How much stuff can one inject intravenously before pressure becomes a problem?

Factual Questions
1

As the title suggests I wish to fight my ignorance in the safe injection volumes of things (like when they hook you up to an IV etc…) How much strain can the circulatory system take? Ounce or maybe liter or maybe galon and why would there be such a redundancy present? For all intents and purposes assume that the substance injected is actually the blood of the person donated previously so there are no worries about dying from blood dilation or anything like that.

P.S. No I am not a drug addict whos stash fell into a pool I am just curious

2

I do not know how much extra fluid one’s veins can hold, and I’m sure that varies depending on the person. What I do know is that the average pair of kidneys can remove 16 mL of fluid every minute. To gain ground, you have to inject faster than that.

If you add water faster than that, what my animal physiology professor told us (I think… this is at the space of a few years) is that your cells absorb the water through osmosis, and eventually begin to burst. When too many of your brain cells start to do this, you seizure and die.

Who knew drinking water was so dangerous?

3

That would be if it were pure waster you were injecting. It causes a condition known as hyponatremia, wherein your electrolytes become severely diluted.

If you were to continually inject a properly balanced saline solution, I imagine that after the pressure built up, fluid would begin moving into the interstitial spaces en masse, overloading your lymph system and saturating your subdermal tissues with water. I can’t really say what would happen after that. I suppose that you might actually begin to have the lungs fill with fluid, at which point you would drown. You might begin bursting the capillaries and other small venous networks.

4

Pure water, of course. The thing to keep in mind is that the smaller elements of the circulatory system, which form the greatest percentage of the total length, are relatively permeable. That is what allows your lymph system to function, as smaller particles and fluid can filter in and out of capillaries. So you would probably see the excess fluid being deposited in these are and building up.

5

You better not be injecting any drugs Vic, I ain’t bailing you out of jail again.
:smiley:

6

Nobody fully read the question.

OP says to assume it’s the patient’s own, predonated blood.

Well, if you’re going to get continuous pints of blood, you have to be continuously bleeding - internally or externally - to justify the IVs. (I doubt that a doctor would order blood for someone who wasn’t bleeding. There may be exceptions, however, but I have never seen one.)

So, the pt.'s pressure wouldn’t go up. The transfusions would simply replace blood that was being lost.
Anyway…

There was an awful case of hemorrhaging when I was a night call lab tech back in the 50’s-60’s. If I remember correctly the guy had esophageal varicoses (varicose veins of the food tube), which ruptured. He bled as fast as I could get replacement blood up to the floors.

In the middle of the night, I hand carried two pints to the floor. This was a small ~200-bed hospital. When I stepped off the elevator, I could smell the blood pouring out of this poor bastard. Actually it probably smelled more like meat. I mean it hit with incredible force. It’s a smell I have experienced in an autopsy, but nowhere else.

We must have pumped 12 or more pints of blood into this guy before he died.

And if I may…

I’d like to put in a plug in here for the American Red Cross Volunteers. They’re the unsung heroes behind the scene. When I (and other techs) got into I NEED BLOOD AND I NEED IT NOW situations, I’d call the Red Cross. They’d scour the local hospitals for spare pints of the needed blood type and hustle them over to my lab. If that wasn’t enough, they’d line up emergency donors.

And when these people would come into the lab carrying that life saving fluid, they exuded an aura of goodness, of saintliness about them. Honest. Except for their “holiness,” they’d be otherwise very ordinary folks. And they had no pretensions. They didin’t think of themselves as a cut above anyone else. They were simply doing a job - for no pay whatever - that they knew was important.

7

I suspect it is quite a large amount. I once ended up in the hospital due to shock from internal bleeding and they gave me about 5-6 liters of saline solution intravenously before they thought my fluid levels were normal. As far as I could tell, any excess just gets removed by your kidneys.

8

There are so many variables that more info would be needed. Basically hydrostatic pressure (“blood pressure”) that exceeds oncotic pressure (the “pull” that large intravascular molecules cause) results in fluid leaving the vasculature.

When fluid leaves the vasculature of the lower extremities (as happens in pregnancy when the large uterus impedes blood flow back to the heart) you get edema (puffy ankles).

When fluid leaves the pulmonary vasculature you get what is commonly called pulmonary edema, as in congestive heart failure.

9

The answer is: “It depends”. It depends on how dehydrated you are to begin with, if you are still actually losing fluid as new fluid is being infused, the type and concentration of the fluid being infused, the health of the kidneys, and also the health of the heart and the lungs. It also depends on the size of the individual, their body-mass index, and probably the degree of sunspot activity going on at the time. ( :smiley: )

If you’re otherwise healthy, it’s a lot of work to volume-overload a person via IV fluids. It can be done, but it isn’t real easy. Main symptom would be shortness of breath, as the excess fluid back up into the lungs. The breathing difficulty would be worst when one is lying flat, and eased somewhat by sitting up.

I think it would be pretty tough to get significant vascular rupture from pressure overload. The vascular bed is pretty well-designed and has a LOT of flex.

If one is infusing whole blood into an otherwise healthy individual my wild-ass semi-educated guess would be that after 4 units, volume overload would be a significant risk. Again, many other factors come into play. Whole blood is seldom used for transfusion anyway, just because the risk of volume overload is there. Packed red cells are preferred.

