With ethical approvement, the investigators want to assess the incidence, circumstances and outcomes of patients with perioperative cardiac arrests over a period of 8 years.

Currently, there is little data and information about a cardiovascular arrests during anesthesia. Little is also known about the health-related quality of life afterwards. In the investigators research project, the investigators want to find out if there are, for example, specific factors that cause cardiovascular arrests and factors that can improve the chances of survival after a cardiovascular arrest. The investigators are also looking for possible factors and measurements that can minimize or even prevent future events during anesthesia.

A perioperative cardiac arrest is a special form of in-hospital cardiac arrest. It was claimed that perioperative cardiac arrests are under-investigated. The spare existing data suggest incidences of perioperative cardiac arrest to be between 0.5 - 3 per 10.000 for adult patients and 2 - 10 per 10.000 for paediatric patients. Data on circumstances, predictors and outcomes of perioperative cardiac arrest are rare, especially for paediatric patients. Some reports suggest that incidence is negatively associated with a country's higher development. As no Swiss data is available on this topic, this retrospective audit aims to bridge the knowledge gap and finally intends to make clinicians aware of potential risks or contributing factors of survival, which might raise safety for all patients undergoing procedures under anaesthesia.

The investigators will include all patients of all ages with a perioperative cardiac arrest at Bern University Hospital from 1st January 2015 until 31st December 2021 (7 year observational period).

Inclusion Criteria is a perioperative cardiac arrest between 1st January 2015 and 31st December 2021 at Bern University Hospital.

A perioperative cardiac arrest is defined as:

• ≥5 chest compressions (direct, mechanical or extracorporeal Cardiopulmonary Resuscitation (CPR))
• and/or defibrillation (unsynchronised direct current (DC) shock for ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) either - external or internal defibrillation with manual or Automated External Defibrillation (AED), shocks by implanted cardioverter defibrillators (ICDs) for VF/pVT, precordial thump)
• In a patient having a procedure under the care of an anaesthesia team (nurse or anaesthesiologist) at the Bern University Hospital: General anaesthesia, regional anaesthesia/ analgesia, sedation, local anaesthesia or monitored anaesthesia care
• Regional block performed by anaesthesiologist outside of operating room
• Obstetric analgesia including remifentanil patient-controlled analgesia (PCA).

Exclusion Criteria:

• A perioperative cardiac arrest before 1st January 2015 or after 31st December 2021
• <5 chest compressions (direct, mechanical or extracorporeal Cardiopulmonary Resuscitation (CPR))
• All in-hospital cardiac arrests, that occur without being under anaesthesia care
• Patients already admitted to a hospital with a cardiac arrest (out-of hospital cardiac arrests)

The investigators will include all patients of all ages with a perioperative cardiac arrest at Bern University Hospital from 1st January 2015 until 31st December 2021.