Rapid infusion

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KGflyboy

KGflyboy

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Physician
Which do you think would infuse blood products faster? A standard 18 guage in the antecubital fossa, or the 18 guage over the needle introducer catheter found in a central line kit placed in the femoral vein? Or would it be the same? Of course a Cordis or other rapid infusion catheter would be ideal, but I'm curious if there is any difference between the two options above.
Angiocath.jpeg
 
Should be the same I'd imagine. Flow is going to be determined by the width and length of the catheter. The fatter the catheter, and the shorter the catheter, the faster the flow.

In more scientific terms, it's Poiseuille's Law.

So if the catheters are the same diameter (they are if they are both 18g), the shorter of the two should infuse the fastest assuming the other factors that dictate flow (fluid viscosity, pressure gradient) are the same.
 
I was trying to upload a chart from a lecture I gave, but I cannot do it without going through 30 steps to set up an account to host the image file.

An 18 g 1.25" catheter will infuse about 90-100 mL/min via gravity for crystalloid. pRBC's will be less. With a Level I infuser, you can increase this to 205 mL/min. An 8.5 Fr Cordis will infuse 674 mL/min via gravity and 857 mL/min via a Level I.

The length of the catheter affects flow rates exponentionally. An 18 g 1.25" catheter will have more flow than a 16 g 1.5" catheter usually. This is why central lines have such limited flow rates.
 
Yeah that's what I was thinking. I've seen several charts comparing the rates of different access catheters. Suppose both catheters were the exact same size. Put one in a small vein and one in the femoral vein. Are they going to infuse at the same rate? I think that probably would, unless you were trying to infuse into the tiniest of brings in one's hand where the vein diameter might me small enough to limit flow during a rapid infusion. But I don't know if this is actually true. I couldn't find data on this.
 
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As one of my old attendings used to say, “Short and fat is where it’s at.” Both in terms of access and body habitus.
 
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