1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Does it matter what size syringe used?

Discussion in 'Anaesthetics' started by paris, Nov 18, 2006.

  1. paris

    paris New Member

    Joined:
    Aug 7, 2005
    Messages:
    69
    Likes Received:
    0
    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. I thought that the solution is injected via cannula anyway so the size of syringe used make no differance.

    Can someone explain this please.

    Thanks
     
  2. Varied A

    Varied A New Member

    Joined:
    Jun 23, 2004
    Messages:
    946
    Likes Received:
    0
    The only time you would be administering the drug fast enough to exert force upon the vein is in an emergency, when really it's the least of your worries. Almost all IV injections should be given over a period of minutes rather than all at once. Furthermore, you should be using the smallest size cannula possible, which will further reduce the pressure on the vein.

    All of that combined with the fact that I've never heard of doing what you said nor can I find any info on it suggests to me that it's probably not nescessary...
     
  3. paris

    paris New Member

    Joined:
    Aug 7, 2005
    Messages:
    69
    Likes Received:
    0

    In ophthalmic we inject 2.5 mls of Fluorescein dye all at once followed by: number of photographs taken at interval from 10-20 seconds after injection of dye and at late phase at 5 minutes and on. The question is dose it make any differance whether we use 5mls or 10 mls syringe regardless the size of the venflon excerting pressure on the vein?
     
  4. Varied A

    Varied A New Member

    Joined:
    Jun 23, 2004
    Messages:
    946
    Likes Received:
    0
    Erm, fluorescein only comes in eye drop form, I'd hope that you're not injecting that?! :s
     
  5. belis

    belis New Member

    Joined:
    Apr 30, 2004
    Messages:
    863
    Likes Received:
    0
    It does not. Fluorescin sodium can be injected to produce a fluorescein angiogram.
     
  6. Varied A

    Varied A New Member

    Joined:
    Jun 23, 2004
    Messages:
    946
    Likes Received:
    0
    Interesting, I just googled fluorescien angiogram - 6 weeks in ophthalmology earlier this year obviously did me no good. I'm intrigued though as to why it's not in the BNF for this use?

    Referring back to the original question, you got me intrigued - I've looked through a couple of nursing procedure books and some articles on IV administration, and can find nothing about it, and so I still think it's rather unlikely that a 10ml syringe would offer any benefit.
     
  7. andy2

    andy2 New Member

    Joined:
    Feb 20, 2005
    Messages:
    119
    Likes Received:
    0
    Several misconceptions here
    1) Pressure from a syringe is simple physics (i.e. pressure=force/area) hence one will develop a higher pressure with a two ml syringe than a 10 ml. This is why if you are trying to unblock a cannula a 2ml syringe is better.
    2) As long as you are injecting into a peripheral vein then the difference in pressure developed should not make any difference- veins are relatively high capacitance vessels and will expand to absorb the increased volume.
    3) contrary to much nursing teaching many IV drugs can, and should, be given rapidly - this is what I do as an anaesthetist every day. There are some drugs which have to be given slowly (as examples vancomycin, phenytonin and amioderone outwith arrest situations) but the great majority can be bolused fairly rapidly.
    4) Cannula size- although a smaller cannula will have a greater resistance to flow, and so cause a greater drop in pressure along its length, the most important determinant is the driving pressure. Small cannulae cannot provide the higher flow rate of larger cannuale (again simple physics/Hagen Pousille equation). There seems to be a trend towards putting small cannulae in large veins - this is annoying as it removes a site of venous access for a decent sized cannula, and if the patient needs fast fluids makes this nigh on impossible. With a wee dod of lignocaine larger (18G+) cannulae are no more sore to site than small ones and are a damn sight more use. They also last longer as they are less likely to kink. If you must insist on 20/22G cannulae then please put them in the hand/wrist veins and not the juicy ones in the ACF.
     
    #7 andy2, Nov 19, 2006
    Last edited: Nov 19, 2006
  8. Varied A

    Varied A New Member

    Joined:
    Jun 23, 2004
    Messages:
    946
    Likes Received:
    0
    That could have something to do with the insistance of doctors that nurses only cannulate or take blood from the ACF and do not go anywhere else ;)
     
  9. andy2

    andy2 New Member

    Joined:
    Feb 20, 2005
    Messages:
    119
    Likes Received:
    0
    Although this relates only to my personal experience I've never met a doctor who insisted nurses only cannulate the ACF -if they are doing this they need serious re-education. I've met plenty of nurses who insist they should only cannulate the ACF, and only use pink/blue venflons but that is usually down to
    a) unwillingness to have to go through the 'failure' required to improve ones skills and b) BS teaching by 'practice development nurses' who spend a lot of time teaching skills they are hardly proficient in themselves. (i.e. if you can only cannulate the ACF then you cover this up by inventing spurious reasons as to why your students should only do this).

