UMBILICAL CATHETERIZATION: PLACEMENT TECHNIQUE AND RISKS - MEDICINE - 2024

The umbilical catheterization is the procedure through which a thin and highly flexible tube is placed in the vein or one of the two umbilical arteries of the umbilical stump of the newborn. The goal of this procedure is to provide immediate vascular access when peripheral catheterizations are not a good option.

The peripheral blood vessels of a neonate are very difficult to access, especially in preterm or low birth weight neonates. For example, this catheterization is performed when there is a need to take blood samples in the newborn, in case a blood transfusion is warranted or for resuscitation in unstable neonates.

It is also used for parenteral hydrations or intravenous medication that warrants it, and even for the measurement of the neonate's blood pressure. Some literatures refer that with proper care and in the absence of complications, the catheter can be intraluminal (within the lumen) for weeks.

However, the majority report a duration that should not exceed 5 days in an umbilical arterial catheterization and 2 weeks in an umbilical venous catheterization.

Technique for the placement of an umbilical catheter

The technique for placing the umbilical catheter in the newborn should be carried out with extreme caution and absolute command of it. The choice of the catheter will depend on the condition of the neonate, in terms of weight and prematurity.

For example, a 3.5 French catheter will be used for a very low birth weight or premature neonate. In the case of a term newborn with adequate weight, a 5 French catheter will be used.

As prior knowledge, the terms high position and low position should be mastered. The high position refers to the limit of localization that the tip of the catheter may have in the upper part of the body of the newborn. On the contrary, the low position refers to the limit of localization that the catheter tip can have in the lower part of the body of the neonate.

The position of the catheter tip must be high or low to avoid the risk of thrombosis or occlusions of direct branches of the main artery, as well as to avoid direct infusion into any of these branches.

According to studies, catheters placed in the low position have a higher risk of complications than catheters placed in the high position.

Steps to follow to place an umbilical catheter

Restraint of members

Initially, the 4 limbs of the newborn are held, in order to avoid sudden movements that may make it difficult to place the catheter.

Care must be taken that the extremities are visible at all times, to notice any sudden changes or movements alluding to vasospasm.

Measurements

Measurements are made for correct placement. There are different techniques that are used depending on whether the catheter is arterial or venous.

If it is an arterial catheter, for the high position the weight of the newborn is multiplied in kg by 3 and 9 cm is added by the length of the umbilical stump; the result is interpreted in cm.

For the low position, the weight of the newborn is multiplied in kg by 3, 9 cm is added by the length of the stump and, finally, it is divided by 2.

In case of placing a venous catheter, the weight in kg is multiplied by 3, 9 cm corresponding to the umbilical stump are added, it is divided by 2 and 1 cm is added.

Another method that is used frequently is to take the measurement from the shoulder to the umbilical scar of the newborn in cm. Of this measurement, for the high position, 66% plus the measurement from the umbilical scar to the xiphoid process of the newborn is used.

For the low position, only 66% (2/3) of the measurement from the shoulder to the umbilical scar of the newborn is used.

Asepsis

The asepsis and antisepsis of the umbilical stump, the abdomen of the newborn and the instruments to be used are performed.

Knot

A knot is placed at the base of the stump with elastic tape for hemostasis.

Identification of vein and arteries

One vein and two arteries must be identified. As characteristics for its differentiation, the vein is larger than the arteries and is normally located at the 12 o'clock position on the stump.

The vein can continue to bleed, while the arteries hardly bleed due to vasospasm.

Catheter flushing

The catheter is flushed with a heparinized solution prophylactically (although there is no evidence to show that it prevents thrombosis at the catheter tip), and is connected to a closed 3-way stopcock.

Vessel dilation

The vessel to be catheterized is dilated with a dissection forceps, and the umbilical vein or artery is catheterized to the expected height. The advancement of the catheter cannot be forced.

Catheter fixation

To fix the catheter, the ideal method is to place adhesive tape on both sides of the umbilical stump, as well as two supports raised slightly above the height of the stump. Later an adhesive containing both supports and the center the catheter is passed.

In this way, the umbilical stump is visible for monitoring, and cord care can be given without problem.

Position verification

Finally, the location of the catheters should be corroborated by thoracoabdominal radiographs.

Umbilical catheterization risks and complications

Limb ischemia

It is the most frequent complication, with the presence of cyanosis or, on the contrary, whitening of the lower limbs. It is usually corrected with reflex vasodilation by heating the contralateral limb. If not corrected, the catheter should be removed.

Thrombosis and embolism

The tip of the catheter tends to thrombus; continuous infusion must be maintained.

Infections

These occur under conditions of misuse of asepsis and antisepsis techniques.

Blood loss

They can be generated by heparinization and poor haemostasis with tape prior to catheterization.

Vascular perforation

It occurs by forcing the catheter to advance, creating a false catheterization pathway.

Necrotizing enterocolitis

It is related to feeding while the catheter is in place, although the evidence is not abundant.

Arterial hypertension

It is usually related to the long duration of the catheter, and to the possible formation of thrombi.

Post-catheter care

- Carry out the handling with strict aseptic technique.

- Monitor the vital signs and the appearance of the stump, see if there is bleeding or not.

- Observe signs of thrombosis and / or vasospasm.

- Record the volume of blood drawn and the volume of fluid infused on the nursing sheet.

References

1. Gordon B. Avery, Mary Ann Fletcher. Neonatology: pathophysiology and management of the newborn. Panamerican Medical Ed. P. 537-539.
2. MacDonald MG. Umbilical artery catheterization. In: MacDonald MG, Ramasethu J, eds. Atlas of procedures in neonatology. 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2002: 152-70.
3. Barrington KJ. Umbilical artery catheters in the newborn: effects of position of the catheter tip. Oxford, England: Cochrane Collaboration, 1998. P 215.
4. John P. Magnan, MD, MS. Umbilical Vein Catheterization Technique. (2017) Recovered from: emedicine.medscape.com
5. Westrom G, Finstrom O, Stenport G. Umbilical artery catheterization in newborns: thrombosis in relation to catheter tip and position. Acta Paediatr Scand. 1979; 68: 575.