Fluid bolus by gravity or pump?

[delphine22]

No one seems to be able to give me a straight answer on this. I was thinking (uh oh, here she goes again) my way made more sense, but there might be something obvious I'm missing, so please correct me!

When I have to give a liter NS bolus quick ("wide open," as they say) and I have peripheral access that's reasonably stable, and the pt is not a CHFer or has other fluid balance problems (besides needing fluid), I hang gravity tubing. My preceptor told me I should put it on the pump and set it to 999 mls/hr.

My thinking is, what if that's faster than the PIV can take? I'm afraid of blowing my IV bc the pump "pushed" the fluid in too fast.

However, it seems the gravity tubing (and I don't use it a lot, and have no ER experience) varies its flow with what the vein can handle, and will flow slower if the pt's moving around or the catheter is smaller. Obviously this is not ideal for a fidgety pt, but if mine's relatively still, and I want to protect their IV, is gravity tubing the better choice?

My preceptor was doubtful it would go in fast enough. But I had a 500cc bolus flow into a 20g IV in less than 20 minutes. So obviously the vein could handle more than the pump would have set it at (half an hour).

Please give me your thoughts/experience. Thanks! :)

[silentRN]

I think it just depends on the access you have.

[aCRNAhopeful]

See Poiseuille's law in the post above. In other words you can increase flow rate by decreasing length of the catheter, increasing the pressure on the IV bag, decreasing viscosity of the fluid, and most of all increasing radius of the catheter (increases flow rate by the increased radius to the fourth power!). In most instances gravity is much faster than the IV pump as long as you have optimized all the factors I listed above

[IVRUS, BSN, RN]

This would be based on Poiseuille's law. Flow rates are directly proportional to the fourth power of the inner radius, and inversely related to the length of the tube. It gets complicated, but basically means that a large, short PIV flows faster than a central line, and a central line flows faster than a PICC.

Totally disagree.... A central line dumps directly into the SVC where flow rates are ten times greater than that in the arm. So, a peripheral IV catheter will not get the medicine to someone's heart quicker. Now, I agree that a PICC has a long tube in which the fluid must flow through to get into the heart, so a shorter IV catheter, such as one which is placed in the subclavian vein and threaded to the SVC will have the solution to the heart quicker... But remember, a PICC is a central line!

[aCRNAhopeful]

Totally disagree.... A central line dumps directly into the SVC where flow rates are ten times greater than that in the arm. So, a peripheral IV catheter will not get the medicine to someone's heart quicker. Now, I agree that a PICC has a long tube in which the fluid must flow through to get into the heart, so a shorter IV catheter, such as one which is placed in the subclavian vein and threaded to the SVC will have the solution to the heart quicker... But remember, a PICC is a central line!

I dont think anyone would deny that a central line is closer to the heart than a PIV but thats not the point. The most effective way to get volume into a patient fast is a large bore peripheral IV hung by gravity (or pressure bag). Hang the same bag of LR to a 18cm triple lumen and the flow rate will be significantly less than the large bore IV. It's simple physics. Now if your talking about a cordis with a huge inner radius and shorter length then maybe it'll give the 16g PIV a run for it's money.

Volume flow rate = pressure gradient * radius^4/ 8 * viscosity * length

[IVRUS, BSN, RN]

But a peripheral IV catheter accepts flow rates according to its size, yes I get that, but if you have a central line, like my example of a triple lumen, percutaneously placed line, and it's tip is in the SVC, then I do not believe that the peripheral infusion will get to the heart any sooner that the catheter that I'm describing here. Once any medication is put into a catheter, it reaches the systemic circulation in less than 23 seconds.

An IV catheter in the arm, does NOT have the flow rates of that dumping into the SVC, even if it is to gravity and is a large bore. The medication flowing is also dependant on head height. So, how can that be the quickest way to get the drug? One must consider that the diminished flow rates in the peripheral vasculature will have a profound effect on the quickness that it reaches the heart lungs, and therefore metabolized. I still don't see it.

[aCRNAhopeful]

We are talking about different things. You are saying that if you give a medication through a central line it will reach its target tissue faster than if you had given that same medication via a PIV. No one would question that. The thread was about giving a fluid bolus. Therefore flow rate is the key issue. A PIV has a faster flow rate than a triple lumen. Also I would disagree that a medication given given through a PIV would have a "profound" difference on the speed it reaches the lungs. It would be delayed by a matter of seconds but thats it. It definitely would not have an effect on metabolism unless you're talking about adenosine or something that is metabolized in seconds. Even a medication like succs which is heavily metabolized before ever reaching its target tissue at the neuromuscular junction doesnt require a dosage adjustment based on PIV vs central line. With that said, if I have a patient in the OR with a central line and a large bore IV i will use the PIV for my volume resuscitation and mantenance fluid line and I will use the central line to to push drugs that I want to work immediately because it works a little bit faster than the peripheral. So yes I agree with that part

[MunoRN, RN]

It's important to remember that the fluid flow physics that come into play are not limited to the catheter itself, since the pressures and resistance that the catheter is out-flowing into also must be considered. But in terms of the fluid flow of central lines vs peripheral IV's, the passive flow capacity of a typical central line isn't actually significantly lower than that of typical peripheral catheter. When considering the ability free flow fluids into a patient you have to consider the limitations of a peripheral location as well such as positional decreases in fluid flow rate and limitations in distal peripheral venous flow. If I can focus solely on troubleshooting a peripheral IV free-flow infusion then I prefer using a peripheral site and no pump, the problem is that if a patient requires fluid that emergently there are usually other things that also need to be done.

[dandelion9]

Pressure bags. Always. That's an unspoken rule on our unit. :)

[calivianya, BSN, RN]

This thread has been enlightening. I never knew why PICCs took so long to do boluses. I figured it was something to do with the line but I didn't know exactly what. I'll do gravity with a pressure bag for peripherals and IJs/fems/subclavians, but on a PICC pumps at 999 can be faster. I figured that out when it took me more than an hour and a half to get a bolus in through a PICC using a pressure bag once. I never did that again.

[spacemonkey15]

Depends on the fluid I'm bolusing, the IV access it's going through, what I have available and how badly the patient requires the fluid bolus. We generally give our colloids by gravity via a CVC or swan introducer, if it's taking too long then a pressure bag (provided it's not a bottle of albumin ) or a 3 way tap and a 50ml syringe is a good way to get it into the patient quicker.

[suzikjg]

In my workplace, we give bolus fluids via gravity. However, depending on patient's IV line, if it's infusing very slow despite putting it on gravity or pressure bag, we will put on pump. In fact, I find there are less infiltration events happen using pump than pressure bag...

[VANurse2010]

It depends on the patient's status and why you're hanging it. Only one way or the other in all circumstances is wrong.