• Klaus U Klein, Amelie Johannes, Melanie Brückner, Rainer Thomas, Stephan Matthews, Katrin Frauenknecht, Petra Leukel, Johanna Mazur, Alicia Poplawski, Ralf Muellenbach, Clemens J Sommer, Serge C Thal, and Kristin Engelhard.
• 1Department of Anaesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany. 2Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria. 3Department of Anaesthesia and Critical Care, University Hospitals, Wuerzburg, Germany. 4Institute of Neuropathology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany. 5Core Facility Bioinformatics, Division Biostatistics and Bioinformatics, Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany. 6Division Biostatistics and Bioinformatics, Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
• Crit. Care Med. 2016 May 1; 44 (5): e253-63.

ObjectiveSystemic PaO2 oscillations occur during cyclic recruitment and derecruitment of atelectasis in acute respiratory failure and might harm brain tissue integrity.DesignControlled animal study.SettingUniversity research laboratory.SubjectsAdult anesthetized pigs.InterventionsPigs were randomized to a control group (anesthesia and extracorporeal circulation for 20 hr with constant PaO2, n = 10) or an oscillation group (anesthesia and extracorporeal circulation for 20 hr with artificial PaO2 oscillations [3 cycles min⁻¹], n = 10). Five additional animals served as native group (n = 5).Measurements And Main ResultsOutcome following exposure to artificial PaO2 oscillations compared with constant PaO2 levels was measured using 1) immunohistochemistry, 2) real-time polymerase chain reaction for inflammatory markers, 3) receptor autoradiography, and 4) transcriptome analysis in the hippocampus. Our study shows that PaO2 oscillations are transmitted to brain tissue as detected by novel ultrarapid oxygen sensing technology. PaO2 oscillations cause significant decrease in NISSL-stained neurons (p < 0.05) and induce inflammation (p < 0.05) in the hippocampus and a shift of the balance of hippocampal neurotransmitter receptor densities toward inhibition (p < 0.05). A pathway analysis suggests that cerebral immune and acute-phase response may play a role in mediating PaO2 oscillation-induced brain injury.ConclusionsArtificial PaO2 oscillations cause mild brain injury mediated by inflammatory pathways. Although artificial PaO2 oscillations and endogenous PaO2 oscillations in lung-diseased patients have different origins, it is likely that they share the same noxious effect on the brain. Therefore, PaO2 oscillations might represent a newly detected pathway potentially contributing to the crosstalk between acute lung and remote brain injury.

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