I’ve been following more vampire drama than is probably good for me, and it’s caused me to wonder about some practicalities. In the typical case, the creepy vampire has bitten the neck of a young woman; she’s standing at first, but slumps, then falls to the floor, dead. The blood loss appears to have ceased before she falls from her upright position.
Let’s assume we have a healthy adult woman who suffers some kind of trauma to the neck or collarbone region; she proceeds to lose blood from this wound at a rapid pace, until she dies. How much of her blood, either expressed as a total volume or as a fraction of the total, could she have lost? Certainly she would die before her heart pumps all of it through one particular open artery. Would it even be reasonable to say in this case that she were drained of her blood? Certainly there must be some car accidents or something in which the victim would lose more. The fact that the person remains held upright until she dies must factor into it as well. Anyone have insight to share?
The human body has around 5L of blood. (~70mL/Kg)
Hemorrhagic shock (the shock you go into from bleeding out) gets really really bad odds for survival if you end up losing 2L in 15-20 mins from an accident, even in an ER.
So if the Vampire’s blood has an anti-coagulant in it, and he goes for a carotid artery (because a jugular vein would bleed too slowly- gotta go for an artery for the spurting blood), he could theoretically cause death for her pretty much when she’s lost 2L.
And according to my pathophys notes: Rapid Hemorrhagic shock is blood loss that makes it difficult for the body to compensate due to the speed of the loss of blood volume. Significant shock symptoms arise at >15% blood loss within minutes to hours.
For slower blood loss, there can be compensation by the body, this is more along the lines of days to months- and here it’s possible for up to 70% of the blood to be lost with few symptoms being present.
It’s all up to the time element in the blood loss.
So you can tolerate a rapid blood loss of up to 15% or so, before you start to have symptoms of anemia, shock, and perfusion/ tissue oxygenation problems. Once you’ve rapidly lost 15% or more, you’ll start to get the clammy, pale look, and the possibility of fainting comes into play.
Just a thought, but would the fact that the blood which is being drawn from the artery is being stopped before it reaches the brain (it’s been a while since GCSE biology, but I’m quite sure that arteries go to organs from the heart), hence for all intents and purposes cutting it off, have a faster effect?
Imho, you are confusing the world of science fiction with the world of fantasy. Vampire fiction has rarely (since Matheson’s I am Legend) been scientifically based. That being said, fantasy vampires do what they do without scientific basis.
I hate it when fictional vampires drain a human in, like, six seconds. Even if you’re magical, you can’t even drink that fast through a straw, let alone two little tooth holes!
Fair enough and a totally valid point. The loss of blood to the brain would induce fainting. My notes from class are meant to be applied to actual trauma victims coming in- usually they’ve got massive bleeds due to trauma (most common being vehicular accidents).
So yeah- I didn’t really factor in the blood loss to the head causing signs of fainting and such- so I guess you’d have a greater morbidity in those cases.
I would imagine that the physiology of a human vampire would have some similarities to a vampire bat,so how much blood would he/she need on a nightly basis?