Apnea testing is the final decisive examination in the strictly regulated process of brain death assessment. There is no standardized method found in the literature for apnea testing except for the inspection of possible spontaneous chest movements. In addition, the test itself lasts for several minutes leading to the collapse of the lungs.

Electrical impedance tomography (EIT) is a non-invasive, real-time monitoring technique, which is suitable for detecting changes in lung volumes during ventilation. With its help, one can examine the spontaneous initiation of inspiration, the development of atelectasis and the reopening of collapsed regions by mechanical ventilation.

Furthermore, the apnea test provides for analysing the effect of changes in pulmonary perfusion on impedance in the absence of noise generated by ventilation.

The aim of the study is to assess the eligibility of electrical impedance monitoring for the detection of possible spontaneous initiations of inspiration during apnea test in patients with suspected brain death. The study could contribute to the opening of new areas in the clinical use of the electrical impedance device. An additional aim is to observe the collapse and the reopening by recruitment manoeuvers of different pulmonary regions.

Inclusion Criteria:

• Patients with suspected brain death undergoing apnea test for detecting the absence of spontaneous breathing

Exclusion Criteria:

• age under 18
• pregnancy
• pulmonectomy, lung resection in the past medical history
• clinically end stage chronic obstructive pulmonary disease (COPD)
• severe hemodynamic instability (vasopressor refractory shock)
• severe bullous emphysema and/or spontaneous pneumothorax in the past medical history
• chest drainage in situ due to pneumothorax and/or bronchopleural fistula