Modelling an Adult Human Head on a Donut-shaped Head Positioner for Pressure Ulcer Prevention

Introduction: Frequent repositioning has been shown to reduce the risk of pressure ulcers, but it can be challenging to perform during surgery where patients endure prolonged deformations in their weight-bearing soft tissues. Donut-shaped gel head positioners are commonly used in adult surgery to protect the occiput by moving the forces from the bony prominence.

Methods: To determine magnitudes and distributions of occipital soft tissue loads while using head positioners, we employed a three-dimensional anatomically-realistic finite element model of an adult head and related computational methodology of analysis reported in our previous work. The head applied its weight in simulations where it was resting on donut-shaped positioner, fluidised positioner, and standard medical foam. Scalp stresses were calculated for each positioner and compared across positioners.

Results: Stresses in skin and fat tissues of the head resting on the donut-shaped positioner formed a focal circular distribution around the occiput and peaked at the inferior head/neck region. The donut-shaped positioner considerately increased the exposure of these scalp tissues to elevated stresses compared to a fluidised positioner, and also, although less profoundly, with respect to foam.

Conclusions: Donut-shaped positioners off-load a central region at the back of the head but shift loads to a ring of scalp tissues which is highly deformed, especially in the inferior head/neck area. A medical foam is more successful than a donut positioner in dispersing scalp loads but is still limited in conformability relative to a fluidised positioner which maximizes head envelopment, and hence, the contact area.