Painkilling medication is usually prescribed following most forms of surgery. However, the use of morphine to treat the post-operative pain of children having their tonsils removed could lead to potentially life-threatening respiratory problems, according to the findings of a new study.
The effects of morphine were so severe that the study’s Drug Safety Monitoring Board halted the study period early. In contrast, the study showed that ibuprofen could be used safely and effectively as an alternative.
“These results should prompt clinicians to re-evaluate their post-tonsillectomy pain treatment regimen. Due to the unpredictable respiratory side-effects of morphine, its use as a first-line treatment with current dosage ranges should be discontinued for outpatient tonsillectomy,” says study co-author Dr. Doron Sommer.
Tonsillectomy is commonly used to treat cases of childhood sleep apnea – according to the American Academy of Otolaryngology – Head and Neck Surgery (AAOHNS), 80% of tonsillectomies are now carried out to treat obstructive sleep problems.
Previous research in 2009 and 2012 demonstrated that the use of codeine to treat post-operative pain – previously the standard course of treatment – could cause potentially life-threatening respiratory problems in children. Subsequently, the US Food and Drug Administration (FDA) gave codeine its strongest warning – a “Boxed Warning.”
The new study, published in Pediatrics, was conducted by staff from Motherisk Program at The Hospital for Sick Children, McMaster University in Ontario, Canada, and McMaster Children’s Hospital.
A prospective, randomized clinical trial saw 91 children aged 1-10 being randomly assigned post-operative painkillers to take at home following outpatient tonsillectomy surgery. Painkillers were to be prescribed from September 2012 to January 2014.
One group of participants was given standard doses of oral morphine (0.2-0.5 mg/kg) and acetaminophen (10-15 mg/kg) to take every 4 hours. The other group of participants were given standard doses of oral ibuprofen (10 mg/kg) and acetaminophen (10-15 mg/kg) to take every 6 hours and every 4 hours respectively.
Parents were instructed to measure their children’s oxygen saturation and any pauses in breathing using a home pulse oximeter. They were also taught how to assess their children’s pain levels using the Objective Pain Scale and Faces Scale and recorded pain levels on the first and fifth days after surgery.
Both groups had their pain effectively managed by their medication, but there was a marked difference in the frequency of oxygen desaturation incidents in which the blood’s oxygen concentration falls.
On the first night post-surgery, 68% of the children receiving ibuprofen demonstrated improvement in oxygen desaturation events. In comparison, only 14% of the group receiving morphine showed improvement and over time more desaturation events were recorded, up to a rate of 11-15 events per hour.
Due to the serious respiratory risk that was being observed, particularly in one incident where a child suffered a life-threatening adverse drug reaction to morphine which included oxygen desaturation, the study was ended midway through the planned study period.
“The evidence here clearly suggests children with obstructive sleep apnea should not be given morphine for post-operative pain. We already know that they should not get codeine either,” says study author Dr. Gideon Koren.
Despite the problems identified with morphine, some positives were taken by the team. “The good news is that we now have evidence that indicates ibuprofen is safe for these kids, and is just as effective in controlling their pain, so there’s a good alternative available for clinicians to prescribe,” says Dr. Koren.
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