Background Extracorporeal cardiopulmonary resuscitation (eCPR) is a rescue therapy for a selected group of patients. Extracorporeal membrane oxygenation (ECMO) is initiated to bypass the cardiac system and bridge time to definitive treatment of the cardiac arrest (CA) origin. eCPR treatment is very time-critical and, if indicated, should be initiated as early as possible. Patient selection for this highly specific treatment is challenging and relies on numerous factors. In the following phase of intensive care treatment, neuroprognostication is performed. However, following current guidelines, this is only recommended 72hours after CA. Once ECMO is initiated, a complex intensive care treatment is expected, without a guarantee for full neurological recovery. There is a recognized clinical need for more precise selection criteria, alongside predictive values, to enable earlier, reliable neuroprognostication.

Aim This study aims to investigate whether super-early neuroprognostication before ECMO initiation is feasible. Super-early neuroprognostication will be performed using automated pupillometry and cerebral near-infrared spectroscopy (cNIRS) before ECMO initiation.

Methods Patients evaluated for eCPR treatment at the Department of Emergency Medicine will be included in this study. By a study member not involved in clinical treatment, cNIRS and automated pupillometry will be performed before ECMO initiation and at predefined intervals: 10-20 minutes after ECMO Initiation, 1 hour (±15 minutes), 2 hours (±15 minutes), and 3 hours (±15 minutes). Follow-up measurements will be taken 24 hours (± 6 hours), 48 hours (± 6 hours), and 72 hours ± 6 hours after ECMO initiation. The secondary objective is to interpret the collected data regarding outcome parameters.

Inclusion Criteria:

• All patients ≥ 18 years evaluated for eCPR treatment at the Department of Emergency Medicine

Exclusion Criteria:

• Return of spontaneous circulation before ECMO initiation.
• Anatomical infeasibility for measurement, including but not limited to:
• Severe facial trauma or deformity preventing the placement of the automated pupillometry device.
• Scalp injuries, dressings, or conditions that interfere with the correct positioning of near-infrared spectroscopy (NIRS) sensors.
• Pre-existing ocular conditions that preclude reliable pupillometry (e.g., enucleation, opaque cornea, or severe anisocoria unrelated to neurological status).

All patients ≥ 18 years evaluated for eCPR treatment at the Department of Emergency Medicine.