Overview of Umbilical Artery Catheterization
A procedure called umbilical arterial catheterization involves inserting a small tube into a newborn baby’s umbilical artery. This allows doctors to take blood samples directly from the artery and measure the baby’s blood pressure. It’s a common procedure for very premature babies, meaning babies born well before their due date. The process is relatively simple, but it requires a doctor or nurse with specialized training.
This procedure is useful in managing the health of newborns, especially those who are extremely premature. However, just like any medical procedure, it carries some risks. Potential complications could occur, but these will be closely monitored and managed by the healthcare team.
Anatomy and Physiology of Umbilical Artery Catheterization
The umbilical artery is the part of the body that comes from the front branch of the internal iliac artery, which is an artery located in the pelvic region. When a baby is still inside the womb, this artery extends into the umbilical cord, carrying blood which does not have much oxygen in it from the baby to the placenta – the organ that provides oxygen and nutrients to the baby.
Generally, there are two umbilical arteries and one umbilical vein inside the umbilical cord. However, in about 1% of pregnancies, an umbilical artery may not develop properly or at all, leading to there being only one umbilical artery instead of two. This condition is often not associated with any other abnormalities but if there are other irregularities present in the baby, then there could be a higher chance for chromosomal disorders.
The umbilical arteries can be recognized due to their position further down within the umbilical cord. They possess thicker walls and smaller tubes for carrying blood, compared to the umbilical vein.
Why do People Need Umbilical Artery Catheterization
An umbilical artery catheter is a small tube we place in a newborn’s belly button. We use it mostly for three things: to measure the gases in the artery blood, to take blood samples often, or to monitor blood pressure all the time in very tiny babies or very sick newborns. In some cases, the catheter provides a temporary solution for giving necessary nutrition directly into the bloodstream in situations where it’s not possible to get access via other routes.
One rare complication associated with this catheter is stubborn low blood sugar levels (refractory hypoglycemia) especially when we are providing a sugar solution (dextrose) through the catheter.
Inserting an umbilical artery catheter can be an important step in treating very sick newborns. However, because there can be risks with any procedure, it’s important to weigh up the pros and cons before proceeding. For example, the smallest babies (weighing less than 2.2 pounds or 1000 grams), premature babies needing breathing machine (ventilator) support, babies with brain damage due to lack of oxygen or blood flow (hypoxic-ischemic encephalopathy) who are given treatment by cooling the body (therapeutic hypothermia), or seriously ill older preterm or full-term babies who also need a ventilator to breathe, might benefit from this catheter as it allows for frequent blood testing.
When a Person Should Avoid Umbilical Artery Catheterization
There are certain conditions that may prevent a doctor from inserting an umbilical arterial catheter (a small tube placed in the belly button to deliver medicines or fluids). Some of these conditions include:
Omphalitis, an infection in the belly button after birth; necrotizing enterocolitis, a serious disease where parts of the gut are destroyed; omphalocele, a birth defect where some organs are outside the body; gastroschisis, another birth defect where the intestines are outside the body; and peritonitis, inflammation of the inner lining of the abdomen.
Equipment used for Umbilical Artery Catheterization
This is a list of items your doctor will use during your procedure. All the items will be cleaned and sterilized which means they are made free of germs. These items include:
* A sterile gown, gloves, cap, and mask: These are worn by the doctor to ensure cleanliness and to prevent the spread of any bacteria or infections.
* Sterile drapes: These are placed over your body during the surgery to maintain a clean working environment.
* Bactericidal solution: This is a cleaning solution that kills bacteria.
* Umbilical tie: It’s used to secure the umbilical catheter in place.
* Measuring tape: This is used to measure the size, depth or other necessary dimensions during the procedure.
* Scissors and scalpel: These are sharp instruments used for cutting or opening tissues.
* Toothed iris forceps and two curved, nontoothed iris forceps: These are types of tweezers used to grasp and hold tissues or other small items during surgery.
* Two curved mosquito hemostats: These are small tools used to control bleeding by clamping off blood vessels.
* Umbilical catheter-5-French (Fr) gauge for infants weighing >1200 g, 3.5-Fr gauge for infants weighing >1500 g: These are thin tubes inserted into the umbilical cord for infants of different weights, they help in giving fluids or medicines, and in drawing blood.
* Three-way stopcock, Intravenous (IV) tubing: This equipment is used for the flow of medicine or fluid into your veins.
* Needle driver: It’s used to hold sutures which are special sewing threads for stitching wounds.
* 3-0 silk suture: This is a type of thread used for stitching wounds after the procedure.
* Sterile saline flush: This is a saltwater solution used to clean and rinse wounds or surgical sites.
* 4 x 4-inch gauze sponges: These are used to soak up blood and other fluids during surgery.
Who is needed to perform Umbilical Artery Catheterization?
The procedure should be carried out by a trained healthcare professional or advanced practitioner. There should also be additional staff like a nurse during the procedure. Their role is to help observe the patient from start to finish.
Preparing for Umbilical Artery Catheterization
Before a procedure involving an umbilical arterial catheter, your doctor will explain the process and obtain your consent, following the rules of their local hospital. It’s important to keep the baby warm during this procedure to prevent a condition called hypothermia, which is when the body loses heat faster than it can produce it. To do this, they may use a special warming lamp and place a heat-generating mattress underneath the baby as needed.
