title: Cerebral autoregulation after hypothermic circulatory arrest in operations on the aortic arch.
abstract: BACKGROUND
  The purpose of this study was to determine whether patients who undergo thoracic aorta repairs with the aid of hypothermic circulatory arrest experience impairments in cerebral autoregulation, and to ascertain the influence of three different techniques of cerebral protection on autoregulatory function.
  
  
  METHODS
  Sixty-seven patients undergoing elective aortic arch procedures with hypothermic circulatory arrest were tested for cerebral dynamic autoregulation using continuous transcranial Doppler velocity and blood pressure recordings. Twenty-three patients were treated using hypothermic circulatory arrest without adjuncts (group 1), 25 using antegrade cerebral perfusion (group 2), and 19 using retrograde cerebral perfusion (group 3).
  
  
  RESULTS
  There were no hospital deaths. Two major strokes occurred in this series; 9 patients experienced temporary neurologic dysfunction: in all these patients severe impairment of cerebral autoregulation was observed. Cerebral autoregulation in the immediate postoperative period was preserved only in patients treated with antegrade cerebral perfusion. Severe impairments were observed in the other two groups in which the degree of autoregulatory response was inversely correlated to the duration of the cerebral protection time during hypothermic circulatory arrest. Postoperative improvement of autoregulatory function was observed in the majority of patients. Our data suggest the exposure to brain damage in the presence of autoregulation impairment, thus indicating that postoperative hypotensive phases may further contribute to neurologic impairment.
  
  
  CONCLUSIONS
  The status of cerebral autoregulation in the postoperative period after hypothermic circulatory arrest procedures is profoundly altered. The degree of impairment is influenced by the cerebral protection technique. This study indicates the beneficial role of antegrade perfusion during hypothermic circulatory arrest for the preservation of this function and suggests that postoperative cerebral autoregulation impairment can be regarded as an expression of central nervous system injury.
authors.affiliation: Department of Surgery, University of Siena, Siena, Italy. euxneri@tin.it
authors.forename: Eugenio
authors.initials: E
authors.lastname: Neri
authors.forename: Carlo
authors.initials: C
authors.lastname: Sassi
authors.forename: Lucio
authors.initials: L
authors.lastname: Barabesi
authors.forename: Massimo
authors.initials: M
authors.lastname: Massetti
authors.forename: Giorgio
authors.initials: G
authors.lastname: Pula
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Buklas
authors.forename: Rossana
authors.initials: R
authors.lastname: Tassi
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Giomarelli
mesh_terms: D000368:Aged; D001013:Aorta, Thoracic / Q000601:surgery*; D001921:Brain / Q000502:physiology*; D005260:Female; D006324:Heart Arrest, Induced / Q000009:adverse effects / Q000401:mortality; D006706:Homeostasis; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged