Cautionary notes specific to pediatric central venous catheterization
Caution during puncture
Ultrasound-guided techniques are recommended for children with small veins that are difficult to puncture. Select a thinner, lighter probe than for adults. A linear probe or hockey-stick probe can be used.
Recommended catheters
Catheter kits 3–4 Fr and 5 cm long are available for newborns. Select a size that is suitable for the patient’s physique.
Cautionary notes for preparation
The position of the patient should be stable. In smaller children, it is especially important to secure an area for puncture manipulations. For instance, placing a pillow under the neck or using tape to extend the neck can help secure an area to operate.
The lumen of small vessels easily collapses under the weight of an ultrasound probe or a needle. Creating traction on the skin by taping around the puncture site, such as on the mandible or above the clavicle, can help maintain skin tension and reduce pressure on the vessel during the procedure.
Anatomy
The IJV is often located lateral and anterior to the CA, but may also be directly superior (3.2%), laterally parallel (3.2%), or lateral and posterior (1.4%) to it .
The vertebral artery runs medial and posterior to the IJV; hence, there is a risk of arterial puncture. Compared to adults, children’s vertebral arteries are larger compared with their IJV and the distance from the skin to the vertebral artery and from the vertebral artery to the IJV is shorter.
Practical puncture techniques
In low–birth weight infants, use a syringe smaller than that used in adults to confirm backflow of blood.
The pressure on the vessel from the puncture needle can cause the anterior wall of the vessel to stick to the posterior vessel or collapse the lumen, which can lead to both the anterior and posterior walls being penetrated simultaneously, and backflow of blood may not appear despite vein puncture. Pulling the needle back will create a space between the anterior and posterior walls and cause the vessel lumen to expand and fill with blood; thus, if the vessel has been penetrated, backflow of blood may appear in the process of withdrawing it.
It can be difficult to differentiate arterial and venous blood by color in patients with cyanotic heart disease. Confirm venous residence of the wire using ultrasound imaging, or if this cannot be determined via ultrasound, measure the pressure by inserting a plastic cannula from a venous indwelling needle via the guidewire. Confirmation can also be performed by attaching a pressure transducer directly to the needle. Do not insert a dilator unless it is certain that the guidewire resides in the vein.
Test punctures are not recommended in small children. A hematoma caused by a test puncture will make the procedure even more difficult and could easily cause blockage.
Even if the needle tip is definitely inside the vein, it is difficult to insert a guidewire into a vein with a small diameter; thus, consider using a guidewire with a hydrophilic monofilament. However, be careful of breakage when using metal needles.
Complications
Owing to their small size, guidewires should not be inserted in children as deeply as in adults. Neonates and infants have thin ventricular and atrial walls that are easily penetrated.
Cardiac tamponade is a lethal complication. The right ventricle and right atrium are common perforation sites, and perforations can occur in children from the guidewire (even J type), dilator, or catheter. Symptoms may not appear right away with a guidewire puncture, and a puncture may be difficult to diagnose with radiograph after catheterization is finished. Therefore, if a decrease in blood pressure is observed, quickly perform an echocardiogram to search for cardiac tamponade.
Other considerations
Neonates have fragile skin; hence, be careful not to damage it by suturing too tightly when fixing a catheter.