A number of sudden deaths in public places recently has put automated external defibrillators in the spotlight once again, with experts and members of the public calling for them to be more widely deployed to save lives in cases of sudden cardiac arrest.

AEDs are portable devices that use electric shocks to get hearts pumping again following sudden cardiac arrest. Unlike cardiopulmonary resuscitation, which requires special training to administer, AEDs are easier to operate, with users just needing to follow the audio instructions.

Li Yongjun, a vascular surgery professor at Beijing Hospital, said more AEDs need to be installed in busy places such as airports, train stations and stadiums, so people experiencing sudden cardiac arrest have a better chance of surviving.

"Promoting them in public places is also a reflection of social progress," he said. "We need to pay respect to life, including the minority of those who may have sudden cardiac arrest."

Jia Dacheng, a doctor at Beijing Emergency Medical Center, said defibrillation should be completed within four minutes of sudden cardiac arrest to be most effective, and AEDs were the most effective portable device for that purpose.

"It is specially designed for nonprofessionals so the public can use it without training," he said. "Such devices should be installed in all public places with high population flows."

Cardiovascular diseases have become a top killer in China in recent years, with experts estimating about half a million people die due to sudden cardiac arrest each year.

Two deaths due to sudden cardiac arrest attracted widespread public attention recently.

On Nov 27, 35-year-old Godfrey Gao, a Chinese-Canadian actor and model, died of cardiac arrest while filming a television reality show in Ningbo, Zhejiang province.

He died even though he received immediate first aid from medical staff on location before being sent to hospital.

Two days later, a 61-year-old man from Liaoning province had a sudden cardiac arrest on a subway train in Beijing. He died later despite rescue efforts from subway staff and emergency medical staff. There was no AED available for use in the subway when the man's heart stopped beating, according to media reports.

Although more AEDs have been installed in public places across China in recent years, they are still in short supply. Although there is no official data on the number of AEDs in China, it is estimated that there is less than one device for every 1 million people, according to a report by China National Radio, which added that the ratio in Japan was 1,550 for every 1 million people.

In the subways of big cities such as Beijing and Shanghai, which are used by millions of passengers every day, AEDs are only installed at some major stations, the report said.

Li, from Beijing Hospital, said compared with promoting the installation of AEDs in public places, promoting CPR training among the public may be more important in saving lives in emergencies.

"AEDs can only perform an accessory role in first aid, and sustained cardiopulmonary resuscitation efforts may be needed," he said. "In case of emergency, medical staff must be called to perform rescue efforts."