title: Retinal large vessel oxygen saturations correlate with early blood loss and hypoxia in anesthetized swine.
abstract: BACKGROUND
  Noninvasive monitoring would likely improve trauma care. Using laser technology, we monitored the oxygen saturation in retinal vessels during exsanguination and hypoxia.
  
  
  METHODS
  Seven anesthetized swine were bled at 0.4 mL/kg/min for 40 minutes. During exsanguination, retinal venous saturation (SrvO2) was measured using an eye oximeter, and central venous saturation (SvO2) was measured using a fiber-optic catheter. After the shed blood was reinfused, the FiO2 was progressively decreased from 0.97 to 0.07. Femoral artery oxygen saturation (SaO2) and retinal artery oxygen saturation (SraO2) were measured at each increment.
  
  
  RESULTS
  During exsanguination, SrvO2 correlated with blood loss (r = -0.93) and SvO2 (r = 0.94). SraO2 correlated with SaO2 during incremental hypoxia (R2 = 0.93 +/- 0.15).
  
  
  CONCLUSIONS
  In this model of exsanguination, retinal venous oxygen saturation correlates with blood volume and with central venous oxygen saturation. The SraO2 correlates with SaO2 during graded hypoxia. Use of an eye oximeter to noninvasively monitor trauma patients appears promising and warrants further study.
authors.affiliation: Department of Emergency Medicine, University of Alabama at Birmingham, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: Denninghoff
authors.forename: M H
authors.initials: MH
authors.lastname: Smith
authors.forename: R A
authors.initials: RA
authors.lastname: Chipman
authors.forename: L W
authors.initials: LW
authors.lastname: Hillman
authors.forename: P M
authors.initials: PM
authors.lastname: Jester
authors.forename: C E
authors.initials: CE
authors.lastname: Hughes
authors.forename: F
authors.initials: F
authors.lastname: Kuhn
authors.forename: L W
authors.initials: LW
authors.lastname: Rue
mesh_terms: D000758:Anesthesia; D000818:Animals; D001810:Blood Volume; D005260:Female; D005263:Femoral Artery; D006470:Hemorrhage / Q000097:blood* / Q000503:physiopathology / Q000628:therapy; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology; D007834:Lasers; D010092:Oximetry / Q000295:instrumentation / Q000379:methods; D010100:Oxygen / Q000097:blood*; D012151:Resuscitation; D012171:Retinal Vessels; D013552:Swine
chemical_list: D010100:Oxygen