Blood Loss - A Practical Demonstration

Now what we are going to do is a small demonstration, how different surfaces affect blood volumes. So, what you come across, you need to relate to the surface the blood is actually sitting on to give you some idea of how much blood the potential patient has lost and you will see from this demonstration how different surfaces absorb blood at a different rate. In front of me, there are four glasses with a quarter of a pint of blood in each glass. Also in front of me are four different surfaces. We have got sand, gravel, a blanket, and we have got brick. And what we are going to do is to apply the blood to each surface in the same amount so you can see the difference in spread and absorption of that blood. So the first surface we are going to actually pour blood on to is actually ground soil and this is a very sandy surface.

You can clearly see how the blood absorbs into the soil, but it also runs and trickles and travels quite a long way. It has not absorbed directly into the ground very quickly, but it has spread an awful long way. The second surface that we are going to demonstrate is gravel. So, we'll use exactly the same amount of blood and use the same technique.

As you can clearly see, exactly the same amount of blood on a totally different surface gives you a totally different fingerprint. The third surface we're going to use is an ambulance blanket. Again, the same amount of blood poured into the same area.

And you can see the way the blanket gradually stops to absorb the blood. A bit bigger fingerprint than the gravel, but nowhere near as bad as on to the soil. Another thing to note about the ambulance blanket or any clothing is the blood will penetrate through, carpet is a classic where it goes through from the surface and spreads out underneath. So again, don't be fooled by the pattern on the top that's gone through four layers of ambulance blanket and spread out on the surface below. The final surface we're going to use is brick paving. So again, exactly the same amount of blood poured on a brick paving surface.

Now, you can see there's no absorption. Looks like a massive pool of blood and it stays in the position it fell. So, you can clearly see if we pan through from hard surfaces to clothing or blankets, to gravel, and onto the soil itself, the massive difference pattern that you will get from the same amount of blood depending on the surface it falls on. So remember, what might not look a lot of blood could actually be an awful lot of blood, it's just the way it's being presented because of the surface it's lying on. So finally, what we're going to have a look at is the absorbency of two different types of dressing. A size four ambulance dressing and a major trauma or a battlefield dressing used in the military or for gunshots or bullet wounds. Again, we've got the same amount of blood, but we'll pour the first one on to the size four dressing. And you will see how it slowly absorbs the blood we were just applying to the dressing. You will note it's absorbed the quarter of a pint of blood, but very quickly, it's penetrated through the bandage. The carrying capacity of this bandage is nowhere enough to cope with a quarter of a pint of blood as you can see it's dried away penetrating. So again, we're now going to apply to the military-grade bandage, and you'll see again how this bandage absorbs the same amount of blood, but there's no penetration through the dressing whatsoever.

It's absorbed and held all of the blood actually into the dressing area without coming through apart from through the bandage area where I spilt it. Compare that to an ambulance dressing, which is leaked totally and completely failed. So, using the appropriate bandages to deal with the appropriate bleed is extremely important, as I think you'll see this demonstration clearly shows.