Impact of Altered Airway Pressure on Intracranial Pressure, Perfusion, and Oxygenation: A Narrative Review

Objectives: A narrative review of the pathophysiology linking altered airway pressure and intracranial pressure and cerebral oxygenation. Data Sources: Online search of PubMed and manual review of articles (laboratory and patient studies) of the altered airway pressure on intracranial pressure, cerebral perfusion, or cerebral oxygenation. Study Selection: Randomized trials, observational and physiologic studies. Data Extraction: Our group determined by consensus which resources would best inform this review. Data Synthesis: In the normal brain, positive-pressure ventilation does not significantly alter intracranial pressure, cerebral oxygenation, or perfusion. In injured brains, the impact of airway pressure on intracranial pressure is variable and determined by several factors; a cerebral venous Starling resistor explains much of the variability. Negative-pressure ventilation can improve cerebral perfusion and oxygenation and reduce intracranial pressure in experimental models, but data are limited, and mechanisms and clinical benefit remain uncertain. Conclusions: The effects of airway pressure and ventilation on cerebral perfusion and oxygenation are increasingly understood, especially in the setting of brain injury. In the face of competing mechanisms and priorities, multimodal monitoring and individualized titration will increasingly be required to optimize care. Drs. Chen, Menon, and Kavanagh helped with conception and design, and drafting the article for important intellectual content. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's website (https://ift.tt/29S62lw). Supported, in part, by research funds (to Dr. Kavanagh) from the Canadian Institutes of Health Research. Dr. Chen is supported by National Natural Science Foundation of China (Grant Number: 81701942). Dr. Menon received support for article research from National Institute for Health Research, United Kingdom. He is a Professorial Fellow, Queens' College, Cambridge, United Kingdom, and a Senior Investigator, National Institute for Health Research, United Kingdom. Dr. Kavanagh disclosed that he has a patent pending for a device for mechanical ventilation. He holds the Dr Geoffrey Barker Chair in Critical Care Research. For information regarding this article, E-mail: brian.kavanagh@utoronto.ca Copyright © by 2018 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.

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