title: Brain temperature in volunteers subjected to intranasal cooling.
abstract: OBJECTIVE
  Intranasal cooling can be used to initiate therapeutic hypothermia. However, direct measurement of brain temperature is difficult and the intra-cerebral distribution of temperature changes with cooling is unknown. The purpose of this study was to measure the brain temperature of human volunteers subjected to intranasal cooling using non-invasive magnetic resonance (MR) methods.
  
  
  METHODS
  Intranasal balloons catheters circulated with saline at 20°C were applied for 60 min in ten awake volunteers. No sedation was used. Brain temperature changes were measured and mapped using MR spectroscopic imaging (MRSI) and phase-mapping techniques. Heart rate and blood pressure were monitored throughout the experiment. Rectal temperature was measured before and after the cooling. Mini Mental State Examination (MMSE) test and nasal inspection were done before and after the cooling. Questionnaires about the subjects' personal experience were completed after the experiment.
  
  
  RESULTS
  Brain temperature decrease measured by MRSI was -1.7 ± 0.8°C and by phase-mapping -1.8 ± 0.9°C (n = 9) at the end of cooling. Spatial distribution of temperature changes was relatively uniform. Rectal temperature decreased by -0.5 ± 0.3°C (n = 5). The physiological parameters were stable and no shivering was reported. The volunteers remained alert during cooling and no cognitive dysfunctions were apparent in the MMSE test. Postcooling nasal examination detected increased nasal secretion in nine of the ten volunteers. Volunteers' acceptance of the method was good.
  
  
  CONCLUSIONS
  Both MR techniques revealed brain temperature reductions after 60 min of intranasal cooling with balloons circulated with saline at 20°C in awake, unsedated volunteers.
authors.affiliation: Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, 751 85, Uppsala, Sweden, lucian.covaciu@akademiska.se.
authors.forename: L
authors.initials: L
authors.lastname: Covaciu
authors.forename: J
authors.initials: J
authors.lastname: Weis
authors.forename: C
authors.initials: C
authors.lastname: Bengtsson
authors.forename: M
authors.initials: M
authors.lastname: Allers
authors.forename: A
authors.initials: A
authors.lastname: Lunderquist
authors.forename: H
authors.initials: H
authors.lastname: Ahlström
authors.forename: S
authors.initials: S
authors.lastname: Rubertsson
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D001831:Body Temperature / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D002404:Catheterization / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000295:instrumentation / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D012965:Sodium Chloride / Q000008:administration & dosage; D013817:Thermography / Q000379:methods; D055815:Young Adult
chemical_list: D012965:Sodium Chloride