This shows that sleep studies are a useful tool for helping predict risk.
Explore This IssueDecember 2009
She noted that in the UK, there is a practical and commonsense approach to the sleep study. Patients are triaged according to their level of risk into high, moderate, or low risk, and procedures are scheduled according to how severe is their risk of having perioperative complications. High-risk groups would go to a pediatric specialty center with an ICU; moderate risk would have availability for CPAP [continuous positive airway pressure]; and low risk could be operated on at a local general hospital, she said.
A fourth reason is that primary snoring alone may represent a risk. How would we know that unless we have done sleep studies to see if primary snorers were primarily snorers or if they had severe obstructive sleep apnea? she said.
Con: Robert Yellon, MD, Professor of Otolaryngology, University of Pittsburgh School of Medicine.
Guidelines from both the American Academy of Pediatrics and the American Thoracic Society suggest that polysomnography (PSG) is the gold standard for diagnosis of primary snoring versus obstructive sleep apnea syndrome. But the question that comes up is: Is PSG always required to document OSA prior to T&A [tonsillectomy and adenoidectomy]? he said. Also, does primary snoring require adenotonsillectomy?
Although some studies in the medical literature suggest that PSG is superior to clinical evaluation in distinguishing OSA from primary snoring, the quality of those studies varies, he said. In addition, there is a lack of standardization, making it difficult to have a good definition of what constitutes a normal versus an abnormal study.
Some labs use a nasal flow thermistor, and others use a nasal pressure sensor, which is more sensitive to detect hypopneas. You’ll find a higher obstructive index using the pressure sensor. And a child may have OSA but you may make a diagnosis of primary snoring if you just use a thermistor, he said.
Additionally, there are variations in the definition of hypopnea. Some labs would say a 50 percent reduction in airflow with 4 percent reduction in oxygen saturation; and others would say only a 30 percent reduction of airflow with a 4 percent reduction in oxygen saturation. Other labs do not measure end tidal CO2, and some do; this is essential to confirm or exclude hypoventilation. And some labs do not differentiate between central versus obstructive apneas; they just report an apnea index, Dr. Yellon said. What would be considered normal at one center could be abnormal in another.