title: The impact of hypercapnia on systolic cerebrospinal fluid peak velocity in the aqueduct of sylvius.
abstract: Phase-contrast magnetic resonance imaging measurements of systolic cerebrospinal fluid peak velocity (CSFVPeak) in the aqueduct of Sylvius have been shown to be sensitive enough to detect even minor changes in cerebral compliance. Clinically relevant changes in cerebral compliance can be caused by changes in cerebral blood volume (CBV). Changes in arterial carbon dioxide partial pressure, which correlate well with end-tidal carbon dioxide concentration (ETCO(2)), cause changes in CBV. In this study, we investigated the effect of hypercapnia-induced changes in CBV on systolic CSFVPeak in anesthetized patients (n = 8). Hypercapnia (ETCO(2) = 60 mm Hg) increased systolic CSFVPeak in the aqueduct of Sylvius as compared with normocapnia (ETCO(2) = 40 mm Hg) (hypercapnia: -5.67 +/- 0.74 cm/s versus normocapnia: -3.54 +/- 0.98 cm/s). In addition to the already known decrease in systolic CSFVPeak, changes in cerebral compliance can also prompt an increase in systolic CSFVPeak.
  
  
  CONCLUSIONS
  Magnetic resonance imaging measurements of systolic cerebrospinal fluid peak velocity (CSFVPeak) in the aqueduct of Sylvius are sensitive enough to detect even minor changes in cerebral compliance. We investigated the effect of hypercapnia-induced changes in cerebral blood volume on systolic CSFVPeak in anesthetized patients. Hypercapnia (end-tidal carbon dioxide concentration = 60 mm Hg) increased systolic CSFVPeak.
mesh_terms: D000328:Adult; D000768:Anesthesia, General; D001810:Blood Volume / Q000502:physiology; D002535:Cerebral Aqueduct / Q000502:physiology*; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006935:Hypercapnia / Q000134:cerebrospinal fluid* / Q000503:physiopathology; D008297:Male; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology