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Placing a Cannula

From Mediwikis

Cannulae can be placed to infuse fluids, medication, or take venous blood samples.

Wash your hands

Introduce yourself to the patient, explain purpose of cannula and gain consent.


  1. Correct gauge cannula- blue is too small to give fluids or meds rapidly. Pink is fine for most patients, green or larger if they are likely to need fluids faster.
  2. Cleaning device
  3. Tourniquet
  4. Tape & Plaster


  1. Secure Tourniquet, Identify Vein, Release Tourniquet
  2. Clean injection area for 30 seconds, leave to dry for 30 seconds
  3. Remove equipment from packaging, remove cap from cannula (place near at hand and DO NOT LOSE)
  4. Tourniquet on again
  5. Say you would wash hands again at this point
  6. Put gloves on
  7. Remove cover from needle
  8. Tether skin with fingers distal to insertion point....best to use your non-dominant thumb. See video
  9. Insert needle until flashback, advance a millimetre or so more, withdraw needle into cannula and advance. Keep the skin tethered throughout using your non-dominant thumb
  10. Tourniquet off and apply pressure with finger immediately proximal to cannula to prevent blood spillage
  11. Retract needle fully, place straight in sharps bin
  12. Place cap on cannula, tape it down to the skin, cover with plaster.


  • "I would rinse with 10ml Saline, fill out a cannula observations form, and attach any appropriate extensions."

Tips for real life

  1. The lower the vein is below heart level, the bigger and easier it will be
  2. Asking patient to clench fist to increase size of veins is fine for cannula placement, providing you don't want to immediately take a K+ reading from it - it may be falsely elevated
  3. Don't panic! Look all over for veins, from antecubital fossa to the veins on the back of the hand. "Houseman's vein" is often easily cannulated, on the lateral (radial) surface of wrist
  4. Feel as well as touch - self palpate to learn this
  5. Cannulating the back of a patient's dominant hand is annoying...