Letters from Maine

Listen carefully

Publish date: October 28, 2017

The widespread use of fetal ultrasound has dramatically decreased the number of delivery room surprises. In this country, most infants with a cardiac anomaly detected in utero probably are delivered at tertiary medical centers, leapfrogging over the maternity units at their local community hospitals. But infants with critical cardiac conditions continue to arrive unheralded at every hospital, both large and small. And many of these babies are asymptomatic without tachypnea or cyanosis. A study reported in the October 2017 Pediatrics by Hu et al. suggests a strategy for detecting these little masters of disguise before their lesions get them into serious trouble (doi: 10.1542/peds.2017-1154).

Pulse oximetry has been widely debated as a method for detecting congenital heart disease, because of course it misses the cases that are acyanotic. In a series of more than 150,000 asymptomatic neonates, these investigators combined cardiac auscultation with pulse oximetry and achieved a sensitivity of 96% in detecting critical congenital heart disease and 92% for major congenital heart disease. Their false-positive rate for both categories was just a bit over 1%.

^{Courtesy Dr. William G. Wilkoff}

Dr. William G. Wilkoff

The abstract left me with several questions, because I wondered if there was something about the auscultation procedure they were using. The paper doesn’t describe the exact technique used or the timing, but it does say that the clinicians who did the auscultating were “highly trained” and closely supervised. And the procedure was performed in a “quiet environment.”

This may be another case in which the training of the examiner and the environment are critical to a positive result. As I think back to the conditions in which I examined newborns, I wonder how careful I was that my auscultating was being done in a quiet environment. If I was in the nursery, there may have been other babies crying, a radio playing, or nurses conversing with one another. I may have been deluding myself that, over the years in practice, I had developed the ability to cancel out those auditory distractions. It was probably dumb luck that I didn’t miss any critical murmurs.

And then there is the timing. The investigators don’t describe how soon after birth the auscultation was performed. Is there an optimum time in relation to the neonate’s transition from his/her fetal circulation? How long did the examiners listen? Were they in a rush to get back to their offices and busy waiting room or were they hospitalists?

I found this to be an interesting study, and if repeated by other investigators, it provides an example of how technology advancement doesn’t always render our old examining skills obsolete. In fact, it may demand we sharpen them.

Dr. Wilkoff practiced primary care pediatrics in Brunswick, Maine for nearly 40 years. He has authored several books on behavioral pediatrics, including “How to Say No to Your Toddler.” Email him at pdnews@frontlinemedcom.com.

Listen carefully

Recommended Reading