It's a terrifying experience for families, having a child who goes into cardiac arrest, and a new report has found minutes matter.

Less than 10 per cent of pediatric patients who suffer cardiac arrest outside the hospital survive.

But a new study from the Lawson Health Research Institute has found the time spent at the scene by a paramedic to treat children who've experienced heart failure makes a difference.

The study's lead author Dr. Janis Tijssen says, "We're hoping the study might provide guidance for paramedics in terms of how long to stay on the scene to provide basic life support."

In a joint study with Toronto's Hospital for Sick Children, researchers found the survival rate was the highest when treatment at the scene lasted from 10 to 35 minutes.

Under 10 minutes the number drops substantially - as it did when paramedics spent more than 35 minutes at the scene.

Treatment Time on Scene and Survival Rates

  • 10-35 minutes - 10.2 per cent
  • Under 10 minutes - 5.3 per cent
  • Over 35 minutes - 6.9 per cent

In the latter case, the study pointed to an apparent paradox - while resuscitation rates were higher, that didn't translate into a greater rate of survival.

"Spending longer, you're delaying definitive care that can be provided at the hospital and that involves understanding why the cardiac arrest happened so some investigations can be done at the hospital which can't be done at the scene," Tijssen says.

The study also found that overall infants had the lowest rate of survival at 3.7 per cent, followed by children at 9.8 per cent, with teens having the highest rate at 16.3 per cent.

Cardiac arrest in children is quite rare and the reasons are varied, but the cause often depends on the age of the child. For example Sudden Infant Death Syndrome (SIDS) in an infant vs. an underlying heart condition in an older child.

The study also sheds light on the optimal treatments at the scene, Tijssen explains.

"What we found was that inserting an IV - intravenous line...was found to be beneficial to the patients. We're not sure why because some of the resuscitation drugs were not beneficial to the patients."

The study looked at more than 2,200 children, and also found that with most patients - 68.7 percent - paramedics had in fact spent between 10 and 35 minutes at the scene.