If he can figure out which babies will be born unable to breathe properly, Dr. Stephen M. Black thinks he can help change that.

"When these kids are born, you have a short amount of time to intervene or you get brain damage," says Dr. Black, cell and molecular physiologist at the Medical College of Georgia Vascular Biology Center.

Unfortunately, persistent pulmonary hypertension comes as a surprise in full-term babies, says Dr. Jatinder J.S. Bhatia, chief of the MCG Section of Neonatology. The pregnancy seems uneventful until the hours following birth when breathing trouble requires rapid transport to a neonatal intensive care unit.

"What happens in utero is that all your gas exchange is through the placenta, so there is only about 8 percent of cardiac output actually going through the lungs," says Dr. Black. "When you are born, obviously there is 100 cardiac output and you need to breathe."

When babies can't breathe well, physicians quickly determine whether the primary problem is the heart or lungs, Dr. Bhatia says. When it's the lungs, babies first get oxygen therapy and possibly mechanical ventilation. If it is pulmonary hypertension, the powerful vasodilator, nitric oxide, is used to reduce high pressures in the pulmonary circuit and allow the transition to a normal circulation. Neonatologists also have begun using the popular erectile dysfunction drug, Viagra, to dilate tiny pulmonary vessels.

If these therapies fail, they turn to the more invasive extracorporeal membrane oxygenation, which resembles heart-lung bypass used during heart surgery. This approach is most helpful for newborns with conditions such as pulmonary hypertension as well as aspirating waste products in utero, congenital heart disease and congenital diaphragmatic hernia.

Dr. Black's focus is the babies whose vessels have become thick-walled, inflexible pipes that cannot transition to an elastic state. Flexibility enables adequate bloo
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Contact: Toni Baker
tbaker@mcg.edu
706-721-4421
Medical College of Georgia
5-Oct-2006