[another_someone]

A couple of weeks ago, I was listening to a broadcast (over the Internet) on BBC7 of Agatha Christie's Unnatural Death.  The premise of the story was that an several people were murdered by having a syringe full of air injected into their veins, which caused a blockage that lead to heart failure that was indistinguishable from a natural heart attack.

Over many years I had assumed that this method of killing, while maybe not as undetectable as claimed in the book, nonetheless was an effective way of killing a person.

Thinking about this more recently, it occurred to me that air bubbles in the blood stream is exactly what causes divers bends, and although the bends can be fatal, they can as easily cause permanent paralysis, or any number of other outcomes, and the end result cannot be absolutely predicted, nor can one say that the outcome was indistinguishable from a natural heart attack.

While one cannot reasonably expect fiction writers to get all their fact right (some make a greater effort to do so than others), as a matter of personal curiosity, how right or wrong was Agatha Christie in this matter?

George

[qazibasit]

Well its nothing new. But injection of air not always leads to death. Still it is distinguishable coz u can find the site of injection and yes if given intra arterial can cause myocardial infarction but usually the air is diffused into the interstitium due to high laminar blood flow in the vessels.

[iko]

It depends on the amount of air injected intravenously in a short time.
For a rabbit 20mL may be enough, much more for humans, probably (ask Dr.Mengele for details). The lethal effect is due to the air bubbles accumulating in the right circle (right atrium&ventricle) being compressed by the pump and stopping blood flow.
A little amount of air (bubbles from a heavily-shaken sterile saline bottle) is safely used to spot abnormal communications from the right to the left atriums under echo-scan.
iko

[another_someone]

Thanks for the clarification.

George

[iko]

You're welcome.
I forgot to say that air embolism in divers is quite different but sometimes lethal as well. In this case little bubbles formed by too fast decompression aren't only in the right circle (right atrium, ventricle and to the lungs) but also in the arteries: in a medium/small vessel even a tiny air bubble may temporarily stop blood from flowing and carrying oxygen around.  The most devastating consequences are obviously in cases of cerebral embolism.
iko

[Mjhavok]

Isn't the bends caused when nitrogen comes out of solution in the body?

Steven

[iko]

Exactly, Steven.
And little gas bubbles in the arteries cause troubles.
Ask the physics about tension forces in a bubble that lead to a block of the blood flow. I know that it happens.
iko