Morphine after childhood surgery may be life threatening

Treating post-operative pain with morphine can cause life-threatening respiratory problems in some children who have had their tonsils and/or adenoids removed, a new research has warned.

The study, conducted by the Motherisk Programme at The Hospital for Sick Children (SickKids) and by McMaster University and McMaster Children's Hospital, has identified a significant risk for potentially-fatal breathing disruption when morphine is administered at home after surgery to treat pain in children who undergo tonsillectomy with or without adenoidectomy.

This surgery is commonly and effectively used to treat childhood sleep apnea. The study also showed ibuprofen is a safe and effective alternative.

In the study, 91 children between the ages of one and 10 were randomly assigned to receive post-operative painkillers at home following their outpatient tonsillectomy surgery to treat obstructive sleep apnea.

Parents were given a prescription to fill and were instructed about the use of a home pulse oximeter to measure oxygen saturation and apnea events (pauses in breathing) the night before and the night after surgery.

Parents were also taught to use the Objective Pain Scale and Faces Scale to assess their children's pain levels on post-operative days one and five.

From September 2012 to January 2014, one group was given post-operative standard doses of oral morphine (0.2 to 0.5 mg/kg) and acetaminophen (10-15 mg/kg) every four hours to treat their pain, while the other group was prescribed standard doses of oral ibuprofen (10 mg/kg) every six hours and acetaminophen (10-15 mg/kg) every four hours.

Pain was effectively managed and comparable in both groups. On the first post-operative night, 68 per cent of children in the ibuprofen group showed improvement in oxygen desaturation incidents (a drop in oxygen concentration in the blood).

On the same night, only 14 per cent of children in the morphine group improved. In fact, in the short term, the condition of these children worsened, with substantially more desaturation events in the morphine group - roughly 11 to 15 events per hour.

Both groups had similar minimal levels of other adverse drug reactions and bleeding.
Last year, midway through the planned study period, an interim analysis was conducted by the study's Drug Safety Monitoring Board.

In addition to the general findings, which strongly demonstrated serious respiratory risk associated with morphine, one child suffered a life-threatening adverse drug reaction including oxygen desaturation after being treated with morphine.

These severe outcomes prompted the Board to halt the study period early and the research team notified both hospitals' Research Ethics Boards, as well as Health Canada.
The study is published in the Journal PEDIATRICS.