Large bore IV access showdown: does short and thick really do the trick?

For decades now we’ve all been reciting the mantra that any sick or shocked patient needs:

“2 large bore IVs”

We’ve also all been taught that “short and thick does the trick” due to Poiseuille’s Law which states that flow is directly proportional to the fourth power of the radius, and inversely proportional to the length:

poiseuilles law

But despite our best efforts we couldn’t find a direct comparison of the various types of IV cannulas and catheters we used at work to see which one is actually best. We had unanswered questions that needed answers.

Which IV cannula/catheter delivers IV fluid the fastest?  
How much faster is a 14G compared to a 16G, 18G or 20G?
Is a standard 14G faster than a RIC line or sheath introducer?
And just how much slower is a central line at delivering fluid?

Behold, the Large Bore IV Access Showdown. We’ve hooked up all of the major types of IV lines you’re likely to find in an average Australian ED to a rapid infusor device, and timed how long it took to pump through a litre of saline.

So which line was best? You’ll have to watch the video and find out!
(If you can’t stand the wait, skip ahead to the results at the 10:40 mark)

So the 8.5Fr RIC line was the winner!

Here’s our video on how to insert a RIC line

Here’s our rather unscientific, but hopefully visually useful comparison of the relative speeds at which fluid can be pumped through the different lines in our test:

Relative rates of different IV cannulasClick to enlarge

And here’s our table of results:

FINAL RESULTS

Please feel free to download, share, embed, or otherwise distribute the video and results. And feel free to run your own trials and let us know if they’re similar or different!

For more information on the various types of large bore IV access check out our post on the ETM Course site on large bore vascular access devices. The astute will have noticed that we didn’t use a MAC-line (multi-lumen access catheter) in this test. This was because we don’t stock them in the ED we did the test in, and they are rarely (if ever) found in your average Australian ED, however most if not all of the other lines are.

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