Oxygen test has potential to detect some critical congenital heart defects in newborns

American Heart Association/American Academy of Pediatrics Scientific Statement

July 06, 2009 Categories: Scientific Statements/Guidelines
Statement highlights:
  • Early detection of critical congenital heart disease is important for avoiding serious health consequences.
  • A non-invasive measure of oxygen saturation in the blood is a reasonable way to detect congenital heart disease in newborns, but there is not yet enough data available to make the test mandatory.
  • The associations call for more research on the topic.
DALLAS, July 6, 2009 — A test that measures oxygen levels in newborns can detect “critical” congenital heart disease, but there are variables involved with the test that require more study before it is adopted for universal newborn screening, according to a new joint statement from the American Heart Association and the American Academy of Pediatrics.
The scientific statement is published online today in Circulation: Journal of the American Heart Association and in Pediatrics.
A critical congenital heart defect is one a child is born with that requires surgery or catheter intervention in the first year of life, such as tetralogy of Fallot and coarctation of the aorta, among others.  The benefits of the oxygen test, called a pulse oximetry screening, outweigh the risks, but the best way to implement pulse oximetry screening is not well established by research. 
Thus, the organizations affirm that the test can be used at a physician’s discretion, and call for more research to determine whether the test should become part of the routine assessment of all newborns in the United States.
In the research reviewed, the test’s ability to detect critical congenital heart disease varied widely, from zero to 100 percent.
According to the statement, most studies that have analyzed pulse oximetry in newborn screening were relatively small, and screening protocols differed with respect to both age at screening and cutoff levels for an abnormal screen.
A normal oxygen reading is between 97-100 percent.
Because oxygen levels in healthy newborns can vary considerably in the first 24 hours of life, the authors note that testing after 24 hours would appear the best strategy.  False positive rates were just .035 percent in infants screened after 24 hours.
“The statement is important because there hasn’t been any strong guidance so far regarding the use of pulse oximetry as a diagnostic technique in newborns,” said William T. Mahle, M.D., FAAP, chair of the writing committee and associate professor of pediatrics at Emory University School of Medicine in Atlanta.  “Some hospitals across the country have adopted it and others haven’t, so we wanted to review the available evidence and offer a consensus opinion on the topic.”
The test potentially can identify significant or life-threatening heart defects that may otherwise go unnoticed or at least unnoticed before a newborn is released from the hospital, Mahle said.  Early identification of certain defects is important, and can allow doctors to begin appropriate treatment or transfer to a specialty hospital.
Pulse oximetry was developed in the early 1970s, based on the fact that red blood cells that carry oxygen absorb different wavelengths of light vs. those that don’t carry oxygen.  Oxygenated blood cells absorb infrared light, while deoxygenated cells absorb red light.  The test measures how much oxygen is in blood that flows through the arteries.
Arterial blood oxygen levels are measured by a device with a thin wire, tipped by a small red light.  The wire is taped to an infant’s foot for a few minutes to obtain a reading.  In older children and adults, pulse oxygen is often measured by a device clipped on a finger.
The overall cost of the test is reasonable, and is about the same as the cost of other newborn screening tests.
As of 2002, the prevalence of congenital cardiovascular defects in the United States is about 9 per 1,000 live births Mahle said. 
Co-authors include Jane W. Newburger M.D., M.P.H.; G. Paul Matherne, M.D.; Frank C. Smith, M.D.; Tracey R. Hoke, M.D.; Robert Koppel, M.D.; Samuel S. Gidding, M.D.; Robert H. Beekman III, M.D.; and Scott D. Grosse, Ph.D.  Author disclosures are on the manuscript.
The American Heart Association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events.  The association has strict policies to prevent these relationships from influencing science content.  Revenues from pharmaceutical and device corporations are available at www.americanheart.org/corporatefunding.
NR09-1078 (Circ/Mahle-PulseOx)
About the American Heart Association
Founded in 1924, we’re the nation’s oldest and largest voluntary health organization dedicated to building healthier lives, free of heart disease and stroke.  To help prevent, treat and defeat these diseases — America’s No. 1 and No. 3 killers — we fund cutting-edge research, conduct lifesaving public and professional educational programs, and advocate to protect public health.  To learn more or join us in helping all Americans, call 1-800-AHA-USA1 or visit americanheart.org.
The American Academy of Pediatrics is an organization of 60,000 primary care pediatricians, pediatric medical subspecialists and pediatric surgical specialists dedicated to the health, safety and well being of infants, children, adolescents and young adults.  Learn more at www.aap.org.
Congenital Heart Disease Fact Sheet
Congenital means inborn or existing at birth.  Among the terms you may hear are "congenital heart defect," "congenital heart disease" and "congenital cardiovascular disease."  The word "defect" is more accurate than "disease." 
What is a congenital heart defect?
Congenital heart defects are structural problems with the heart present at birth.  They result when a mishap occurs during heart development soon after conception and often before the mother is aware that she is pregnant.  Defects range in severity from simple problems, such as "holes" between chambers of the heart, to very severe malformations, such as complete absence of one or more chambers or valves.
  • About 36,000 children are born with a heart defect in the U.S. each year.
  • Some defects are so mild that there are no outward symptoms; in other cases, the defect is so severe that the baby becomes ill soon after birth. 
  • Most of children with a congenital heart defect can benefit from surgery, even those with severe defects. 
  • Other treatments include catheter-based intervention or medication
  • At least nine of every 1,000 infants born in the U.S. each year have a heart defect.
  • That’s almost one percent of live-born infants.
  • There is nothing that parents could have done to prevent these defects.
Signs and Symptoms
Sometimes the defect is so mild that there are no outward symptoms.  In other cases, it’s so severe that the newborn becomes ill soon after birth. In still other cases, signs and symptoms occur only in later childhood.
In severe cases, some babies are blue or have very low blood pressure shortly after birth.  Other defects cause breathing difficulties, feeding problems, or poor weight gain.  Minor defects are most often diagnosed during a routine medical check up.  Minor defects rarely cause symptoms. 
Types of defects
At least 18 distinct types of congenital heart defects are recognized, with many additional anatomic variations. If your child is born with a heart defect today, the chances are better than ever that the problem can be overcome and that a normal adult life will follow.

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