Why does tapping on a vein make it bulge?

Discussion in 'Clinical Rotations' started by SmokD, Sep 9, 2011.

  1. SDN is made possible through member donations, sponsorships, and our volunteers. Learn about SDN's nonprofit mission.
  1. SmokD

    SmokD 5+ Year Member

    Joined:
    Jun 3, 2009
    Messages:
    167
    Likes Received:
    2
    Location:
    NYC
    Status:
    Medical Student
    Tittle speaks for itself. Anesthesiologist asked the question in the room and I told him I'd look it up. Please do my homework for me :D (I did do a brief google search to no avail)
     
  2. SDN Members don't see this ad. About the ads.
  3. KSDeacon

    KSDeacon Rock Chalk Jayhawk!!!! 5+ Year Member

    Joined:
    Jun 20, 2007
    Messages:
    288
    Likes Received:
    0
    Status:
    Medical Student
    only thing i could think of would be related to some form of auto-regulation, whereby tapping on it causes compression and then some rapid expansion. I dunno...
     
  4. septoplasty

    septoplasty Exceptional 5+ Year Member

    Joined:
    Nov 10, 2010
    Messages:
    521
    Likes Received:
    27
    Location:
    Call Room
    Status:
    Fellow [Any Field]
    "Idiopathic" would be a good word to use in conjunction when describing the above.
     
  5. peytonm

    peytonm 5+ Year Member

    Joined:
    Sep 5, 2011
    Messages:
    6
    Likes Received:
    0
    Location:
    Denver
    Status:
    Medical Student
    I always thought it was because you were holding the hand down (allowing gravity to work), and then tapping on more proximal veins which opens the venous valves, thus allowing blood to pool at the distal veins. Just a thought.
     
  6. scudrunner

    scudrunner ASAPAC Supporter 7+ Year Member

    Joined:
    Mar 20, 2009
    Messages:
    704
    Likes Received:
    101
    Location:
    Skimming the tree tops
    Status:
    Resident [Any Field]
    It doesn't. I worked as a phlebotomist for a few years and never noticed a bulging reaction just by tapping on a vein. Some old-timers will slap the skin but that doesn't help either. Maybe they were looking for something like reactive hyperemia. The only thing that makes the vein bulge is a downstream occlusion with a tourniquet.
     
  7. tkim

    tkim 10 cc's cordrazine 10+ Year Member

    Joined:
    Aug 2, 2002
    Messages:
    7,570
    Likes Received:
    279
    Location:
    New England
    Status:
    Attending Physician
    Verified
    Physician
    Worked as a medic for 12 years. It works.
     
  8. thepoopologist

    thepoopologist Ph.D in Clinical Meconium Bronze Donor 7+ Year Member

    Joined:
    Oct 24, 2009
    Messages:
    3,434
    Likes Received:
    423
    Status:
    Resident [Any Field]
    "Idiopathic-Autoregulating-Vasodilation"

    oH yEs, iNdeed
     
  9. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    I'll go ahead and give a quasi-physiological reason:

    Tapping the vein causes reflex mechanism producing venous dilation in response to venous congestion. In other words, you trick your vein into thinking there is a lack of blood flow to the area for a split second, so a compensatory (and fleeting) increase in blood flow follows. Then it all returns to normal seconds later.
     
  10. Arch Guillotti

    Arch Guillotti Senior Member Lifetime Donor SDN Administrator 10+ Year Member

    Joined:
    Aug 8, 2001
    Messages:
    6,772
    Likes Received:
    413
    Status:
    Attending Physician
    Verified
    Physician
    Don't know but it definitely works.
     
  11. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    Local stasis = area where you're tapping.
     
  12. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    You might want to look up what the word 'stasis' means. If there was real stasis below the tourniquet, you wouldn't be able to fill up vials of blood with the needle.

    Real stasis is tapping/rubbing the vein and causing a stop of blood flow for a split second.
     
  13. SmokD

    SmokD 5+ Year Member

    Joined:
    Jun 3, 2009
    Messages:
    167
    Likes Received:
    2
    Location:
    NYC
    Status:
    Medical Student
    That sounds sciency enough, I think I'll go with that :cool: Thanks!

    EDIT: On second thought, I dont get this. Can veins be autoregulated? They lack smooth muscle, so how do you alter the capacitance of a vein?
     
  14. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    I don't buy it.
     
  15. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    Sounds fair enough.
     
  16. Isoprop

    Isoprop Fascinating, tell me more 5+ Year Member

    Joined:
    Oct 15, 2007
    Messages:
    4,198
    Likes Received:
    26
    Status:
    Medical Student
    From http://www.ncbi.nlm.nih.gov/pubmed/15219306

     
  17. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
  18. leviathan

    leviathan Drinking from the hydrant Moderator Emeritus 10+ Year Member

    Joined:
    Sep 30, 2003
    Messages:
    2,356
    Likes Received:
    11
    Location:
    Vancouver, BC, Canada
    Status:
    Fellow [Any Field]
    Verified
    Physician
    Veins do have smooth muscle (but less than arteries) and have the ability to alter their capacitance via alpha and nitric oxide receptors among other things.
     
