Final answer:
The nurse declines to administer mannitol due to increased serum osmolality. Mannitol could worsen this condition by increasing solute concentration in the blood, which may lead to complications such as dehydration or cellular damage.
Step-by-step explanation:
The condition that supports the nurse's intervention to decline the administration of mannitol to the patient is increased serum osmolality. Mannitol is an osmotic diuretic that promotes water loss by osmosis and is used to reduce brain swelling. However, when serum osmolality is increased, this indicates that there is already a high concentration of solutes in the blood, and administering mannitol would further increase this osmolality, potentially leading to additional health complications such as dehydration or damage to cells, rather than resolving cerebral edema or cerebral tissue swelling.
Mannitol administration might be indicated for conditions like cerebral edema, cerebral tissue swelling, or increased intracranial pressure (ICP), where the benefits of reducing swelling and pressure outweigh the risks associated with increased osmolality.