Final answer:
A pressure ulcer is a serious condition due to long-term, unrelieved pressure on the skin, leading to tissue necrosis, especially in immobilized patients.
Step-by-step explanation:
A pressure ulcer, also known as a decubitus ulcer, is a serious condition that affects the skin and its underlying tissue resulting from excessive pressure. It occurs most often in bony areas of the body when there is long-term, constant pressure that reduces blood flow, leading to tissue necrosis or death. These ulcers are seen frequently in patients who are immobilized, such as the elderly with debilitating conditions, and require vigilant care to prevent them. Hospitals and long-term care facilities often implement a schedule of turning patients every few hours to mitigate this risk. Without proper treatment, which may include the removal of necrotized tissue, these ulcers can become infected and pose a life-threatening risk.