Critical illness related cardiac arrest: Protocol for an investigation of the incidence and outcome of cardiac arrest within intensive care units in the United Kingdom

Introduction

Cardiac arrest is often categorised by the location of the event, as there are important differences in population characteristics, aetiology and outcome.^1–3 Within a hospital, cardiac arrest is usually not further categorised, yet there may be clinically relevant differences between patients treated by different specialities or in locations with varying levels of patient monitoring available. ³ Critical Illness Related Cardiac Arrest (CIRCA) as a distinct entity is not well described epidemiologically. There is currently a knowledge gap regarding how many occur in critical care units in the UK, or the impact of CIRCA on patient outcome.

Study type

The CIRCA study is a prospective observational cohort study in adult general critical care units participating in the Case Mix Programme and based in hospitals that participate in the National Cardiac Arrest Audit.

Inclusion and exclusion criteria

Inclusion

1. Age 18 years old or more; and either

2. Cardiac arrest (defined as receipt of chest compressions or defibrillation) occurring while in-hospital and within critical care (defined as either intensive care unit (ICU) providing level 3 care, HDU providing level 2 care or combined ICU/HDU); or

3. Family member of a patient surviving to discharge from intensive care after a cardiac arrest within critical care. A family member is defined as a person with a close familial, social or emotional relationship to the patient and is not restricted solely to next-of-kin.

Exclusion

None.

Objectives

Primary objective: incidence of CIRCA (defined as cardiac arrest while in the critical care unit) in adults in England and Wales

Secondary objectives: outcomes for CIRCA; risk factors for CIRCA; determining what risk factors are associated with outcomes (ICU and hospital survival and quality of survival) in patients experiencing CIRCA; quality of life for life for patients after CIRCA at 90 days, 180 days and 12 months; quality of life for family members of patients surviving CIRCA at 90 days, 180 days and 12 months.

Target study size

The best current estimate of UK incidence (based on systematic review and a single UK unit) is 5446 to 7329 cardiac arrests occur in 4066 to 5472 patients in critical care annually. Based on this estimate, we intend to recruit from 100 units for 12 months, giving us an anticipated number of cardiac arrest events of 1320–2200 among 986 to 1643 patients from a total of around 75,000 admissions.