title: Induction, maintenance, and reversal of therapeutic hypothermia with an esophageal heat transfer device.
abstract: OBJECTIVE
  To evaluate a novel esophageal heat transfer device for use in inducing, maintaining, and reversing hypothermia. We hypothesized that this device could successfully induce, maintain (within a 1 °C range of goal temperature), and reverse, mild therapeutic hypothermia in a large animal model over a 30-h treatment protocol.
  
  
  METHODS
  Five female Yorkshire swine, weighing a mean of 65 kg (range 61-70) kg each, were anesthetized with inhalational isoflurane via endotracheal intubation and instrumented. The esophageal device was connected to an external chiller and then placed into the esophagus and connected to wall suction. Reduction to goal temperature was achieved by setting the chiller to cooling mode, and a 24h cooling protocol was completed before rewarming and recovering the animals. Histopathologic analysis was scheduled for 3-14 days after protocol completion.
  
  
  RESULTS
  Average baseline temperature for the 5 animals was 38.6 °C (range 38.1-39.2 °C). All swine were cooled successfully, with average rate of temperature decrease of 1.3 °C/h (range 1.1-1.9) °C/h. Standard deviation from goal temperature averaged 0.2 °C throughout the steady-state maintenance phase, and no treatment for shivering was necessary during the protocol. Histopathology of esophageal tissue showed no adverse effects from the device.
  
  
  CONCLUSIONS
  A new esophageal heat transfer device successfully and safely induced, maintained, and reversed therapeutic hypothermia in large swine. Goal temperature was maintained within a narrow range, and thermogenic shivering did not occur. These findings suggest a useful new modality to induce therapeutic hypothermia.
authors.affiliation: Department of Emergency Medicine, Advocate Christ Medical Center, Oak Lawn, IL 60453, United States. Electronic address: kulstad@uic.edu.
authors.forename: Erik
authors.initials: E
authors.lastname: Kulstad
authors.forename: Anja K
authors.initials: AK
authors.lastname: Metzger
authors.forename: D Mark
authors.initials: DM
authors.lastname: Courtney
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rees
authors.forename: Patrick
authors.initials: P
authors.lastname: Shanley
authors.forename: Timothy
authors.initials: T
authors.lastname: Matsuura
authors.forename: Scott
authors.initials: S
authors.lastname: McKnite
authors.forename: Keith
authors.initials: K
authors.lastname: Lurie
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D004947:Esophagus; D005260:Female; D007036:Hypothermia, Induced / Q000295:instrumentation*; D017694:Rewarming / Q000295:instrumentation*; D013552:Swine
keywords: Therapeutic hypothermia; cooling; esophageal; medical device; swine mode; temperature maintenance