A protocol for recording cardiopulmonary arrest (CRP) data in the in-hospital surgical block has been designed with the Utstein template model. The database is hosted in accordance with European legislation on patient data protection.

Invitation to participate will be sent to Spanish hospitals in the first phase. Once this is over, participation in the registry will be opened to European hospitals. Survival and neurological outcome will be evaluated upon discharge from the surgical block. The study design is a prospective observational registry of a cohort of subjects who have suffered a CRP in the surgical block.

Patients will be enrolled by participating researchers from Spanish hospitals that have a pediatric surgery service, in addition to surgery on adult patients, who will collect and upload the data into a protected web-based electronic database. The recorded variables are grouped as follows: patient variables, hospital data, data prior to cardiopulmonary arrest (CRP), data from cardiopulmonary arrest (CRP), data after cardiopulmonary resuscitation (CPR), results of cardiopulmonary resuscitation (CPR). For the study, cardiorespiratory arrest (CRP) is defined as cardiac arrest for which resuscitation is attempted with chest compressions, defibrillation, or both. In the pediatric population it may include patients receiving chest compressions for poor perfusion in the setting of severe bradycardia.

The inclusion criteria are: all patients older than 1 month who undergo sedation, anesthesia or monitored anesthetic surveillance performed by an anesthesiologist and suffer cardiorespiratory arrest in the surgical block. Subsequent episodes of cardiorespiratory arrest (CRP) in the same subject may be included. Exclusion criteria: hospitals that do not have a pediatric surgery service in their service portfolio, patients being treated with extracorporeal circulatory support (ECMO, extracorporeal circulation pump or ventricular assistance) at the time of cardiorespiratory arrest. Patients who suffer cardiac arrest and require any type of extracorporeal circulatory support for the recovery of spontaneous circulation after performing the corresponding cardiopulmonary resuscitation (CPR) will not be eliminated.

The data collection period will be valid for 48 months, starting on June 1, 2025 and the last day being June 1, 2029.

Inclusion Criteria:Patients over 1 month of age who suffer cardiac arrest in the surgical unit and/or in those places where some type of monitored surveillance technique, sedation and/or anesthesia is performed by an anesthesiologist or internal resident specialist (EIR) of the specialty of Anesthesiology.

Exclusion Criteria:

• Patients with procedures defined as major outpatient surgery in the hospital where the cardiac arrest occurs.
• Patients in supportive treatment extracorporeal circulatory system (ECMO) or ventricular assist at the time of cardiac arrest.

All patients over 1 month of age who suffer cardiac arrest in the surgical block (BQ). Cardiac arrest is defined by the application of chest compressions and/or defibrillation. In the pediatric population it may include patients receiving chest compressions for poor perfusion in the setting of severe bradycardia.

We define BQ as "the space in which all the operating rooms are grouped, with the equipment and characteristics necessary to carry out all the planned surgical procedures. The BQ includes the premises where the care process of the surgical procedure takes place (operating room and post-anesthesia recovery unit) and the support premises it requires. In these locations we include the pre-operating room where patients wait, within the surgical block, to enter the operating room.

Data collected in the Utstein template can be shared with other SEDAR researchers. The data will be encrypted.