Incidence of non-hospital cardio-respiratory arrest (ACR) in France is around 40 000 cases per year, with mortality remaining very high, with 75% of patients dying before arrival in hospital. The investigators know some validated predictive factors for recovery of spontaneous cardiac activity (RACS) such as age, no flow (time between ACR and onset of CPR), type of initial electrical activity (FV, TVSP), or the value of CO2 expired.

However, the use of these prognostic criteria in the conduct of CPR maneuvering is in practice limited. Lactate is now a well-known prognostic biological marker used in many pathological conditions such as shock states or the severe traumatized patient. Some data have also demonstrated the prognostic value of lactate on morbidity and mortality after ACR after resumption of spontaneous cardiac activity.

The hypothesis of our study is that the evaluation of the initial lactate in the early cardiopulmonary resuscitation could be a prognostic factor of RACS.

Incidence of non-hospital cardio-respiratory arrest (ACR) in France is around 40 000 cases per year, with mortality remaining very high, with 75% of patients dying before arrival in hospital. This disease is associated with a high morbidity since today the investigator find less than 5% survival at 1 year with a favorable neurological outcome.

The recommendations of ILCOR 2015 underline in this case the importance of implementing therapeutic measures in the extra-hospital step. Indeed, the survival of ACR patients will depend mainly on the alert delay at the UAS center, the immediate implementation of cardiopulmonary resuscitation (CPR) maneuvers and the early delivery of external electric shock.

The investigators know some validated predictive factors for recovery of spontaneous cardiac activity (RACS) such as age, no flow (time between ACR and onset of CPR), type of initial electrical activity (FV, TVSP), or the value of CO2 expired.

However, the use of these prognostic criteria in the conduct of CPR maneuvering is in practice limited.

Today, none of these prognostic factors allow us to adapt the cardiopulmonary resuscitation maneuvers to the different clinical situations, and it is recognized that a CPR must be carried out for 30 minutes in all cases.

On the basis of these data, it seemed important to investigate other predictive factors for RACS, which would remain simple to implement, and allow case-by-case customization the cardiopulmonary resuscitation.

Lactate is now a well-known prognostic biological marker used in many pathological conditions such as shock states or the severe traumatized patient. Some data have also demonstrated the prognostic value of lactate on morbidity and mortality after ACR after resumption of spontaneous cardiac activity. Unfortunately, all of these studies were carried out intra-hospital. To date, no prospective study has demonstrated the prognostic value of a lactate assay as soon as the pre-hospital medical team arrives and during pre-hospital cardiopulmonary resuscitation.

An experimental study published in the American Journal of Emergency Medicine in 1985, however, suggests that early evaluation of lactate in the course of cardiac arrest may be a valuable prognostic factor. Indeed, in this study on canine cardiac arrest experimental model, Donna et al found that the lactate concentration would reliably predict the no-flow describing an linear increase of lactate as a function of the no-flow duration. If these results can be extrapolated to humans, lactate measurement from the arrival of the pre-hospital medical team could provide an estimate of the no-flow period and therefore a reliable and easily reproducible predictive factor for RACS .

In addition, improvements in biomedical equipment allow us to perform lactate assays directly at the patient's bedside, with reliable results in just 13 seconds.

The hypothesis of our study is that the evaluation of the initial lactate in the early cardiopulmonary resuscitation could be a prognostic factor of RACS.

For this purpose, the investigators propose to carry out a prospective, open, multicenter intervention study in different SMURs in the PACA region, in France.

Inclusion Criteria:

• Male >18 years of age
• Women over 50 years of age (ie, with amenorrhea> 1 year).
• Victim of non-traumatic cardiopulmonary arrest.
• Medical decision to start or continue cardiopulmonary resuscitation.
• Consent of family or person of trust if present (and patient as soon as possible).
• patient affiliated to the social security

Exclusion Criteria:

• Refusal of family or trusted person to participate in the study
• Pre-paramedical management with use of adrenaline and protection of the airways
• Use of the intraosseous line from the outset or after failure of the peripheral venous pathway by the medical team outside hospital
• Minor Patient
• vulnerable patient under legal protection (guardianship or curators)