Morphine treatment questioned for children after tonsillectomy

by Bruce Sylvester: Researchers report that treating post-tonsillectomy pain with morphine can cause some children to develop life-threatening respiratory problems. The study also showed that ibuprofen is a safe and effective alternative to morphine in this clinical circumstance.  The finds are published in the Jan. 26 online edition of Pediatrics.

“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,” said co-author Doron Sommer, MD, clinical professor of surgery at McMaster University Michael G. DeGroote School of Medicine and a surgeon for McMaster Children’s Hospital, both located in Hamilton, Ontario.

The investigators reported a significant risk of potentially-fatal breathing disruption when morphine is administered for post-surgical treat pain in children who undergo tonsillectomy, with or without adenoidectomy. This surgery is used to treat childhood sleep apnea.

The investigators enrolled 91 children between the ages of one and 10. They were randomized to receive post-operative painkillers at home following outpatient tonsillectomy to treat obstructive sleep apnea.

Parents received prescriptions and were instructed about the use of a home pulse oximeter to measure oxygen saturation and apnea events on the night before and the night after surgery. They were also trained to use the Objective Pain Scale and Faces Scale (one to five) measure the child’s pain levels on post-operative days.

From September 2012 to January 2014, one group of subjects received post-operative standard doses of oral morphine (0.2 to 0.5 mg/kg) and acetaminophen (10-15 mg/kg) every four hours, while the other group received oral ibuprofen (10 mg/kg) every six hours and acetaminophen (10-15 mg/kg) every four hours. Pain was comparable and well managed in both groups.

During the first post-operative night, 68 per cent of subjects using ibuprofen group achieved improvement in oxygen desaturation incidents. Only 14 per cent of children in the morphine group showed similar improvement.

Also, during the first post-operative night, the morphine-treated subjects showed substantially more desaturation events per hour.

Both groups had similar minimal levels of other adverse drug reactions and bleeding.

The authors noted that this study builds on two prior studies (2009 and 20120) which indicated that codeine administered for post-operative pain in the same patient population could cause respiratory problems and fatal outcomes for children who have a genetic disposition toward ultra-rapid metabolization of codeine. Both Health Canada and the U.S. Food and Drug Administration (FDA) issued warnings about the risks associated with giving codeine to this population of children. Many physicians began to prescribe morphine, believing that the response to the drug would be more predictable.

Midway through the newly reported study, an interim analysis by the study’s Drug Safety Monitoring Board showed that, in addition to the general findings showing serious respiratory risk associated with morphine, one child suffered a life-threatening adverse drug reaction, including oxygen desaturation, after being treated with morphine. The Board halted the study early and the researchers notified both hospitals’ Research Ethics Boards, as well as Health Canada.

“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,” said  Gideon Koren, MD, co-author of the study and Professor of Pediatrics, Pharmacology and Toxicology, Pharmacy and Molecular Genetics at the University of Toronto in Toronto, Ontario.

“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.”