Infant Heart Screening

Infant Heart Screening

Screening for Critical Congenital Heart Defects in Infants: the accuracy and implementation of pulse oximetry as a standard of care

Diana Pinney

Concordia University, Nebraska

February, 2013

Critical Congenital Heart Defects

Within the first week of life, all infants should be screened for critical congenital heart defects (CCHDs). (CDC, 2013) This screening is required because not all infants display signs of heart defects before they are sent home from the hospital. (CDC, 2013) There are 7 defects that are categorized as CCHDs, which make up 17-31% of total congenital heart diseases. (CDC, 2013)

Heart screenings are performed using a pulse oximeter, which measures the amount of oxygen in the blood. (CDC, 2013) This test is looking for a healthy range of dissolved oxygen or a hypoxic range. (CDC, 2013) Hypoxia is an absence of dissolved oxygen in the blood. A normal pulse oximeter reading’s range is between 95%-100% while less than 90% is considered abnormal. (Mayo Clinic, 2012)

Below is a flow chart designed to facilitate a pulse oximeter test.

(CDC, 2013)

As with all screenings, a negative pulse oximeter test does not necessarily mean the infant has no CCHD and a positive test does not guarantee this outcome and requires more testing. (CDC, 2013) Further tests include echocardiograms and genetic testing, all more expensive than the relatively cheap and fast pulse oximeter test. (CDC, 2013)

The United States Department of Health and Human Services (DHHS) Secretary’s Advisory Committee on Heritable Disorders in Newborns and Children voted in 2010 to require CCDH testing as part of the uniform screening panel. (CDC, 2013) While many states have officially not added CCHD screening to their uniform screening panel, many hospitals perform this test as a standard of care. (Newborn Foundation Coalition, 2013) Even though the DHHS began recommending pulse oximetry in 2010, Walker (2012) reports that only about one-fifth of the states have legally required the implementation of this test.

Identifying an Appropriate Population

Though Louisiana named June 1st Congenital Heart Disease Awareness Day in 2012, no legislative action has been taken on implementing CCHD screening in hospitals. (NFD, 2013) The state of Louisiana’s Department of Health and Hospitals do not list CCHD in their recommended newborn screening panel. (Department of Health and Hospitals, 2013)

According to the CDC, coming in second behind Mississippi, Louisiana’s self reported adult obesity rate is 33.4%. (CDC, 2012) This statistic is relevant because many studies have shown that the risk of newborn heart defects increases when the mother is obese. (National Institutes of Health, 2010)

In a case control study comparing mothers of infants with heart defects and all women who delivered babies at a single hospital between 1992 and 2001, it was found that obese mothers have an increased risk for birthing infants with CCHDs than do mothers of average weight. (Cedergren and Kallen, 2003)

Using this information, if one were to pick a population and location that needed screening for CCHDs, a logical choice would be a place where this screening is not already required by law in a population that has a higher than average weight.

New Orleans is the most populous city in Louisiana. (GeoNames, 2013) Louisiana is also a state where screening is not required by law, and the state which has the second highest obesity rate in the county. Therefore, a logical choice to begin screenings in this case would be a large city with hospital infrastructure already in place in an area where obesity is common and screenings for CCHDs are not already mandated by law.

CCHD Data and Studies

According to the CDC (2013), 300 infants die each year of CCHDs and CHDs make up 24% of infant deaths related to birth defects.

Ewer, et al. (2011) conducted a screening test to determine the accuracy of pulse oximetry testing. This study is significant because pulse oximeter testing has been approved for use in America, but not all states and hospitals have implemented this cheap and easy screening. Other countries have not recognized this test or do not have access to it. (Lifebox, 2013) For example, 3 out of 4 patients in Africa do not have access to this technology, although free units are available through the non-profit organization, Lifebox. (Lifebox, 2013)

The other screening option includes a fetal ultrasound, which carries a detection rate of 15-50%. (Ewer, 2011)

To test the accuracy of pulse oximetry, Ewing et al. 2011) screened 20,055 newborn babies at a United Kingdom hospital. 53 children were found to have a CCHD, which makes the prevalence rate 0.26%. There were 169 false positives and 40 other diseases that were discovered. (Ewing et al., 2011)

The satisfactory sensitivity of 75% means that this test successfully identified 75% of babies that had CCHDs and 49.06% of infants with CHDs. With only 169 false positives, the test correctly identified infants who tested negative with 99.16 percent accuracy. (Ewer et al., 2011) This study’s “main outcome was the sensitivity and specificity of pulse oximetry for detection of critical congenital heart defects.” (Ewer et al., 2011) Ewer et al. (2011) determined that “pulse oximetry is a safe, feasible test that adds value to existing screening. It identifies cases of critical congenital heart defects that go undetected.”

