Blood Transfusions

[TeeDee]

I was watching some pulp fiction earlier on - someone giving a direct blood transfusion to another family member.

So in the very very Hypothetical Hollywood type scenario where blood is being transfused from one to another - how much can be 'safely' , but realistically ( ie if you REALLY needed to do so ) be tapped off in X time?? Is there a rule of general thumb or some sort of medical ratio of pints over Hours?

 

[Pattree]

I don’t know the answer to your question but I do seem to remember that the first ever blood transfusion was direct. The doctors concerned were so pleased with the outcome for the recipient that they forgot about the donor. He spent some time convalescing. If memory serves both donor and recipient were imprisoned criminals.

They were also incredibly lucky because blood typing hadn’t been discovered at that point. It took several fatal subsequent experiments before blood types became understood.

 

[Tengu]

But, to start, you would have to know the peoples blood type?

 

[Broch]

I was watching some pulp fiction earlier on - someone giving a direct blood transfusion to another family member.

So it the very very Hypothetical Hollywood type scenario where blood is being transfused from one to another - how much can be 'safely' , but realistically ( ie if you REALLY needed to do so ) be tapped off in X time?? Is there a rule of general thumb or some sort of medical ratio of pints over Hours?

Really interesting question, not that I'm about to experiment

I may be totally off the mark here but I would think it's more about blood pressure levels than flow rate. Presumably, for blood to flow from one person to another, there has to be a pump (or a head) that maintains the delivered blood pressure above the recipients blood pressure. I would think that the increase would have to be very marginal, which would result in a slow rate of transfer.

 

[TeeDee]

O

But, to start, you would have to know the peoples blood type?

Outside the scope of this question - assume you know.

 

[TeeDee]

Really interesting question, not that I'm about to experiment

I may be totally off the mark here but I would think it's more about blood pressure levels than flow rate. Presumably, for blood to flow from one person to another, there has to be a pump (or a head) that maintains the delivered blood pressure above the recipients blood pressure. I would think that the increase would have to be very marginal, which would result in a slow rate of transfer.

Is it as simple as the donor heart IS the pump ? That is the positive head of pressure?

I wonder if there is any history of such early transfusions beyond Patrees comments. Must be some medical staff here that have sat through the history of transfusions type classes.

 

[Broch]

Is it as simple as the donor heart IS the pump ? That is the positive head of pressure?

I wonder if there is any history of such early transfusions beyond Patrees comments. Must be some medical staff here that have sat through the history of transfusions type classes.

How would you make sure the donor's blood pressure is higher than the receiver? Without that there will be no blood flow.

(I confess to being totally ignorant on this subject and just trying to get my head around how it would work )

 

[slowworm]

So it the very very Hypothetical Hollywood type scenario where blood is being transfused from one to another - how much can be 'safely' , but realistically ( ie if you REALLY needed to do so ) be tapped off in X time?? Is there a rule of general thumb or some sort of medical ratio of pints over Hours?

Are you doing research for a very realistic vampire novel?

I can't help, I'd pass out after the first few drops.

 

[Broch]

I have a vision of the donor being up a set of step ladders, the nurse sucking on the transfer pipe until blood comes out and then inserting it into the delivery needle - so making sure there is the right flow rate by climbing up or down the ladder (but then, I'm an engineer!)

 

[TeeDee]

How would you make sure the donor's blood pressure is higher than the receiver? Without that there will be no blood flow.

(I confess to being totally ignorant on this subject and just trying to get my head around how it would work )

I maybe well off the mark but i'm thinking if one is in need of a impromptu top up the pressure maybe lower in the recipient for big hole / big cuts type reasons.

Off to do some research

 

[forrestdweller]

I don’t know the answer to your question but I do seem to remember that the first ever blood transfusion was direct. The doctors concerned were so pleased with the outcome for the recipient that they forgot about the donor. He spent some time convalescing. If memory serves both donor and recipient were imprisoned criminals.

They were also incredibly lucky because blood typing hadn’t been discovered at that point. It took several fatal subsequent experiments before blood types became understood.

iirc there's a scene in "hot shots2" where they give direct blood transfusion to one fellow, forgetting to unhook the donor until he's empty... (no idea why that comes into my mind right now... )
i also read/heard somewhere that green coconuts were used in WW2 in the Pacific as substitute for blood donors if nothing else was available, BUT i've no idea this is correct or a myth...

 

[HillBill]

Simple answer is no. You need a pump. You need matching blood types (as already mentioned) If you're giving someone an emergency blood transfer, By default, they've either lost some (you be buggered in that case) or they have a blood or liver problem... (you be buggered in that case too) So yeah... nah. It can never be a self sustaining closed circuit. You can give someone yours... but whos giving you theirs?

 

[TeeDee]

Simple answer is no. You need a pump. You need matching blood types (as already mentioned) If you're giving someone an emergency blood transfer, By default, they've either lost some (you be buggered in that case) or they have a blood or liver problem... (you be buggered in that case too) So yeah... nah. It can never be a self sustaining closed circuit. You can give someone yours... but whos giving you theirs?

But thats no different to me giving Blood down the blood bank is it.

A healthy non injured person ( Hence all the questions I tick off before I'm allowed to actually give blood and the mandatory finger ***** iron test ) will be able to donate a pint ( " A pint!!? Thats very nearly an Armfull!!" - Hancock ) and then have a sit down , biscuit , crisps and a glass of the weakest known squash in existence ( Only a great white could discern the diluted fruity flavour ) and dismissed to be able to repeat the process in X weeks.

