Out-of-hospital cardiac arrest (OHCA) is a major public health problem, with around 40,000 victims each year in France. Their survival rate remains dramatically low, at less than 10%.

In the event of pre-hospital cardiac arrest, rescuers perform resuscitation techniques using equipment for which they have been trained. They perform cardiopulmonary resuscitation (CPR) by alternating 30 chest compressions with 2 insufflations (30/2) with a manual insufflator bag.

In basic life supports, insufflations should result in chest rise, but guidelines do not specify a precise volume.

Recently, medical devices have been developed that enable precise measurement of ventilatory volumes. In simulation, these devices show hyperventilation in volume and frequency in mannequins. But no clinical study has analyzed insufflator bag ventilation maneuvers in real-life situations on pre-hospital cardiac arrest patients.

The aim of this study is to analyze ventilation parameters in current practice in relation to standards, and the factors influencing the quality of ventilation maneuvers.

Inclusion Criteria:

• Out of hospital cardiac arrest with CPR performed by the Firefighters
• Age 18 and over
• BLS team on site before arrival of physician staffed ALS means
• CPR ventilation initially provided with Bag-valve- mask
• Measuring device records ventilatory parameters

Exclusion Criteria:

• trauma related OHCA
• airway obstruction during CPR
• OHCA on hanging
• tracheostomized patient
• obstacle to using the Bag-valve-mask
• CPR time less than 2 minutes

Civilian population in hyperurban areas