title: Brain death assessment using instant spectral analysis of heart rate variability.
abstract: OBJECTIVE
  Confirmation of brain death requires an urgent diagnosis to allow rapid vital organ removal for transplantation. Evaluation of forebrain functions is commonly performed through electroencephalogram. Nevertheless, there are, for the moment, no methods that allow for an instantaneous evaluation of brainstem functions. During acute brain injury, heart rate variability is an independent neurologic prognosis indicator resulting from a close relationship between brain stem and cardiac autonomic nervous system. This study aims to evaluate a new heart rate variability spectral analysis method, on a beat-to-beat basis, continuously over the time, during brain death.
  
  
  METHODS
  Prospective, nonrandomized, observational study.
  
  
  METHODS
  Intensive care unit.
  
  
  METHODS
  Ten patients (age range 25-64 yrs, mean age 41 yrs) with acute brain injury leading to brain death.
  
  
  METHODS
  No intervention beyond standard of care
  
  
  RESULTS
  Heart rate, arterial blood pressure, heart rate variability in time and frequency domains method, which included calculation of the instant center frequency of spectrum. Brain death was associated with tachycardia (R-R interval 703 +/- 69 vs. 551 +/- 34 msec, p <.05), dramatic reduction of the global spectral power (44.919 +/- 31.511 vs. 3.204 +/- 1.469 msec(2), p <.05), and an abrupt shift of instant center frequency to a higher frequency range (0.17 +/- 0.01 vs. 0.26 +/- 0.03 Hz, p <.05).
  
  
  CONCLUSIONS
  Such a method allows an instant, noninvasive determination of brainstem death based on a time and frequency domain analysis of heart rate variability.
authors.affiliation: U127-INSERM, Lariboisière Hospital, Paris, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Baillard
authors.forename: Benoit
authors.initials: B
authors.lastname: Vivien
authors.forename: Pascale
authors.initials: P
authors.lastname: Mansier
authors.forename: Laurence
authors.initials: L
authors.lastname: Mangin
authors.forename: Sylvain
authors.initials: S
authors.lastname: Jasson
authors.forename: Bruno
authors.initials: B
authors.lastname: Riou
authors.forename: Bernard
authors.initials: B
authors.lastname: Swynghedauw
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001049:Apnea / Q000503:physiopathology; D001341:Autonomic Nervous System / Q000503:physiopathology; D001926:Brain Death / Q000175:diagnosis* / Q000503:physiopathology*; D001930:Brain Injuries; D001933:Brain Stem / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D005583:Fourier Analysis; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012306:Risk; D013997:Time Factors; D014019:Tissue Donors