Air in IV lines

[zacarias]

Hey all!!

I'm a new nurse and have a couple questions about IV lines. I saw an MD say that a correctly administered IV line should not have even the tiniest airbubble in it. I wonder if he's ever set up an IV himself.

Anyway, my question is, when I hang a new bag of fluid or something, sometimes the pump says "air in line" and beeps and I have to fix it. I'm wondering if there's something that I'm doing wrong when I spike the new bag. Also, when I give IV pushes, there is sometimes air bubbles that I see. I'm wondering if this is just an occurence that can happen every time you access a port along the IV line that communicates with the outside. I was just wondering if anyone had any pointers. Thanks.

[nialloh, RN]

Originally posted by Agnus

However, I am trying to understand, in an adult, how it is a lot of air when it enters a central line versus a peripheral.

Maybe the air dosn't have time to start to break up or dissolve before it hits the heart. Just a thought.

[rileygrl11, BSN, RN]

Agnus - because air in a central line is so close to the heart. The peripherally site air gets taken care of when it hits the lungs. The air in the central line goes directly into the heart.

[Agnus]

Yes, it enters through the superior vena cava mixes with blood from the inferiour vena cava (as in blood from peripheral circulation) from there goes to the lungs.

Blood entering the heart though a central veinous line does not enter the general circulation without exiting the heart first via the pulmunary valve then to the lungs then back to the left atrium.

If it was an Art. line I could understand the rational.

It is only because on the off chance there is a septal defect? Even that does not explain it completely. Because if that were the case ANY air could be a problem, even from a peripheral line.

Perhaps we are more concerned about the volume that could enter though a disconected line. But why would that volume be > than if it entered though a disconected peripheral line?

Sorry to be so dense.

[NsgTiger]

Angus - I think with a central line the air embolus issue is the same principle as in a peripheral line. It takes 200-300ml of air to cause a problem (air can become trapped in the right vent.). I think it is just more likely for a large volume of air to enter with a central line (during insertion and removal) and that is why it is such a big deal with holding breath upon removal of the line. Make sense?

[Agnus]

Originally posted by NsgTiger

Angus - I think with a central line the air embolus issue is the same principle as in a peripheral line. It takes 200-300ml of air to cause a problem (air can become trapped in the right vent.). I think it is just more likely for a large volume of air to enter with a central line (during insertion and removal) and that is why it is such a big deal with holding breath upon removal of the line. Make sense?

The problem I am having, is why a large volume of air is more apt to enter a disconected central line than a disconected periferal line. I know there is an answer. I think that I knew this once.

I think we are getting close.

[cannoli]

I think it's because the great vessels are larger and have a greater negative pressure and are more apt to suck air in, theoretically.

[cannoli]

Also, in regard to the above, it is closer to the heart, and the negative pressure. When a peripheral IV infiltrates there is a greater positive pressure which causes the blood to back up in the tubing when the IV runs dry.

[Agnus]

Originally posted by cannoli

Also, in regard to the above, it is closer to the heart, and the negative pressure. When a peripheral IV infiltrates there is a greater positive pressure which causes the blood to back up in the tubing when the IV runs dry.

This is making sense to me

[NsgTiger]

To quote my icu text:

"This is more likely [air embolus] if the patient is in an upright position, because air can be pulled into the venous system with the increase in negative intrathoracic pressure during inhalation."

Good question Angus, I think I myself am just begining to make sense of this

[Agnus]

Thank you all for helping me relearn this.