RN here. There are two main types of IV lines. Peripheral IVs and central lines. Peripheral IVs are typically inserted into a small vein of the arm or hand and have a tiny diameter. This is what most people think of as an IV. Central lines (google PICC ) have a much larger diameter and are inserted in larger veins and terminate in one of the body's large vessels -e.g Superior Vena Cava very close to the heart. The real danger of air in the circulatory system is that if a bubble is large enough and makes it to the brain it can cause a blockage called an embolism in one of the smaller vessels supplying blood to the brain. This would essentially cause a stroke. A small amount of air passing (<10ml-about the size of a test tube from HS chemistry) passing through a peripheral IV just simply can't form a large enough bubble to pose a danger. In fact it has been estimated that you would need as much as 100ml of air pushed through a peripheral IV to do harm. Those tiny bubbles just get dissolved in your blood very quickly. A central line however is a much different situation. Because they have a much larger diameter and are placed in larger vessels with larger volumes of blood then it doesn't take much air for a large bubble to form. A few tiny bubbles of air that you would typically see in IV tubing is not likely to do any harm but as little as 2-3ml air pushed in all at once with a medication for instance could easily be dangerous in a central line. That's why nurses trained to clear all the air from syringes used for central lines. It all about how big of bubble can form in your blood. So if you have peripheral IV in your arm or hand and you see a few bubbles in your IV tubing don't let it concern you it's just not enough to hurt you.
I read IV as Roman numerals and only came here for clarification on why it was ok for 4 drips to have air bubbles running through their lines. I had completly had 100% no idea what was going on.
The most feared complication of an 'air embolus' (in that you could die immediately) requires enough air to obstruct the outflow tract of the right ventricle. Basically causes an air ball-valve effect that prevents any blood from leaving the right side of the heart. Smaller amounts of air that are introduced into your veins will simply be absorbed as they move through pulmonary capillaries in the lung and not cause you any issue. In regards to how much, most traditional studies show that 200cc should be fatal. Recently case reports have suggested somewhere between 50-100cc could be as well, but I can't find any precisely agreed upon amount.
The other potential complications can occur only if there is some way that air can travel from the right side of your heart to the left, without passing through the lungs. Most commonly, this would be through a patent foramen ovale, or PFO, that allows blood to be shunted without passage through the lungs. There are other possibilities but require some kind of 'abnormal' communication. In that scenario, an air embolism could cause a myocardial infarction or stroke due to obstruction of an artery as mentioned as it was able to cross from venous to systemic circulation without being 'filtered' through the lungs.
So, in practice, we use filters or aspiration of fluid and blood to clear IV lines to try and prevent it, but small amounts of air should not cause any detriment as you noticed.
Because the danger of air in IV lines is over exaggerated. You need enough air to fill the heart to a level high enough that it is not able to pump blood any more. Small bubbles will just absorb into the blood
Doctor here, at medical school we were taught that anything over 10ccs of air given IV can be lethal, as an air embolus that size can cause cardiopulmonary arrest. All veins are, practically speaking, a non stop highway to the heart, and it is unlikely the air would pass through the heart, and certainly would go no further than the capillary bed of the lungs, which would be the next port of call. 10ccs of air would fill a roughly 90-100cm length of UK IV giving set tubing. Smaller bubbles are usually harmless as they can dissolve into the blood and other tissues without causing any havoc. In fact, tiny bubbles are deliberately injected IV during 'bubble study' echocardiograms which are used to detect holes in the heart.
There's a difference between a rapid infusion of a large volume of air and a slow infusion of a small volume of air. For the most part, our bodies can deal with small amounts of small volumes (a small number of small bubbles), but the danger comes when you introduce a large volume of air quickly into the circulatory system. In popular culture the bad guy injects a large volume of air into a victim's neck quickly, causing death due to an embolism.
Pump fed IV-lines have built in bubble detectors to make sure that they're not a threat to the patient, but gravity fed lines can be more of a problem if proper precautions are not met and most medical professionals have the proper training to reduce the incidence of harmful bubbles in IV-lines.
I was in the hospital for a knee surgery a while back, and they kept me overnight. During one of my IV changes, I saw a pretty large air bubble (maybe 20 inches of line) go into my hand. I asked the nurse about it, and she was most of the way through telling me that it was nothing when my heart felt like it was jumping out of my chest. The heart monitor I was hooked up to started alarming. She looked worried. I was worried. Then it passed.
Someone else came by (guessing a head nurse?), and asked me about what happened. I said I saw some air in my IV, which she said was normal, but didn't seem pleased when I mentioned how much there was. I had a different nurse for the rest of my stay.
Air is only of major concern in arterial lines. True, don't inject more than 30 ml or so in a venous line, but air in the arterial system can be very dangerous with just tiny bubbles.
1) you need a lot of air to cause any big issues.
2) if you're using a pump it'll alarm like a banshee at the slightest bubble, often when a bag has run empty you'll see a bunch of air in it cause it's above the pump and no longer flowing. This is the same with gravity fed, there is no pressure so the air doesn't get pushed in.
3) if you've hung and primed the tube like a noob, it's often easiest to let the bag empty for a bit till the air moves down, the you lock the port near the wrist and use a syringe to suck the air out. This way you don't waste whatever you're giving your patient, however this method requires you to watch the air move down.
4) Cause the tubes are so thin it looks likes like a lot of air when it's actually only a little bit
Your IV drip may be required to have a [little dime-shaped thing](https://shop.pall.com/us/en/medical/infusion-therapy/iv-fluids/supor-aef-intravenous-filter-set-zidgri78m2i#attr_description) somewhere along it, which passively separates and expels the air from the drip. It's pretty cool.
