Intended for healthcare professionals

Student Education

Practising venous cannulation

BMJ 2008; 336 doi: https://doi.org/10.1136/sbmj.0806244 (Published 01 June 2008) Cite this as: BMJ 2008;336:0806244
  1. Nicholas B N Timmis, fifth year medical student1,
  2. Geoffrey N Morris, consultant anaesthetist2
  1. 1University of Bristol
  2. 2Southmead Hospital, Bristol

Nicholas B N Timmis and Geoffrey N Morris give an alternative method for developing this practical skill

All junior doctors need to be able to insert a peripheral cannula confidently, but the teaching of this technique to medical students is somewhat hit and miss. When we get an opportunity to practise in the wards, we often fail because we haven't had the chance to practise in a relaxed environment, where we can iron out our early fumbling. The system that we describe here gives a good opportunity for students to practise cannulation on a simple but surprisingly realistic model so that cannulation in patients becomes more successful and, importantly, less painful.

Before beginning it is important to choose the correct size of cannula. The options, in order of decreasing bore size, are 16 gauge (grey) for surgical emergencies; 18 gauge (green) for blood transfusions; 20 gauge (pink) for maintenance of intravenous fluids; and 22 gauge (blue) for difficult veins, slow intravenous fluids, or intravenous drugs in a patient who can take oral fluids (blue).fig 1 fig 2 fig 3 fig 4 fig 5 fig 6 fig 7 fig 8 fig 9

Step 1

Use a BD Venflon and a cooked piece of penne pasta. Using a BD Venflon is essential because the depth of its plastic casing means that the pasta sits nicely at an accessible height for cannulation (other brands often have deeper casings).

Step 2

Open the cannula, unfold its wings, and remove the plastic sheath that covers the needle. Insert the sheath through the pasta to stent it. The pasta simulates the skin, and the tapering end of the sheath creates a space to cannulate, simulating the vein

Step 3

Put the stented pasta into the cannula box ready for practice. In a real scenario remember to wear gloves, clean the overlying skin, …

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