Blood transfusions and Christianity? Inspired by this question, if we choose to allow a doctor to heal us, how far is too far?

In Lev 17:13-14:


  13 “‘Any Israelite or any foreigner residing among you who hunts any
  animal or bird that may be eaten must drain out the blood and cover it
  with earth, 14 because the life of every creature is its blood. That
  is why I have said to the Israelites, “You must not eat the blood of
  any creature, because the life of every creature is its blood; anyone
  who eats it must be cut off.”


Some groups have gone far enough to say that they won't take blood transfusions or even transplants. Does the preservation of life supersede this verse?

And, although a bit Sci-Fi, does the above verse conflict with the idea of artificial blood?

I think it's fine, but I've been wrong about stuff before.
In Mark 3:1-6, Jesus heals a crippled man's hand on the sabbath:


  Jesus went into the synagogue again and noticed a man with a deformed hand. 2 Since it was the Sabbath, Jesus’ enemies watched him closely. If he healed the man’s hand, they planned to accuse him of working on the Sabbath.
   3 Jesus said to the man with the deformed hand, “Come and stand in front of everyone.” 4 Then he turned to his critics and asked, “Does the law permit good deeds on the Sabbath, or is it a day for doing evil? Is this a day to save life or to destroy it?” But they wouldn’t answer him.
  
  5 He looked around at them angrily and was deeply saddened by their hard hearts. Then he said to the man, “Hold out your hand.” So the man held out his hand, and it was restored! 6 At once the Pharisees went away and met with the supporters of Herod to plot how to kill Jesus.


I believe this sets a precedent that law wasn't created to destroy life but to give it.