title: Cerebral oxygenation during intermittent hypoxemia and bradycardia in preterm infants.
abstract: BACKGROUND
  Episodes of hypoxemia and bradycardia frequently occur with apnea of prematurity in preterm infants. Little is known about the impact of different event types on the brain.
  
  
  OBJECTIVE
  To describe the influence of hypoxemia and bradycardia, either isolated or in combination, on cerebral oxygenation.
  
  
  METHODS
  In 16 preterm infants with intermittent hypoxemia and/or bradycardia, cerebral tissue oxygen saturation (StO2, as measured by near-infrared spectroscopy), heart rate and pulse oximetric saturation (SpO2) were recorded simultaneously for 16 h. Events were classified as isolated bradycardia (type 1), isolated hypoxemia (type 2) or combined (simultaneous, type 3; bradycardia first, type 4; hypoxemia first, type 5). Primary outcome was a score representing the area below baseline for cerebral StO2 desaturation during an event. Secondary outcomes were duration and depth of cerebral desaturation.
  
  
  RESULTS
  Patients had a median (range) gestational age of 25.9 (22.6-30.4) weeks and a postnatal age of 32.5 (7-58) days. The median (quartiles) number of events was 49 (34-58). Isolated hypoxemias were the most frequent events (24; 9-36) and isolated bradycardias the least common (0; 0-1). Cerebral StO2 baseline was not different between event types. Cerebral desaturation score, duration of event and depth of cerebral desaturation were smallest for isolated bradycardias and largest for combined events, especially for those starting with hypoxemia followed by bradycardia. Regardless of event type, 12/16 infants maintained cerebral StO2 >60% despite severe SpO2 desaturations.
  
  
  CONCLUSIONS
  Isolated bradycardias had the lowest impact on cerebral desaturation, and combined events had the highest. Most infants preserved cerebral oxygenation >60% during events.
authors.affiliation: Division of Neonatology and Pediatric Critical Care, Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany.
authors.forename: Manuel B
authors.initials: MB
authors.lastname: Schmid
authors.forename: Reinhard J
authors.initials: RJ
authors.lastname: Hopfner
authors.forename: Susanne
authors.initials: S
authors.lastname: Lenhof
authors.forename: Helmut D
authors.initials: HD
authors.lastname: Hummler
authors.forename: Hans
authors.initials: H
authors.lastname: Fuchs
mesh_terms: D001919:Bradycardia / Q000503:physiopathology*; D001921:Brain / Q000502:physiology*; D005865:Gestational Age; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D010092:Oximetry; D010100:Oxygen / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared
chemical_list: D010100:Oxygen