In a combat life saver course with the army I saw a guy forget to bleed the air from an entire IV drip line and open the drip into the other guys arm.
I about dove across the room to turn it off, only to be told by the instructor that it was no big deal.
I thought for sure the dude was about to die lol. Those IV lines were long too, so there was a lot of air that should have been purged. But it was probably only a few tens of mL (guess).
Im a dairy farmer, when our cows go down with milk fever we give them a 500mL bag of Calpromag (Calcium and Magnesium mixture/solution?) via the Jugular Vein or the Milk Vein, I have seen what happens when air gets into the veins, the cow died within 2 minutes, it wasn't a very nice sight
Air bubbles from an IV line travel through the veins, back to the right side of the heart, and out to the lungs, where the bubbles easily leave the circulation and get exhaled. Unless you have a specific type of defect in your heart, there's no way for those bubbles to reach your brain or other organs. The danger comes when large amounts of air enter an IV line and lock up the right side of the heart, preventing normal blood flow, but that takes a lot more than bubbles.
Another RN here. Large amounts of air in the circulatory system can be dangerous. The biggest threat is a pulmonary embolism, which blocks blood flow to the lungs with a very minuscule risk of obstructing a coronary artery. Another risk is if you have a patent foramen ovale (hole between left and right atria) where bubbls from the venous system can enter the arterial system and travel to the brain and cause a CVA or stroke. However, this takes a significant amount of air to be pumped into your system in a pretty quick amount of time.
You were probably receiving fluids or medication at a rate between 25-200 mL/hour. This is not a very fast rate. Any air bubbles that did get pumped into your IV would quickly dissipate and dissolve in your bloodstream.
Excluding the drip chamber, a standard 6' IV tubing set is ~10mL. So while those gaps looked big, every inch of gap is roughly 0.14 mL. Given this small volume of air and the slow rate it's going in, your body has plenty of time to mix that air in your blood so that it becomes very minuscule bubbles and dissolves in your bloodstream.
I'm not a doctor or nurse, but I do work as a technician for a large international company that makes IV pumps (the machines that control the flow of your IV, assuming it's not just gravity fed).
The tube *should* be 'primed' (run some liquid through it) ahead of time so that there are no large bubbles. Also the little drip chamber helps avoid air bubbles that are in the bag from passing down the line (also you can inject medications into the chamber so that any air in the syringe won't actually get into the line).
The pumps themselves also have a sensor that detects when there is air in the line and causes an (very loud annoying) alarm to go off, alerting the nurse/doctor.
Truthfully, there will probably always be a little bit of air in the IV unless your IV is filled with some fluid that doesn't allow many bubbles or the bag is pre-packaged and doesn't have **any** air in it. Water (what we use for testing) always has quite a few small bubbles. As for the medical significance behind the air, others appeared to have answered that.
Something to consider is the IV line has a bit of a lensing effect, making the air bubble look a lot bigger then it really is.
Paramedic here. Air isn't as dangerous as people believe. Like, there's a quarter of a CC in a saline flush, and people always make sure they get that out. I guess it's best practices, so kudos for them, but it's not lethal.
Ill look for the study when I find the time, but there was a man who went in for a pneumopericardiogram which is where they insert air into the sac around your heart, but not *in* your heart. Well, they missed. 100ml air right into the heart, no issue. Also, no image. So they repeated another 100ml air and the patient arrested and died. I could be off a bit on the story, but I do believe the jist was 100ml air didn't outright kill the dude. Also there's a story of London HEMS transporting a patient and a couple things happened that lined up to cause an air embolism. That patient's name was Ruby, for your Google-fu.
Straight from UptoDate "Small amounts of air can be removed from the pulmonary vascular bed by gas diffusion across the arteriolar wall and into the alveolar spaces. However, when the capacity of the lung to remove gas is exceeded (eg, 50 mL or more) pulmonary outflow tract obstruction with or without concomitant arterial embolization can occur :"
So, unless the amount of air is large (exceeding the entirety of volume contained in the IV tubing) your pulmonary bed is going to be able to handle it.
If it does exceed that, first you get an outflow obstruction causing circulatory issues, and then maybe it also makes it to the left heart side. Still, stroke is not the top concern.
I see a lot of posters ask (paraphrasing) "how can a bunch of air get injected through the IV catheter?" With today's modern equipment it is near impossible unless there is a major mechanical malfunction or human error.
The time in medicine when this was a very possible problem was when glass bottles were used for intravenous fluids. Back in old days, there were not 'bags' of IV fluids, there were glass bottles. These bottles needed to be pressurized to push the IV fluids into your body. They did not have IV fluid pumps or even fancy valves that would equalize the pressure so the fluids could flow by using gravity. So they pumped air into the glass bottle to make the fluid flow. If they (medical staff) were not paying attention, once the fluid was gone it would just be air flowing into the vein.
This is how they figured out that enough air delivered fast enough into your vein will kill you. And yes, you do need 50 to 200mLs or more of air delivered quite rapidly to kill you. So a couple bubbles in the IV line going slowly into any vein will have an insignificant effect on your health.
Injecting air into an IV to kill someone is an urban legend. A massive amount of air is dangerous, but a small amount is not.
When I was really sick in the hospital a few years back, I was hooked up to all kinds of IVs. I remember one day the nurse was hooking one up and there was an air bubble in it and I honestly thought I was going to die that day. I was very relieved to find out that it would not kill me.