So donating an amount of blood can clearly be done and be done safely.

The real question is how quickly a healthy body can renew the lost blood to be in a position to relatively safely donate once more without being detrimental to the Donor.
Optimal practice maybe to have an interval of hours? or days?

But what could a healthy person donate-create-and donate once more?

 

[Chris]

12-16 weeks is the safe limit between donations from one person, mostly due to the amount of iron it takes from your system but also the rate at which you can recreate red blood cells.

Maximum donation in the UK is no more than 15% of total blood volume. This is estimated by multiplying body weight by ‘estimated blood volume’, for which there are set figures for adult men and women, children and infants.

Pressure wise we have several options. You go artery to vein, or if vein to vein then you simply utilise Ye Olde Gravity and place the donor higher than the recipient. Or use a pump.

 

[TeeDee]

12-16 weeks is the safe limit between donations from one person, mostly due to the amount of iron it takes from your system but also the rate at which you can recreate red blood cells.

Maximum donation in the UK is no more than 15% of total blood volume. This is estimated by multiplying body weight by ‘estimated blood volume’, for which there are set figures for adult men and women, children and infants.

Pressure wise we have several options. You go artery to vein, or if vein to vein then you simply utilise Ye Olde Gravity and place the donor higher than the recipient. Or use a pump.

Thanks Chris.

Sounds like you have first hand experience of this?

If so - any idea how , if push really came to shove - last ditch type medicine ( high fantasy event ) , one could drain a donor ? which would I assume push the safety limits for the donor - meaning less than ideal , ,less than H&S and quite frankly rolling the dice of life.

 

[Chris]

Thanks Chris.

Sounds like you have first hand experience of this?

If so - any idea how , if push really came to shove - last ditch type medicine ( high fantasy event ) , one could drain a donor ? which would I assume push the safety limits for the donor - meaning less than ideal , ,less than H&S and quite frankly rolling the dice of life.

I’m only really familiar with it due to a course I was on years ago. The US military have the concept of a ‘Walking blood bank’ for emergency field transfusions. In the UK I believe it’s referred to as an Emergency Donor Panel. More likely scenario is blood would be drawn and then transfused into a casualty, as direct transfusions carry more risk. It’s also not ideal as blood loss for the donor reduces combat effectiveness, so preference would always be blood bags which are ready to go.

I don’t know the answer to worst case scenario limits for the donor based on actual evidence, though I assume it’d be the same as for any other kind of haemorrhage. 40% or more blood loss is considered fatal. 30-40% is very concerning and 15-30% will have detrimental effects. In real money, anything beyond 3L and you’re in big trouble - this is catastrophic haemorrhage and would likely cause death due to hypovolemic shock. Approx 2L will cause shock, loss of consciousness and is a medical emergency. 1L is enough that you will need medical support, observation and fluids/possibly blood transfusion. About half a litre, or a pint is where it’s accepted you can go to without likely causing a second casualty. We really don’t have that much to spare.

Edit to add: Just in case it wasn’t clear to anyone reading this, I am not a doctor and you shouldn’t use any of the above information in practice.

 

[FerlasDave]

I have a vision of the donor being up a set of step ladders, the nurse sucking on the transfer pipe until blood comes out and then inserting it into the delivery needle - so making sure there is the right flow rate by climbing up or down the ladder (but then, I'm an engineer!)

IIRC the earliest examples of direct blood transfusions were from the napoleonic war. I remember seeing paintings in which the donor was placed in an elevated position in order to increase blood pressure. Of course remembering that if someone is in need of transfusion then their blood pressure will be low in any case.

 

[Broch]

This is the general loss vs effect guidance

Blood Loss	Percentage of Total Blood Volume	Effects

0.25 L (250 mL)

~5%

No significant effect in a healthy person.

0.5 L (500 mL)

~10%

Possible mild dizziness, slight weakness. Often tolerated well.

1.0 L (1000 mL)

~20%

Noticeable weakness, fast heart rate (tachycardia), possible mild shock.

1.5 L (1500 mL)

~30%

Confusion, low blood pressure, rapid pulse, cold and clammy skin. Moderate to severe shock.

2.0 L (2000 mL)

~40%

Severe shock, fainting, extreme weakness, very low blood pressure, risk of organ failure.

>2.5 L (2500 mL)

~50%

Life-threatening, unconsciousness, likely death without immediate treatment.

 

[Broch]

Having researched this a bit now I would suggest you can't take more than 1L or you end up with two casualties instead of one - and even then 1L will be really pushing it.

Blood replacement times:

• Plasma (fluid part): Replenished within 24–48 hours by the body increasing fluid intake.
• Red blood cells (RBCs): Take 4–6 weeks to fully restore after a significant loss, as bone marrow produces new cells.
• Iron levels: If depleted, it may take weeks to months to fully recover, especially without supplements.

 

[Pattree]

This is interesting!

One issue might be that I wouldn’t give permission as doner or as recipient.

If you have the facility to type my blood then you will probably have facility to do the job conventionally.

In a hospital it is always done using a blood bag even when the interval is a few minutes and less than 2 meters.

(Gravity alone works with a blood bag but there are pressure cylinders where a lot of blood is needed in an artery as for a burst aorta. )

If you can find the identical twin that I didn’t know I’d got them maybe - just maybe.