  19. septoplasty

    septoplasty Exceptional 5+ Year Member

    Joined:
    Nov 10, 2010
    Messages:
    521
    Likes Received:
    27
    Location:
    Call Room
    Status:
    Fellow [Any Field]
    That should sufficiently deter the pimping session away from you, possibly onto a fellow classmate who is asked to explain the above, which would be quite the situation. LOL
     
  20. 45408

    45408 aw buddy 7+ Year Member

    Joined:
    Jun 13, 2004
    Messages:
    16,983
    Likes Received:
    30
    Status:
    Resident [Any Field]
    The stasis no longer applies when you apply a vacuum tube upstream of the occlusion. You're now providing a way out.
     
  21. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    There would not be a build-up of pressure if it was static. Pressure would only build if there was flow.
     
  22. 45408

    45408 aw buddy 7+ Year Member

    Joined:
    Jun 13, 2004
    Messages:
    16,983
    Likes Received:
    30
    Status:
    Resident [Any Field]
    If you have a capped syringe full of fluid, you can push on the plunger and increase the pressure without any flow. It will be static. As soon as you provide a way out, then you'll have flow.
     
  23. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    Unless a tourniquet can block off deep veins, there is no stasis. I don't know what type of tourniquets that you use, but I haven't cut off all circulation in over a 1000 blood draws. Heck, with teenage boys, I sometimes don't even use a tourniquet.
     
  24. DrHogFan

    DrHogFan 5+ Year Member

    Joined:
    Mar 5, 2011
    Messages:
    48
    Likes Received:
    0
    Location:
    South Arkansas
    Status:
    Resident [Any Field]
    could seriously be taken out of context
     
  25. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    Not by a normal person.
     
  26. Morsetlis

    Morsetlis Preliminary Medicine 5+ Year Member

    Joined:
    Jan 22, 2010
    Messages:
    4,927
    Likes Received:
    34
    Location:
    St. George's, Grenada
    Status:
    Medical Student
    None of you are normal people.
     
  27. 45408

    45408 aw buddy 7+ Year Member

    Joined:
    Jun 13, 2004
    Messages:
    16,983
    Likes Received:
    30
    Status:
    Resident [Any Field]
    Yes, there is. We aren't talking about cutting off all circulation. We're talking about occluding the primary outflow for a superficial vein, not whether or not an insignificant perforator is still allowing a microliter of blood through it.
     
  28. ToldYouSo

    ToldYouSo Student 7+ Year Member

    Joined:
    Oct 11, 2008
    Messages:
    976
    Likes Received:
    75
    Location:
    New York
    Status:
    Medical Student
    hSDN
    Alumni

    :corny:
     
  29. Instatewaiter

    Instatewaiter But... there's a troponin 10+ Year Member

    Joined:
    Apr 28, 2006
    Messages:
    5,734
    Likes Received:
    1,528
    Location:
    Washington
    Status:
    Fellow [Any Field]
    Now I don't know what you Canadians call residency but from this comment I imagine it involves no shirts and a significant amount of leather
     
  30. mrwesticles

    mrwesticles

    Joined:
    Jul 5, 2011
    Messages:
    162
    Likes Received:
    1
    Status:
    Medical Student
    It's it answering the door to your knocking, duh.
     
  31. leviathan

    leviathan Drinking from the hydrant Moderator Emeritus 10+ Year Member

    Joined:
    Sep 30, 2003
    Messages:
    2,356
    Likes Received:
    11
    Location:
    Vancouver, BC, Canada
    Status:
    Fellow [Any Field]
    Verified
    Physician
    If you don't know what those words are you might want to hit the step 1 books a few more times. :rolleyes:
     
  32. tkim

    tkim 10 cc's cordrazine 10+ Year Member

    Joined:
    Aug 2, 2002
    Messages:
    7,570
    Likes Received:
    279
    Location:
    New England
    Status:
    Attending Physician
    Verified
    Physician
    Why would he read step 1 books when he's already a resident?
     
  33. WildMed16

    WildMed16 5+ Year Member

    Joined:
    Jan 13, 2011
    Messages:
    47
    Likes Received:
    0
    Status:
    Resident [Any Field]
    I was told recently by an anesthesia resident that tapping the vein actually causes a histamine release and subsequent vasodilation. Thought it made sense...
     
  34. McGillGrad

    McGillGrad Building Mind and Body 10+ Year Member

    Joined:
    Dec 21, 2002
    Messages:
    3,922
    Likes Received:
    16
    Status:
    Resident [Any Field]
    meh, sounds like mumbo jumbo.
     
  35. Tubed

    Tubed 5+ Year Member

    Joined:
    Mar 29, 2010
    Messages:
    27
    Likes Received:
    0
    Status:
    Resident [Any Field]
    I'm an anesthesia resident and that's what I was told by a senior resident during my PGY1 year. I later regurgitated it to an attending when he asked why I was tapping my pt's veins and he looked at me very disapprovingly. I now use the hand-waving mumbo-jumbo response and people seem to accept that just fine...
     

About the ads

Share This Page