Umbilical artery catheterisation for neonates

Arterial tray

You will need:

• 1 scalpel blade handle
• 2 probes: fine and medium
• 4 mosquito artery forceps: 2 curved, 2 straight
• 2 pair dissecting forceps: toothed, non-toothed
• 2 iris forceps
• 1 pair vein scissors
• 1 pair suture scissors
• 1 needle holder
• 2 bowls
• cotton wool swabs
• gauze swabs
• tape measure.

Other equipment

You will also need:

• surgical mask
• sterile gown and gloves
• 1 plastic drape (sterile)
• 1 scalpel blade no. 11
• 1 umbilical artery catheter
  • 3.5 Fr < 1200 g baby
  • 5 Fr =1200 g baby
• 1 blood pressure monitoring kit (transducer), if available
• 3-way tap and syringe
• 1 x 5 mL syringe and 18G needle
• 1 x 10 mL ampoule 0.9 per cent saline
• 1 packet 3/0 black silk suture
• 2 per cent aqueous chlorhexidine solution as skin prep. (dilate 1:1 with sterile water if infant)
• infusion pump
• parenteral administration set and ordered parenteral solution
• 1 mL ampoule heparin 1,000 units/mL (labelled)
• 1 cm wide leukoplast for taping of catheter.

1. Set out equipment, observing strict sterile technique.
2. Estimate the position of catheter tip:
   1. The correct position is in the descending aorta above the origin of the mesenteric and renal arteries (to avoid occlusion of these vessels).
   2. Calculate the catheter length from the formula [weight (kg) x 3] + 9 cm.
   3. Remember to add the length of the cord stump.
3. Consider the use of appropriate measures to relieve distress including:
   1. use oral sucrose
   2. containing the infant by holding
   3. securing the catheter as soon as possible
   4. avoidance of placing clamps or sutures on the skin.
4. Flush the selected catheter via the three-way tap with heparinised saline. Leave the syringe attached to three-way tap throughout the procedure.
5. Prepare the umbilical stump and surrounding 3-4 cm of abdomen with a chlorhexidine based solution. Wait two minutes.
6. Drape around the umbilical stump with sterile towels and/ or a plastic drape with a small hole (approx. 3 cm diameter).
7. Tie a short piece of umbilical tape around the base of the cord. (secure enough to maintain haemostasis but not too tight to prevent passage of the catheter).
8. Grasp the end of the cord clamp with a pair of straight forceps and pass the forceps to the assistant. Whilst the assistant applies gentle upward traction, slice the cord with the scalpel, 1-1.5 cm from the skin margin.
9. Blot and identify the umbilical vessels on the cut surface:
   1. the single thin walled umbilical vein
   2. smaller thick walled round arteries, generally constricted so that their lumen appear pinpoint. They often protrude from the cut surface of the umbilical cord
10. Gently dilate, then probe the orifice of the artery prior to inserting the catheter:
    • Use initially one tip and then both tips of the iris forceps. Allow the tips of the forceps to spring apart.
    • The tips should be gradually advanced to the curve of the forceps. The straight probe can then be used prior to cannulating with the catheter.
    • Obstruction may be encountered at the anterior abdominal wall or bladder. This can usually be overcome by 30-60 seconds of gentle, steady pressure. Avoid excessive pressure or repeated probings.
    • If unsuccessful, seek advice from a more experienced person. The most common error arises after cannulating the layer between the vascular intima and the muscle. This usually occurs if dilatation of the artery in the cord has been inadequate.
11. Ensure patency of catheter by checking for easy withdrawal of blood and ‘pulsation’ of blood/saline in the catheter
12. Secure catheter with 3/0 black silk suture by placing a purse string suture:
    • Use several small bites around the base of the cord. Do not include the skin.
    • Commence the suture close to the catheter so that the first knot lies at the base of the catheter.
    • Tighten the purse string and knot securely.
    • Tie the purse string around the catheter tightly.
    • Strap with goal post strapping.
13. Label arterial line clearly (in order to distinguish from an umbilical venous catheter)
14. Connect catheter to infusion fluid.
15. Confirm the position of catheter by x-ray. A correctly placed catheter aims caudally prior to then ascending via the aorta and the catheter tip sits above the level of T10.
16. Check for arterial waveform on arterial transducer after it is connected and calibrated.

Ongoing management of umbilical arterial catheterisation includes the following:

• Observe skin colour.
• Note any skin blanching or bruising of limbs, toes or buttocks prior to, during and following the procedure, and at any time that catheter is in situ. Report immediately.
• If one limb is involved, warm opposite limb to induce reflex vasodilation of affected limb.
• If above measures fail, the catheter may be withdrawn 0.5-1 cm and observe.
• Remove catheter if blanching persists > 30 minutes.
• Maintain infant supine or in lateral position for 24 hours post procedure to observe for haemorrhage from umbilical stump.

Ongoing management of the line:

• Keep catheter and infusion line clear of blood as blood clots may form.
• Remove all air bubbles in the infusion line and catheter.
• Interruption to infusion must be for as short a time as possible.
• Do not flush catheters quickly.
• Filters are not used for IA lines. All connections must be Luer lock.

Potential complications of umbilical arterial catheterisation include:

• bleeding due to accidental disconnection or dislodgement, or from open connections
• vasospasm of the femoral artery causing blanching of the toes and foot, which is less common with high than low catheters (the opposite limb may be warmed with a warm moist towel; if blanching persists, the catheter must be removed)
• embolisation from blood clot or air in the infusion system
• thrombosis - this may involve:
  • femoral artery resulting in limb ischaemia, gangrene
  • renal artery resulting in hypertension, haematuria, renal failure
  • mesenteric artery resulting in gut ischaemia, necrotising enterocolitis
• vascular perforation of the umbilical arteries, haematoma formation and retrograde arterial bleeding
• infection - prophylactic antibiotics are not required.

• Collect the required equipment:
  • alcohol swab
  • sterile stitch cutter (optional) or sterile blade
  • specimen container
  • tapes.
• Ensure the procedure is performed by medical staff.
• Clean the stump with an alcohol swab.
• Turn infusion pump off and clamp infusion line.
• Remove sutures and withdraw catheter to within 3-4 cm of skin.
• Tape the catheter to skin and maintain infant supine.
• Wait for pulsation in catheter to stop (this usually takes 10-20 minutes).
• Remove rest of catheter. If any bleeding is noted, apply positive pressure below level of stump.
• Send tip for culture and sensitivity only if infection is suspected.
• Do not nurse infant prone for 4 hours following removal. Observe for bleeding.

• University of Iowa Childrens Hospital

References

Umbilical Artery Catheterisation Protocol, Southern Health Care Network - Monash Medical Centre, Newborn Services venous catheters in newborns. J Pediatr 2000;136:837-40.