The doctor will then attach a three-way valve (also known as a stopcock) to the catheter and flush it with a salt-water solution to ensure it is clean. A less concentrated salt-water solution is used to prevent an excess amount of salt in the baby’s system. The flushing syringe is then left attached to the valve, with the valve in the off position.
Before the catheter is inserted, the doctor has to determine how far in it needs to go. The best place for the tip of the catheter is in the major artery that carries blood away from the heart, above the points where several important blood vessels branch off. This is to make sure the catheter doesn’t block these vessels. This spot, towards the middle of the baby’s back, has fewer protective clotting problems compared to a position lower down, near the lower back.
The precise length of the catheter is calculated using a formula that is based on the baby’s weight. There are other ways to work out how far to insert the catheter, and the length of the catheter outside the skin is added to this measurement.
How is Umbilical Artery Catheterization performed
Before beginning the procedure, it’s important that the baby is kept still to avoid any movements. The doctor will clean the baby’s umbilical cord and the skin around it with a germ-killing solution. To clean it properly, a nurse or assistant might hold the cord and lift it up. After cleaning, the area is covered with a sterile material, and a tie is placed on the cord. This tie is tight enough to avoid bleeding, but loose enough to let the doctor insert tubes easily into the blood vessels.
The doctor then cuts the cord around half an inch away from the baby’s skin. The doctor identifies the umbilical arteries, which are the blood vessels in the umbilical cord that have thicker walls and smaller inner spaces. The doctor will hold the cut portion of the cord and gently explore the opening of the artery with a small surgical tool. This tool is allowed to spring open to widen the artery, which is then held in this position for around 30 seconds.
The catheter, a thin tube, is then gently inserted into this widened artery. To do this, the doctor might use another surgical tool or use their fingers. The tube needs to be inserted carefully. If it feels stuck or difficult to push in, the doctor will apply gentle and steady pressure. Too much pressure or repeated attempts could hurt the blood vessel. If the tube cannot be inserted in one artery, the doctor will try the other one.
Once the tube is inserted to the right depth, it is kept in place by stitches around the base of the cord, and the tie that was put in earlier is removed. To check if the tube has been placed correctly, the doctor will take an X-ray (radiologic confirmation) to see if the tip is between the sixth and ninth bones of the spine (vertebrae T6-T9). If required, the tube can be pulled back a bit, but should not be pushed in further once it has been secured, to avoid the risk of introducing infection. As soon as the correct position of the tube is confirmed, a solution mixed with a blood-thinning medicine (heparin) is started through the tube.
Possible Complications of Umbilical Artery Catheterization
When using umbilical arterial catheters, which are small tubes inserted into blood vessels, one major concern is thromboembolism. This means that a blood clot might block blood vessels. Normal function of these vessels may be impaired which can cause different medical issues. If the blood vessels leading to the intestine are blocked, this can lead to problems such as gut ischemia (insufficient blood flow to the gut), bowel infarction (a part of bowel not receiving blood and dying), and necrotizing enterocolitis (severe infection that causes the bowel to die).
Issues can also arise if blood vessels that feed the kidneys are blocked. This can lead to high blood pressure or sudden kidney failure. Another problem can be the blocking of minor vessels, which can develop into ischemic injuries to the back, buttocks and lower extremities (areas that are not getting enough blood). To avoid these problems, it is crucial to remove the catheter as soon as any signs of such issues appear.
Other possible complications during catheter insertion include damage to vessels, the peritoneum (the membrane that covers abdominal organs), or the bladder, and formation of false aneurysm (a bulging blood vessel). Catheter-related infections and bleeding are also quite common. A rare, but critical, complication can be refractory hypoglycemia (persistent low blood sugar levels). This usually happens when the catheter is placed close to the celiac and mesenteric arteries (arteries that supply the stomach).
Though there is a theoretical risk of severe bowel infection (necrotizing enterocolitis) in infants as a result of being fed while an umbilical arterial catheter is in place, there is no substantial evidence supporting this risk. Consequently, it is not recommended to stop feeding an infant in such cases.
What Else Should I Know About Umbilical Artery Catheterization?
When a newborn baby is critically ill, a tool called an umbilical arterial catheter can be vital for their treatment. However, this procedure isn’t without risk, and doctors have to weigh up the potential downsides before choosing to use it.
This catheter is especially beneficial for certain newborns. This includes those who are very underweight (less than 2.2lbs), those who are born early and need help breathing, babies with a condition called hypoxic-ischemic encephalopathy who are being cooled to slow their brain activity, or late preterm or full term babies who need help breathing. This is primarily due to the fact that these groups often require frequent blood tests.
In order to ensure that the catheter is used properly, it’s crucial to follow standard guidelines specifically designed for its use in newborns.
Some people might worry that this catheter could increase the risk of a severe intestinal disease called necrotizing enterocolitis when the baby is being fed through a tube. But according to research, this concern isn’t necessary, and so there’s no need to stop tube feeding while the catheter is in use.
