September 8, 2006

New techniques may ease birth defect’s impact

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Following her recent surgery, Miracle Miller was in the good hands of Edmund Yang, M.D., and her mother, Renata Miller.
Photo by Susan Urmy

New techniques may ease birth defect’s impact

A combination of new techniques at the Monroe Carell Jr. Children's Hospital at Vanderbilt may improve survival rates for children with congenital diaphragmatic hernia, a serious birth defect.

“While I was pregnant, my baby's condition was looking worse and worse,” said Renata Miller, a new mother whose daughter, Miracle, was the first to receive a new version of the repair surgery.

Miller, who is from Shreveport, La., was evaluated in the Center for Advanced Maternal Fetal Care at the Monroe Carell Jr. Children's Hospital at Vanderbilt with ultrasound exams and an MRI of her unborn baby.

These tests showed that the baby had a hole in her diaphragm so large that her liver and intestines had all entered the chest cavity, keeping her lungs from developing in her tightly cramped chest.

“Babies who are born with this severe level of the condition generally have a 30 percent to 50 percent chance of survival,” said Edmund Yang, M.D., a pediatric surgeon at Children's Hospital. “They often need to go on a heart/lung support machine called ECMO (Extracorporeal Membrane Oxygenation) right after birth to artificially oxygenate their blood and help pump the blood through the babies' system.”

Ironically, it may be the use of ECMO and a resulting delay in surgery to take pressure off the underdeveloped lungs that causes the most severe cases of this birth defect to be fatal. Babies are put on blood thinning medications at the start of ECMO to make sure their blood doesn't clot within the machine. That makes any surgery very risky unless the babies are nearly ready to be taken off ECMO. A few of the most serious babies die because their lungs just never recover enough.

Some surgeons have been trying to give the babies at highest risk for death a better chance by performing an “early repair” of the diaphragmatic hernia defect — repairing the diaphragm right after birth, just as babies go on the ECMO machine.

“We had a theory that by repairing the hernia right away, the most compromised lungs might have a better chance to grow while the baby is on ECMO,” Yang said.

But Yang, working with resident Tom Rauth, M.D., researched children who had the repair over the last 10 years and found a very high rate of bleeding after surgery (25 percent) along with a high use of blood products.

“We knew the early repair surgery could cause severe, life-threatening bleeding, but changes in our ECMO program convinced us the early repair surgery could be made safe.”

The ECMO team at Vanderbilt Children's had recently put together a system of heparin-coated parts for the machinery that allowed doctors to avoid use of blood thinners for a critical recovery time period right after surgery. In Miracle Miller's case, her hernia was repaired within three hours of birth, just minutes after being put on the ECMO machine, without use of any heparin.

“We had had so much bad news by the time we came here to Vanderbilt, I was ready to try,” Miller said. “That's around the time I decided to name her Miracle. That's what I needed, was a miracle.”

“Right from the planning of the delivery to the neonatal resuscitation, to the ECMO, and through the repair and recovery — it is a team effort that involves 20-30 people,” said Yang.

Miracle did very well. Heparin was not used for the first 12 hours. Eleven days later she was taken off ECMO, and by Yang's standards, she has done far better than expected. Today, at 8 weeks old she is eating and breathing on her own and growing well.

“Every time you do surgery on these little ones, it's an insult to their system and it sets them back. These babies are so fragile they can't take multiple setbacks or complications,” Yang said. “You only get one shot, and I think that taking care of both the ECMO and the repair of the hernia may have given her a better chance to recover.”

Yang has done the early repair, using the heparin-coated tubing, on two more babies with severe congenital diaphragmatic hernia. All three have done well.