Syringe sizes used

  1. Someone told me that for instance when administering a 5ml solution (bolus), one should use a 10ml syringe, as this reduces the force exerted upon the vein regardless the presence of a cannula. The reason for this is that Pressure = Force/Area. Assuming the force exerted by the administering nurse is constant, the syringe with the larger diameter, and hence area, will produce less pressure, translating to a lesser force upon the vein.

    I don't understand this please can someone explain to me in simple term as i thought that since the bolus solution is given through venflon it doesn't make any differance of what size syringe used.

    thnks
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  2. 7 Comments

  3. by   RGN1
    You should use a 10ml syringe because the pressure coming from that bore will not blow the vein. Anything smaller & the pressure coming out can blow the vein. Just because it is coming therough a venflon it doesn't make any difference
  4. by   pie_face
    not sure about this one, would like to see the research this advice is based on. Could it be that the force element of the equation is the important factor, ie how hard and fast you push the drug, or are you suggesting that giving 0.1 ml/min via a 2ml syringe is going to pop a vein? In my 10 years i cant remeber that happening, it is also worth thinking about peads where due to the concentrations and doses being given a 10ml syringe could be innacurate. As i said though would like to see the research as its not something i've spent a lot of time thinking about.
  5. by   augigi
    Using Ovid Medline, the only articles I could find using the search term "Syringe size" were about:
    - the effect on bruising with heparin injection
    - the function of syringe pumps with different syringes

    In fact the only relevant article I found was:
    Thobani, S U. Steward, D J. The accuracy and variability of bolus injections with different sized syringes. Canadian Journal of Anaesthesia. 39(2):198-201, 1992 Feb.

    This article said the closer the syringe size to the bolus size, the more accurate the bolus (bolus <5ml). For bolus >5ml, there was no difference in the accuracy based on the syringe size.
  6. by   cariad
    what about the guage of the cannula, we use all different sizes here and the smaller ones dont take too much force.
  7. by   RGN1
    All I know is that when I did my IV & cannulation courses we were told not to use a syringe under 10 mls for bolus injections because there was a risk of blowing the vein with any size under that. Of course you can probably get away with it time & time again but that's what we were told.

    Just to add this was for adults only I don't know about paeds at all.
  8. by   madwife2002
    I was informed that anything under a 6mls stringe for use with a PICC causes untold pressure and may have serious consequences I will find the research and post it.
  9. by   Noahm
    Quote from RGN1
    All I know is that when I did my IV & cannulation courses we were told not to use a syringe under 10 mls for bolus injections because there was a risk of blowing the vein with any size under that. Of course you can probably get away with it time & time again but that's what we were told.

    Just to add this was for adults only I don't know about paeds at all.
    I was taught this as well. I always use 10 ml syringes.

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