title: Intravenously administered indocyanine green may cause falsely high near-infrared cerebral oximetry readings.
abstract: BACKGROUND
  Near-infrared spectroscopy assesses cerebral tissue oxygen saturation (Scto2) based on the absorption spectra of oxygenated and deoxygenated hemoglobin. It has been reported that IV-administered dyes including methylene blue, indigo carmine, and indocyanine green (ICG) may cause falsely low-pulse oximetry readings (Spo2). Although methylene blue and indigo carmine may also decrease Scto2, the effect of ICG has not been documented.
  
  
  METHODS
  Simultaneous changes in the heart rate, arterial blood pressure, Scto2, and Spo2 were measured after IV administration of ICG (12.5 mg diluted in 5.0 mL 0.9% NaCl) in 15 patients undergoing carotid endarterectomy under sevoflurane-remifentanil anesthesia.
  
  
  RESULTS
  After the dye administration, no change in heart rate or arterial blood pressure was observed in any patient. Scto2 increased by 13.3±4.0 percentage points, reaching the peak at 42.0±28.4 seconds after the administration, whereas Spo2 decreased by 1.9±1.2 percentage points, reaching the peak at 64.0±42.5 seconds (P<0.0001 both).
  
  
  CONCLUSIONS
  ICG falsely increases the spectroscopy-determined cerebral oxygen saturation for up to 12 minutes but dampens pulse oximetry readings.
authors.affiliation: Departments of *Anesthesiology and Pain Medicine ‡Physiology, Chonnam National University Medical School, Gwangju, South Korea †Cephalogics, LLC, Cambridge, MA.
authors.forename: Kyung Y
authors.initials: KY
authors.lastname: Yoo
authors.forename: Ho Y
authors.initials: HY
authors.lastname: Baek
authors.forename: Seongtae
authors.initials: S
authors.lastname: Jeong
authors.forename: Bertan
authors.initials: B
authors.lastname: Hallacoglu
authors.forename: JongUn
authors.initials: J
authors.lastname: Lee
mesh_terms: D000368:Aged; D000768:Anesthesia, General; D001794:Blood Pressure / Q000187:drug effects; D016894:Endarterectomy, Carotid; D005189:False Positive Reactions; D005260:Female; D006339:Heart Rate; D006801:Humans; D007208:Indocyanine Green / Q000008:administration & dosage*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D010092:Oximetry / Q000379:methods*; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared
chemical_list: D007208:Indocyanine Green