Final answer:
To prevent aspiration of blood in severe epistaxis, the patient should lean forward and breathe through the mouth while pinching the nose. Tilting the head back should be avoided, and for profuse bleeding, nasal packing might be necessary.
Step-by-step explanation:
When caring for a patient with severe epistaxis, an effective way to prevent aspiration of blood is to have the patient lean forward and breathe through their mouth while pinching the soft part of the nose. It's important to avoid having the patient tilt their head back, which can cause blood to flow down the throat and lead to aspiration. For profuse bleeding, you may also need to utilize nasal packing or a nasal sponge to help control the hemorrhage while maintaining an open airway.