of capillary blood flow is application of shear force to the skin (sometimes referred to as skin shear). Shear force may be applied to the skin, for example, by a surface pulling the skin in a direction generally parallel to the skin through frictional engagement with the skin.
Implementation Method 2
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 3
interface pressure between the support surface and the user's body generally remains below the vascular occlusion threshold
Data Source
AI summary
A support surface overlay includes a selectively inflatable compartment including a plurality of selectively inflatable 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.