BudWiederman, MD, MA, Evidence eMended Editor, Grand Rounds
I'm continuing my rant from last month about the importance of physical exam, which this study supports. At first glance,
this article may seem to just state the obvious, but some clinical pearls reveal themselves.
This study concludes that screening pulse oximetry in asymptomatic newborns only picks
up a small proportion of children with important congenital heart disease, but that
adding cardiac auscultation to the screening process improves detection of critical
heart disease in this population. Of course, that isn't surprising; pulse oximetry
will detect only those instances where the disease process is causing hypoxia, and
many very critical cardiac defects (e.g. aortic coarctation, large left-to-right shunt
lesions) will be missed by pulse oximetry alone. That's the obvious part of the study's
conclusion, but dig a little deeper for the details which are quite helpful.
First of all, this was a huge study, performed in 15 birth hospitals in Shanghai,
China, and encompassing 172,865 deliveries of asymptomatic newborns over a 30-month
period. Successful screening rates were in the mid- to high-90s in all hospitals.
Of those deliveries, 167,190 newborns comprised the study population, with the dropouts
due to 1385 symptomatic newborns who bypassed the screening procedures and 4108 with
incomplete screening data. Second, the 165,143 infants with negative screens all had
successful clinical follow-up at 6 weeks of age (to ensure no missed heart disease).
Furthermore, the first 27,201 (how did they decide on that number?) asymptomatic babies
also had telephone follow-up at 1 year of age. Those are just amazing follow-up results,
I suspect nothing like that would be achievable in the US.
Cutting to the chase, auscultation proved to be important. Pulse oximetry alone identified
34 of 44 cyanotic congenital heart disease patients, and adding auscultation brought
the number up to 42. For noncyanotic but major congenital heart disease (defined as
causing death or requiring intervention during infancy), the numbers were 90 of 203
for pulse oximetry, with an increase to 187 with auscultation added. The researchers
also broke down the false positive rates for screening by the timing of the screening
process. Rates were slightly higher earlier in life, no surprise, and screening a
little later, at least 37 hours of life, seemed to be an optimal time for minimizing