title: Predictors of electrocerebral inactivity with deep hypothermia.
abstract: OBJECTIVE
  Cooling to electrocerebral inactivity (ECI) by electroencephalography (EEG) remains the gold standard to maximize cerebral and systemic organ protection during deep hypothermic circulatory arrest (DHCA). We sought to determine predictors of ECI to help guide cooling protocols when EEG monitoring is unavailable.
  
  
  METHODS
  Between July 2005 and July 2011, 396 patients underwent thoracic aortic operation with DHCA; EEG monitoring was used in 325 (82%) of these patients to guide the cooling strategy, and constituted the study cohort. Electroencephalographic monitoring was used for all elective cases and, when available, for nonelective cases. Multivariable linear regression was used to assess predictors of the nasopharyngeal temperature and cooling time required to achieve ECI.
  
  
  RESULTS
  Cooling to a nasopharyngeal temperature of 12.7°C or for a duration of 97 minutes was required to achieve ECI in >95% of patients. Only 7% and 11% of patients achieved ECI by 18°C or 50 minutes of cooling, respectively. No independent predictors of nasopharyngeal temperature at ECI were identified. Independent predictors of cooling time included body surface area (18 minutes/m(2)), white race (7 minutes), and starting nasopharyngeal temperature (3 minutes/°C). Low complication rates were observed (ischemic stroke, 1.5%; permanent paraparesis/paraplegia, 1.5%; new-onset dialysis, 2.2%; and 30-day/in-hospital mortality, 4.3%).
  
  
  CONCLUSIONS
  Cooling to a nasopharyngeal temperature of 12.7°C or for a duration of 97 minutes achieved ECI in >95% of patients in our study population. However, patient-specific factors were poorly predictive of the temperature or cooling time required to achieve ECI, necessitating EEG monitoring for precise ECI detection.
authors.affiliation: Department of Anesthesiology, Duke University Medical Center, Durham, NC; Brain Injury Translational Research Center, Duke University Medical Center, Durham, NC; Division of Neurology, Department of Medicine, Duke University Medical Center, Durham, NC.
authors.forename: Michael L
authors.initials: ML
authors.lastname: James
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Andersen
authors.affiliation: Department of Anesthesiology, Duke University Medical Center, Durham, NC.
authors.forename: Madhav
authors.initials: M
authors.lastname: Swaminathan
authors.affiliation: Department of Anesthesiology, Duke University Medical Center, Durham, NC.
authors.forename: Barbara
authors.initials: B
authors.lastname: Phillips-Bute
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Hanna
authors.affiliation: Perfusion Services, Duke University Medical Center, Durham, NC.
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Smigla
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Barfield
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Syamal D
authors.initials: SD
authors.lastname: Bhattacharya
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Judson B
authors.initials: JB
authors.lastname: Williams
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC.
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Gaca
authors.affiliation: Division of Neurology, Department of Medicine, Duke University Medical Center, Durham, NC.
authors.forename: Aatif M
authors.initials: AM
authors.lastname: Husain
authors.affiliation: Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC. Electronic address: gchad.hughes@duke.edu.
authors.forename: G Chad
authors.initials: GC
authors.lastname: Hughes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic / Q000601:surgery*; D001833:Body Temperature Regulation; D001921:Brain / Q000503:physiopathology*; D058256:Brain Waves; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000009:adverse effects / Q000401:mortality; D004569:Electroencephalography; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D015999:Multivariate Analysis; D009305:Nasopharynx / Q000503:physiopathology*; D011183:Postoperative Complications / Q000401:mortality / Q000517:prevention & control; D011237:Predictive Value of Tests; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013817:Thermography; D013997:Time Factors; D055815:Young Adult