A new United States study suggests that traditionally low survival rates from cardiac arrests that happen outside a hospital can be improved when bystanders perform compression-only CPR.
The research, published in the Journal of the American Medical Association, involved 4415 adults in Arizona who had cardiac arrest in non-hospital settings between 2005 and 2009, and who received no bystander CPR, conventional CPR with rescue breathing, or chest compression-only CPR.
Some doctors say compression-only CPR is easier to learn and perform than conventional CPR.
Among those who did not get CPR, only 5.2% survived long enough to be discharged from hospital, compared with 7.8% who received CPR with rescue breathing and 13.3% who had compression-only CPR.
The study noted that a public-awareness campaign was begun in Arizona in 2005 to improve the "dismal" survival rates and increase knowledge of hands-only CPR.
Bystander intervention had risen significantly, with some form of CPR in nearly 40% of non-hospital cardiac arrests last year, up from 28% in 2005.
The overall number of survivors of such cardiac arrests also increased from 22 in 2005 to 99 last year, the study noted.
St John training product manager Brett Derecourt, of Wellington, said the study did not definitively prove that compression-only CPR produced better results than CPR with rescue breathing.
The latest of a regular series of reviews of CPR was being undertaken by the International Liaison Committee on Resuscitation, taking into account the latest research, and the outcome would be known by December, he said.
The Arizona study had highlighted CPR's positive effects and it was "really interesting" that a public education campaign had had "such a good effect on outcomes".
"It shows that the more people that know about CPR, the more likely the person is going to have CPR done on them and therefore survive.
"Everyone should learn to do CPR and if you are faced with a situation where you need to do CPR and you haven't learned it then you [should] push on the chest hard and fast and ring 111 because they will give you instructions when you phone."
• New Zealand already had a relatively high CPR intervention rate.
It was done in about 50% of cardiac-arrest cases outside hospital, and 8%-10% of patients ultimately survived.
About 1100 New Zealanders experienced cardiac arrest outside hospital each year, at home in 70% to 80% of cases.