You should also consider the basic action of the smooth muscle in the tunica media. This layer of the vein will cause dilation from the tourniquet. There is a phenomenon called the stress-relaxation phenomenon. The smooth muscles stretch only to a certain point, then the muscle relaxes so that there is way to palpate a superficial vein. If you are using US for insertion, palpation is not the goal but this action will cause the relaxation so that the vein may not appear the same on US. This action can happen when the tourniquet remains on for extended periods of time. Once you enter the vein with the finder needle, you can remove the tourniquet. Then pass the wire and proceed with the procedure. I also know that some do not use a tourniquet at all when using US and MST to reach deep veins. When placed appropriately, the tourniquet will distend the superficial veins and not the deep veins which lie under the muscle tissue. My thought is that a tourniquet that obstructs flow in these deep veins would also obstruct arterial flow which would be too tight, especially for extended periods. If you do not use a tourniquet for this procedure, please share your experiences. I have never seen anything published about this, just replying based on my knowledge of anatomy.
Lynn Hadaway, M.Ed., RN, BC, CRNI
Lynn Hadaway Associates, Inc.
126 Main Street, PO Box 10
Milner, GA 30257
Office Phone 770-358-7861
I have frequently performed US guided PICC insertion without a tourniquet without any difficulty. Have found a lightly tightened tourniquet useful to improve vessel margin visualization on the superficial veins. Totally agree with shortest period for tourniquet application.
Timothy L. Creamer, RN
Clinical Specialist, Bard Access Systems
Timothy L. Creamer RN, CRNI
I'm an advocate of "no tourniquet". I want to accurately assess to vein to catheter ratio and a tourniquet may distort the actual size. If I felt I needed a tourniquet to enlarge the vein for safe placement, I would in all likelihood, not place the line and send this patient for a more appropriate line in a larger vessel.
It may be a hard transition away from using a tourniquet, but maybe something to think about. As stated earlier in this blog, a tourniquet may move the position of a shallower vein placing the catheter in an unsafe position (maybe annoying a nerve) and when using it to enlarge a basilic vein may not even do its desired task due to the depth of the vessel. Another issue to think about is venous spasm. If the tourniquet is left tied too long, you may create a venous spasm making it difficult if not impossible to thread a guidewire.
I often will NOT use a tourniquet and always measure vein without it.
Tourniquets seem to make some veins tougher to cannulate - I speculate it's those veins that already have thick/tough tunica media. They're easier to penetrate with the needle if they're relaxed.
Also, sometimes the tourniquet application temporarily "rearranges" the arrangement of vessels, and puts the vein in a bad position relative to artery/nerves.
Mari Cordes, BS RN
Mari Cordes, BS RNIII VA-BC
Vascular Access Department
University of Vermont Medical Center