Airway control and ventilation is vital during cardiopulmonary resuscitation (CPR) in cardiac arrest. Endotracheal intubation is the gold standard for airway control, but several studies have shown high rates of unrecognized placements of the tube in the esophagus instead of in the airway out-of-hospital. This is lethal. There are no failproof technique for recognising such mistakes clinically in the cardiac arrest situation. Changes on the air volume in the lungs with ventilation changes the impedance (resistance to alternating current) through the thorax. This impedance is already measured routinely by the defibrillators used during CPR. We propose that we can measure ventilation volumes and also discover failed intubations by monitoring this impedance during CPR with the possibility of giving feedback on both to the rescuers.

On the anesthesiologist manned ambulance in Oslo ventilation volumes during CPR will be controlled with a ventilator, the tidal volume varied in random order between 500, 700 and 100 ml, and the volumes be measured continuously as will the impedance between the defibrillator electrodes. In case of failed CPR, the patient will be declared dead. Thereafter the lungs will be ventilated with 700 ml followed by removal of the endotracheal tube, placement of an endotracheal tube in the esophagus and ventilation of this tube, again with monitoring of the impedance.

Inclusion Criteria:

• Cardiac arrest

Exclusion Criteria:

• <18 years old trauma pregnancy