When Vampire Novels Get It Wrong–Part I

I admit it: I nitpick the science in novels I read.

Take Anne Rice’s Interview With A Vampire–those best-known vampire novel of the last few decades. When I read this novel, I couldn’t help being distracted by the fact that, when the vampires in it are draining blood from someone they can hear the person’s heartbeat (okay, I can buy that part; Rice’s vampires have supersensitive senses, including hearing) and the person’s heartbeat is getting slower and slower until the vampire drains so much blood that the person dies.

"This is not what would happen," I said to myself.

A person about to die from vampire predation would be suffering from acute posthemorrhagic anemia, whose symptoms are known, though in the real world they are more commonly caused by accidents than vampire predation. The symptioms include faintness, dizziness, thirst, and sweating. Gradually slowing heartbeat AIN’T one of them, though.

In fact, you get just the opposite.

If you suddenly lose a whole bunch of blood then there is a mechanical process that takes place which is relatively easy to understand. With the sudden subtraction of a bunch of your blood volume that means you’ve got LESS blood in your circulatory system. That means that your blood pressure goes DOWN. That means that your heart will pump FASTER to try to keep your blood pressure up so that oxygen can keep getting to your cells, and you will go into TACHYCARDIA.

Eventually, the amount of blood loss will overtax the heart’s ability to pump fast so that it can’t push through enough blood because the chambers don’t have the chance to fill completely and the heartbeat will be rapid and weak. The heart itself will also start suffering oxygen deprivation and you’ll have a myocardial infarction or "heart attack." Eventually you get things like uncontrollable falling blood pressure and fatal cardiac arrythmias.

Not quite so romantic–eh?

But in Interview with the Vampire it’s such a seductive experience that the vampires have to STOP themselves from draining a victim so that they don’t get drug down into death with him.

Why that is, I’m not sure. If all you’re doing is moving blood from the victim to yourself then (assuming you can metabolize blood), you’d be STRONGER as the victim gets closer to death.

What’s more, the process of killing a victim by vampirism would be so revolting that it would have built-in factors that would cause you to want to let go at a certain point.

Unless vampires do something that allows them to bypass the normal rules of cardiology, their victims’ hearts won’t just slow gently down as they drop into the sleep of death. It’ll be a much more traumatic thing than that with the victims’ hearts speeding up, getting faster and weaker and more irregular until the victim dies, possibly amid classic heart attack symptoms like chest pain and numbness in the left arm and nausea and vomiting and dizziness and things like that.

ICK!

What vampire wouldn’t want to pull away before THAT happens!

Reading the novel, I also found myself wondering: "Just how long do these vampire predations go on? Wouldn’t it take quite a long time to get enough blood out of a person to kill him?"

It turns out that the amount of blood you can lose without dying depends on how fast you lose it. If you lose it rapidly, you can only stand to lose about 1/3rd of your blood volume (3-4 pints). But if you lose it slowly–say, over a 24 hour period–you can lose up to 2/3rds of your blood volume (6-8 pints). If a vampire sucked you dry slowly, over the course of a day, he could get a lot more out of you before you died, but that isn’t the way vampire predations are typically depicted. They’re much faster things.

So in a classic vampire attack, the vampire would only be able to pull 3-4 pints of blood out of a person before the person died.

That’s still a LOT of blood–especially if it’s being taken from two little holes in the blood vessels of the neck. I mean, I assume from the way that vampire attacks on the neck are classically depicted that they’re either going after the carotid artery or the jugular vein, but even though these are large blood vessels, it seems to me that it would take a significant amount of time to suck 3-4 pints out of one of these, especially (in the case of the carotid artery) without starving the brain of oxygen and causing the victim to go unconscious for that reason (as opposed to hypnotism or something).

Such long predations might be possible in the seclusion of a house, but not in a darkened alley in London with lots of people walking around and stuff.

Now, I know that vampires are supposed to be supernatural beings who may have ways of circumventing what would normally happen in the real world in such situations (like their ability to hypnotize the victim into staying still for all of this), but I still think that the authors of vampire stories could do with some medical research as part of all the other research (e.g., of a historical nature) that they do for their stories.