Since pulse oximetry testing has emerged as one of the only ways to quickly, cheaply and accurately measure dissolved oxygen in the bloodstream, it is difficult to comment on validity since separate ways to easily measure dissolved oxygen seem to not be in use. Therefore, it could be assumed that testing the validity of pulse oximetry has already been completed since its use is so ubiquitous.

If accuracy came into question in a modern hospital setting, it would be easy and effective to retest an infant using a different machine.

CCHDs are diagnosed based on a spectrum of what is deemed ‘low blood oxygen’ so results on either end of this spectrum may be included in the data of a screening study depending on the bias of the researcher or physician and their personal or professional histories surrounding these defects.

Ethical Considerations

Ethical considerations regarding screening for CCHDs from the public health and epidemiological point of view center around mother and infant. An important point to consider for the mother is the low cost of the test and scientific proof of its accuracy in identifying critical defects. Infants with undetected CCHDs have high risk of morbidity and mortality. (Kochilas, 2013) Pulse oximetry testing takes “less than 5 minutes, less than 4 dollars and is less invasive than a Band-Aid.” (Villanueava-Whitman, 2012) If a pulse oximeter test comes back within the undesirable range, an ultrasound or echocardiogram is performed to confirm results. (CDC, 2013) When considering the infant, the use of pulse oximetry on a newborn is entirely noninvasive, painless and cannot do harm, only good.

Recommendations

Increasing participation levels in pulse oximetry screening is widely accepted as a highly effective method of preventing infant mortality from undetected CCHDs though, many states and counties have not adopted this simple, fast and noninvasive test into their standards of care.

A tactic for increasing participation levels could start at the city, county or state legislative level in places where legislation has not already been enacted. Advocacy groups or other kinds of lobbies could be very effective in connecting with elected officials and encouraging them to introduce legislation requiring hospitals to add pulse oximetry to the screenings performed on newborns. The high morbidity and mortality of CCHDs and the relative ease of implementing this test into standards of care would make this cause an easy one for many politician to get behind.

Public health could also play a large role in educating pregnant women of the potential issues their newborns might face if a CCHD were to go undetected. The most effective way to increase participation levels in screenings for CCHDs would be for medical professionals and other sources of prenatal knowledge to include information on CCHD screening in all of their consultations. When future mothers are informed of the risks of maternal obesity and the negligible cost and ease of this test, it is safe to predict that many will take it upon themselves to make sure their newborns are screened for potential critical congenital heart defects.

References

Cedergren, M. I., and Kallen, B. A. J. (2003, September 6). Maternal

obesity and infant heart defects. Obesity Research. (11)9: 1065-1071. DOI:10.1038/oby.2003.146

Centers for Disease Control and Prevention. (2013). Screening for critical

congenital heart defects. Retrieved from http://www.cdc.gov/ncbddd/pediatricgenetics/pulse.html

Centers for Disease Control and Prevention. (2013). Screening for critical

congenital heart defects. Retrieved from h ttp://www.cdc.gov/ncbddd/pediatricgenetics/CCHDscreening.html

Centers for Disease Control and Prevention. (2012). Prevalence of self

reported obesity among U.S. adults. Retrieved from http://www.cdc.gov/obesity/data/adult.html

Department of Health and Hospitals. (2013). American college of medical

genetics recommended newborn screening panel. Retrieved from http://new.dhh.louisiana.gov/index.cfm/page/472

Ewer, A., et al. (2011, August 27). Pulse oximetry screening for congenital

heart defects in newborn infants (PulseOx): a test accuracy study.

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GeoNames. (2013). Louisiana – largest cities. Retrieved from

http://www.geonames.org/US/LA/largest-cities-in-louisiana.html

Kochilas, L. (2013). Newborn screening for critical congenital heart

diseases (CCHD). Retrieved from http://www.health.state.mn.us/divs/phl/newborn/docs/cchd.pdf

Lifebox. (2013) Retrieved from http://www.lifebox.org

Mayo Clinic. (2012). Hypoxemia (low blood oxygen). Retrieved from

http://www.mayoclinic.com/health/hypoxemia/MY00219

National Institutes of Health. (2010). Risk of newborn heart defects

increases with maternal obesity. Retrieved from http://www.nih.gov/news/health/apr2010/nichd-07.htm

Newborn Foundation Coalition. (2013). Newborn CCDH screening

progress. Retrieved from http://cchdscreeningmap.org

Walker, C. (2012, November 28). The Network for Public Health Law.

Critical congenital heart defect & pulse oximetry screening: a public

health law opportunity. Retrieved from

http://www.networkforphl.org/the_network_blog/2012/11/28/147/critical_congenital_h

eart_defect_pulse_oximetry_screening_a_public_health_law_opportunity/

Villanueava-Whitman, E. (2012, November 29). Inexpensive blood test

can save newborn lives. The Des Moines Register. Retrieved from

http://www.usatoday.com/story/news/2012/11/29/blood-test-can-

save-newborn-lives/1736603/