Sunday, March 23, 2008

March 23, 2008

We are back in Fort Worth at the Ronald McDonald House.

Rylie continues to do well. He is eating well, and gaining weight.

Ryan is doing well. He is eating and gaining weight. He got put back on oxygen because he had several episode where his blood oxygenation dropped down below 60%. He had his eyes open this evening and he was looking around at everything.

Reese is stable. Her blood oxygen saturation runs between 83% and 97%. Randall got to hold Reese today. It would appear that she likes to get her feet rubbed; while Randall was holding her, he was rubbing her feet, and her oxygen saturation was between 95% and 98%.

Okay, there seems to be some confusion about Reese's condition, as well as her pending surgery. Let me see if I can clear things up. Reese does not need surgery to close a hole in her heart. Reese does need surgery to close a Patent Ductus Arteriosis. Below, there is a link to a website that helps to explain what a PDA is and why surgery may be needed:

http://www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/pda.htm

The ductus arteriosis is a normal stucture that is needed in fetal development. Oxygenated blood from the placenta comes into the right side of the heart. The right side of the heart pumps the blood out to the Pulmonary artery which feeds the blood to the lung. Unborn children have not yet taken a breath, so the lungs have not yet expanded, and there is a high resistance to blood flow. The ductus arteriosis allows the oxygenated blood to be shunted away from the lungs and into the aorta, so that it can be circulated to the rest of the body.

Once a baby is born, the child takes a breath, the lungs expand, and the resistance to blood flow through the lungs drops dramatically. This normally starts a series of physiological processes that cause the ductus arteriosis to close. If it does not close, it is still patent, and so it is called a Patent Ductis Arteriosis. Premature infants are at an increased risk for PDA.

Once the lungs are expanded, the pulmonary artery and veins have a low resistance to blood flow; this makes the pulmonary vasculature a low pressure system. The aorta, however, is a high pressure system. In a child with a PDA, blood flows from the high pressure of the aorta to the lower pressure of the pulmonary artery. This causes back pressure on the right side of the heart, such that the right side of the heart has to work harder to pump the blood out; this causes the right side of the heart to enlarge. The extra blood that goes into the pulmonary artery, circulates through the lungs, and then back to the left side of the heart; this extra blood makes the left side of the heart enlarge, and become a less efficient pump. The result of the enlargement of the heart is easily seen with a regular x-ray; the heart has an enlarged, globular appearance. Reese's x-rays have shown this change since shortly after she was born, but recent x-rays reveal that it is getting worse.

All of the extra blood being forced through the lungs causes fluid to leak out of the blood vessles, and can cause increased fluid in the lungs and around the lungs. This can also be seen on a regular chest x-ray, and Reese's chest x-ray, do show those changes.

Because the high pressure side of the system is losing blood to the low pressure side of the system, there is not adequate blood pressure to supply blood to all of the areas of the body that need it. This is especially true when the body needs to digest food. The body needs to shunt blood to the bowel in order to be able to digest the food; that means that there is less blood to go to other areas of the body. Combine that with a low blood pressure, and you get a problem. That is why Reese has only been getting minimal amounts of milk at each feeding. She gets the majority of her nutrition from her IV.

All of these problems combine to cause heart failure. Reese's x-rays and echocardiograms show a steady progression of heart failure. Therefore, she needs surgery to correct the PDA. Once the PDA has been closed, the high pressure of the aorta will no longer be shunting blood into the low pressure system of the pulmonary ateries; this should allow the heart to function more normally, and return to a more normal shape, and Reese should start to improve (we hope). But, we may have waited too long; after the surgery, she may need some type of medication to help her heart pump better. Dr. Riley said that it is impossible to predict which child will need this kind of therapy.

So, this is not heart surgery; the heart will not be cut open. However, there are still a large number of risks associated with the surgery. The surgical team does these procedures regularly, so they are well skilled in doing this surgery. Any doctor will tell you that in order to get the best results out of any surgery, you want to have a surgeon that has performed a large number of the procedures. This team has done this procedure many, many times, and so we have the best doctors and nurses available for this procedure. But, as a doctor, I still worry about the risks involved.

First, the skin has to be cut. The skin is the body's best defense against infection. Anytime you cut the skin or put a needle through the skin, you increase the risk for bleeding and infection.

After the skin is opened, the incision is carried down to the area of the ribs. An incision is made in the tissue between the 5th and 6th ribs on the left side. The ribs are spread apart, and the left lung is deflated. This carries a significant risk because then only the right lung will be capable of oxygenating blood; with her decreased heart function, she may not be able to oxygenate her blood adequately. If this happens, she will need to be placed on a heart-lung machine for the rest of the surgery.

There are a large number of very important structures that run through the area of the surgery. The surgeon has to be very careful to identify these structures and to make sure that these structures do not get injured.

The surgeon needs to identify the Azygos Vien. This vien is fairly large in newborns, and any injury to it could cause a risk of heavy bleeding.

The surgeon has to identify the Thoracic Duct. When the blood goes from an artery, through a capillary, and into a vein, fluid leaks out of the blood vessles, and into the surrounding tissue. The body has a sytem of lymphatics that collects this fluid and carries it back to the subclavian vein, in order to be re-introduced into the blood supply. The thoracic duct is an important part of the lymphatic system; it carries all of the lymphatic fluid from below the heart and lungs as it travels through the thoracic cavity. If the surgeon were to injure this stucture, it would cause leaking of fluid into the area around the left lung (this is called the pleural space). This could lead to increase length of time to heal, and might even cause the need for additional surgery.

The surgeon has to identify the superior vena cava, the aorta, and the pulmonary artery. The ductus arteriosis is between the aorta and the pulmonary artery. Now the surgeon has to identify the recurrent branch of the laryngeal nerve. This is a branch that comes off of the Vagus nerve, and wraps around the ductus ateriosis, and back up to the larynx (the voice box). Any damage to this nerve could cause partial paralysis of the vocal cords, which would permanently effect her speech.

After the surgeon has identified all of these structures, he must begin the process of closing the PDA without causing any damage to these structures. Once the PDA is closed, the layers of tissue that have been cut during the surgery have to be repaired. During this repair, the same stuctures are at an increased risk for damage, so great care has to be taken.

During the surgery, the left lung will be deflated. This serves two purposes: it allows the surgeon a better field of view during the surgery; and, it helps to prevent damage to the lung tissue itself. However, there will always be some damage to the lung tissue. This damage causes the lung to leak air, fluid, and blood. Therefore, after the surgery, a tube is placed inside the pleural space, routed out through the skin, and attached to a vaccuum device; this allows all of the leaking air, fluid, and blood to be pulled out of the pleural space, and allows the left lung to expand to its original size. The chest tube will stay in for several days until all of the leaks have stopped.

Anybody who has ever had surgery will tell you that there is significant pain after the surgery. Reese will have pain; but, as an infant, she will not be able to tell anybody that she hurts. The nurse has assured us that adequate pain medication is given to Reese after surgery, such that we need not worry that she will be hurting unnecessarily.

I hope this has helped to clear-up any misunderstandings about Reese's need for surgery.

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