title: Prediction of safe duration of hypothermic circulatory arrest by near-infrared spectroscopy.
abstract: OBJECTIVE
  Hypothermic circulatory arrest is widely used for adults with aortic arch disease as well as for children with congenital heart disease. At present, no method exists for monitoring safe duration of circulatory arrest. Near-infrared spectroscopy is a new technique for noninvasive monitoring of cerebral oxygenation and energy state. In the current study, the relationship between near-infrared spectroscopy data and neurologic outcome was evaluated in a survival piglet model with hypothermic circulatory arrest.
  
  
  METHODS
  Thirty-six piglets (9.36 +/- 0.16 kg) underwent circulatory arrest under varying conditions with continuous monitoring by near-infrared spectroscopy (temperature 15 degrees C or 25 degrees C, hematocrit value 20% or 30%, circulatory arrest time 60, 80, or 100 minutes). Each setting included 3 animals. Neurologic recovery was evaluated daily by neurologic deficit score and overall performance category. Brain was fixed in situ on postoperative day 4 and examined by histologic score.
  
  
  RESULTS
  Oxygenated hemoglobin signal declined to a plateau (nadir) during circulatory arrest. Time to nadir was significantly shorter with lower hematocrit value (P <.001) and higher temperature (P <.01). Duration from reaching nadir until reperfusion ("oxygenated hemoglobin signal nadir time") was significantly related to histologic score (r (s) = 0.826), neurologic deficit score (r (s) = 0.717 on postoperative day 1; 0.716 on postoperative day 4), and overall performance category (r (s) = 0.642 on postoperative day 1; 0.702 on postoperative day 4) (P <.001). All animals in which oxygenated hemoglobin signal nadir time was less than 25 minutes were free of behavioral or histologic evidence of brain injury.
  
  
  CONCLUSIONS
  Oxygenated hemoglobin signal nadir time determined by near-infrared spectroscopy monitoring is a useful predictor of safe duration of circulatory arrest. Safe duration of hypothermic circulatory arrest is strongly influenced by perfusate hematocrit value and temperature during circulatory arrest.
authors.affiliation: Departments of Cardiac Surgery, Pathology, Neurology, and Anesthesia and Intensive Care, The Children's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: T
authors.initials: T
authors.lastname: Sakamoto
authors.forename: S
authors.initials: S
authors.lastname: Hatsuoka
authors.forename: U A
authors.initials: UA
authors.lastname: Stock
authors.forename: L F
authors.initials: LF
authors.lastname: Duebener
authors.forename: H G
authors.initials: HG
authors.lastname: Lidov
authors.forename: G L
authors.initials: GL
authors.lastname: Holmes
authors.forename: J S
authors.initials: JS
authors.lastname: Sperling
authors.forename: M
authors.initials: M
authors.lastname: Munakata
authors.forename: P C
authors.initials: PC
authors.lastname: Laussen
authors.forename: R A
authors.initials: RA
authors.lastname: Jonas
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001834:Body Water; D001835:Body Weight; D001921:Brain / Q000098:blood supply*; D001923:Brain Chemistry; D002545:Brain Ischemia / Q000175:diagnosis*; D006324:Heart Arrest, Induced; D006400:Hematocrit; D007036:Hypothermia, Induced; D016343:Monitoring, Intraoperative / Q000379:methods*; D010100:Oxygen / Q000097:blood; D019265:Spectroscopy, Near-Infrared; D018709:Statistics, Nonparametric; D013552:Swine
chemical_list: D010100:Oxygen