I just read the comment posted by Pam Jasper, Clinical Specialist, Bard, regarding vein size/catheter size ratio that takes into account the AREA of the vein and the catheter, ie 2 dimensional, versus only looking at the 1 dimensional aspect of vessel and catheter diameter. Â This makes a lot of sense to me and I HAVE NEVER HEARD OF IT BEFORE. Â My question now becomes whether there are any studies that support looking at appropriate catheter size to vessel size from this angle, or are they all based on the 1 dimensional diameter only method? Â I looked at the formula for calculating the area and also the chart that accompanied her post, and had also NEVER SEEN THESE BEFORE EITHER! Â I know it makes a lot of sense to me, and supports what I've seen myself on the ultrasound, because when I have looked at a vessel WITH A CATHETER IN IT, it sure never looked like it took up 30% of the area! Â Now I know why. Â The conclusion that could be drawn from this information is that a smaller vein could accommodate a larger catheter than what I thought, but.....IS THAT CORRECT? Â I would love to see more discussion on this from our local experts. Â Obviously there are other factors to consider that can contribute to thrombogenicity, ie Virchow's Triad, but I would really like to know which interpretation of size ratio is supported by data! Â Comments? Â Lynn? Â What do you say about this!
Addendum: Â I always measure vessel size without any tourniquet. Â This seems obvious to me. Â A tourniquet can swell a vessel to almost double if not more of it's "un-tourniqueted" size. Â It would not be appropriate to document size while the tourniquet is on - that means nothing as far as I'm concerned. Â Â
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Halle Utter RN, BSN
Intravenous Care, INCÂ