A nurse is caring for a patient experiencing a sickle cell crisis. Which nursing action is the most effective to reduce the vasoconstrictive effects that can worsen the crisis?

A. Encourage intense physical exercise: Exercise increases oxygen demand and can worsen sickling and hypoxia, further exacerbating the crisis. B. Limit fluid intake: Dehydration increases blood viscosity, which promotes sickling and vessel obstruction. Fluids should be increased, not limited. C. Encourage the patient to drink plenty of fluids: Hydration is a priority in sickle cell crisis. It reduces blood viscosity, which helps the "sludge" of sickled cells flow more easily through the vasculature, reducing vaso-occlusion. D. Apply cold compresses: Cold causes vasoconstriction, which slows blood flow and worsens the sickling process. Warmth is preferred for pain.