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Blood Oxygen Test Finds Heart Defects in Newborns
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Study Suggests That Pulse Oximetry Test May Help Screen for Heart Malformations
By Brenda Goodman
Reviewed by Laura J. Martin, MD
Aug. 22, 2011 -- All newborns should get a simple oxygen test to check for serious heart defects before they come home from the hospital, a federal advisory panel says.
Heart malformations are the most common kind of birth defect. They affect an estimated one out of 100 births worldwide.
In 25% of cases, the defects are life-threatening. But the diagnosis is sometimes missed because a baby's heart and lungs continue to mature in the first few days after birth and nothing may look or sound wrong.
"It's very hard, in the first days of life, to make this diagnosis, even by the good doctor doing an expert physical exam," says Alan R. Fleischman, MD, medical director of the March of Dimes in White Plains, N.Y.
Parents bring home "a healthy, normal baby, only to have them die in their arms," says Mona Barmash, president of the Congenital Heart Information Network (CHIN) and mother of a son with heart defects.
How Pulse Oximetry Works
The test, called pulse oximetry, measures how much oxygen is in the blood using a small light sensor that's taped around a baby's wrist, the palm of a hand, or the bottom of a foot.
"It looks like a Band-Aid, with a little light probe where the center of the Band-Aid would be," says Dennis Davidson, MD, chief of neonatology at Steven and Alexandra Cohen Children's Medical Center in New Hyde Park, N.Y.
Several large studies have shown that pulse oximetry, or pulse ox, which costs $5 to $10 and takes about five minutes, can pick up cases of serious heart malformations early enough so that they can be corrected with surgery.
The test is mandated by law in two states: New Jersey and Maryland. In other states, some hospitals are doing it voluntarily, though it is not yet in widespread use, says study researcher Alex R. Kemper, MD, associate professor of pediatrics at Duke University.
In 2009, the American Heart Association and the American Academy of Pediatrics issued a statement supporting the promise of pulse oximetry screening, but they held off on endorsing its widespread use, pending more research to determine what numbers should be considered normal and abnormal and what the next steps should be for babies who failed the test.
Kemper and 10 other experts were asked by the Health and Human Services Department's Advisory Committee on Heritable Disorders in Newborns to develop a plan to put pulse oximetry screening into effect.
Specifically, the panel said pulse oximetry screening should be performed in healthy babies at least 24 hours after birth but before hospital discharge.
They advised that the pulse oxygen should be tested with a probe on the right hand or foot when the baby is awake and alert.
A pulse oxygen level less than 90% in either the right hand or foot, or a level less than 95% that continued to be low after repeated measurements, would signal the need for further investigation with heart sonogram, preferably read by a pediatric cardiologist.
The panel's plan has already been endorsed by the American College of Cardiology, the American Heart Association, and the American Academy of Pediatrics. It is published in the journal Pediatrics.
If Health and Human Services Secretary Kathleen Sebelius endorses the panel's recommendations, it will nudge states to add pulse oximetry screening to the routine blood and hearing tests most already do for newborns, Fleischman says.
While the test itself is easy and inexpensive, Barmash says it is the prospect of what to do with a positive result that concerns smaller hospitals that may not have the equipment or expertise to do the specialized heart sonogram.
"The implementation is difficult in rural areas. For example, if they identify a baby with a pulse ox less than 95, it requires transport. So all the docs and the administrators are saying, 'well what if it's a false positive, look at all the costs you're incurring,'" Barmash tells WebMD.
But she says the test has a low false-positive rate -- less than 1%. And there are other questions to be answered.
For example, Kemper says doctors are not sure that the oxygen test result cutoffs should be the same for all areas. In places at high altitude, for example, where there's less oxygen in the air, it could be that the cutoffs should be adjusted.
But even as an imperfect tool, studies suggest the test could save lives.
"If you look at data out of California," says Kemper, "there are about 30 deaths annually due to critical congenital heart defects that are either not detected or detected late. I think that illustrates the opportunity to really improve the care that we provide."
SOURCES: Kemper, A. Pediatrics, Aug. 22, 2011.Alex R. Kemper, MD, associate professor of pediatrics, Duke University.Alan R. Fleischman, MD, medical director, March of Dimes, White Plains, N.Y.Mona Barmash, president, Congenital Heart Information Network (CHIN), Margate, N.J.Dennis Davidson, MD, chief of neonatology, Steven and Alexandra Cohen Children's Medical Center, New Hyde Park, N.Y. ©2011 WebMD, LLC. All Rights Reserved.