The impact of altitude on screening for critical congenital heart disease

The objectives were to determine the frequency with which pulse oximetry identifies critical congenital heart defects in asymptomatic full-term and late preterm newborns using the AAP expert panel algorithm in a variety of different hospital settings and to evaluate the impact of altitude on the rate of positive screens.

We conducted a prospective clinical study of implementation of a newborn pulse oximetry screening for congenital heart disease in 34 independent hospitals. Infants were eligible for enrollment if their gestational age was 35-44 weeks.

Of the 34 sites which enrolled infants into our study, 24 were located at or below 2000 feet; 5 were located between 4700 and 6000 feet and 5 were located above 6000 feet in altitude. We screened 6109 infants; 65 (1.1%) had a positive screen. There were no differences in median gestational age, birth weight, mode of delivery or race/ethnicity for infants with a positive screen compared to infants with a negative screen. Infants with positive screens were more often male and more often born at sites located at high altitudes. The frequency of a positive screen increased from 0.2% for infants born at sites at or less than 2000 feet to 6% for sites located above 6000 feet. We stopped enrollment at the site located at 8163 feet after enrolling 65 infants because 23 (35%) were positive.

Screening infants for critical cardiac defects at altitude is complicated by the increased false positive screens.