# What is the blood ejection speed outward from human body vein? [closed]

At what height blood can eject from human vein ? I see, sometime there is direct blood transfer from one person to patient. So sometime blood bottle is kept at certain height and blood is transfered from person to upper bottle and then from that bottle to patient directly. At what height blood can go ?

EDIT

For example, I had not mentioned before, What would be the blood pressure outside from body after cutting certain nerve or vein or whatever which carries blood-speedily, when we go inside vacuum chamber ?
Consider any chamber where you will be able to remove air/atmosphere inside it and a person is provided with oxygen cylinder. Now what will be the blood ejection speed outward from the body ? At what height ? You will have to consider atmospheric pressure also when we leave normally on earth. So question is, at what height in vacuum (where there is no pressure from outside world) ?

• I'm a little uncertain based on your title and wording, but are you asking how elevated a human donor has to be, vs. the recipient, for an unaided (no pump) blood transfusion? Commented Mar 20, 2014 at 14:26
• @AtlLED At what height blood can go if one's vein got cut by knife or something ? Commented Mar 20, 2014 at 14:32
• This question appears to be off-topic because even though it presents a biological scenario it is about basic principles of physics. Commented Mar 21, 2014 at 5:02
• You can use Bernoulli's equation and the equation of continuity to measure velocity of blood from the cut site. Then add the effect of gravity of calculate the distance covered. Commented Mar 21, 2014 at 6:40
• This question appears to be off-topic because it is about physics. Commented Apr 1, 2014 at 21:51

Ah, I'm afraid there are a near infinite number of variables that will make a general answer impossible. Factors such as: age, sex, weight, which vein, additional damage, heart condition, cholesterol level, body position, body temperature, and how the vein was cut and exposed will all lead to different answers.

A general answer from someone with lots of trauma experience, not very far. Rarely if ever greater than 10cm. Veins just don't have the pressure that arteries do.

• Central venous pressure is something like 5 mm of mercury.
– kmm
Commented Mar 20, 2014 at 19:32
• @kmm I'm not so sure a chest/back wound required to expose the venae cavae would spurt, even at it's higher pressures. You simply have to go through so much to get there that it seems unlikely. Also at that point you almost assuredly have arterial if not aortic damage. That average of 5mm for a healthy adult [caucasian] male at room temp has to pass a lot of tissue. There are a lot of ways to get blood splatter, but neatly cutting through a vein isn't a particularly good one. Commented Mar 21, 2014 at 1:50
• For a further point of clairification, the CVP is normaly limited to the blood pressure in the proximal SVC, not the more distal portions that would be more exposed to puncture. The pressure change would make more of a pulsing uzze than big spirts. If the punture was small enough to take full advantage of the pressure changes, you could get some distance from the body, but nothing like an artery. Commented Mar 21, 2014 at 4:07
• Agreed. The OP was asking about veins, which have almost no pressure even where their pressure is highest.
– kmm
Commented Mar 21, 2014 at 13:31
• @AtlLED I edited my question. Commented Mar 21, 2014 at 17:18