Abstract
BackgroundMild 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.Methods/DesignSub-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.DiscussionThis 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 registrationClinicalTrials.gov: NCT01946932.
Highlights
Mild to moderate cognitive impairment is common amongst long-term survivors of cardiac arrest
The brain is susceptible to circulatory arrest and hypoxic-ischemic brain injury accounts for approximately 70% of the in-hospital mortality of cardiac arrest (CA) patients admitted to intensive care [2]
Cognitive impairment measured by the three tests: Rivermead Behavioural Memory Test (RBMT), Frontal Assessment Battery (FAB) and Symbol Digit Modalities Test (SDMT) will be correlated to participation in society (MPAI-4/return to work), health related quality of life (HRQoL) for patients and caregivers (SF-36v2©), and caregivers feeling of burden (ZBI©)
Summary
Global brain injury and cognitive dysfunction are well described consequences of cardiac arrest but the prevalence of impairment and the consequences for patients and their relatives have never before been described in a large international cohort. More subtle neuroprotective effects of systemic cooling may be revealed This sub-study is an extension of the follow-up platform that we use in the TTM-main trial. Patients with myocardial infarction were found to lack significant long-term memory impairments [6,53,54], but to have a similar pattern of HRQoL as patients having suffered cardiac arrest [55] They share the same cardiovascular risk factors and risk of mood disturbances due to acute hospitalization, which makes them a relevant population to study as controls. The simple cognitive screening model used in the TTM trial is easy to apply in any clinical setting and with minimal resource utilization The results from this sub-study could be used to evaluate whether the suggested screening model is able to identify patients at risk. GL and TC drafted the manuscript that was read, revised and approved by all co-authors
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