Bystanders who perform CPR should focus on chest compressions, not mouth-to-mouth breathing, new international guidelines say.

Cardiopulmonary resuscitation is a first aid procedure for an unconscious person whose breathing and/or pulse have stopped.

The technique aims to protect the heart and brain until the heart can resume pumping in a normal rhythm, usually after receiving an electric shock.

Dr. Michael Shuster of the Heart and Stroke Foundation of Canada demonstrates the new CPR technique.

Instead of two breaths for every 15 chest pumps, the new guidelines call for two breaths for every 30 chest compressions.

For children, the ratio changes from one breath for every five chest compressions to two breaths for every 30 compressions.

"These changes are designed to make CPR more effective and easier to remember and perform," said Dr. Michael Schuster of the Heart and Stroke Foundation of Canada, who helped review scientific evidence used to prepare the new guidelines.

Moving blood, oxygen

It's hoped the changes will boost the number of people who are likely to perform the life-saving technique, which can now be taught in about 20 minutes instead of four hours.

Studies showed blood circulation dropped when compressions were interrupted, and time was being wasted after each interruption, the foundation said.

Effective compressions create more blood flow through the heart to the rest of the body to keep someone alive and buying time until rescuers try defibrillation. The foundation also encourages greater access to defibrillators in public places such as airports, casinos and hockey arenas.

The guidelines recommend rescuers minimize interruptions and "push hard and push fast" when giving chest compressions.

Home is where the need is greatest

Peter Doig of Halifax knows the benefits of CPR. His daughter, then a 20-year-old lifeguard, saved his life when his heart stopped 15 years ago. The foundation estimated 80 per cent of cardiac arrests happen at home.

"The ambulance was here in about six minutes," Doig recalled. "In the meantime she did CPR. She worked her butt off, six or seven minutes."

Rescuers are also now asked to start CPR immediately if there is no regular breathing.

Sudden cardiac arrest can happen after a heart attack, or as a result of electrocution or near-drowning.

Every year, about 35,000 to 45,000 Canadians suffer cardiac arrest, according to the foundation. In the U.S., it's estimated that more than 95 per cent of cardiac arrest victims die before they get to the hospital.

Two-thirds of Canadians reported receiving some CPR training, said the foundation. It recommends training to learn and refresh skills.

The new recommendations for lay rescuers, emergency medical personnel and other emergency health-care providers appear in Monday's online issue of the journal Circulation.