Dose angio catherter size matter angiopain when potassium fluid injected via IV?

[Ironprostate]

Today, i met a patient who complain about her arm pain. she was injected 10 DW mixed potassium 40mEq 1L via 24G IV catherter. No signs of phlebitis and redness and swelling. But she so painful so I removed it. Other than this, My senior nurses order me to keep the more larger size IV catherter like 18G or 20G. I dont understand what national beneath this?

[JKL33]

I've had both and will pass on the unmedicated childbirth.

Ha, ha. After I wrote that it occurred to me that the fact that one of these resulted in a "sweet little bundle of joy" and the other doesn't, probably had something to do with my respective pain tolerances.

[Double-Helix, BSN, RN]

It's not the size of the catheter that matters, but rather the size of the vessel. A larger vessel with greater blood flow will do a better job carrying the med into the blood stream than a small vein will. This will lead to less pain/vascular irritation. Ideally, a smaller catheter in a larger vessel would be used.

[Guest219794]

I see where your head is going and it may seem counter intuitive to you but actually a smaller catheter is preferred for irritating solutions because its smaller size allows more blood to flow around the catheter walls increasing hemodilution of the fluid which decreases the exposure of the downstream vessel walls to concentrated irritants. Regardless of the catheter size the fluid is not going to be concentrated on a specific area of the vessel it will be directed downstream so it won't be beating against the vessel wall at all. Each size of IV has a max flow rate and no matter how much pressure is put behind the fluid it is limited to that flow rate which also limits its pressure as it exits the catheter. Remember a 24 gauge is often used in premature infants with tiny, tiny veins yet we are still able to give fluid boluses through them. Granted the rate is slower but even with toddlers I have hand pushed boluses through small gauge IVs hundreds of times without issue related to the pressure of the fluid. Does this make sense?

This.

These folks know a thing or two about the subject.

Bigger is not better: Use the smallest gauge IV catheter to administer the prescribed therapy. Good flow rates are possible even with a small gauge catheter. Using an IV catheter too large for the vein will obstruct blood flow and might cause thrombosis distal to the IV site.

It is not the size of the IV, it is the size and flow of the vein that matters. We end up using big IVs to prove we are in big veins. But, if I nearly fill the lumen of the vein with an 18 g catheter, how ell will a vesicant be diluted.

Regarding the higher pressures- yes, smaller IV s have higher pressures at a given flow rate. But, the pressure is not the issue- it is the PH. I think that is nursing myth that gets passed on.

Off the subject- we use too much IV potassium, when PO would do.

[Susie2310]

What was the rate of the infusion?

[Mavrick, BSN, RN]

The simple answer is: Bernoulli's Principle "The faster a fluid moves the less pressure it exerts"

Or if you prefer: Bernoulli's Equation "P+1\2 *rho v^2 + rho * gh = constant"

Although it seems counterintuitive, a smaller gauge catheter will exert less pressure on the walls of the vein.

A real world example is when you're taking a shower and the curtain gets pushed up against you. The air pressure in the bathroom is greater than the air pressure in the shower because of the speed of the water.

Just simple Physics. LOL!

[applewhitern, BSN, RN]

I worked at one hospital where the docs would give p.o. potassium if not contra-indicated; we would give something like 40 mEq p.o. q 2 hr, depending on their K+ level, of course. Now I am at a hospital where they apparently have never heard of taking it by mouth~ everybody gets it IV and it burns the daylights out of them. Do we get to use lidocaine? Of course not. Sometimes I really prefer our "old timey" way of doing things.

[Guest219794]

The simple answer is: Bernoulli's Principle "The faster a fluid moves the less pressure it exerts"

Or if you prefer: Bernoulli's Equation "P+1\2 *rho v^2 + rho * gh = constant"

Although it seems counterintuitive, a smaller gauge catheter will exert less pressure on the walls of the vein.

A real world example is when you're taking a shower and the curtain gets pushed up against you. The air pressure in the bathroom is greater than the air pressure in the shower because of the speed of the water.

Just simple Physics. LOL!

This is why wings are shaped the way they are- to create lift as air is forced to move faster over the top of the wing(low pressure) compared to the slower moving air (high pressure) on the bottom of the wing. That is a little different than what happens with a smaller IV.

I don't know much about physics, but I know what happens when you decrease the diameter of the outlet of a hose. Bring your new car over to my house so I can pressure wash it. My pressure washer is going to put out the same volume over time regardless of which nozzle I use, just like my IV pump will do regardless of catheter size.

