Codeine is not a safe pain medication for kids with sleep apnea who have been sent home after having their tonsils out, warns a report by Canadian researchers in the New England Journal of Medicine.
The researchers discovered the risk the narcotic poses to small children after a two-year-old boy died following the surgery.
“You know, we are all very proud that kids go home right away and we do not threaten them and we don’t scare them (with a hospital stay),” says the report’s senior author, Dr. Gideon Koren.
“But this is one area that we need to be much more careful.”
Koren is director of the Motherisk program at the Hospital for Sick Children in Toronto and holds the Ivey Chair in Molecular Toxicology at the University of Western Ontario.
He says while a tonsillectomy can cure sleep apnea, the surgery is not effective in up to 30 per cent of cases, making it crucial to monitor children in hospital for at least 24 hours after the operation.
“The kid may still have sleep apnea, and then if he or she receives codeine, it may be life-threatening for them.”
Getting your tonsils out used to be almost a rite of passage for kids with frequent sore throats or tonsils big enough to obstruct the airway during sleep.
Now, doctors prescribe antibiotics to kids with enlarged tonsils, sparing them the risks of anesthetic.
Kids usually outgrow sore throats anyway, Koren says.
But the relatively easy procedure to remove the two masses of tissue at the back of the throat remains common for kids who occasionally stop breathing while asleep.
Snoring is a typical symptom of obstructive sleep apnea, which affects three per cent of Canadian preschoolers.
“It’s not rare at all,” Koren notes.
The condition is dangerous enough to warrant the surgery.
To open the airway as fully as possible, doctors usually remove the adenoids as well — the pair of tissues that sit high in the throat behind the nose.
Every year, thousands of Canadian kids find themselves propped up in a hospital bed following a tonsillectomy, Popsicle in hand.
But they don’t usually stay the night. Instead, they’re sent home with a prescription to treat the pain.
The report describes the unusual case of a toddler with sleep apnea who was otherwise healthy yet died early on the third day after surgery at an outpatient clinic.
Unbeknownst to doctors, he had excess copies of a gene that controls how the body metabolizes codeine.
When the child’s mother administered a syrup containing codeine and acetaminophen, his body produced at least twice the normal amount of morphine.
The coroner checked that the boy received the proper amount by measuring the amount left in the bottle. “Although his dose of codeine was as prescribed, he internally poisoned himself,” says Koren.
“His levels (of morphine) went up and up.”
Codeine itself doesn’t alleviate pain, but the body breaks some of it down into morphine—normally, about 10 per cent.
A small percentage of people have an “ultra-rapid” metabolism genotype, meaning their bodies convert a much larger amount into the pain-relieving opiate.
One per cent of Caucasians have multiple sets of the morphine-producing gene. The rate in non-Caucasians is much higher: up to 30 per cent of people of African origin are super-metabolizers.
In this particular fatality, the child was not Caucasian.
Other conditions may have also played a role in his death, but the highly toxic level of morphine in his body — 32 nanograms per millilitre — was a big factor, Koren says.
The boy had inhaled food into his lungs and also developed a lung infection and pneumonia, conditions children become more susceptible to after a tonsillectomy. So his breathing was compromised, and the codeine didn’t help.
Codeine acts as a sedative on the brain stem, which is responsible for the drive to breathe. The drug keeps the patient from reacting normally to lack of oxygen or accumulation of carbon dioxide.
Koren expects to see more cases of children with sleep apnea and the ultra-rapid metabolism genotype, but he’s confident doctors will issue different prescriptions in light of the discovery.
Bruce Carleton, head of the drug safety network that funded the research and a senior clinician scientist at the Child and Family Research Institute in Vancouver, says he’s hopeful that researchers will soon be able to customize drug treatment by testing patients’ saliva prior to surgery.