Healing in combat

Even in a heated battle, adventurers can heal. They heal themselves by using second wind, and allies can administer first aid with the Heal skill or use healing powers on them.
    When a power heals your character, he or she doesn’t have to take an action to spend a healing surge. Even if he or she is unconscious, the power uses a healing surge and restores hit points. Some healing powers restore hit points without requiring your character to spend a healing surge.

Published in Player's Handbook, page(s) 293, Rules Compendium, page(s) 257.