The main goal of this observational study is the evaluation of Chest Compression Synchronized Ventilation (CCSV) regarding oxygenation in terms of PaO2 assessed by routine blood gas analysis, hemodynamic effects, 30-day outcome and safety in comparison to Intermittent Positive Pressure Ventilation (IPPV) as data in humans is sparse especially in direct comparison to other ventilation modes.

Cardiac arrest patients in Vienna, Austria will be preclinically randomized (IPPV and CCSV) and ventilated accordingly during CPR. Differences in oxygenation, decarboxylation, systemic perfusion and cerebral oxygenation, the patient's 30-day outcome as well as ventilator-associated adverse events (e.g., pneumothorax) will be recorded and analyzed.

Inclusion Criteria:

• OHCA
• Correct endotracheal intubation (seen by capnography)
• The patient is being treated by the Vienna Emergency Medical Services within the scope of emergency ventilation.
• MEDUMAT Standard from Weinmann Emergency is used.
• Mechanical ventilation is performed according to the specified indications.

Exclusion Criteria:

• Patients eligible for eCPR (as defined by the standard operating procedure of the Emergency Medical Service Vienna)
• Patients recovering (reaching sustained ROSC) before starting mechanical ventilation or in the first three minutes of it
• Any other mechanical ventilation during the ongoing CPR before study inclusion
• Traumatic cardiac arrest
• Suspected or known pregnancy
• Clinically suspected (tension-)pneumothorax

Adult out-of-hospital cardiac arrest patients in Vienna