Investigators designed the novel combining technique that rescuer start the chest compression with one hand during calling for help to the Emergency Medical System (EMS) via a cell phone with another hand when he witnessed the arrest victim. This method may be helpful to reduce the hand-off time and increase the faction time of chest compression until the arrival of EMS members.

To verify this hypothesis, we conducted a random, controlled simulation study.

This study used a random, controlled design in the simulation setting using a manikin. Study participants were recruited from healthy adult (age > 18 years) laypersons who attended the BLS training courses provided by the BLS training class.

The simulation scenario consists of witness of an out of hospital cardiac arrest and activation of the EMS system with the prepared cellular phone. Interventional method contained the immediate starting of the chest compression with one hand during the calling for help to the EMS via a cell phone with another hand.

We compare the quality of CPR between the novel interventional method (start CPR during Call to EMS) and conventional method (First Call to EMS and then start CPR).

Inclusion Criteria:

• All healthy volunteers who attended the basic CPR training class
• Agreement with the simulation trial

Exclusion Criteria:

• volunteers who had some healthy problem which may affect the study results
• Not agreement with the simulation trial