QtM, MD

10

I’ll second that one. I was in Blood Bank the day a 15 year-old girl was brought in from a t-bone car accident. She had massive internal bleeding, and in the OR, the surgeon said he could hear her hemorrhaging. In a three hour period, we pumped 23 units of RBCs and 6 or more units of FFP. She survived, but it was harrowing for about 45 minutes. No crossmatch, no nothing, just pull a segment off the unit, and grab a sticker from the back. This was about an hour north of the Louisville ARC depot and west of the Bloomington IN sub-depot, and both of them handed us blood within an hour. Oh yeah, she was O neg and when it was all over, she was full of O pos.

If you can donate, please do it. 30 some-odd anonymous donors helped me save this girl’s life.

Vlad/Igor, MT(ASCP)

11

First of all, there *are * other reasons for needing transfusions, anemia to name one.
Secondly, 12 units of blood in a patient bleeding out is often a drop in the bucket. Working trauma in a major metropolitian hospital I’ve been involved in saves where 100 units of blood were used on one patient. But, after 4 units many other issues come into play that, if untreated, would undo all the benefits of the blood. Just one is the replacement of calcium. Banked blood is preserved with citrate which leaches calcium. If not replaced, hypocalcemia results, and the patient dies.
Now, for the ops question. It depends on the fluid. If the patient isn’t animic, or bleeding one extra unit of blood would cause an increase in blood pressure.
If the patient is in shock. Not from bleeding several liters of normal saline or lactated Ringers must be given to maintain a survivable blood pressure. There are drugs added to IV solutions that giving more than a few drops a minute would kill.
Patients that have kidney failure can’t tolerate even one liter of extra fluid.
So, without knowing details about the individual patient’s conditions your question is unanswerable.
The closest anyone could come is “It depends”

Well, there you go. I didn’t see you there Dr Q :slight_smile:

12

Anemia due to blood loss, intravascular hemolysis or chemo, yes.
Anemia due to poor nutrition, low iron or pernicious anemia, no.

Vlad/Igor

13

Not quite true. I had one patient with a hemoglobinof 2.5 due to poor nutrition (a diet of vodka will do that to you). His bone marrow just stopped producing red cells. He needed packed red cells because he was really not perfusing his tissues at all well.

The same thing can happen with severe iron deficiency and pernicious anemia. Of course, after transfusing, one must treat the underlying cause, or one ends up in the same position further down the road.

But if an anemia is severe enough, a transfusion will benefit to at least some extent, no matter the cause of the anemia.

QtM, MD

14

Qadgop is the medical expert here, so all I can offer is my own anecdote. It might give you a ballpark number to work with.

Due to a rare genetic liver disorder called primary type I hyperoxaluria, I had to get a kidney/liver transplant just over two years ago. The condition caused a buildup of calcium oxalate crystals in my soft tissues (eyes, fingertips, kidneys) and bones (because the oxalates bind easily with calcium).

In order to keep my new systems sufficiently flushed, so the buildup of oxalate crystals wouldn’t flood the newly grafted kidney, I was saturated with thirty pounds of fluid. That’s right, pounds—or at least that’s what I was told afterward. However, I was also constantly on dialysis at the time as well, cleaning my blood and removing excess fluid, so it would be difficult to say exactly how over-loaded I was at any given time. Excess fluid in the bloodstream tends to cause tissue swelling, like swollen ankles and general puffiness (also called edema). The body finds places, in other words, to stick that fluid. It doesn’t necessarily stay within the veins.

It works in reverse for kidney dialysis. I’ve been on this as well. The machine removes excess fluid from the bloodstream only; eventually, the over-saturated soft tissues leach fluid back into your circulatory system. For this reason you can only be on dialysis for a limited part of the day. It’s possible to deplete the volume of water in your bloodstream so that your blood pressure bottoms out and you crash—in other words, you get extremely nauseated, headaches, and so on. In a few hours, fluid seeps back into your veins and your BP goes back up.

I am not a doctor, as I said, just an end-user of Stuff Injected Into The Vascular System.

15

Docs have me give 2 Units of packed red blood cells for low hemoglobin postpartum(after the baby is born) all the time. Most of these women had low hemoglobin before delivery and not more than a 500 cc blood loss. It’s not unusal for any woman to have 2000 cc of Lactated Ringer’s or normal saline before delivery and 3000 cc of LR or NS with 20 Units of Pitocin added–that’s 5 liter bags of fluid in one morning.

Cyn, OB/GYN RN

16

Wouldn’t that be the other way around? I thought O neg was what was used in emergency transfusions. If she was Rh negative and got Rh positive blood, she could have a hemolytic reaction. O neg is the universal donor, right? :confused:

17

Type O blood can be given to anyone, and O neg is the safest to give when there isn’t time for a crossmatch (to give type-specific blood). In this case, we only had 6 units of O neg on hand, and she went through four of those in the ER. An O neg person exposed to O pos blood will develop an antibody to the Rh factor (AKA the D antigen), so the second time they receive blood they may have a hemolytic reaction. This was the first time this girl had received any blood, so she hadn’t had the chance to make an antibody. She was given 50 units of Rhogam, an anti-D antibody usually given to O neg pregnant women. I wanted to follow up on this girl to see if she did develop an anti-D antibody, but I lost track of her.

Vlad/Igor