Paediatrics: Intravenous cannulation

2021-03-05 12:00 AM

IV cannulation is required for the infusion of fluids or drugs. Any blood sampling necessary may also be done at the time of insertion.

Intravenous cannulation

IV cannulation is required for the infusion of fluids or drugs. Any blood sampling necessary may also be done at the time of insertion. This ‘com-bined’ technique will save puncturing the child twice.

Equipment

  • An alcohol impregnated swab.
  • IV cannula: 24G in newborns, 21G in older children.
  • IV extension set and 3-way tap with Luer lock flushed with 0.9% saline.
  • Tourniquet (older children).
  • Fixing tape or transparent occlusive dressing to fix cannula in site.

Procedure

  • Carefully identify a suitable vein. The dorsum of the hand or foot or antecubital fossa is ideal. Other suitable sites include the anatomical snuff box, volar aspect of the forearm, great saphenous vein at the medial malleolus or knee. Whilst not ideal, scalp veins can be used, but the hair usually needs to be shaved. If possible, avoid larger veins if a percutaneous central line insertion is likely to be needed later.
  • Tip: transillumination of hand or foot with a ‘cold’ light source can be very useful for locating ‘hidden’ veins, particularly in the newborn. In an emergency, or if one or more normal sites have been used, scour the whole body and use whatever vein you can find!
  • Consider at least 45min of local anaesthetic cream applied under an occlusive dressing over the intended vein before starting. Remove the cream before starting.
  • Ensure good vein perfusion, e.g. warm extremity before cannulation.
  • If needed, ask an assistant to help with keeping the child’s limb steady. This may require wrapping a young child in a towel or sheet.
  • In older children, apply a tourniquet proximal to the vein. In infants, if attempting the hand dorsum, apply compression and immobilization by flexing the wrist, then grasping with the index and middle fingers over the dorsum, whilst the thumb is placed over the child’s fingers.
  • Clean the site with an alcohol impregnated swab.
  • Insert cannula at an angle of 10–15° to the skin with the bevel upright, just distal and along the line of the vein.
  • When the stylet tip penetrates into the vein lumen blood will flashback (not always if the vein is small!).
  • Once vein lumen is entered advance 1–2mm, to ensure the cannula is also in vain, and then advance the cannula over stylet up into the vein.
  • Remove stylet, and collect any blood required from the cannula hub.
  • Flush cannula with 0.9% saline to confirm IV placement (fluid should infuse without resistance) and to prevent clotting, then connect IV line.
  • Secure cannula with appropriate adhesive tape or dressing leaving the skin over the cannula tip visible so that extravasation can be observed.
  • Splint extremity to prevent the cannula kinking.
  • This is a difficult procedure to master, particularly in the newborn. Do not be afraid to ask for senior help if unsuccessful after 2 or 3 attempts.