    Cannulation is a simple motor skill, and only gets better with practice - the only reason I'm pretty good at it is because I've put in several thousand in the past couple of years.
    FWIW the ACF is also a more hazerdous place to cannulate as you are more likely to inadvertenly cannulate the brachial artery -which risks direct arterial damage, distal ischaemia and inadvertent intra-arterial injection. This is one reason why I avoid the ACF unless it is the only option. Given how risk averse most nurses are I think if they knew this they'd avoid this area too.
     
  10. Varied A

    Varied A New Member

    Joined:
    Jun 23, 2004
    Messages:
    946
    Likes Received:
    0
    I agree with you, many don't! I've had discussions with many nurses over these kinds of issues, and certainly in the trust I predominantly work for, the cannulation policy (which was written by a senior doctor with no nursing input) quite clearly states that nurses must only cannulate or take blood from the ACF.
     
  11. paris

    paris New Member

    Joined:
    Aug 7, 2005
    Messages:
    69
    Likes Received:
    0
    Yes you are correct in saying that fluorescein comes as eye drop form but is also used to evaluate the retinal disorders in ophthalmology by injecting dye the into the vein.

    http://www.opsweb.org/Op-Photo/Angio/FAMovie/FAMovie.htm
     
  12. paris

    paris New Member

    Joined:
    Aug 7, 2005
    Messages:
    69
    Likes Received:
    0

    I looked in the hospital Fluorscein angiograhy protocol and procedure for nurses and it does states that nurses must only cannulate in ACF. This will need to be looked at. Thanks for pointing this out. Though it does not state that nurses must only take blood from the ACF.
     
  13. andy2

    andy2 New Member

    Joined:
    Feb 20, 2005
    Messages:
    119
    Likes Received:
    0
    I have a feeling that any 'senior doctor' saying that nurses 'must only cannulate the ACF' is unlikely to be someone who cannulates regularly -otherwise you would not be saddled with this nonsense.
     
  14. Varied A

    Varied A New Member

    Joined:
    Jun 23, 2004
    Messages:
    946
    Likes Received:
    0
    If we weren't subject to such constant nonsense from senior doctors and were allowed to use common sense and evidence perhaps we'd get some proper work done and not get so much berating from doctors in general ;)
     
  15. andy2

    andy2 New Member

    Joined:
    Feb 20, 2005
    Messages:
    119
    Likes Received:
    0
    watch it mate -as a student nurse I'm not sure you are really in a position to comment on the dynamics in the NHS. Short of asking the nurses to enact my management plans I seldom 'tell them what to do' or interfere with what they get up to - I even bite my tounge as I watch them yet again bugger up the last decent vein and fail to take off the one crucial blood sample that is required (mind you the housemen are pretty good at that too).
     
  16. pipedreamer

    pipedreamer New Member

    Joined:
    Jan 26, 2004
    Messages:
    490
    Likes Received:
    0
    Maybe it's not in the BNF because it's not being used as a drug in its IV form - only as a (presumably inert) contrast medium. Although if that was the case then surely the eyedrops wouldn't be in there either?

    I'm surprised you never got to see any fluorescin angios in six weeks of opthalmology. I did a week's attachment recently and was under the impression that it was a fairly routine outpatient investigation.
     
  17. Varied A

    Varied A New Member

    Joined:
    Jun 23, 2004
    Messages:
    946
    Likes Received:
    0
    Errrm, I think I am just as well placed as anybody else who is in contact with the NHS, and I am perhaps more qualified to talk about NHS politics in so much as how it relates to nursing than you, a doctor, are. :)
     
  18. 1stNP

    1stNP New Member

    Joined:
    Apr 23, 2006
    Messages:
    5
    Likes Received:
    0
    Fluorescien dye is not licensed drug in the UK for the use as IV and has been used since 1980's i think. Perhaps thats why it is not in the BNF????. In many hospital Fluorescien angiography clinic is nurse led???? i think.
     
  19. yeliab_cram

    yeliab_cram New Member

    Joined:
    May 15, 2005
    Messages:
    1,519
    Likes Received:
    0
    Vaied A - Must every discussion you get involved in on these forums come back to this same nurses vs doctors argument?

    would you like some dip to go with that chip on your shoulder???
     
  20. andy2

    andy2 New Member

    Joined:
    Feb 20, 2005
    Messages:
    119
    Likes Received:
    0
    The thing is John, when I was a student I used to think I had a handle on how things worked -I had spent a considerable amount of time as a nursing auxiliary working on a variety of wards and obviously spent lots of time on the wards as a med student. As it turned out once I started work I knew very little about the dynamics of wards, the sort of BS nonsense that NHS workers have to put up with everyday and the hidebound, 'its the protocol' attitude that results in pink venflons in the ACF.

    I'd be careful of parroting back the 'if the senior doctors stopped interfering' lines i used to hear from my nursing colleagues -'cos guess what if the consultants just upped and buggered off everyone would be in a bit of mess.

    Its about team working, respecting the individual team members and their skills and abilities - that respect should be just as much in evidence for the senior medical staff as for the most junior newly qualified nurse.
     

Share This Page