Final answer:
Keeping the head of the bed elevated to 30 degrees is the most appropriate nursing intervention for an unconscious patient with a diagnosis of ineffective cerebral tissue perfusion, as it helps reduce intracranial pressure.
Step-by-step explanation:
An unconscious patient with a nursing diagnosis of ineffective cerebral tissue perfusion related to cerebral tissue swelling would benefit most from an intervention that aims to reduce intracranial pressure and promote venous drainage from the brain. The appropriate nursing intervention to be included in the plan of care for such a condition is a. Keep the head of the bed elevated to 30 degrees. This position helps lower intracranial pressure by promoting venous return, thereby potentially improving cerebral perfusion. While interventions such as encouraging coughing and deep breathing (c) and clustering nursing interventions to provide uninterrupted rest periods (d) are important in general patient care, keeping the head of the bed elevated is specifically targeted towards addressing the cerebral swelling and its effects on brain perfusion.