title: A Model to Simulate Clinically Relevant Hypoxia in Humans.
abstract: In case of apnea, arterial partial pressure of oxygen (pO2) decreases, while partial pressure of carbon dioxide (pCO2) increases. To avoid damage to hypoxia sensitive organs such as the brain, compensatory circulatory mechanisms help to maintain an adequate oxygen supply. This is mainly achieved by increased cerebral blood flow. Intermittent hypoxia is a commonly seen phenomenon in patients with obstructive sleep apnea. Acute airway obstruction can also result in hypoxia and hypercapnia. Until now, no adequate model has been established to simulate these dynamics in humans. Previous investigations focusing on human hypoxia used inhaled hypoxic gas mixtures. However, the resulting hypoxia was combined with hyperventilation and is therefore more representative of high altitude environments than of apnea. Furthermore, the transferability of previously performed animal experiments to humans is limited and the pathophysiological background of apnea induced physiological changes is poorly understood. In this study, healthy human apneic divers were utilized to mimic clinically relevant hypoxia and hypercapnia during apnea. Additionally, pulse-oximetry and Near Infrared Spectroscopy (NIRS) were used to evaluate changes in cerebral and peripheral oxygen saturation before, during, and after apnea.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Bonn; lars.eichhorn@ukb.uni-bonn.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Eichhorn
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Bonn.
authors.forename: Florian
authors.initials: F
authors.lastname: Kessler
authors.affiliation: Institute of Clinical Chemistry and Clinical Pharmacology, University of Bonn.
authors.forename: Volker
authors.initials: V
authors.lastname: Böhnert
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Bonn.
authors.forename: Felix
authors.initials: F
authors.lastname: Erdfelder
authors.affiliation: Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover.
authors.forename: Anja
authors.initials: A
authors.lastname: Reckendorf
authors.affiliation: Institute of Physiology 2, University of Bonn.
authors.forename: Rainer
authors.initials: R
authors.lastname: Meyer
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Bonn.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Ellerkmann
mesh_terms: D001049:Apnea / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000032:analysis; D004242:Diving; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D010092:Oximetry; D010100:Oxygen / Q000032:analysis; D010313:Partial Pressure; D019265:Spectroscopy, Near-Infrared
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen