Nux uses Mad Max as a "blood bag" in Fury Road.
At first he is suspended upside down in the Citadel to hasten blood draining. Later, Mad Max is chained to the front of a car with a blood line going from his neck along a chain back to Nux. Most of the blood line looks red even during the first road chase scene, but I don't know if the blood was actively flowing through it at that moment.
Mad Max suffers several injuries throughout the film, yet he remains very physically active and mentally alert. He fought for several hours despite heat, dehydration, and lack of rest. At one point in the film, Max gives his blood to Furiosa for a few minutes, thus reducing his blood volume even more.
Wikipedia says that a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties. Beyond that, a person develops a rapid heartbeat as the heart gears up to pump the lower volume through the body quickly to keep the body oxygenated. Severe blood loss can lead to shock, reduced body temperature, lethargy, lowered mental acuity, unconsciousness, and death.
So how much blood did he lose?
I prefer answers from canon sources. (Movie scripts, novelization, or comments by cast and crew.)