A family member is getting one next week. I know im looking at it wrong, but if you have 8 pints of blood and they add in more where does the extra blood go? Or do they take some out first?
Tia
In: 4
They don’t give transfusions unless the blood count is low to begin with. So if you need 8 pints but only have 5, then you don’t have to make extra room.
Today transfusions are usually just the red blood cell component of blood, so its less about the added fluid volume and more about having more red blood cells.
But as for fluid volume, your blood vessels have muscle around them that allows them to become larger or smaller. So the total volume of blood can fluctuate somewhat without any issues just by opening up more vessels to make room. This happens all the time when you go from being dehydrated to hydrated as blood is mostly just water.
Your body is not like a rigid glass, it’s more like a water balloon, it can expand and shrink based on how much food, blood, water, air is in it.
So really that 8 pints of blood is just an average, a bigger guy might have 9 or 10 pints, someone super small maybe only 6 or 7.
Plus, blood is mostly water, so depending on how hydrated or dehydrated you are can play into how much volume your blood takes up.
There is room for a bit extra in your blood vessels.
Think about it like this; if you are not dehydrated but you sit an drink 2 pints of water, that water gets absorbed into your blood system. It will happen gradually over maybe an hour or two, but there is room for it.
Your blood then gets filtered through your kidneys, and if you have drunk lots, you will make more urine than usual and pee more, which balances out the amount of liquid in your blood to a normal type level.
Since your family member is getting g a transfusion next week (and not today) it means they are anaemia but not dehydrated. So they have enough fluid in their blood vessels, but not enough red cells. The blood they will be given is not whole blood (ie straight out of someone else and nothing done to it). Donated blood is processed and split into different useful products. They will get a transfusion of concentrated red cells that will be about 350-500 millilitres per unit. So if they only get one unit, that’s like drinking a bit less than a pint.
The blood transition will be don’t slowly, often over 3-4 hours so that there isn’t a sudden increase in the volume in their blood vessels. This allows the body/blood vessels to adapt to the extra volume in the same way it would if the extra volume was coming from the gut.
So people tend to think of blood as a unique thing in and of itself, but really “blood” is just water with a bunch of blood components in it. The amount of “blood” you have fluctuates with the amount of water you have in your system. Our bodies can account for that. Most of the blood in our bodies is sitting in our veins. Roughly 70% of our blood is in our veins at any given time. That number will increase and decrease as you get more or less hydrated. Adding a pint of blood is really no different than drinking a pint of water.
Latest Answers