title: Body temperature affects cerebral hemodynamics in acutely brain injured patients: an observational transcranial color-coded duplex sonography study.
abstract: BACKGROUND
  Temperature changes are common in patients in a neurosurgical intensive care unit (NICU): fever is frequent among severe cases and hypothermia is used after cardiac arrest and is currently being tested in clinical trials to lower intracranial pressure (ICP). This study investigated cerebral hemodynamics when body temperature varies in acute brain injured patients.
  
  
  METHODS
  We enrolled 26 patients, 14 with acute brain injury who developed fever and were given antipyretic therapy (defervescence group) and 12 who underwent an intracranial neurosurgical procedure and developed hypothermia in the operating room; once admitted to the NICU, still under anesthesia, they were re-warmed before waking (re-warming group). We measured cerebral blood flow velocity (CBF-V) and pulsatility index (PI) at the middle cerebral artery using transcranial color-coded duplex sonography (TCCDS).
  
  
  RESULTS
  In the defervescence group mean CBF-V decreased from 75 ± 26 (95% CI 65 to 85) to 70 ± 22 cm/s (95% CI 61 to 79) (P = 0.04); the PI also fell, from 1.36 ± 0.33 (95% CI 1.23 to 1.50) to 1.16 ± 0.26 (95% CI 1.05 to 1.26) (P = 0.0005). In the subset of patients with ICP monitoring, ICP dropped from 16 ± 8 to 12 ± 6 mmHg (P = 0.003). In the re-warming group mean CBF-V increased from 36 ± 10 (95% CI 31 to 41) to 39 ± 13 (95% CI 33 to 45) cm/s (P = 0.04); the PI rose from 0.98 ± 0.14 (95% CI 0.91 to 1.04) to 1.09 ± 0.22 (95% CI 0.98 to 1.19) (P = 0.02).
  
  
  CONCLUSIONS
  Body temperature affects cerebral hemodynamics as evaluated by TCCDS; when temperature rises, CBF-V increases in parallel, and viceversa when temperature decreases. When cerebral compliance is reduced and compensation mechanisms are exhausted, even modest temperature changes can greatly affect ICP.
authors.forename: Federica
authors.initials: F
authors.lastname: Stretti
authors.forename: Miriam
authors.initials: M
authors.lastname: Gotti
authors.forename: Silvia
authors.initials: S
authors.lastname: Pifferi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Brandi
authors.forename: Federico
authors.initials: F
authors.lastname: Annoni
authors.forename: Nino
authors.initials: N
authors.lastname: Stocchetti
mesh_terms: D000328:Adult; D000368:Aged; D058633:Antipyretics / Q000627:therapeutic use; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D001831:Body Temperature; D001921:Brain / Q000098:blood supply; D001930:Brain Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D005260:Female; D005334:Fever / Q000188:drug therapy; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007035:Hypothermia; D007362:Intensive Care Units; D007427:Intracranial Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging; D018615:Ultrasonography, Doppler, Color / Q000379:methods; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
chemical_list: D058633:Antipyretics