Dynamic Shear and Normal Forces on Patient Skin in Sling Lift Transfers

The sling lift transfer system is commonly used in hospital and care home settings to transfer immobile and limited mobility patients from bed to chair or gurney. Even though this is the current standard of care, injuries to patients because of the forces applied to skin by the lift occur frequently. The lifts cause both normal and shear forces on the skin, and previous studies have only measured and reported on the applied normal forces with no assessment of shear. In this work, we use a novel shear and normal force sensor designed specifically to assess forces on skin and report the dynamic normal and shear forces during a sling lift. The shear forces are shown to be up to 8N for a partial lift of an adult male and occur both laterally and longitudinally along the thigh. Shear forces pull the skin and can cause injury, especially as skin tends to thin with age and become more susceptible to damage. This is the first reporting of shear forces during patient lifts.