Pediatric OSA Screening

The ranks of children at risk for obstructive sleep apnea are ballooning, due in part to now-rampant childhood obesity rates, making pediatric sleep testing more important than ever before. If OSA is left undiagnosed and untreated, the possible consequences run the gamut from cognitive and behavioral to cardiovascular and metabolic.

While polysomnography is the gold standard of sleep testing, it is “not a perfect test, but it is the best test we have,” said Carole Marcus, MBBCh, director of the sleep center at Children’s Hospital of Philadelphia. The few studies that have looked at abbreviated four-channel sleep studies in children have not shown a great correlation between children’s sleep patterns and a trustworthy diagnosis of OSA. “But, any sleep study is better than no sleep study.”

Ways to identify young patients who need sleep studies are limited but slowly expanding. “We know that history and physical exam are extremely poor at predicting which children have OSA vs. which children are just snoring,” Dr. Marcus said. “Nocturnal pulse oximetry has good predictive ability, but it also has a high false-negative rate because some children have a lot of arousals and tend to arouse before they really desaturate. And then there are some false positives because children also may have a bit of asthma, restrictive lung disease caused by obesity, etc.”

Robert Beckerman, MD, medical director of The Comprehensive Sleep Disorders Center at Children’s Mercy Hospitals and Clinics, Kansas City, Mo., added that such at-home, unattended studies often don’t produce good data. The pulse ox comes off the finger, and results can be misleading. “Plus 25 percent of children with sleep apnea don’t even have significant pulse ox desaturation – they have partial obstruction all night,” he explained. “They sweat, they don’t wake up completely, but they do have brain wave arousals, and their carbon dioxide level is elevated.”

Dr. Beckerman suggested that a carbon dioxide measurement must be included in all pediatric OSA testing. “Most (adult) sleep labs don’t do carbon dioxide measurements, so they often miss sleep apnea in children. In pediatric studies, measuring carbon dioxide is a must.”

Other common pre-PSG screening tools include at-home audio and video recordings of a child sleeping and/or snoring. “These are great in theory,” Dr. Marcus said, ” but what happens in practicality is parents bring videos in which a blanket is pulled up to the child’s nose, and there’s almost no sound. It’s hard to assess.”

The use of medical imaging has come into play in recent years as a tool to identify patients with obstructing physiology. Yet Dr. Marcus said even such technology has limits. And you certainly can see the adenoids by putting a scope down.

“But the size of the tonsils and adenoids really don’t predict whether a child has OSA or not,” Dr. Marcus explained. “It’s a combination of the muscle tone of the airway during sleep and the structural components [that cause OSA]. Epidemiologically, studies have shown that the bigger your tonsils, the more likely you are to have sleep apnea, but the individual correlation is poor. For normal children, imaging really is not going to help.”

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Continuing efforts are under way to improve techniques to screen children for OSA, and David Gozal, MD, professor and chairman of pediatrics at University of Chicago, is heading one of those efforts. “Sleep studies are expensive, and there are not enough trained people and facilities to handle the increasing need for pediatric studies,” Dr. Gozal said, “so we knew we needed to find a better way to do this.”

In 2006, Dr. Gozal and fellow researchers undertook a pilot study and then reported their findings in 2009. The researchers found that four proteins in a child’s urine can “reliably distinguish” between a child with OSA and one with simple habitual snoring.

The National Institutes of Health and the National Heart, Lung, and Blood Institute recently funded the researchers to continue their work. At the end of three years, Dr. Gozal hopes to have an extensively validated set of candidate biomarkers to serve as an early diagnostic method that is much cheaper and easier to implement than all the other options available.

“We’ve already developed the model T, now we want to perfect the Rolls Royce,” Dr. Gozal said. Yet there would still be a long road to the marketplace if OSA testing were to become as simple as a pregnancy test. “We’ll need to develop the right tools, antibodies and everything that can be contained in a little kit. . Cost would be minimal – $20 give or take. That’s where I would like to take the field.”

Contact Valerie Neff Newitt at [email protected].