Final answer:
The nurse should assess for a decrease in intracranial pressure (ICP) to determine if mannitol is having the desired outcome in a patient with a head injury. Signs of reduced ICP may include improvements in neurological function or direct measurements of decreased pressure.
Step-by-step explanation:
The nurse is evaluating the efficacy of mannitol, an osmotic diuretic, administered intravenously to a patient with a head injury. Mannitol functions by drawing water out of the swollen tissue, thereby reducing tissue volume and decreasing intracranial pressure (ICP). To determine if the mannitol is having the desired outcome, the nurse should assess for a decrease in ICP. This may be done via direct monitoring methods such as intraventricular or intraparenchymal ICP monitoring or by observing for clinical signs such as improved neurological function, reduced headache, or alleviation of other symptoms caused by increased ICP.
Signs of increased intracranial pressure may also be indirectly assessed by noting changes in vital signs, ocular symptoms, or changes in the level of consciousness. While other changes like increased blood pressure and decreased body temperature may occur, they are not the primary indicators of medication efficacy in this context. Additionally, unlike mannitol, if glucose is acting as an osmotic diuretic in poorly controlled diabetes, it primarily leads to polyuria, polydipsia, and polyphagia but does not directly reduce intracranial pressure.