Final answer:
A patient who has suffered an ischemic stroke should be encouraged to begin mobilization as soon as medically possible to prevent muscle atrophy and other complications, facilitating better recovery.
Step-by-step explanation:
The principle of care that should inform the nurse's response to the family of a patient who has experienced an ischemic stroke is that the patient should mobilize as soon as she is physically able. Early mobilization is crucial as lack of mobility can lead to complications such as contractures, muscle atrophy, and increased risk of additional strokes. Moreover, physiotherapists recommend exercises to help restore muscle function and minimize functional impairments, suggesting that remaining in bed without physical activity can have detrimental effects on recovery.