title: Effects of pharyngeal cooling on brain temperature in primates and humans: a study for proof of principle.
abstract: BACKGROUND
  Pharyngeal cooling decreases brain temperature by cooling carotid arteries. This study was designed to evaluate the principle of pharyngeal cooling in monkeys and humans.
  
  
  METHODS
  Monkeys (n = 10) were resuscitated following 12 min of cardiac arrest. Pharyngeal cooling (n = 5), in which cold saline (5°C) was perfused into the cuff at the rate of 500 ml/min, was initiated simultaneously with the onset of resuscitation for 30 min. Patients (n = 3) who were in an intensive care unit were subjected to 30 min of pharyngeal cooling under propofol anesthesia.
  
  
  RESULTS
  In the animal study, core brain temperature was significantly decreased compared with that in the control group by 1.9°C (SD = 0.8, P < 0.001) and 3.1°C (SD = 1.0, P < 0.001) at 10 min and 30 min after the onset of cooling, respectively. The cooling effect was more evident in an animal with low postresuscitation blood pressure. Total dose of epinephrine, number of direct current shocks, and recovery of blood pressure were not different between the two groups. The pharyngeal epithelium was microscopically intact on day 5. In the clinical study, insertion of the cuff and start of perfusion did not affect heart rate or blood pressure. Tympanic temperature was decreased by 0.6 ± 0.1°C/30 min without affecting bladder temperature. The pharynx was macroscopically intact for 3 days.
  
  
  CONCLUSIONS
  Pharyngeal cooling rapidly and selectively decreased brain temperature in primates and tympanic temperature in humans and did not have adverse effects on return of spontaneous circulation, even when initiated during cardiac arrest in primates.
authors.affiliation: Department of Anesthesiology, Okayama University Medical School, Okayama, Japan. yoshit@cc.okayama-u.ac.jp
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Takeda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Koji
authors.initials: K
authors.lastname: Fumoto
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Danura
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Naito
authors.forename: Naoki
authors.initials: N
authors.lastname: Morimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katayama
authors.forename: Soichiro
authors.initials: S
authors.lastname: Fushimi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Matsukawa
authors.forename: Aiji
authors.initials: A
authors.lastname: Ohtsuka
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Morita
mesh_terms: D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000502:physiology*; D016887:Cardiopulmonary Resuscitation; D006323:Heart Arrest / Q000503:physiopathology; D006801:Humans; D007036:Hypothermia, Induced; D008251:Macaca; D010614:Pharynx / Q000473:pathology / Q000502:physiology*; D012151:Resuscitation