The goal of this retrospective observational cohort study is to evaluate whether the progressive implementation of updated post-cardiac arrest care guidelines has improved survival and neurological recovery in adult patients admitted to the intensive care unit (ICU) after successful resuscitation from cardiac arrest.

Cardiac arrest is one of the leading causes of death worldwide. More than half of patients successfully resuscitated from cardiac arrest die before hospital discharge, largely due to a complex condition known as Post-Cardiac Arrest Syndrome (PCAS), which affects the brain, heart, and all major organ systems. Over the past decade, the European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) have published updated post-resuscitation care guidelines in 2010, 2015, and 2021, introducing progressively refined treatment recommendations. However, no study has yet evaluated whether the local adoption of these evolving guidelines has translated into measurable improvements in patient outcomes over time.

The main questions this study aims to answer are:

• Has survival to ICU discharge improved across three successive guideline periods (2010, 2015, and 2021) in adult cardiac arrest patients admitted to the ICU?
• Has neurological recovery at ICU and hospital discharge improved across the three guideline cohorts?
• What is the local level of adherence to each set of guideline recommendations, and how does it relate to patient outcomes?
• What is the impact of individual new interventions introduced by each guideline update on survival and organ function?
• Do outcomes differ based on whether the cardiac arrest occurred outside or inside the hospital, or based on its underlying cause (cardiac, respiratory, metabolic, toxicological, or traumatic)?

Researchers will compare three patient cohorts defined by the guideline period active at the time of ICU admission - Cohort A (January 2011-December 2015, treated according to 2010 guidelines), Cohort B (January 2016-March 2021, treated according to 2015 guidelines), and Cohort C (April 2021-April 2024, treated according to 2021 guidelines) - to determine whether progressive guideline implementation is associated with improved survival and neurological outcomes over time. Cohort A serves as the reference group.

Participants in this study are adult patients (aged 18 years or older) who experienced cardiac arrest of any cause - whether in or out of hospital - were successfully resuscitated, and were subsequently admitted to ICU at the S. Chiara Hospital in Trento, Italy. Data are collected retrospectively from digitized medical records and cover clinical characteristics, cardiac arrest details, ICU treatments, laboratory and imaging findings, and patient outcomes including survival, length of stay, ventilator-free days, and neurological status at discharge (assessed using the Cerebral Performance Category scale). No interventions are performed as part of this study. Patient data are fully anonymized prior to analysis.

INCLUSION CRITERIA:

• Resuscitated from cardiac arrest and subsequently admitted to the intensive care unit (ICU)
• Age ≥18 years at the time of ICU admission
• Out-of-hospital or in-hospital cardiac arrest
• Cardiac arrest of any etiology, including cardiac, respiratory, metabolic, toxicological, and traumatic causes

Exclusion Criteria:

• Age <18 years at the time of ICU admission (pediatric patients)
• Not admitted to ICU

Patients will be selected from the clinical records of the General Intensive Care Unit (ICU1) of S. Chiara Hospital, Trento, Italy, the main teaching hospital of the Azienda Sanitaria Universitaria Integrata del Trentino (ASUIT). S. Chiara Hospital serves as the primary referral center for critical care in the Trentino region and operates in close collaboration with Trentino Emergenza, the regional emergency medical service. Data will be retrieved from the hospital's digitized clinical records system, which is validated on an hourly basis by ward clinical staff, ensuring high data quality and completeness. The study covers a 14-year period (January 2011- December 2024), spanning three successive ERC-ESICM guideline eras. All data will be anonymized.

Data protection regulations and institutional policies limit the dissemination of individual-level data. Therefore, only aggregated results will be made publicly available.