was in ER lots of times due to variou stuff (gallstones, excessive gas, GERD) and got an IV everytime
mom always got anxious when IV was about to end
2-3 times I was alone in ER and nurses were busy (car crash victims etc were brought in) so IVs got empty with plenty of air bubbles
only thing happened to me was in 1 of those my blood got up to the IV after 10 minutes or so but nothing else happened
why air bubbles in IVs are not an emergency or looked after instantly? When called on a empty IV (not dripping anymore) nurses act cool and cut the drip valve as if everything is normal
In: 73
Long story short, tiny amounts of air, including the amount in some visible bubbles, are below the threshold where you get problems. You don’t want to give large bubbles, or suddenly give lots of tiny bubbles, and good procedure involves safeguards to reduce the amount of air given, but a couple mLs of air in a relatively healthy person isn’t an emergency.
The thing that can kill you is a fairly large amount of air *injected* into you **all at once**. The reason why providers are so careful to get all the air out of a needle isn’t that a tiny amount of air will kill you – it’s that pressing until liquid appears ensures there’s *no* air, vs guessing “hey, maybe this small amount of air that’s probably left won’t kill them.”
With an IV, though, the fluid is being drawn in, not injected, and the air bubbles you see tend not to actually get into your blood – they tend to act as momentary stoppers to the flow and not as part of a continuous line of stuff going into your blood. And, if air *does* get in, it’s going in a very little bit at a time, and it’ll dissolve in and then be expelled.
There is pressure throughout the human body, with the exception of the operation of your lungs, which can draw a vacuum. This vacuum only exists in the cavity where the lungs are though.
The fluid in an IV bag flows into your veins because gravity pulls downward on the fluid, and the bag is always hung higher than your body. However, the air bubbles are buoyant. They float upwards in the fluid. This prevents large bubbles from entering through the IV needle. Tiny bubbles are harmless. It’s probably also worth noting that the bag is not pressurized. All the flow relies on gravity.
When your IV bag empties, it’s actually more likely that a small amount of blood will flow out into the IV than it is that the air will flow in. There is no suction in your veins, only pressure.
*Injecting* air bubbles involves pressure outside the body pushing inward. This is more dangerous because you can *force* dangerous amounts of air into the body.
Doctor here. As others have said above, small bubbles usually aren’t a problem. And yes, you probably got some small bubbles infused into your blood. We see bubbles on ultrasound when people are getting IV fluids, even when it looks like there are no bubbles in the tubing.
Bubbles in the veins go to the right side of the heart, then the lungs. They then get stuck in the pulmonary capillaries. If they are tiny, the gas dissolves into the blood. Even if they are moderate, it’s usually not a problem, because the lung can usually handle a bit of temporary obstruction to blood flow. Big amounts take too long to dissolve, and block too much blood flow. In this case, we’re talking about 350mL of air, but there have been some complications with as little as 20-50 mL.
The bigger problem is if it ends up on the arterial side. About 10% of us have a hole in our heart that connects the left and right sides, called a patent foramen ovale (PFO). It was part of how we got oxygen from mom while in the womb. It’s supposed to close up after birth, but there are people walking around with a tiny hole and don’t know. If air, or a blood clot goes through this hole, it ends up going to the rest of the body, like the brain, the gut, or the blood vessels to the heart. In this case, as little as 0.5 mL can cause a cardiac arrest. Tiny bubbles could cause strokes. If a patient has a hole in their heart, we can put filters on the IV to prevent air bubbles.
Given how common occult PFOs are, I don’t understand why we don’t have filters on all IVs all the time.
The danger with these bubbles generally lies with them getting pushed in. If the tubing is filled with air, and then you start injecting fluid into it without “priming” the line (filling it with fluid,) it will push the air in first.
When you’re dealing with a “dry bag” situation, the air is on top, and the fluid beneath it. When the fluid runs out, your blood pressure is higher than the air pressure, and a bit of fluid will remain in the line, and blood will actually backflow into the tubing as the pressure from your blood overcomes the tiny amount of fluid remaining. The air will not flow into your body since it’s lighter than blood and the fluid, unless something is pushing it down.
If you were to say, get a cut on your arm through a vein, you wouldn’t worry about air flowing into the cut, because the pressure of the blood exiting the vein is greater than the pressure of the air. As a matter of fact, most IVs when placed are completely open to air for a few seconds before tubing is attached (generally) and there is no concern of the air rushing into the vein at that point.
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As an RN that has worked in the ED, when the bag runs out, there is only air for about an inch at the very top. Due to the water seal, the bubble cannot travel down on its own if it’s just hung to gravity, if it’s attacked to a pump, the pump will automatically stop it as well. If a new bag is hung, we will “back prime” the tube to eject the inch at the top. It is a very fast process and you probably didn’t even notice. All that being said, air bubbles killing you is extremely difficult to do. I think it was found that it takes pretty much several feet of just air to actually do any damage. Little bubbles are absolutely harmless
I mean in truth it’s more of a myth. Sometimes you froth up an injection and inject that to watch with a scope to see how soon or not so soon those bubbles circulate through the heart. TIL huh?
It takes a lot of air to cause an air embolisms and more often than not it’s from a traumatic injury where a large blood vessel is cut and sucks air in. We are talking jugular vein or femoral vein big. The little bubbles you see in the IV line are entire metabolized by the blood before they reach anywhere they can do any trouble. The paramedic didactum says that you need at least 60ml of air rapidly pushed into a vein before you even have to start worrying about any issues. For reference that’s about twice the volume of the tubing used in most IVs.
IV pumps have a built in air-inline sensor that alarms and stops the flow until it gets re-primed. Bubbles larger than a certain diameter cause the system to stop. Those bubbles never actually make it to a patient. An IV bag becoming empty will not harm you.
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