• Olaf Hoffmann, Hannah Tempel, Stefan Wolf, Alexander Gratopp, and Farid Salih.
• Alexianer St. Josefs-Krankenhaus Potsdam, Dept. of Neurology, Allee nach Sanssouci 7, 14471 Potsdam, Germany; Charité-Universitätsmedizin Berlin, NeuroCure Clinical Research Center, Charitéplatz 1, 10117 Berlin, Germany; Medizinische Hochschule Brandenburg Theodor Fontane, Fehrbelliner Str. 38, 16816 Neuruppin, Germany.
• J Crit Care. 2022 Oct 1; 71: 154091.

PurposeWe investigated cerebral perfusion pressure (CPP) at the time loss of cerebral blood flow (CBF) occurred during brain death (BD). We hypothesized that a critical closing pressure (CrCP) may be reached before CPP drops to 0 mmHg.Materials And Methods14 patients with increasing intracranial pressure (ICP) leading to BD were included. Transcranial Duplex (TCD) ultrasonography was used to investigate CBF. Starting at a CPP of 30 mmHg, TCD was repeated until waveforms indicated loss of CBF. We then analyzed CPP by the time TCD indicated absent CBF and clinical BD was established.ResultsIn 12 patients, CPP was positive when clinical BD was manifest and TCD illustrated absent CBF. Across all patients, mean CPP at clinical BD manifestation was 10.0 mmHg (range 0-20 mmHg); mean CPP by the time CBF stopped was 7.5 mmHg (0-20 mmHg). In four patients, clinical BD preceded loss of CBF. Here, the mean CPP difference from clinical BD to loss of CBF was 8.8 mmHg (5-15 mmHg).ConclusionsCrCP may be reached although CPP is still positive, resulting in complete loss of CBF and BD. By including bedside TCD, neuromonitoring may contribute to early identification of patients at risk to experience loss of CBF and subsequent BD.Copyright © 2022 Elsevier Inc. All rights reserved.

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