title: Microcirculatory dysfunction and tissue oxygenation in critical illness.
abstract: Severe sepsis is defined by organ failure, often of the kidneys, heart, and brain. It has been proposed that inadequate delivery of oxygen, or insufficient extraction of oxygen in tissue, may explain organ failure. Despite adequate maintenance of systemic oxygen delivery in septic patients, their morbidity and mortality remain high. The assumption that tissue oxygenation can be preserved by maintaining its blood supply follows from physiological models that only apply to tissue with uniformly perfused capillaries. In sepsis, the microcirculation is profoundly disturbed, and the blood supply of individual organs may therefore no longer reflect their access to oxygen. We review how capillary flow patterns affect oxygen extraction efficacy in tissue, and how the regulation of tissue blood flow must be adjusted to meet the metabolic needs of the tissue as capillary flows become disturbed as observed in critical illness. Using the brain, heart, and kidney as examples, we discuss whether disturbed capillary flow patterns might explain the apparent mismatch between organ blood flow and organ function in sepsis. Finally, we discuss diagnostic means of detecting capillary flow disturbance in animal models and in critically ill patients, and address therapeutic strategies that might improve tissue oxygenation by modifying capillary flow patterns.
authors.affiliation: Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark.|Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Østergaard
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Granfeldt
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Secher
authors.affiliation: Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark.|Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Tietze
authors.affiliation: Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark.
authors.forename: N K
authors.initials: NK
authors.lastname: Iversen
authors.affiliation: Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark.
authors.forename: M S
authors.initials: MS
authors.lastname: Jensen
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: K K
authors.initials: KK
authors.lastname: Andersen
authors.affiliation: Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Nagenthiraja
authors.affiliation: Faculty of Dentistry, University of Monterrey, Monterrey, Mexico.|Critical Care College of Nuevo León, Monterrey, Mexico.
authors.forename: P
authors.initials: P
authors.lastname: Gutiérrez-Lizardi
authors.affiliation: Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Mouridsen
authors.affiliation: Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University, Aarhus, Denmark.|Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
authors.forename: S N
authors.initials: SN
authors.lastname: Jespersen
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: E K
authors.initials: EK
authors.lastname: Tønnesen
mesh_terms: D002196:Capillaries / Q000503:physiopathology; D016638:Critical Illness; D006801:Humans; D008833:Microcirculation / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D012039:Regional Blood Flow; D018805:Sepsis / Q000503:physiopathology
chemical_list: D010100:Oxygen