why do veins blow during a blood draw

Dear JSINR,
Blowing a vein can occur from several things. 1. Using too large of an IV catheter. INS standards say that one should always use the smallest gauge and length IV catheter possible for the prescribed therapy. 2. Your angle of insertion is importnat as well. The elderly population have had many age related changes with their skin and blood vessels. Because their vessels are more superficial (secondary to loss of SQ tissue) you may need to insert your device at a very shallow 5-10 degree angle. 3. In addition, once you've gained successful enry into your vessel and you've advanced your catheter's hub to insertion, release your tourniquet. You also should pay attention to how tight your tourniquet is on the pt. Elderly pt's usually require light tourniquet application to keep from blowing the vein. Hope this helps. Ii is also an art and if you take a little extra time with assessment and filling up the selected vein or vein your success rare will slowly increase.


You also need to figure out what you are doing incorrectly so you can fix it. I have been an infusion nurse for 25 years now and still enjoy the challenge immensely. First. you need to figure out why you are unsuccessful and with your description I have 2 suggestions and if you could be more specific I can pinpoint your problem area down even more. I would like to know if you are hitting the vein and then it blows or if you are hitting it,getting a nice flashback and then you advance the cannula and then it blows? Those are two different issues! What product are you using if it is an introcan I have a nice step by step instruction sheet I wrote that I can E mail to you. There are slight differences in products so you should always read the manufacturers instructions or make sure that you know them. 1. Make sure you perform a good assessment. You need to know what you are going to infuse.


What is the ph and osmolarity of the IVFs and medications and are they phlebogenic/irritating. Anything with a ph of less than 5 or greater than 9 and/or osmolarity of greater than 600 needs a vein that will provide good hemodilution and is best given through a central line. Keep that in mind so you can advocate for that if needed. 2 Apply the tourniquet. I like to apply above the ACF so I can assess the entire vasculature. A safety tip is to Always unsnap the gown all the way up or tape up the gown so you never forget to pop the tourniquet. Apply a warm pack if needed to the selected vein while you get your supplies ready. Select veins that are soft,are not in areas of flexion and ones that are proximal to previous recent venipunctures. Look at the length of the vein you have and select the appropriate catheter length. if you have a nice straight section but it is only an inch long select an inch catheter, You can select a longer length and tunnel it a bit but that is a more difficult technique.


I will not go into the direct and indirect technique for accessing the vein b/c I think it will confuse you but I will describe the technique. 3. Reapply tourniquet,prep and all that stuff. Now here is an important point and a one of two of the most common mistakes I see. DO NOT make your angle of approach too deep. The angle will vary based upon the vein but usually you just need a slight angle of usually no more that 15-30 degrees and if the vein is on the surface and you can see it and feel it you should just go in almost flush to the skin. So now perform your venipuncture and observe for blood in the flashback chamber. Once you see the flashback,stop advancing the catheter and drop the angle of your approach to flush with the skin. Some brands have an early flashback mechanism and you can see the blood come back through the cannula before you see it in the flashback chamber, You must now advance the catheter a bit more once your angle is dropped.


I see this as a common mistake as well. In all IV catheters the needle is longer than the cannula so your needle may be in the vein BUT your cannula is not! The larger the gauge the greater the amount you need to advance into the vein. I suggest about 1/8 of an inch or so. You can see why it it important to get a straight section of the vein so when you advance a bit more you do not advance it into a side wall and then out of the vein. You know all is good if you keep seeing blood coming back. Now pull the needle back just a bit. The needle will give the catheter stability during threading but b/c you have pulled it back you will not damage the vein and make an additional holes or in it. so advance the remainder of the catheter and flush and secure.

  • Views: 42

why do you draw blood from veins
why do you need a fistula for dialysis
why do they put stents in your heart
why do veins collapse when drawing blood
why do veins blow during iv start
why do you need a fistula for dialysis
why use a tourniquet when drawing blood