The numbers may seem confusing but I’ve always wondered something and when I found a few expired saline bags in the storage closet I decided to do a completely scientific and infallible test.
Now that Rogue Medic is sitting up in his chair I will confess this is in no way an “accurate” demonstration, but all elements were equal so I can only assume that the same thing would happen proportionately under different situations.
Like, say, actually starting lines on people.
In the past I have made the in field decision, like many of us do, to get the 18g when others may try for the 16g. But if I know I can get the 20g, but maybe get the 18g, shouldn’t I err on the side of some access is better than no access?
Maybe, maybe not.
So I went out to the workbench, hooked up a 20g angiocath and opened the line wide open.
How long do you think it took to empty a 1000ml bag? More on that later.
Taking into account the widespread myth that D50 can’t fit through a 20g needle (then where does it go?) what is the difference between a 20g and an 18g?
In my wonderfully arranged protocol manual there is an entry under abdominal pain and multi-systems trauma that mentions starting “2 large bore IVs…” but does that mean a 16g? 18g? Certainly not a 20g, right?
But it seems like such a small difference to step from the 18g to the 20g and slamming fluid into these kinds of patients can be debated all year long, but I have to follow my protocols. So what is the difference in fluid flow between those two catheters?
The 20g drained in 18:08.
The 18g drained in 12:31.
That’s a considerable difference and far more than I would have expected. Maybe a few minutes, but 6? So now wondering how fast a 16g can go, alas, I am out of expired bags. But if the trend continues I would expect to be able to drain that 1000ml bag in 6 minutes or so.
6 minutes to run in a liter of fluid or 18 minutes just from going 16g to 20g? That’s huge.
We all know that in a bumpy rig with other concerns that line can get away from us sometimes and you look up at what you thought was a slow bolus and see an empty bag, so I used to err on the side of time instead of volume, just in case.
But that was back when I had 45 minute transport times. Now that I’m just a few minutes out should I change my way of thinking of getting access?
We’ll see, but I just wanted to pass along my experiment.