Final answer:
Battle sign indicates potential skull fracture and is seen as bruising behind the ears. Leukocytosis, an elevated white blood cell count, is a common response to burns and reflects the body's reaction to stress, infection, or inflammation.
Step-by-step explanation:
When performing the secondary assessment on a trauma patient, Battle sign's presence indicates the bruising behind the ears, suggesting a potential skull fracture. In the case of a patient who has been admitted to the burn unit with a severe burn covering their left upper extremity and shoulder, a blood test revealing leukocytosis is an expected finding. Leukocytosis, which is an elevated white blood cell count, is a common response to burns or other types of significant bodily stress as the body mounts a response to infection or inflammation.