In the matter of how far is too far when allowing doctors to heal us, when what you do is in violation of gods commandments.
In Acts 15:28&29 we see that the command to have nothing to do with blood is still relevent:
"For the holy spirit and we ourselves have favored adding no further burden to you except these necessary things: 29 to keep abstaining from things sacrificed to idols, from blood, from what is strangled, and from sexual immorality. If you carefully keep yourselves from these things, you will prosper. Good health to you!”
What Luke is saying here is that we are to continue to follow those commandments of the old law. It was not just to not eat blood. We are told to abstain from it.
Abstain,Merriam-Webster.com,Merriam-Webster, n.d. Web. 23 Nov. 2013:
"To refrain deliberately and often with an effort of self-denial from an action or practice (abstain from drinking, consumption of a food or a drug or indulgence in sexual intercourse)"
If we are abstain from blood, then we reject it in any form. To illustrate, when your doctor tells you to abstain from drinking alcohol, do consume it in another form? Would you then inject the alcohol into your veins? If you have alcohol in you then you have not abstained from it. This is the same way with blood.
That is with medical reasons aside.
In the US, the chances of getting diseases from a blood transfusion are low, but are still possible. Why risk it when you can use blood alternatives that have no risk?
Transfused blood can take up to a full day to reach full oxygenation. A blood substitute can be fully oxygenated immediately. Natural replenishment of lost red blood cells usually takes months, so an oxygen-carrying blood substitute can perform this function until blood is naturally replenished.
Artificial blood is OK to use by that scripture. In some cases they don't even use plasma such as saline and Hyper-branched polymer-protected porphyrins.
"Often simple saline solution, Ringer’s solution, and dextran can be used as plasma volume expanders, and these are available in nearly all modern hospitals. Actually, the risks that go with use of blood transfusions are avoided by using these substances."
Insight from the scriptures shares with us many reasons why it is better to abstain from blood. It also has information an many different bloodless options available.
Here is another magazine one the topic. How can blood save your life?
There is of course another angle to this. What if you should die because you rejected and abstained from blood? We gain courage from Matthew 16:24-25:
"Then Jesus said to his disciples: “If anyone wants to come after me, let him disown himself and pick up his torture stake and keep following me. 25 For whoever wants to save his life will lose it, but whoever loses his life for my sake will find it.
We have faith in the resurrection, so we know if we lose our life because we observed Gods commandments that he will give it back to us and add to it.