title: Detection of cerebral arterial gas embolism using regional cerebral oxygen saturation, quantitative electroencephalography, and brain oxygen tension in the swine.
abstract: BACKGROUND
  Cerebral air emboli occur as a complication of invasive medical procedures. The sensitivity of cerebral monitoring methods for the detection of air emboli is not known. This study investigates the utility of electroencephalography and non-invasively measured cerebral oxygen saturation in the detection of intracerebrovascular air.
  
  
  METHODS
  In 12 pigs oxygen saturation was continuously measured using transcranial near-infrared spectroscopy and oxygen tension was continuously measured using intraparenchymal probes. Additionally, quantitative electroencephalography and microdialysis were performed. Doses of 0.2, 0.4, 0.8, and 1.6 ml of air were injected into the cerebral arterial vasculature through a catheter.
  
  
  RESULTS
  Oxygen saturation and electroencephalography both reacted almost instantaneously on the air emboli, but were less sensitive than the intraparenchymal oxygen tension. There was reasonable correlation (ρ ranging from 0.417 to 0.898) between oxygen saturation, oxygen tension, electroencephalography and microdialysis values.
  
  
  METHODS
  Our study is the first to demonstrate the effects of cerebral air emboli using multimodal monitoring, specifically on oxygen saturation as measured using near-infrared spectroscopy.
  
  
  CONCLUSIONS
  Our results show that non-invasively measured oxygen saturation and quantitative electroencephalography can detect the local effects of air emboli on cerebral oxygenation, but with reduced sensitivity as compared to intraparenchymal oxygen tension. Prospective human studies using multimodal monitoring incorporating electroencephalography and oxygen saturation should be performed.
authors.affiliation: Diving Medical Center, Royal Netherlands Navy, PO Box 1000, 1780 CA Den Helder, The Netherlands; Laboratory of Experimental Intensive Care and Anaesthesiology (L.E.I.C.A.), Department of Anaesthesiology, Academic Medical Center, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: r.p.weenink@amc.nl.
authors.forename: R P
authors.initials: RP
authors.lastname: Weenink
authors.affiliation: Laboratory of Experimental Intensive Care and Anaesthesiology (L.E.I.C.A.), Department of Anaesthesiology, Academic Medical Center, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: m.w.hollmann@amc.nl.
authors.forename: M W
authors.initials: MW
authors.lastname: Hollmann
authors.affiliation: Laboratory of Experimental Intensive Care and Anaesthesiology (L.E.I.C.A.), Department of Anaesthesiology, Academic Medical Center, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: m.f.stevens@amc.nl.
authors.forename: M F
authors.initials: MF
authors.lastname: Stevens
authors.affiliation: Department of Radiology, Academic Medical Center, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: j.kager@amc.nl.
authors.forename: J
authors.initials: J
authors.lastname: Kager
authors.affiliation: Department of Surgery, Academic Medical Center, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: t.m.vangulik@amc.nl.
authors.forename: T M
authors.initials: TM
authors.lastname: van Gulik
authors.affiliation: Diving Medical Center, Royal Netherlands Navy, PO Box 1000, 1780 CA Den Helder, The Netherlands; Laboratory of Experimental Intensive Care and Anaesthesiology (L.E.I.C.A.), Department of Anaesthesiology, Academic Medical Center, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands. Electronic address: r.a.vanhulst@amc.nl.
authors.forename: R A
authors.initials: RA
authors.lastname: van Hulst
mesh_terms: D000818:Animals; D019540:Area Under Curve; D001784:Blood Gas Analysis; D001921:Brain / Q000098:blood supply* / Q000473:pathology; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D004569:Electroencephalography; D004618:Embolism, Air / Q000150:complications / Q000175:diagnosis*; D005260:Female; D020766:Intracranial Embolism / Q000150:complications / Q000175:diagnosis*; D007427:Intracranial Pressure; D017551:Microdialysis; D017063:Outcome Assessment, Health Care; D013223:Statistics as Topic; D013552:Swine
keywords: Air embolism; Animal models; Brain ischemia; Electroencephalography; Near-infrared spectroscopy