Final answer:
Residents with head or spinal cord injuries need to be repositioned every two hours to prevent pressure ulcers and improve circulation, as they are at increased risk due to limited mobility.
Step-by-step explanation:
A resident with a head or spinal cord injury should be repositioned at least every two hours. This practice helps to reduce the risk of pressure ulcers, which are injuries to the skin and underlying tissue resulting from prolonged pressure on the skin. Those who have limited mobility due to head or spinal injuries are at a higher risk because they cannot easily change positions on their own. Regular repositioning not only prevents the development of pressure ulcers but also improves circulation and can help prevent muscle stiffness and discomfort associated with immobility.