Head Computed Tomography for Predicting Neurological Outcome After Cardiac Arrest

Head Computed Tomography for Predicting Neurological Outcome After Cardiac Arrest- a TTM-2 Substudy

The European Resuscitation Council (ERC) and the European Society of Intensive Care Medicine (ESICM) joint guidelines for post-resuscitation care recommend a multimodal approach to prognostication of neurological outcome.

However, head computed tomography (CT) which is commonly used for predicting long-term neurological outcome after cardiac arrest has not yet been examined prospectively in a clinical trial.

The primary purpose of the TTM-2 CT-substudy is to prospectively investigate and compare various methods of diagnosing generalized oedema on CT after cardiac arrest and it´s ability to predict long-term neurological outcome.

This study is a sub-study to the international multicenter Targeted Hypothermia Versus Targeted Normothermia After Out-of-hospital Cardiac Arrest (TTM-2) Trial (ClinicalTrials.gov Identifier: NCT02908308).

All patients from participating centers still unconscious 48 hours after cardiac arrest will be routinely examined with CT. All other inclusion and exclusion criteria as well as treatment, neurological prognostication, withdrawal of life-sustaining therapy or follow-up will be handled according to TTM-2- protocol. Ethical approval for the main trial and this sub-study have been obtained from the Swedish Ethical Review Authority at Lund University (2015/228 and 2017/36). Both a patients´ next of kind or conscious patients have the opportunity to withdraw patients from the trial.

Pseudonymized original CT images will be uploaded to a two-way secured digital platform from Lund University (LUSEC). Two study radiologists blinded from clinical data will perform analyses according to protocol. Various methods of diagnosing generalized oedema will be investigated including eye-balling (oedema "yes"/"no"), as well as manual and automated measurements of the differentiation between the grey and white matter (GWR) by placing circular regions of interest (ROI). Primary outcome is the neurological outcome at 6 months after cardiac arrest using the modified Rankin Scale (mRS).

Secondary outcomes include neurocognitive outcomes such as the Glasgow Outcome Score-Extended version (GOS-E), Symbol-Digit-Modalities-Test (SDMT) and the Montreal Cognitive Assessment Score (MoCA).

The results of the radiological evaluations will also be correlated with other markers of neuronal injury such as biomarkers, clinical neurological information or neurophysiological examinations.

Additional analyses include evaluation of all available CT images of participating patients to investigate if there is any progression or regression of cerebral oedema.

Inclusion Criteria:

• Out-of-hospital cardiac arrest
• Presumed cardiac cause of cardiac arrest
• Unconscious with a FOUR-score <M4 (not obeying verbal commands)
• Stable return of spontaneous circulation (20 min)
• Eligible for intensive care treatment without restrictions
• Inclusion within 180 minutes of ROSC
• Patient from participating centers, where head CT is routinely performed on all patients still unconscious 48 hours after cardiac arrest

Exclusion Criteria:

• Unwitnessed cardiac arrest with an initial rhythm of asystole
• Temperature on admission <30°C.
• Obvious or suspected pregnancy
• Intracranial bleeding
• On ECMO prior to ROSC
• Severe chronic obstructive pulmonary disorder (COPD) with long-term home oxygen therapy
• Patients from centers not participating in the TTM-2 CT-substudy
• Patients from participating centers not examined with head CT