Cognitive function after cardiac arest and targeted temperature management

University dissertation from Neurology, Lund

Abstract: This thesis focuses on cognitive impairment in Out-of-Hospital Cardiac Arrest (OHCA) survivors with the main aim to evaluate possible effects by targeted temperature management. Secondary aims are to describe the prevalence of cognitive impairment in a large group of OHCA-survivors, the related symptoms of psychological distress and the actual effect of cognitive impairment for the patient’s ability to participate in everyday life and in the society (as work). Methods: In an international trial, OHCA-patients, unconscious after resuscitation, were randomized to 33°C or 36°C controlled temperature. Survivors were invited to a face-to-face follow-up 180 days post-arrest that included screening of cognitive impairment (MiniMental Status Examination), questionnaires of cognitive performance in everyday life (Two Simple Questions, Informant Questionnaire on Cognitive Decline) and Health Related Quality of Life (HRQoL) (Short Form Questionniare-36 version2®). An extended follow-up was performed at 20 sites in five countries and included assessments of memory (Rivermead Behavioural Memory Test), executive functions (Frontal Assessment Battery), attention/processing speed (Symbol Digit Modalities Test), psychological distress (Hospital Anxiety and Depression Scale) and participation (Mayo-Portland Adaptability Inventory-4). A matched control group of ST-elevation myocardial infarction (STEMI) patients performed the same follow-up. Results: OHCA-survivors (n=287) had overall good outcome and HRQoL, but half reported a decreased participation in everyday life and society. In addition, many informants (62%) and patients (36%) reported cognitive problems, and 27% of survivors reported psychological distress. By objective assessments cognitive impairment was found in >50% of the survivors, and OHCA-survivors with cognitive impairment had an increased risk of being on sick leave. Cognitive impairment, depression, fatigue, and mobility restrictions were found important for participation in everyday life and in the society There were no differences in any of these outcomes between the two temperature groups (33°C and 36°C). Cognitive impairment and psychological distress was common also among STEMI-controls (n=119), but OHCA-survivors had significantly more problems with attention/processing speed, return to work and participation compared to STEMI-controls. Conclusion. The two groups of TTM at 33°C and 36°C were similar also when brain injury is assessed in detail indicating no difference in outcome. Cognitive impairment was common in OHCA-survivors but STEMI-controls shared many of the symptoms and that impairment after OHCA needs to be seen in a greater context of risk factors including OHCA-related brain injury, cardiovascular co-morbidity, and critical illness related stressors. OHCAsurvivors had lower participation in everyday life compared to STEMI-controls. A structured follow-up to identify OHCA-survivors in risk for long-term consequences is recommended. Cognitive impairment, fatigue, mobility restrictions and depression deserve increased attention during such follow-up.