How patient migration in bed affects the sacral soft tissue loading and thereby the risk for a hospital-acquired pressure injury

Head-of-bed (HOB) elevation is a common clinical practice in hospitals causing the patient's body to slide down in bed because of gravity. This migration effect likely results in tissue shearing between the sacrum and the support surface, which increases the risk for pressure injuries. StayInPlace (HillRom Inc.) is a commercial migration-reduction technology (MRT) incorporated in intensive care bedframes. Yet, the effects of migration-reduction on tissue shear stresses during HOB elevation are unknown. We analysed relationships between migration and resulting sacral soft tissue stresses by combining motion analysis and three-dimensional finite element modelling of the buttocks. Migration data were collected for 10 subjects, lying supine on two bedframe types with and without MRT, and at HOB elevations of 45 degrees/65 degrees. Migration data were used as displacement boundary conditions for the modelling to calculate tissue stress exposures. Migration values for the conventional bed were 1.75- and 1.6-times greater than those for the migration-reduction bed, for elevations of 45 degrees and 65 degrees, respectively (P < .001). The modelling showed that the farther the migration, the greater the tissue stress exposures. Internal stresses were 1.8-fold greater than respective skin stresses. Our results, based on the novel integrated experimental-computational method, point to clear biomechanical benefits in minimising migration using MRT.