title: Reactivity of cerebral blood flow to carbon dioxide in various types of ischemic cerebrovascular disease: evaluation by the transcranial Doppler method.
abstract: OBJECTIVE
  The response of cerebral blood flow to changes in the arterial carbon dioxide partial pressure (i.e., carbon dioxide reactivity) has been evaluated as a parameter of cerebral perfusion reserve in patients with cerebrovascular disease. In this study, variations in this reactivity in various ischemic cerebrovascular diseases were evaluated by a newly established method, a transcranial Doppler technique.
  
  
  METHODS
  Thirty-three patients with symptomatic cerebrovascular disease, 13 patients with asymptomatic cerebral infarction, and 25 age-matched normal control subjects were investigated. The symptomatic patients were divided into three groups; those with unilateral carotid artery obstruction, those with cortical infarction, and those with lacunar infarction. The carbon dioxide reactivity of each subject was determined by simultaneously measuring the mean spatial Doppler frequency in the middle cerebral artery and the end-tidal carbon dioxide partial pressure under normocapnic, hypercapnic, and hypocapnic conditions.
  
  
  RESULTS
  In the patients with carotid obstruction, the carbon dioxide reactivity of the hemisphere ipsilateral to the obstruction was more impaired than the reactivity of the symptomatic hemispheres in any other group, and was significantly less than in the contralateral asymptomatic hemisphere (p < 0.01). In patients with cortical infarction, the carbon dioxide reactivity of the symptomatic hemisphere was significantly less than in normal control subjects (p < 0.05) and was also less than that of the contralateral asymptomatic hemisphere (p < 0.05). In patients with lacunar infarction, the carbon dioxide reactivity of both hemispheres was significantly less than that in normal controls (p < 0.01), although there was no difference between the symptomatic and asymptomatic hemispheres. In patients with asymptomatic infarction, the carbon dioxide reactivity was also less than that in normal controls (p < 0.01).
  
  
  CONCLUSIONS
  The carbon dioxide reactivity of cerebral blood flow measured by this transcranial Doppler technique may be useful for characterizing the hemodynamic changes that occur in various types of ischemic cerebrovascular disease.
authors: First Department of Internal Medicine, Osaka University Medical School, Japan.
authors: H
authors: H
authors: Maeda
authors: M
authors: M
authors: Matsumoto
authors: N
authors: N
authors: Handa
authors: H
authors: H
authors: Hougaku
authors: S
authors: S
authors: Ogawa
authors: T
authors: T
authors: Itoh
authors: Y
authors: Y
authors: Tsukamoto
authors: T
authors: T
authors: Kamada
mesh_terms: D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D002245:Carbon Dioxide / Q000494:pharmacology*; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000473:pathology; D002544:Cerebral Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D002561:Cerebrovascular Disorders / Q000503:physiopathology*; D004453:Echoencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000187:drug effects
chemical_list: D002245:Carbon Dioxide