"Tragically," Koren said, "we have found that once in 2009 and again now in three additional cases, toddlers who underwent tonsillectomies for sleep apnea and then were treated with codeine were in that ultra-rapid metabolizer group that produce too much morphine. And we have every reason to believe there have been many more such cases, which of course almost certainly occurred in the past, but before anyone knew how to uncover the reason genetically."
About 2 percent to 3 percent of children have obstructive sleep apnea syndrome, which involves structural airway issues that interfere with breathing and, in turn, sleeping. And among those whose sleep apnea is caused by enlarged tonsils, tonsillectomy is often the treatment of choice.
In 70 percent to 80 percent of cases, such surgery successfully improves the patient's sleep apnea condition. And for the children in the recent case studies -- a 3-year old girl, a 4-year-old boy and a 5-year old boy -- the surgery itself was not the problem.
Instead, because of their unidentified ability to overmetabolize codeine, their problems began with the codeine prescribed for pain management after the procedure.
After they were discharged from the hospital, lethargy and signs of heavy sedation set in, as well as other symptoms, including fever, impaired breathing and vomiting. Both boys died within 24 hours after being released from the hospital, while the girl was able to survive after readmission and mechanical ventilation support.
The researchers noted that screening tests for metabolizing mutations are available. But, many medical facilities remain unaware of the risks posed by such mutations. The tests are expensive, amounting to several hundred dollars each. As a result, such screenings are not currently a routine feature of preoperative hospital protocol.
Koren said that in Europe, physicians have long since replac
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