Pathology cases: Aspiration of blood

This is the case of a man who was shot in the chest.  At autopsy, the bullet perforated the left lung, and there was a left hemothorax of around 1400 cc.  At autopsy, both lungs were hyperinflated.

Here are pictures showing the entrance and exit through the left lung:

Here’s a slice through the left lung showing the disruption and diffuse hemorrhage along the path of the bullet:

The right lung was also hyperinflated, but had a pattern of hemorrhage on cut surface that is characteristic of aspiration of blood.  Aspiration of blood results in collection of blood into alveoli where it fills lobules.  This results in little dots of blood scattered throughout the lung:

There are a million reasons why there might be blood in the lungs, and a thousand different patterns for it.  This punctate pattern, however, is suggestive of aspiration.  I’ve seen a similar pattern with a vasculitis, and something a *little* like this in a case where someone was showering their lungs with small thromboemboli.  It’s not only lung injury that provides this, of course.  I see it more often in my practice in gunshot wounds to the head in which death is not rapid and blood drains from the cranium into the mouth, where it is inhaled and swallowed. With aspiration of blood you usually (though not always) see blood in the stomach as well.  In this case there was relatively little blood in the upper trachea and oropharynx, which is often also blood stained in head wounds resulting in aspiration.

Sometimes in cases like these you will be asked to opine about time until death.  You know that the death was not immediate.  The presence of 1.4 liters of blood in the left chest and scene evidence of substantial bleeding at the scene indicates a classic amount of hemorrhage associated with exsanguination.  In general, the heart stops beating when you lose around 40% of your blood volume, which in most folk is 1500-2000cc.  Most articles suggest unconsciousness at about 1400cc and death around 2000cc, but in my experience, we usually get 1400+ cc from the body.  That’s not surprising, since significant blood can be left at the scene or otherwise not harvested.  For a clinical evaluation of the relationship between blood loss and unconsciousness and death, see: Gutierrez, G., Reines, H. and Wulf-Gutierrez, M.E., 2004. Clinical review: hemorrhagic shock. Critical care, 8, pp.1-9.  Of course, in some cases, such as gunshot wounds where there his no space for blood to collect, you might not see much at all.  I recently had a case of a gunshot wound that severed the femoral artery in which almost all of the blood was left at the scene.

The problem is that the rate of bleeding is a function of the size of the hole, the size of the vessel, and the health status of the decedent.  So, you can say it was not immediate, but you really don’t know how long it took.  More important, you certainly don’t know the time until unconsciousness.  A victim may collapse immediately due to the autonomic effects of the trauma, or may struggle for some time.  Be cautious.

Also be aware that estimating blood volume by looking at the rug or a floor is fraught with danger of significant error.  Be very careful and know your literature before you attempt that.