Open Access Highly Accessed Study protocol

Cognitive function after cardiac arrest and temperature management; rationale and description of a sub-study in the Target Temperature Management trial

Gisela Lilja12*, Niklas Nielsen13, Hans Friberg14, Janneke Horn5, Jesper Kjaergaard6, Tommaso Pellis7, Malin Rundgren14, Jørn Wetterslev8, Matt P Wise9, Fredrik Nilsson10 and Tobias Cronberg111

Author Affiliations

1 Department of Clinical Sciences, Lund University, Lund, Sweden

2 Department of Rehabilitation Medicine, Skåne University Hospital, Lund, Sweden

3 Department of Anesthesia and Intensive Care, Helsingborg Hospital, Helsingborg, Sweden

4 Department of Anesthesia and Intensive Care, Skåne University Hospital, Lund, Sweden

5 Department of Intensive Care, Academic Medical Centre, Amsterdam, The Netherlands

6 Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark

7 Intensive Care Unit, Santa Maria degli Angeli, Pordenone, Italy

8 Copenhagen Trial Unit, Centre of Clinical Intervention Research, Copenhagen University Hospital, Copenhagen, Denmark

9 Adult Critical Care, University Hospital of Wales, Cardiff, United Kingdom

10 Research and Development centre, Unit for Medical Statistics and Epidemiology, Skåne University Hospital, Lund, Sweden

11 Department of Neurology, Skåne University Hospital, Lund, Sweden

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BMC Cardiovascular Disorders 2013, 13:85  doi:10.1186/1471-2261-13-85

Published: 12 October 2013



Mild to moderate cognitive impairment is common amongst long-term survivors of cardiac arrest. In the Target Temperature Management trial (TTM-trial) comatose survivors were randomized to 33°C or 36°C temperature control for 24 hours after cardiac arrest and the effects on survival and neurological outcome assessed. This protocol describes a sub-study of the TTM-trial investigating cognitive dysfunction and its consequences for patients’ and relatives’ daily life.


Sub-study sites in five European countries included surviving TTM patients 180 days after cardiac arrest. In addition to the instruments for neurological function used in the main trial, sub-study patients were specifically tested for difficulties with memory (Rivermead Behavioural Memory Test), attention (Symbol Digit Modalities Test) and executive function (Frontal Assessment Battery). Cognitive impairments will be related to the patients’ degree of participation in society (Mayo-Portland Adaptability Inventory-4), health related quality of life (Short Form Questionnaire–36v2©), and the caregivers’ situation (Zarit Burden Interview©). The two intervention groups (33°C and 36°C) will be compared with a group of myocardial infarction controls.


This large international sub-study of a randomized controlled trial will focus on mild to moderate cognitive impairment and its consequences for cardiac arrest survivors and their caregivers. By using an additional battery of tests we may be able to detect more subtle differences in cognitive function between the two intervention groups than identified in the main study. The results of the study could be used to develop a relevant screening model for cognitive dysfunction after cardiac arrest.

Trial registration NCT01946932.

Out-of-hospital cardiac arrest; Hypothermia, induced; Resuscitation; Cardiovascular diseases; Brain injuries; Cognition; Memory; Quality of life; Social participation; Caregivers