Definition of "IV cannulation"

Last modified: 13 hours

IV cannulation (IVC, aka peripheral venous catheter) is the insertion of a cannula into a vein. Arterial cannulation is a variation involving insertion into an artery (commonly the radial artery) to measure beat-to-beat blood pressure, and draw repeated blood samples.

Patient information

Wait. Catheter, cannula, is it the same thing?
A catheter is plastic. A cannula is metal, so a needle. When you draw blood, you insert the metal bit to puncture, and allow blood flow. However, if you want to keep it there, you don't want to keep a piece of metal there, because it can cause trauma to the blood vessel. So you use a piece of metal to pierce through skin, but you retract it, and only keep plastic in there.

  • Administering IV fluids
  • Obtaining blood samples
  • Administering medicines
  • In kids, a local anesthetic gel (e.g. lidocaine) is applied ot the insertion site to facilitate placement
  • Usually placed in a vein on the arm or hand
  • Introduced into the vein by a needle, similarly to blood drawing, which is subsequently removed, while the small plastic tube of the cannula remains in place. Modern catheters consist of synthetic polymers, e.g. teflon, but in the 1950's were PVC plastic
  • The catheter is then fixed by taping it ot the patient's skin, unless there is an allergy to adhesives
  • Newer catheters are equipped with safety features to avoid needlestick injuries

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Needle gauge describes a variety of outer diameters. Note that small gauge numbers indicate larger OUTER diameters. INNER diameter depends on both gauge and wall thickness. Gauges include, starting from the LARGEST to SMALLEST cannulas:

  • Commercially less available:
    • 7, has outer diameter of 4.572mm
    • 8, has outer diameter of 4.191mm
    • 9, has outer diameter of 3.759mm
    • 10, has outer diameter of 3.404mm
    • 11, has outer diameter of 3.048mm
    • 13, has outer diameter of 2.413mm
  • Large bores (aka trauma lines), including:
    • 12, has outer diameter of 2.769mm. It is capable of delivering large volumes of fluid very fast, thus popular in ED
    • 14, has outer diameter of 2.108mm. It is a very large cannula, used in resuscitation settings
  • 16, has outer diameter of 1.651mm. It is a mid sized line, used for blood donation and transfusion
  • 18, has outer diameter of 1.270mm. It is an all purpose line for infusion and blood draws
  • 20, has outer diameter of 0.9081mm. It is another all purpose line for infusion and blood draws
  • 22, has outer diameter of 0.7176mm, and an inner diameter of 0.152
  • 22s, has outer diameter of 0.7176mm, and an inner diameter of 0.337
  • 24, has outer diameter of 0.5652mm
  • 26, has outer diameter of 0.4636mm, and an inner diameter of 0.260mm
  • 26s, has outer diameter of 0.4737mm, and an inner diameter of 0.127mm
  • Commercially less available, since it is odd sizes:
    • 15, has outer diameter of 1.829mm
    • 17, has outer diameter of 1.473mm
    • 19, has outer diameter of 1.067mm
    • 21, has outer diameter of 0.8192mm
    • 23, has outer diameter of 0.6414mm
    • 25, has outer diameter of 0.5144mm
  • Commercially less available:
    • 27, has outer diameter of 0.4128mm
    • 28, has outer diameter of 0.3620mm
    • 29, has outer diameter of 0.3366mm
    • 30, has outer diameter of 0.3112mm
    • 31, has outer diameter of 0.2604mm
    • 32, has outer diameter of 0.2350mm
    • 33, has outer diameter of 0.2096mm
    • 34, has outer diameter of 0.1842mm

The wall thickness become lower, and therefore the inner diameters become proportionately larger (but still smaller in absolute measure).

Patient information

Sizes. How does it work?
The smaller the gauge, the bigger the size. The larger the gauge, the smaller the size. So it's contrary. Large bore which we use in trauma, because we want blood fast and in large amounts, is 12-14 bore. Transfusion is done with a 16 gauge. Infusion is done with an 18 gauge. And 20 is an all purpose line.

  • Hematoma (aka bruise, i.e. collection of blood), due to failure to puncture the vein when the cannula is inserted or removed. This can be prevented by selecting an appropriate vein and gently applying pressure slightly above the insertion point on removal of the cannula
  • Infiltration, where the contents enter the subcutaneous tissue instead of the vein. This can be prevented by selecting an appropriate cannula, and fixing it in place firmly
  • Embolism, caused by air, thrombus, or fragment of catheter breaking off and entering the venous system, potentially causing PE. This can be prevented by using a smaller cannula
  • Phlebitis (i.e. inflammation of the vein), caused by mechanical or chemical irritation, or from infection. This can be avoided by carefully choosing the site for cannulation, and checking for entry contents
  • Infection, which thus should be replaced every 4 days
  • Extravasation, is accidental administration of IV infused drugs into the extravascular space/tissue around the infusion sites, either by leakage (e.g. because of brittle veins in very elderly Pt's), previous venipuncture (e.g. from blood drawn from lab tests prior to therapy), or direct leakage from mispositioned venous access devices
  • Hemorrhage/bleeding
  • Given to most ED and surgical patients
  • In the USA, >25m patients get a peripheral venous line each year

Paperwork for Vascular access device (VAD) care plan includes:

  • Affix Pt label
  • Type of device: Tick for PICC, CVC, PORT-A-CATH, MIDLINE, HICKMAN
  • Date of insertion __/__/____
  • Inserted by ___
  • No of cannulation attempts
  • VAD care plan insertion site, tick Left or Right
  • Vein, tick for Basilic, Brachial, Femoral, Cephalic, Median, Subclavian, Internal Jugular, Other ___
  • Placement, tick for SVC, Mid Clavicular, Femoral, Midline, Other ___
  • Catheter Data, tick for Internal, External, Trimmed; Arrow, Bard, Cook, Other ___; Single Lumen, Doubel Lume, Triple Lumen, Quad Lumen; 3F, 4F, 5F; 20cm, 30cm
  • Maximum flow ___
  • PICC arm circumference, tick for 10cm, 15cm above cubital fossa
  • General guidelines, include No BP or venepuncture above PICC site; no syringe less than 10mL to be used for injecting; observed site daily of infection, swelling, bleeding; do NOT turn fluids off; do NOT disconnect e.g. for showering; make sure all lines are without tension; line change due Monday and Thursday; dressing, Statlock and positive pressure valve (PPV) changes weekly
  • Table, which for columsn includes Insertion day, Day 1 __/__/____, Day 2 __/__/___, Day 3__/__/____... Day 18 __/__/____, Day 19 __/__/____, Day 20 __/__/____. Rows include External catheter measurement; Arm circumference (for PICC only); site pain (0 to 10); inflammation; swelling; bleeding; dressing, Statlock, PPV change due; IV line change due; signature; and designation
  • Legend includes N=Nil, S=slight, M=moderate, L=large
See also
  • Venipuncture
  • French scale
  • CVC (inserted in a central vein, usualy the internal jugular vein of the neck or the subclavian vein of the chest)
  • Arterial catheter (placed ina  peripheral as well as a centarl artery)

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Definition of IV cannulation | Autoprac

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