I have a really small diameter nozzle, analogous to a 24 g IV. It is called my paint stripping nozzle.

I also have a wider diameter nozzle, analogous to an 18 g IV, called my car washing nozzle.

Which would you like me to use on your new car? No doubt Bernoulli could give a great explanation as to why he prefers the wider nozzle on his car.

But, this is all academic- The pain caused by IV K is cause by the PH, not a high pressure (or velocity) stream. This is mitigated by by diluting it with a high flow of blood that moves easily around a small diameter catheter.

[missmollie, ADN, BSN, RN]

This is great information, thanks to all, especially Wuzzie. I just assume if I'm using a 24g, this patient has the infamous thumb vein (that god forbid they bump against anything) and poor cap refill. But my patients are all old.

But, this is all academic- The pain caused by IV K is cause by the PH, not a high pressure (or velocity) stream. This is mitigated by by diluting it with a high flow of blood that moves easily around a small diameter catheter.

So if pain is caused with a 24 g, then it would be a blood flow issue, right? Not the size of the catheter, but rather where the catheter was placed. Which a 24g may have been used due to the difficulty of getting an IV. I hate 24 gauges...they bend so easily.

We do PO potassium too, and I always give a dose of zofran prior to giving the potassium. It upsets stomachs.

[Mavrick, BSN, RN]

This is why wings are shaped the way they are- to create lift as air is forced to move faster over the top of the wing(low pressure) compared to the slower moving air (high pressure) on the bottom of the wing. That is a little different than what happens with a smaller IV.

I don't know much about physics, but I know what happens when you decrease the diameter of the outlet of a hose. Bring your new car over to my house so I can pressure wash it. My pressure washer is going to put out the same volume over time regardless of which nozzle I use, just like my IV pump will do regardless of catheter size.

I have a really small diameter nozzle, analogous to a 24 g IV. It is called my paint stripping nozzle.

I also have a wider diameter nozzle, analogous to an 18 g IV, called my car washing nozzle.

Which would you like me to use on your new car? No doubt Bernoulli could give a great explanation as to why he prefers the wider nozzle on his car.

But, this is all academic- The pain caused by IV K is cause by the PH, not a high pressure (or velocity) stream. This is mitigated by by diluting it with a high flow of blood that moves easily around a small diameter catheter.

Bernoulli's Principle applies to the walls of the hose NOT the outlet.

Your perfect explanation of how airplanes wings get their lift is not demonstrating the pressure of the air in front of the plane. That is resistance and does not provide lift.

I agree that the pain is caused by the pH differential.

But seriously how often do we get to drag Bernoulli into a nursing discussion?

[Wuzzie]

So if pain is caused with a 24 g, then it would be a blood flow issue, right? Not the size of the catheter, but rather where the catheter was placed. Which a 24g may have been used due to the difficulty of getting an IV. I hate 24 gauges...they bend so easily.

Yes! You've got it! With vesicants or other irritants we try for the smallest catheter in the largest vein to increase the amount of blood available to dilute the medication at the point where it is being introduced.

[Wuzzie]

But seriously how often do we get to drag Bernoulli into a nursing discussion?

I just like saying "Bernoulli"!

[IVRUS, BSN, RN]

you metioned that small catherter is more preferred for irritating medication. But when it comes to ChemoTheraphy, does it go same? As far as Im concerened, The first route of CTx is central line like Chemoport or Hickman Cath. or C-line. But sometime, CTx medication was injected via peripehral line. And at that time, facility regulations are that never given the CTx via peripehral line smaller than 22G. hmm.. I was told that bigger size cathterter prevent vein from chance of extravasation. So what rational is beneath this?. thank you for your kindness.

As Wuzzie said appropriately, it is all about blood flow. You always want to choose the smallest IV catheter to do the job, all-the-while allowing for adequate blood flow around said IV catheter. Ideally, I do not like my IV catheters to take up more than 33% of the vein, but sometimes I don't get what I want!! Bigger IV catheters cause more damage to the smooth inner lining of the blood vessel, the Tunica Intima. This damage starts the process of phlebitis and thrombosis. But, another factor one must also consider is the pH of the medication or solution and the Osmolarity. INS standards state that the pH should NOT be extreme and the Osmolarity should NOT be greater than 900, or one does too much damage to the vein, if it is via short peripheral IV catheter. Now if any one of the four Central IV catheters is in place, than any osmolarity or pH works as the blood flow in the central vein (SVC) is approx 10 times greater than that that is in the arms.