title: Determinants of effective cooling during endovascular hypothermia.
abstract: BACKGROUND
  Therapeutic hypothermia is a promising neuroprotective therapy with multiple mechanisms of action. We demonstrated the feasibility of thrombolysis combined with endovascular hypothermia, but not all patients achieved effective cooling. We sought to identify the factors that determined effective cooling.
  
  
  METHODS
  In 26 patients who underwent endovascular hypothermia, we computed four measures of effective cooling: time to reach target; Area-Under-the-Curve (AUC) 34 ratio; AUC-34; and AUC-35. By multivariate regression, we examined the effects of age, weight, starting temperature, body mass index, body surface area (BSA), gender, shivering, and total meperidine dose on the four outcome measures.
  
  
  RESULTS
  In univariate analyses, all four outcome measures were significantly influenced by BSA (p < 0.01 in all univariate analyses). Time to reach target temperature was quicker in older patients (p < 0.01). Shivering and meperidine dose were highly intercorrelated (r = 0.6, p < 0.01) and both marginally influenced all four outcome measures. In multivariate analysis, AUC ratio and time to reach target temperature were significantly influenced by BSA (p < 0.01) and meperidine (p < 0.05); AUC-34 was influenced only by BSA (p < 0.01). The AUC-35 was influenced by BSA (p < 0.01), shivering, and total meperidine dose (p < 0.05).
  
  
  CONCLUSIONS
  The most important determinant of effective cooling during endovascular hypothermia is BSA; larger patients are more difficult to cool and maintain in therapeutic range. Older patients cool more quickly. Shivering was well controlled by the combination of meperidine, buspirone, and surface counter-warming and only minimally influenced cooling effectiveness. Future trials of therapeutic hypothermia may include added measures to cool larger patients more effectively.
authors.affiliation: Department of Neurology, Cedars-Sinai Medical Center, Thalians E240, 8730 Alden Drive, Los Angeles, CA 90048, USA. lydenp@cshs.org
authors.forename: Patrick
authors.initials: P
authors.lastname: Lyden
authors.forename: Karin
authors.initials: K
authors.lastname: Ernstrom
authors.forename: Salvador
authors.initials: S
authors.lastname: Cruz-Flores
authors.forename: Joao
authors.initials: J
authors.lastname: Gomes
authors.forename: James
authors.initials: J
authors.lastname: Grotta
authors.forename: Anthony
authors.initials: A
authors.lastname: Mullin
authors.forename: Karen
authors.initials: K
authors.lastname: Rapp
authors.forename: Rema
authors.initials: R
authors.lastname: Raman
authors.forename: Christine
authors.initials: C
authors.lastname: Wijman
authors.forename: Thomas
authors.initials: T
authors.lastname: Hemmen
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014151:Anti-Anxiety Agents / Q000008:administration & dosage; D019540:Area Under Curve; D002065:Buspirone / Q000008:administration & dosage; D003131:Combined Modality Therapy; D003422:Critical Care / Q000379:methods*; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods* / Q000592:standards; D008614:Meperidine / Q000008:administration & dosage; D008875:Middle Aged; D008954:Models, Biological; D015999:Multivariate Analysis; D009294:Narcotics / Q000008:administration & dosage; D012768:Shivering / Q000187:drug effects / Q000502:physiology; D020521:Stroke / Q000188:drug therapy / Q000628:therapy*; D015912:Thrombolytic Therapy / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D014151:Anti-Anxiety Agents; D009294:Narcotics; D008614:Meperidine; D002065:Buspirone